perlapi

CONTENTS

NAME

perlapi - autogenerated documentation for the perl public API

DESCRIPTION

This file contains the documentation of the perl public API generated by embed.pl, specifically a listing of functions, macros, flags, and variables that may be used by extension writers. At the end is a list of functions which have yet to be documented. The interfaces of those are subject to change without notice. Anything not listed here is not part of the public API, and should not be used by extension writers at all. For these reasons, blindly using functions listed in proto.h is to be avoided when writing extensions.

In Perl, unlike C, a string of characters may generally contain embedded NUL characters. Sometimes in the documentation a Perl string is referred to as a "buffer" to distinguish it from a C string, but sometimes they are both just referred to as strings.

Note that all Perl API global variables must be referenced with the PL_ prefix. Again, those not listed here are not to be used by extension writers, and can be changed or removed without notice; same with macros. Some macros are provided for compatibility with the older, unadorned names, but this support may be disabled in a future release.

Perl was originally written to handle US-ASCII only (that is characters whose ordinal numbers are in the range 0 - 127). And documentation and comments may still use the term ASCII, when sometimes in fact the entire range from 0 - 255 is meant.

The non-ASCII characters below 256 can have various meanings, depending on various things. (See, most notably, perllocale.) But usually the whole range can be referred to as ISO-8859-1. Often, the term "Latin-1" (or "Latin1") is used as an equivalent for ISO-8859-1. But some people treat "Latin1" as referring just to the characters in the range 128 through 255, or somethimes from 160 through 255. This documentation uses "Latin1" and "Latin-1" to refer to all 256 characters.

Note that Perl can be compiled and run under either ASCII or EBCDIC (See perlebcdic). Most of the documentation (and even comments in the code) ignore the EBCDIC possibility. For almost all purposes the differences are transparent. As an example, under EBCDIC, instead of UTF-8, UTF-EBCDIC is used to encode Unicode strings, and so whenever this documentation refers to utf8 (and variants of that name, including in function names), it also (essentially transparently) means UTF-EBCDIC. But the ordinals of characters differ between ASCII, EBCDIC, and the UTF- encodings, and a string encoded in UTF-EBCDIC may occupy a different number of bytes than in UTF-8.

The listing below is alphabetical, case insensitive.

Array Manipulation Functions

av_clear

Frees the all the elements of an array, leaving it empty. The XS equivalent of @array = (). See also "av_undef".

Note that it is possible that the actions of a destructor called directly or indirectly by freeing an element of the array could cause the reference count of the array itself to be reduced (e.g. by deleting an entry in the symbol table). So it is a possibility that the AV could have been freed (or even reallocated) on return from the call unless you hold a reference to it.

void    av_clear(AV *av)
av_create_and_push

NOTE: this function is experimental and may change or be removed without notice.

Push an SV onto the end of the array, creating the array if necessary. A small internal helper function to remove a commonly duplicated idiom.

void    av_create_and_push(AV **const avp,
                           SV *const val)
av_create_and_unshift_one

NOTE: this function is experimental and may change or be removed without notice.

Unshifts an SV onto the beginning of the array, creating the array if necessary. A small internal helper function to remove a commonly duplicated idiom.

SV**    av_create_and_unshift_one(AV **const avp,
                                  SV *const val)
av_delete

Deletes the element indexed by key from the array, makes the element mortal, and returns it. If flags equals G_DISCARD, the element is freed and NULL is returned. NULL is also returned if key is out of range.

Perl equivalent: splice(@myarray, $key, 1, undef) (with the splice in void context if G_DISCARD is present).

SV*     av_delete(AV *av, SSize_t key, I32 flags)
av_exists

Returns true if the element indexed by key has been initialized.

This relies on the fact that uninitialized array elements are set to NULL.

Perl equivalent: exists($myarray[$key]).

bool    av_exists(AV *av, SSize_t key)
av_extend

Pre-extend an array. The key is the index to which the array should be extended.

void    av_extend(AV *av, SSize_t key)
av_fetch

Returns the SV at the specified index in the array. The key is the index. If lval is true, you are guaranteed to get a real SV back (in case it wasn't real before), which you can then modify. Check that the return value is non-null before dereferencing it to a SV*.

See "Understanding the Magic of Tied Hashes and Arrays" in perlguts for more information on how to use this function on tied arrays.

The rough perl equivalent is $myarray[$key].

SV**    av_fetch(AV *av, SSize_t key, I32 lval)
AvFILL

Same as av_top_index() or av_tindex().

int     AvFILL(AV* av)
av_fill

Set the highest index in the array to the given number, equivalent to Perl's $#array = $fill;.

The number of elements in the array will be fill + 1 after av_fill() returns. If the array was previously shorter, then the additional elements appended are set to NULL. If the array was longer, then the excess elements are freed. av_fill(av, -1) is the same as av_clear(av).

void    av_fill(AV *av, SSize_t fill)
av_len

Same as "av_top_index". Note that, unlike what the name implies, it returns the highest index in the array, so to get the size of the array you need to use av_len(av) + 1. This is unlike "sv_len", which returns what you would expect.

SSize_t av_len(AV *av)
av_make

Creates a new AV and populates it with a list of SVs. The SVs are copied into the array, so they may be freed after the call to av_make. The new AV will have a reference count of 1.

Perl equivalent: my @new_array = ($scalar1, $scalar2, $scalar3...);

AV*     av_make(SSize_t size, SV **strp)
av_pop

Removes one SV from the end of the array, reducing its size by one and returning the SV (transferring control of one reference count) to the caller. Returns &PL_sv_undef if the array is empty.

Perl equivalent: pop(@myarray);

SV*     av_pop(AV *av)
av_push

Pushes an SV (transferring control of one reference count) onto the end of the array. The array will grow automatically to accommodate the addition.

Perl equivalent: push @myarray, $val;.

void    av_push(AV *av, SV *val)
av_shift

Removes one SV from the start of the array, reducing its size by one and returning the SV (transferring control of one reference count) to the caller. Returns &PL_sv_undef if the array is empty.

Perl equivalent: shift(@myarray);

SV*     av_shift(AV *av)
av_store

Stores an SV in an array. The array index is specified as key. The return value will be NULL if the operation failed or if the value did not need to be actually stored within the array (as in the case of tied arrays). Otherwise, it can be dereferenced to get the SV* that was stored there (= val)).

Note that the caller is responsible for suitably incrementing the reference count of val before the call, and decrementing it if the function returned NULL.

Approximate Perl equivalent: splice(@myarray, $key, 1, $val).

See "Understanding the Magic of Tied Hashes and Arrays" in perlguts for more information on how to use this function on tied arrays.

SV**    av_store(AV *av, SSize_t key, SV *val)
av_tindex

Same as av_top_index().

int     av_tindex(AV* av)
av_top_index

Returns the highest index in the array. The number of elements in the array is av_top_index(av) + 1. Returns -1 if the array is empty.

The Perl equivalent for this is $#myarray.

(A slightly shorter form is av_tindex.)

SSize_t av_top_index(AV *av)
av_undef

Undefines the array. The XS equivalent of undef(@array).

As well as freeing all the elements of the array (like av_clear()), this also frees the memory used by the av to store its list of scalars.

See "av_clear" for a note about the array possibly being invalid on return.

void    av_undef(AV *av)
av_unshift

Unshift the given number of undef values onto the beginning of the array. The array will grow automatically to accommodate the addition.

Perl equivalent: unshift @myarray, ((undef) x $num);

void    av_unshift(AV *av, SSize_t num)
get_av

Returns the AV of the specified Perl global or package array with the given name (so it won't work on lexical variables). flags are passed to gv_fetchpv. If GV_ADD is set and the Perl variable does not exist then it will be created. If flags is zero and the variable does not exist then NULL is returned.

Perl equivalent: @{"$name"}.

NOTE: the perl_ form of this function is deprecated.

AV*     get_av(const char *name, I32 flags)
newAV

Creates a new AV. The reference count is set to 1.

Perl equivalent: my @array;.

AV*     newAV()
sortsv

In-place sort an array of SV pointers with the given comparison routine.

Currently this always uses mergesort. See "sortsv_flags" for a more flexible routine.

void    sortsv(SV** array, size_t num_elts,
               SVCOMPARE_t cmp)

Callback Functions

call_argv

Performs a callback to the specified named and package-scoped Perl subroutine with argv (a NULL-terminated array of strings) as arguments. See perlcall.

Approximate Perl equivalent: &{"$sub_name"}(@$argv).

NOTE: the perl_ form of this function is deprecated.

I32     call_argv(const char* sub_name, I32 flags,
                  char** argv)
call_method

Performs a callback to the specified Perl method. The blessed object must be on the stack. See perlcall.

NOTE: the perl_ form of this function is deprecated.

I32     call_method(const char* methname, I32 flags)
call_pv

Performs a callback to the specified Perl sub. See perlcall.

NOTE: the perl_ form of this function is deprecated.

I32     call_pv(const char* sub_name, I32 flags)
call_sv

Performs a callback to the Perl sub specified by the SV.

If neither the G_METHOD nor G_METHOD_NAMED flag is supplied, the SV may be any of a CV, a GV, a reference to a CV, a reference to a GV or SvPV(sv) will be used as the name of the sub to call.

If the G_METHOD flag is supplied, the SV may be a reference to a CV or SvPV(sv) will be used as the name of the method to call.

If the G_METHOD_NAMED flag is supplied, SvPV(sv) will be used as the name of the method to call.

Some other values are treated specially for internal use and should not be depended on.

See perlcall.

NOTE: the perl_ form of this function is deprecated.

I32     call_sv(SV* sv, volatile I32 flags)
ENTER

Opening bracket on a callback. See "LEAVE" and perlcall.

ENTER;
ENTER_with_name(name)

Same as "ENTER", but when debugging is enabled it also associates the given literal string with the new scope.

ENTER_with_name(name);
eval_pv

Tells Perl to eval the given string in scalar context and return an SV* result.

NOTE: the perl_ form of this function is deprecated.

SV*     eval_pv(const char* p, I32 croak_on_error)
eval_sv

Tells Perl to eval the string in the SV. It supports the same flags as call_sv, with the obvious exception of G_EVAL. See perlcall.

NOTE: the perl_ form of this function is deprecated.

I32     eval_sv(SV* sv, I32 flags)
FREETMPS

Closing bracket for temporaries on a callback. See "SAVETMPS" and perlcall.

FREETMPS;
LEAVE

Closing bracket on a callback. See "ENTER" and perlcall.

LEAVE;
LEAVE_with_name(name)

Same as "LEAVE", but when debugging is enabled it first checks that the scope has the given name. name must be a literal string.

LEAVE_with_name(name);
SAVETMPS

Opening bracket for temporaries on a callback. See "FREETMPS" and perlcall.

SAVETMPS;

Character case changing

Perl uses "full" Unicode case mappings. This means that converting a single character to another case may result in a sequence of more than one character. For example, the uppercase of ß (LATIN SMALL LETTER SHARP S) is the two character sequence SS. This presents some complications The lowercase of all characters in the range 0..255 is a single character, and thus "toLOWER_L1" is furnished. But, toUPPER_L1 can't exist, as it couldn't return a valid result for all legal inputs. Instead "toUPPER_uvchr" has an API that does allow every possible legal result to be returned.) Likewise no other function that is crippled by not being able to give the correct results for the full range of possible inputs has been implemented here.

toFOLD

Converts the specified character to foldcase. If the input is anything but an ASCII uppercase character, that input character itself is returned. Variant toFOLD_A is equivalent. (There is no equivalent to_FOLD_L1 for the full Latin1 range, as the full generality of "toFOLD_uvchr" is needed there.)

U8      toFOLD(U8 ch)
toFOLD_utf8

This is like "toFOLD_utf8_safe", but doesn't have the e parameter The function therefore can't check if it is reading beyond the end of the string. Starting in Perl v5.30, it will take the e parameter, becoming a synonym for toFOLD_utf8_safe. At that time every program that uses it will have to be changed to successfully compile. In the meantime, the first runtime call to toFOLD_utf8 from each call point in the program will raise a deprecation warning, enabled by default. You can convert your program now to use toFOLD_utf8_safe, and avoid the warnings, and get an extra measure of protection, or you can wait until v5.30, when you'll be forced to add the e parameter.

UV      toFOLD_utf8(U8* p, U8* s, STRLEN* lenp)
toFOLD_utf8_safe

Converts the first UTF-8 encoded character in the sequence starting at p and extending no further than e - 1 to its foldcase version, and stores that in UTF-8 in s, and its length in bytes in lenp. Note that the buffer pointed to by s needs to be at least UTF8_MAXBYTES_CASE+1 bytes since the foldcase version may be longer than the original character.

The first code point of the foldcased version is returned (but note, as explained at the top of this section, that there may be more).

The suffix _safe in the function's name indicates that it will not attempt to read beyond e - 1, provided that the constraint s < e is true (this is asserted for in -DDEBUGGING builds). If the UTF-8 for the input character is malformed in some way, the program may croak, or the function may return the REPLACEMENT CHARACTER, at the discretion of the implementation, and subject to change in future releases.

UV      toFOLD_utf8_safe(U8* p, U8* e, U8* s,
                         STRLEN* lenp)
toFOLD_uvchr

Converts the code point cp to its foldcase version, and stores that in UTF-8 in s, and its length in bytes in lenp. The code point is interpreted as native if less than 256; otherwise as Unicode. Note that the buffer pointed to by s needs to be at least UTF8_MAXBYTES_CASE+1 bytes since the foldcase version may be longer than the original character.

The first code point of the foldcased version is returned (but note, as explained at the top of this section, that there may be more).

UV      toFOLD_uvchr(UV cp, U8* s, STRLEN* lenp)
toLOWER

Converts the specified character to lowercase. If the input is anything but an ASCII uppercase character, that input character itself is returned. Variant toLOWER_A is equivalent.

U8      toLOWER(U8 ch)
toLOWER_L1

Converts the specified Latin1 character to lowercase. The results are undefined if the input doesn't fit in a byte.

U8      toLOWER_L1(U8 ch)
toLOWER_LC

Converts the specified character to lowercase using the current locale's rules, if possible; otherwise returns the input character itself.

U8      toLOWER_LC(U8 ch)
toLOWER_utf8

This is like "toLOWER_utf8_safe", but doesn't have the e parameter The function therefore can't check if it is reading beyond the end of the string. Starting in Perl v5.30, it will take the e parameter, becoming a synonym for toLOWER_utf8_safe. At that time every program that uses it will have to be changed to successfully compile. In the meantime, the first runtime call to toLOWER_utf8 from each call point in the program will raise a deprecation warning, enabled by default. You can convert your program now to use toLOWER_utf8_safe, and avoid the warnings, and get an extra measure of protection, or you can wait until v5.30, when you'll be forced to add the e parameter.

UV      toLOWER_utf8(U8* p, U8* s, STRLEN* lenp)
toLOWER_utf8_safe

Converts the first UTF-8 encoded character in the sequence starting at p and extending no further than e - 1 to its lowercase version, and stores that in UTF-8 in s, and its length in bytes in lenp. Note that the buffer pointed to by s needs to be at least UTF8_MAXBYTES_CASE+1 bytes since the lowercase version may be longer than the original character.

The first code point of the lowercased version is returned (but note, as explained at the top of this section, that there may be more).

The suffix _safe in the function's name indicates that it will not attempt to read beyond e - 1, provided that the constraint s < e is true (this is asserted for in -DDEBUGGING builds). If the UTF-8 for the input character is malformed in some way, the program may croak, or the function may return the REPLACEMENT CHARACTER, at the discretion of the implementation, and subject to change in future releases.

UV      toLOWER_utf8_safe(U8* p, U8* e, U8* s,
                          STRLEN* lenp)
toLOWER_uvchr

Converts the code point cp to its lowercase version, and stores that in UTF-8 in s, and its length in bytes in lenp. The code point is interpreted as native if less than 256; otherwise as Unicode. Note that the buffer pointed to by s needs to be at least UTF8_MAXBYTES_CASE+1 bytes since the lowercase version may be longer than the original character.

The first code point of the lowercased version is returned (but note, as explained at the top of this section, that there may be more).

UV      toLOWER_uvchr(UV cp, U8* s, STRLEN* lenp)
toTITLE

Converts the specified character to titlecase. If the input is anything but an ASCII lowercase character, that input character itself is returned. Variant toTITLE_A is equivalent. (There is no toTITLE_L1 for the full Latin1 range, as the full generality of "toTITLE_uvchr" is needed there. Titlecase is not a concept used in locale handling, so there is no functionality for that.)

U8      toTITLE(U8 ch)
toTITLE_utf8

This is like "toLOWER_utf8_safe", but doesn't have the e parameter The function therefore can't check if it is reading beyond the end of the string. Starting in Perl v5.30, it will take the e parameter, becoming a synonym for toTITLE_utf8_safe. At that time every program that uses it will have to be changed to successfully compile. In the meantime, the first runtime call to toTITLE_utf8 from each call point in the program will raise a deprecation warning, enabled by default. You can convert your program now to use toTITLE_utf8_safe, and avoid the warnings, and get an extra measure of protection, or you can wait until v5.30, when you'll be forced to add the e parameter.

UV      toTITLE_utf8(U8* p, U8* s, STRLEN* lenp)
toTITLE_utf8_safe

Converts the first UTF-8 encoded character in the sequence starting at p and extending no further than e - 1 to its titlecase version, and stores that in UTF-8 in s, and its length in bytes in lenp. Note that the buffer pointed to by s needs to be at least UTF8_MAXBYTES_CASE+1 bytes since the titlecase version may be longer than the original character.

The first code point of the titlecased version is returned (but note, as explained at the top of this section, that there may be more).

The suffix _safe in the function's name indicates that it will not attempt to read beyond e - 1, provided that the constraint s < e is true (this is asserted for in -DDEBUGGING builds). If the UTF-8 for the input character is malformed in some way, the program may croak, or the function may return the REPLACEMENT CHARACTER, at the discretion of the implementation, and subject to change in future releases.

UV      toTITLE_utf8_safe(U8* p, U8* e, U8* s,
                          STRLEN* lenp)
toTITLE_uvchr

Converts the code point cp to its titlecase version, and stores that in UTF-8 in s, and its length in bytes in lenp. The code point is interpreted as native if less than 256; otherwise as Unicode. Note that the buffer pointed to by s needs to be at least UTF8_MAXBYTES_CASE+1 bytes since the titlecase version may be longer than the original character.

The first code point of the titlecased version is returned (but note, as explained at the top of this section, that there may be more).

UV      toTITLE_uvchr(UV cp, U8* s, STRLEN* lenp)
toUPPER

Converts the specified character to uppercase. If the input is anything but an ASCII lowercase character, that input character itself is returned. Variant toUPPER_A is equivalent.

U8      toUPPER(U8 ch)
toUPPER_utf8

This is like "toUPPER_utf8_safe", but doesn't have the e parameter The function therefore can't check if it is reading beyond the end of the string. Starting in Perl v5.30, it will take the e parameter, becoming a synonym for toUPPER_utf8_safe. At that time every program that uses it will have to be changed to successfully compile. In the meantime, the first runtime call to toUPPER_utf8 from each call point in the program will raise a deprecation warning, enabled by default. You can convert your program now to use toUPPER_utf8_safe, and avoid the warnings, and get an extra measure of protection, or you can wait until v5.30, when you'll be forced to add the e parameter.

UV      toUPPER_utf8(U8* p, U8* s, STRLEN* lenp)
toUPPER_utf8_safe

Converts the first UTF-8 encoded character in the sequence starting at p and extending no further than e - 1 to its uppercase version, and stores that in UTF-8 in s, and its length in bytes in lenp. Note that the buffer pointed to by s needs to be at least UTF8_MAXBYTES_CASE+1 bytes since the uppercase version may be longer than the original character.

The first code point of the uppercased version is returned (but note, as explained at the top of this section, that there may be more).

The suffix _safe in the function's name indicates that it will not attempt to read beyond e - 1, provided that the constraint s < e is true (this is asserted for in -DDEBUGGING builds). If the UTF-8 for the input character is malformed in some way, the program may croak, or the function may return the REPLACEMENT CHARACTER, at the discretion of the implementation, and subject to change in future releases.

UV      toUPPER_utf8_safe(U8* p, U8* e, U8* s,
                          STRLEN* lenp)
toUPPER_uvchr

Converts the code point cp to its uppercase version, and stores that in UTF-8 in s, and its length in bytes in lenp. The code point is interpreted as native if less than 256; otherwise as Unicode. Note that the buffer pointed to by s needs to be at least UTF8_MAXBYTES_CASE+1 bytes since the uppercase version may be longer than the original character.

The first code point of the uppercased version is returned (but note, as explained at the top of this section, that there may be more.)

UV      toUPPER_uvchr(UV cp, U8* s, STRLEN* lenp)

Character classification

This section is about functions (really macros) that classify characters into types, such as punctuation versus alphabetic, etc. Most of these are analogous to regular expression character classes. (See "POSIX Character Classes" in perlrecharclass.) There are several variants for each class. (Not all macros have all variants; each item below lists the ones valid for it.) None are affected by use bytes, and only the ones with LC in the name are affected by the current locale.

The base function, e.g., isALPHA(), takes an octet (either a char or a U8) as input and returns a boolean as to whether or not the character represented by that octet is (or on non-ASCII platforms, corresponds to) an ASCII character in the named class based on platform, Unicode, and Perl rules. If the input is a number that doesn't fit in an octet, FALSE is returned.

Variant isFOO_A (e.g., isALPHA_A()) is identical to the base function with no suffix "_A". This variant is used to emphasize by its name that only ASCII-range characters can return TRUE.

Variant isFOO_L1 imposes the Latin-1 (or EBCDIC equivalent) character set onto the platform. That is, the code points that are ASCII are unaffected, since ASCII is a subset of Latin-1. But the non-ASCII code points are treated as if they are Latin-1 characters. For example, isWORDCHAR_L1() will return true when called with the code point 0xDF, which is a word character in both ASCII and EBCDIC (though it represents different characters in each).

Variant isFOO_uvchr is like the isFOO_L1 variant, but accepts any UV code point as input. If the code point is larger than 255, Unicode rules are used to determine if it is in the character class. For example, isWORDCHAR_uvchr(0x100) returns TRUE, since 0x100 is LATIN CAPITAL LETTER A WITH MACRON in Unicode, and is a word character.

Variant isFOO_utf8_safe is like isFOO_uvchr, but is used for UTF-8 encoded strings. Each call classifies one character, even if the string contains many. This variant takes two parameters. The first, p, is a pointer to the first byte of the character to be classified. (Recall that it may take more than one byte to represent a character in UTF-8 strings.) The second parameter, e, points to anywhere in the string beyond the first character, up to one byte past the end of the entire string. The suffix _safe in the function's name indicates that it will not attempt to read beyond e - 1, provided that the constraint s < e is true (this is asserted for in -DDEBUGGING builds). If the UTF-8 for the input character is malformed in some way, the program may croak, or the function may return FALSE, at the discretion of the implementation, and subject to change in future releases.

Variant isFOO_utf8 is like isFOO_utf8_safe, but takes just a single parameter, p, which has the same meaning as the corresponding parameter does in isFOO_utf8_safe. The function therefore can't check if it is reading beyond the end of the string. Starting in Perl v5.30, it will take a second parameter, becoming a synonym for isFOO_utf8_safe. At that time every program that uses it will have to be changed to successfully compile. In the meantime, the first runtime call to isFOO_utf8 from each call point in the program will raise a deprecation warning, enabled by default. You can convert your program now to use isFOO_utf8_safe, and avoid the warnings, and get an extra measure of protection, or you can wait until v5.30, when you'll be forced to add the e parameter.

Variant isFOO_LC is like the isFOO_A and isFOO_L1 variants, but the result is based on the current locale, which is what LC in the name stands for. If Perl can determine that the current locale is a UTF-8 locale, it uses the published Unicode rules; otherwise, it uses the C library function that gives the named classification. For example, isDIGIT_LC() when not in a UTF-8 locale returns the result of calling isdigit(). FALSE is always returned if the input won't fit into an octet. On some platforms where the C library function is known to be defective, Perl changes its result to follow the POSIX standard's rules.

Variant isFOO_LC_uvchr is like isFOO_LC, but is defined on any UV. It returns the same as isFOO_LC for input code points less than 256, and returns the hard-coded, not-affected-by-locale, Unicode results for larger ones.

Variant isFOO_LC_utf8_safe is like isFOO_LC_uvchr, but is used for UTF-8 encoded strings. Each call classifies one character, even if the string contains many. This variant takes two parameters. The first, p, is a pointer to the first byte of the character to be classified. (Recall that it may take more than one byte to represent a character in UTF-8 strings.) The second parameter, e, points to anywhere in the string beyond the first character, up to one byte past the end of the entire string. The suffix _safe in the function's name indicates that it will not attempt to read beyond e - 1, provided that the constraint s < e is true (this is asserted for in -DDEBUGGING builds). If the UTF-8 for the input character is malformed in some way, the program may croak, or the function may return FALSE, at the discretion of the implementation, and subject to change in future releases.

Variant isFOO_LC_utf8 is like isFOO_LC_utf8_safe, but takes just a single parameter, p, which has the same meaning as the corresponding parameter does in isFOO_LC_utf8_safe. The function therefore can't check if it is reading beyond the end of the string. Starting in Perl v5.30, it will take a second parameter, becoming a synonym for isFOO_LC_utf8_safe. At that time every program that uses it will have to be changed to successfully compile. In the meantime, the first runtime call to isFOO_LC_utf8 from each call point in the program will raise a deprecation warning, enabled by default. You can convert your program now to use isFOO_LC_utf8_safe, and avoid the warnings, and get an extra measure of protection, or you can wait until v5.30, when you'll be forced to add the e parameter.

isALPHA

Returns a boolean indicating whether the specified character is an alphabetic character, analogous to m/[[:alpha:]]/. See the top of this section for an explanation of variants isALPHA_A, isALPHA_L1, isALPHA_uvchr, isALPHA_utf8_safe, isALPHA_LC, isALPHA_LC_uvchr, and isALPHA_LC_utf8_safe.

bool    isALPHA(char ch)
isALPHANUMERIC

Returns a boolean indicating whether the specified character is a either an alphabetic character or decimal digit, analogous to m/[[:alnum:]]/. See the top of this section for an explanation of variants isALPHANUMERIC_A, isALPHANUMERIC_L1, isALPHANUMERIC_uvchr, isALPHANUMERIC_utf8_safe, isALPHANUMERIC_LC, isALPHANUMERIC_LC_uvchr, and isALPHANUMERIC_LC_utf8_safe.

bool    isALPHANUMERIC(char ch)
isASCII

Returns a boolean indicating whether the specified character is one of the 128 characters in the ASCII character set, analogous to m/[[:ascii:]]/. On non-ASCII platforms, it returns TRUE iff this character corresponds to an ASCII character. Variants isASCII_A() and isASCII_L1() are identical to isASCII(). See the top of this section for an explanation of variants isASCII_uvchr, isASCII_utf8_safe, isASCII_LC, isASCII_LC_uvchr, and isASCII_LC_utf8_safe. Note, however, that some platforms do not have the C library routine isascii(). In these cases, the variants whose names contain LC are the same as the corresponding ones without.

Also note, that because all ASCII characters are UTF-8 invariant (meaning they have the exact same representation (always a single byte) whether encoded in UTF-8 or not), isASCII will give the correct results when called with any byte in any string encoded or not in UTF-8. And similarly isASCII_utf8_safe will work properly on any string encoded or not in UTF-8.

bool    isASCII(char ch)
isBLANK

Returns a boolean indicating whether the specified character is a character considered to be a blank, analogous to m/[[:blank:]]/. See the top of this section for an explanation of variants isBLANK_A, isBLANK_L1, isBLANK_uvchr, isBLANK_utf8_safe, isBLANK_LC, isBLANK_LC_uvchr, and isBLANK_LC_utf8_safe. Note, however, that some platforms do not have the C library routine isblank(). In these cases, the variants whose names contain LC are the same as the corresponding ones without.

bool    isBLANK(char ch)
isCNTRL

Returns a boolean indicating whether the specified character is a control character, analogous to m/[[:cntrl:]]/. See the top of this section for an explanation of variants isCNTRL_A, isCNTRL_L1, isCNTRL_uvchr, isCNTRL_utf8_safe, isCNTRL_LC, isCNTRL_LC_uvchr, and isCNTRL_LC_utf8_safe On EBCDIC platforms, you almost always want to use the isCNTRL_L1 variant.

bool    isCNTRL(char ch)
isDIGIT

Returns a boolean indicating whether the specified character is a digit, analogous to m/[[:digit:]]/. Variants isDIGIT_A and isDIGIT_L1 are identical to isDIGIT. See the top of this section for an explanation of variants isDIGIT_uvchr, isDIGIT_utf8_safe, isDIGIT_LC, isDIGIT_LC_uvchr, and isDIGIT_LC_utf8_safe.

bool    isDIGIT(char ch)
isGRAPH

Returns a boolean indicating whether the specified character is a graphic character, analogous to m/[[:graph:]]/. See the top of this section for an explanation of variants isGRAPH_A, isGRAPH_L1, isGRAPH_uvchr, isGRAPH_utf8_safe, isGRAPH_LC, isGRAPH_LC_uvchr, and isGRAPH_LC_utf8_safe.

bool    isGRAPH(char ch)
isIDCONT

Returns a boolean indicating whether the specified character can be the second or succeeding character of an identifier. This is very close to, but not quite the same as the official Unicode property XID_Continue. The difference is that this returns true only if the input character also matches "isWORDCHAR". See the top of this section for an explanation of variants isIDCONT_A, isIDCONT_L1, isIDCONT_uvchr, isIDCONT_utf8_safe, isIDCONT_LC, isIDCONT_LC_uvchr, and isIDCONT_LC_utf8_safe.

bool    isIDCONT(char ch)
isIDFIRST

Returns a boolean indicating whether the specified character can be the first character of an identifier. This is very close to, but not quite the same as the official Unicode property XID_Start. The difference is that this returns true only if the input character also matches "isWORDCHAR". See the top of this section for an explanation of variants isIDFIRST_A, isIDFIRST_L1, isIDFIRST_uvchr, isIDFIRST_utf8_safe, isIDFIRST_LC, isIDFIRST_LC_uvchr, and isIDFIRST_LC_utf8_safe.

bool    isIDFIRST(char ch)
isLOWER

Returns a boolean indicating whether the specified character is a lowercase character, analogous to m/[[:lower:]]/. See the top of this section for an explanation of variants isLOWER_A, isLOWER_L1, isLOWER_uvchr, isLOWER_utf8_safe, isLOWER_LC, isLOWER_LC_uvchr, and isLOWER_LC_utf8_safe.

bool    isLOWER(char ch)
isOCTAL

Returns a boolean indicating whether the specified character is an octal digit, [0-7]. The only two variants are isOCTAL_A and isOCTAL_L1; each is identical to isOCTAL.

bool    isOCTAL(char ch)
isPRINT

Returns a boolean indicating whether the specified character is a printable character, analogous to m/[[:print:]]/. See the top of this section for an explanation of variants isPRINT_A, isPRINT_L1, isPRINT_uvchr, isPRINT_utf8_safe, isPRINT_LC, isPRINT_LC_uvchr, and isPRINT_LC_utf8_safe.

bool    isPRINT(char ch)
isPSXSPC

(short for Posix Space) Starting in 5.18, this is identical in all its forms to the corresponding isSPACE() macros. The locale forms of this macro are identical to their corresponding isSPACE() forms in all Perl releases. In releases prior to 5.18, the non-locale forms differ from their isSPACE() forms only in that the isSPACE() forms don't match a Vertical Tab, and the isPSXSPC() forms do. Otherwise they are identical. Thus this macro is analogous to what m/[[:space:]]/ matches in a regular expression. See the top of this section for an explanation of variants isPSXSPC_A, isPSXSPC_L1, isPSXSPC_uvchr, isPSXSPC_utf8_safe, isPSXSPC_LC, isPSXSPC_LC_uvchr, and isPSXSPC_LC_utf8_safe.

bool    isPSXSPC(char ch)
isPUNCT

Returns a boolean indicating whether the specified character is a punctuation character, analogous to m/[[:punct:]]/. Note that the definition of what is punctuation isn't as straightforward as one might desire. See "POSIX Character Classes" in perlrecharclass for details. See the top of this section for an explanation of variants isPUNCT_A, isPUNCT_L1, isPUNCT_uvchr, isPUNCT_utf8_safe, isPUNCT_LC, isPUNCT_LC_uvchr, and isPUNCT_LC_utf8_safe.

bool    isPUNCT(char ch)
isSPACE

Returns a boolean indicating whether the specified character is a whitespace character. This is analogous to what m/\s/ matches in a regular expression. Starting in Perl 5.18 this also matches what m/[[:space:]]/ does. Prior to 5.18, only the locale forms of this macro (the ones with LC in their names) matched precisely what m/[[:space:]]/ does. In those releases, the only difference, in the non-locale variants, was that isSPACE() did not match a vertical tab. (See "isPSXSPC" for a macro that matches a vertical tab in all releases.) See the top of this section for an explanation of variants isSPACE_A, isSPACE_L1, isSPACE_uvchr, isSPACE_utf8_safe, isSPACE_LC, isSPACE_LC_uvchr, and isSPACE_LC_utf8_safe.

bool    isSPACE(char ch)
isUPPER

Returns a boolean indicating whether the specified character is an uppercase character, analogous to m/[[:upper:]]/. See the top of this section for an explanation of variants isUPPER_A, isUPPER_L1, isUPPER_uvchr, isUPPER_utf8_safe, isUPPER_LC, isUPPER_LC_uvchr, and isUPPER_LC_utf8_safe.

bool    isUPPER(char ch)
isWORDCHAR

Returns a boolean indicating whether the specified character is a character that is a word character, analogous to what m/\w/ and m/[[:word:]]/ match in a regular expression. A word character is an alphabetic character, a decimal digit, a connecting punctuation character (such as an underscore), or a "mark" character that attaches to one of those (like some sort of accent). isALNUM() is a synonym provided for backward compatibility, even though a word character includes more than the standard C language meaning of alphanumeric. See the top of this section for an explanation of variants isWORDCHAR_A, isWORDCHAR_L1, isWORDCHAR_uvchr, and isWORDCHAR_utf8_safe. isWORDCHAR_LC, isWORDCHAR_LC_uvchr, and isWORDCHAR_LC_utf8_safe are also as described there, but additionally include the platform's native underscore.

bool    isWORDCHAR(char ch)
isXDIGIT

Returns a boolean indicating whether the specified character is a hexadecimal digit. In the ASCII range these are [0-9A-Fa-f]. Variants isXDIGIT_A() and isXDIGIT_L1() are identical to isXDIGIT(). See the top of this section for an explanation of variants isXDIGIT_uvchr, isXDIGIT_utf8_safe, isXDIGIT_LC, isXDIGIT_LC_uvchr, and isXDIGIT_LC_utf8_safe.

bool    isXDIGIT(char ch)

Cloning an interpreter

perl_clone

Create and return a new interpreter by cloning the current one.

perl_clone takes these flags as parameters:

CLONEf_COPY_STACKS - is used to, well, copy the stacks also, without it we only clone the data and zero the stacks, with it we copy the stacks and the new perl interpreter is ready to run at the exact same point as the previous one. The pseudo-fork code uses COPY_STACKS while the threads->create doesn't.

CLONEf_KEEP_PTR_TABLE - perl_clone keeps a ptr_table with the pointer of the old variable as a key and the new variable as a value, this allows it to check if something has been cloned and not clone it again but rather just use the value and increase the refcount. If KEEP_PTR_TABLE is not set then perl_clone will kill the ptr_table using the function ptr_table_free(PL_ptr_table); PL_ptr_table = NULL;, reason to keep it around is if you want to dup some of your own variable who are outside the graph perl scans, an example of this code is in threads.xs create.

CLONEf_CLONE_HOST - This is a win32 thing, it is ignored on unix, it tells perls win32host code (which is c++) to clone itself, this is needed on win32 if you want to run two threads at the same time, if you just want to do some stuff in a separate perl interpreter and then throw it away and return to the original one, you don't need to do anything.

PerlInterpreter* perl_clone(
                     PerlInterpreter *proto_perl,
                     UV flags
                 )

Compile-time scope hooks

BhkDISABLE

NOTE: this function is experimental and may change or be removed without notice.

Temporarily disable an entry in this BHK structure, by clearing the appropriate flag. which is a preprocessor token indicating which entry to disable.

void    BhkDISABLE(BHK *hk, which)
BhkENABLE

NOTE: this function is experimental and may change or be removed without notice.

Re-enable an entry in this BHK structure, by setting the appropriate flag. which is a preprocessor token indicating which entry to enable. This will assert (under -DDEBUGGING) if the entry doesn't contain a valid pointer.

void    BhkENABLE(BHK *hk, which)
BhkENTRY_set

NOTE: this function is experimental and may change or be removed without notice.

Set an entry in the BHK structure, and set the flags to indicate it is valid. which is a preprocessing token indicating which entry to set. The type of ptr depends on the entry.

void    BhkENTRY_set(BHK *hk, which, void *ptr)
blockhook_register

NOTE: this function is experimental and may change or be removed without notice.

Register a set of hooks to be called when the Perl lexical scope changes at compile time. See "Compile-time scope hooks" in perlguts.

NOTE: this function must be explicitly called as Perl_blockhook_register with an aTHX_ parameter.

void    Perl_blockhook_register(pTHX_ BHK *hk)

COP Hint Hashes

cophh_2hv

NOTE: this function is experimental and may change or be removed without notice.

Generates and returns a standard Perl hash representing the full set of key/value pairs in the cop hints hash cophh. flags is currently unused and must be zero.

HV *    cophh_2hv(const COPHH *cophh, U32 flags)
cophh_copy

NOTE: this function is experimental and may change or be removed without notice.

Make and return a complete copy of the cop hints hash cophh.

COPHH * cophh_copy(COPHH *cophh)
cophh_delete_pv

NOTE: this function is experimental and may change or be removed without notice.

Like "cophh_delete_pvn", but takes a nul-terminated string instead of a string/length pair.

COPHH * cophh_delete_pv(const COPHH *cophh,
                        const char *key, U32 hash,
                        U32 flags)
cophh_delete_pvn

NOTE: this function is experimental and may change or be removed without notice.

Delete a key and its associated value from the cop hints hash cophh, and returns the modified hash. The returned hash pointer is in general not the same as the hash pointer that was passed in. The input hash is consumed by the function, and the pointer to it must not be subsequently used. Use "cophh_copy" if you need both hashes.

The key is specified by keypv and keylen. If flags has the COPHH_KEY_UTF8 bit set, the key octets are interpreted as UTF-8, otherwise they are interpreted as Latin-1. hash is a precomputed hash of the key string, or zero if it has not been precomputed.

COPHH * cophh_delete_pvn(COPHH *cophh,
                         const char *keypv,
                         STRLEN keylen, U32 hash,
                         U32 flags)
cophh_delete_pvs

NOTE: this function is experimental and may change or be removed without notice.

Like "cophh_delete_pvn", but takes a literal string instead of a string/length pair, and no precomputed hash.

COPHH * cophh_delete_pvs(const COPHH *cophh,
                         "literal string" key,
                         U32 flags)
cophh_delete_sv

NOTE: this function is experimental and may change or be removed without notice.

Like "cophh_delete_pvn", but takes a Perl scalar instead of a string/length pair.

COPHH * cophh_delete_sv(const COPHH *cophh, SV *key,
                        U32 hash, U32 flags)
cophh_fetch_pv

NOTE: this function is experimental and may change or be removed without notice.

Like "cophh_fetch_pvn", but takes a nul-terminated string instead of a string/length pair.

SV *    cophh_fetch_pv(const COPHH *cophh,
                       const char *key, U32 hash,
                       U32 flags)
cophh_fetch_pvn

NOTE: this function is experimental and may change or be removed without notice.

Look up the entry in the cop hints hash cophh with the key specified by keypv and keylen. If flags has the COPHH_KEY_UTF8 bit set, the key octets are interpreted as UTF-8, otherwise they are interpreted as Latin-1. hash is a precomputed hash of the key string, or zero if it has not been precomputed. Returns a mortal scalar copy of the value associated with the key, or &PL_sv_placeholder if there is no value associated with the key.

SV *    cophh_fetch_pvn(const COPHH *cophh,
                        const char *keypv,
                        STRLEN keylen, U32 hash,
                        U32 flags)
cophh_fetch_pvs

NOTE: this function is experimental and may change or be removed without notice.

Like "cophh_fetch_pvn", but takes a literal string instead of a string/length pair, and no precomputed hash.

SV *    cophh_fetch_pvs(const COPHH *cophh,
                        "literal string" key, U32 flags)
cophh_fetch_sv

NOTE: this function is experimental and may change or be removed without notice.

Like "cophh_fetch_pvn", but takes a Perl scalar instead of a string/length pair.

SV *    cophh_fetch_sv(const COPHH *cophh, SV *key,
                       U32 hash, U32 flags)
cophh_free

NOTE: this function is experimental and may change or be removed without notice.

Discard the cop hints hash cophh, freeing all resources associated with it.

void    cophh_free(COPHH *cophh)
cophh_new_empty

NOTE: this function is experimental and may change or be removed without notice.

Generate and return a fresh cop hints hash containing no entries.

COPHH * cophh_new_empty()
cophh_store_pv

NOTE: this function is experimental and may change or be removed without notice.

Like "cophh_store_pvn", but takes a nul-terminated string instead of a string/length pair.

COPHH * cophh_store_pv(const COPHH *cophh,
                       const char *key, U32 hash,
                       SV *value, U32 flags)
cophh_store_pvn

NOTE: this function is experimental and may change or be removed without notice.

Stores a value, associated with a key, in the cop hints hash cophh, and returns the modified hash. The returned hash pointer is in general not the same as the hash pointer that was passed in. The input hash is consumed by the function, and the pointer to it must not be subsequently used. Use "cophh_copy" if you need both hashes.

The key is specified by keypv and keylen. If flags has the COPHH_KEY_UTF8 bit set, the key octets are interpreted as UTF-8, otherwise they are interpreted as Latin-1. hash is a precomputed hash of the key string, or zero if it has not been precomputed.

value is the scalar value to store for this key. value is copied by this function, which thus does not take ownership of any reference to it, and later changes to the scalar will not be reflected in the value visible in the cop hints hash. Complex types of scalar will not be stored with referential integrity, but will be coerced to strings.

COPHH * cophh_store_pvn(COPHH *cophh, const char *keypv,
                        STRLEN keylen, U32 hash,
                        SV *value, U32 flags)
cophh_store_pvs

NOTE: this function is experimental and may change or be removed without notice.

Like "cophh_store_pvn", but takes a literal string instead of a string/length pair, and no precomputed hash.

COPHH * cophh_store_pvs(const COPHH *cophh,
                        "literal string" key, SV *value,
                        U32 flags)
cophh_store_sv

NOTE: this function is experimental and may change or be removed without notice.

Like "cophh_store_pvn", but takes a Perl scalar instead of a string/length pair.

COPHH * cophh_store_sv(const COPHH *cophh, SV *key,
                       U32 hash, SV *value, U32 flags)

COP Hint Reading

cop_hints_2hv

Generates and returns a standard Perl hash representing the full set of hint entries in the cop cop. flags is currently unused and must be zero.

HV *    cop_hints_2hv(const COP *cop, U32 flags)
cop_hints_fetch_pv

Like "cop_hints_fetch_pvn", but takes a nul-terminated string instead of a string/length pair.

SV *    cop_hints_fetch_pv(const COP *cop,
                           const char *key, U32 hash,
                           U32 flags)
cop_hints_fetch_pvn

Look up the hint entry in the cop cop with the key specified by keypv and keylen. If flags has the COPHH_KEY_UTF8 bit set, the key octets are interpreted as UTF-8, otherwise they are interpreted as Latin-1. hash is a precomputed hash of the key string, or zero if it has not been precomputed. Returns a mortal scalar copy of the value associated with the key, or &PL_sv_placeholder if there is no value associated with the key.

SV *    cop_hints_fetch_pvn(const COP *cop,
                            const char *keypv,
                            STRLEN keylen, U32 hash,
                            U32 flags)
cop_hints_fetch_pvs

Like "cop_hints_fetch_pvn", but takes a literal string instead of a string/length pair, and no precomputed hash.

SV *    cop_hints_fetch_pvs(const COP *cop,
                            "literal string" key,
                            U32 flags)
cop_hints_fetch_sv

Like "cop_hints_fetch_pvn", but takes a Perl scalar instead of a string/length pair.

SV *    cop_hints_fetch_sv(const COP *cop, SV *key,
                           U32 hash, U32 flags)

Custom Operators

custom_op_register

Register a custom op. See "Custom Operators" in perlguts.

NOTE: this function must be explicitly called as Perl_custom_op_register with an aTHX_ parameter.

void    Perl_custom_op_register(pTHX_ 
                                Perl_ppaddr_t ppaddr,
                                const XOP *xop)
custom_op_xop

Return the XOP structure for a given custom op. This macro should be considered internal to OP_NAME and the other access macros: use them instead. This macro does call a function. Prior to 5.19.6, this was implemented as a function.

NOTE: this function must be explicitly called as Perl_custom_op_xop with an aTHX_ parameter.

const XOP * Perl_custom_op_xop(pTHX_ const OP *o)
XopDISABLE

Temporarily disable a member of the XOP, by clearing the appropriate flag.

void    XopDISABLE(XOP *xop, which)
XopENABLE

Reenable a member of the XOP which has been disabled.

void    XopENABLE(XOP *xop, which)
XopENTRY

Return a member of the XOP structure. which is a cpp token indicating which entry to return. If the member is not set this will return a default value. The return type depends on which. This macro evaluates its arguments more than once. If you are using Perl_custom_op_xop to retreive a XOP * from a OP *, use the more efficient "XopENTRYCUSTOM" instead.

XopENTRY(XOP *xop, which)
XopENTRYCUSTOM

Exactly like XopENTRY(XopENTRY(Perl_custom_op_xop(aTHX_ o), which) but more efficient. The which parameter is identical to "XopENTRY".

XopENTRYCUSTOM(const OP *o, which)
XopENTRY_set

Set a member of the XOP structure. which is a cpp token indicating which entry to set. See "Custom Operators" in perlguts for details about the available members and how they are used. This macro evaluates its argument more than once.

void    XopENTRY_set(XOP *xop, which, value)
XopFLAGS

Return the XOP's flags.

U32     XopFLAGS(XOP *xop)

CV Manipulation Functions

This section documents functions to manipulate CVs which are code-values, or subroutines. For more information, see perlguts.

caller_cx

The XSUB-writer's equivalent of caller(). The returned PERL_CONTEXT structure can be interrogated to find all the information returned to Perl by caller. Note that XSUBs don't get a stack frame, so caller_cx(0, NULL) will return information for the immediately-surrounding Perl code.

This function skips over the automatic calls to &DB::sub made on the behalf of the debugger. If the stack frame requested was a sub called by DB::sub, the return value will be the frame for the call to DB::sub, since that has the correct line number/etc. for the call site. If dbcxp is non-NULL, it will be set to a pointer to the frame for the sub call itself.

const PERL_CONTEXT * caller_cx(
                         I32 level,
                         const PERL_CONTEXT **dbcxp
                     )
CvSTASH

Returns the stash of the CV. A stash is the symbol table hash, containing the package-scoped variables in the package where the subroutine was defined. For more information, see perlguts.

This also has a special use with XS AUTOLOAD subs. See "Autoloading with XSUBs" in perlguts.

HV*     CvSTASH(CV* cv)
find_runcv

Locate the CV corresponding to the currently executing sub or eval. If db_seqp is non_null, skip CVs that are in the DB package and populate *db_seqp with the cop sequence number at the point that the DB:: code was entered. (This allows debuggers to eval in the scope of the breakpoint rather than in the scope of the debugger itself.)

CV*     find_runcv(U32 *db_seqp)
get_cv

Uses strlen to get the length of name, then calls get_cvn_flags.

NOTE: the perl_ form of this function is deprecated.

CV*     get_cv(const char* name, I32 flags)
get_cvn_flags

Returns the CV of the specified Perl subroutine. flags are passed to gv_fetchpvn_flags. If GV_ADD is set and the Perl subroutine does not exist then it will be declared (which has the same effect as saying sub name;). If GV_ADD is not set and the subroutine does not exist then NULL is returned.

NOTE: the perl_ form of this function is deprecated.

CV*     get_cvn_flags(const char* name, STRLEN len,
                      I32 flags)

xsubpp variables and internal functions

ax

Variable which is setup by xsubpp to indicate the stack base offset, used by the ST, XSprePUSH and XSRETURN macros. The dMARK macro must be called prior to setup the MARK variable.

I32     ax
CLASS

Variable which is setup by xsubpp to indicate the class name for a C++ XS constructor. This is always a char*. See "THIS".

char*   CLASS
dAX

Sets up the ax variable. This is usually handled automatically by xsubpp by calling dXSARGS.

dAX;
dAXMARK

Sets up the ax variable and stack marker variable mark. This is usually handled automatically by xsubpp by calling dXSARGS.

dAXMARK;
dITEMS

Sets up the items variable. This is usually handled automatically by xsubpp by calling dXSARGS.

dITEMS;
dUNDERBAR

Sets up any variable needed by the UNDERBAR macro. It used to define padoff_du, but it is currently a noop. However, it is strongly advised to still use it for ensuring past and future compatibility.

dUNDERBAR;
dXSARGS

Sets up stack and mark pointers for an XSUB, calling dSP and dMARK. Sets up the ax and items variables by calling dAX and dITEMS. This is usually handled automatically by xsubpp.

dXSARGS;
dXSI32

Sets up the ix variable for an XSUB which has aliases. This is usually handled automatically by xsubpp.

dXSI32;
items

Variable which is setup by xsubpp to indicate the number of items on the stack. See "Variable-length Parameter Lists" in perlxs.

I32     items
ix

Variable which is setup by xsubpp to indicate which of an XSUB's aliases was used to invoke it. See "The ALIAS: Keyword" in perlxs.

I32     ix
RETVAL

Variable which is setup by xsubpp to hold the return value for an XSUB. This is always the proper type for the XSUB. See "The RETVAL Variable" in perlxs.

(whatever)      RETVAL
ST

Used to access elements on the XSUB's stack.

SV*     ST(int ix)
THIS

Variable which is setup by xsubpp to designate the object in a C++ XSUB. This is always the proper type for the C++ object. See "CLASS" and "Using XS With C++" in perlxs.

(whatever)      THIS
UNDERBAR

The SV* corresponding to the $_ variable. Works even if there is a lexical $_ in scope.

XS

Macro to declare an XSUB and its C parameter list. This is handled by xsubpp. It is the same as using the more explicit XS_EXTERNAL macro.

XS_EXTERNAL

Macro to declare an XSUB and its C parameter list explicitly exporting the symbols.

XS_INTERNAL

Macro to declare an XSUB and its C parameter list without exporting the symbols. This is handled by xsubpp and generally preferable over exporting the XSUB symbols unnecessarily.

Debugging Utilities

dump_all

Dumps the entire optree of the current program starting at PL_main_root to STDERR. Also dumps the optrees for all visible subroutines in PL_defstash.

void    dump_all()
dump_packsubs

Dumps the optrees for all visible subroutines in stash.

void    dump_packsubs(const HV* stash)
op_class

Given an op, determine what type of struct it has been allocated as. Returns one of the OPclass enums, such as OPclass_LISTOP.

OPclass op_class(const OP *o)
op_dump

Dumps the optree starting at OP o to STDERR.

void    op_dump(const OP *o)
sv_dump

Dumps the contents of an SV to the STDERR filehandle.

For an example of its output, see Devel::Peek.

void    sv_dump(SV* sv)

Display and Dump functions

pv_display

Similar to

pv_escape(dsv,pv,cur,pvlim,PERL_PV_ESCAPE_QUOTE);

except that an additional "\0" will be appended to the string when len > cur and pv[cur] is "\0".

Note that the final string may be up to 7 chars longer than pvlim.

char*   pv_display(SV *dsv, const char *pv, STRLEN cur,
                   STRLEN len, STRLEN pvlim)
pv_escape

Escapes at most the first count chars of pv and puts the results into dsv such that the size of the escaped string will not exceed max chars and will not contain any incomplete escape sequences. The number of bytes escaped will be returned in the STRLEN *escaped parameter if it is not null. When the dsv parameter is null no escaping actually occurs, but the number of bytes that would be escaped were it not null will be calculated.

If flags contains PERL_PV_ESCAPE_QUOTE then any double quotes in the string will also be escaped.

Normally the SV will be cleared before the escaped string is prepared, but when PERL_PV_ESCAPE_NOCLEAR is set this will not occur.

If PERL_PV_ESCAPE_UNI is set then the input string is treated as UTF-8 if PERL_PV_ESCAPE_UNI_DETECT is set then the input string is scanned using is_utf8_string() to determine if it is UTF-8.

If PERL_PV_ESCAPE_ALL is set then all input chars will be output using \x01F1 style escapes, otherwise if PERL_PV_ESCAPE_NONASCII is set, only non-ASCII chars will be escaped using this style; otherwise, only chars above 255 will be so escaped; other non printable chars will use octal or common escaped patterns like \n. Otherwise, if PERL_PV_ESCAPE_NOBACKSLASH then all chars below 255 will be treated as printable and will be output as literals.

If PERL_PV_ESCAPE_FIRSTCHAR is set then only the first char of the string will be escaped, regardless of max. If the output is to be in hex, then it will be returned as a plain hex sequence. Thus the output will either be a single char, an octal escape sequence, a special escape like \n or a hex value.

If PERL_PV_ESCAPE_RE is set then the escape char used will be a "%" and not a "\\". This is because regexes very often contain backslashed sequences, whereas "%" is not a particularly common character in patterns.

Returns a pointer to the escaped text as held by dsv.

char*   pv_escape(SV *dsv, char const * const str,
                  const STRLEN count, const STRLEN max,
                  STRLEN * const escaped,
                  const U32 flags)
pv_pretty

Converts a string into something presentable, handling escaping via pv_escape() and supporting quoting and ellipses.

If the PERL_PV_PRETTY_QUOTE flag is set then the result will be double quoted with any double quotes in the string escaped. Otherwise if the PERL_PV_PRETTY_LTGT flag is set then the result be wrapped in angle brackets.

If the PERL_PV_PRETTY_ELLIPSES flag is set and not all characters in string were output then an ellipsis ... will be appended to the string. Note that this happens AFTER it has been quoted.

If start_color is non-null then it will be inserted after the opening quote (if there is one) but before the escaped text. If end_color is non-null then it will be inserted after the escaped text but before any quotes or ellipses.

Returns a pointer to the prettified text as held by dsv.

char*   pv_pretty(SV *dsv, char const * const str,
                  const STRLEN count, const STRLEN max,
                  char const * const start_color,
                  char const * const end_color,
                  const U32 flags)

Embedding Functions

cv_clone

Clone a CV, making a lexical closure. proto supplies the prototype of the function: its code, pad structure, and other attributes. The prototype is combined with a capture of outer lexicals to which the code refers, which are taken from the currently-executing instance of the immediately surrounding code.

CV *    cv_clone(CV *proto)
cv_name

Returns an SV containing the name of the CV, mainly for use in error reporting. The CV may actually be a GV instead, in which case the returned SV holds the GV's name. Anything other than a GV or CV is treated as a string already holding the sub name, but this could change in the future.

An SV may be passed as a second argument. If so, the name will be assigned to it and it will be returned. Otherwise the returned SV will be a new mortal.

If flags has the CV_NAME_NOTQUAL bit set, then the package name will not be included. If the first argument is neither a CV nor a GV, this flag is ignored (subject to change).

SV *    cv_name(CV *cv, SV *sv, U32 flags)
cv_undef

Clear out all the active components of a CV. This can happen either by an explicit undef &foo, or by the reference count going to zero. In the former case, we keep the CvOUTSIDE pointer, so that any anonymous children can still follow the full lexical scope chain.

void    cv_undef(CV* cv)
find_rundefsv

Returns the global variable $_.

SV *    find_rundefsv()
find_rundefsvoffset

DEPRECATED! It is planned to remove this function from a future release of Perl. Do not use it for new code; remove it from existing code.

Until the lexical $_ feature was removed, this function would find the position of the lexical $_ in the pad of the currently-executing function and return the offset in the current pad, or NOT_IN_PAD.

Now it always returns NOT_IN_PAD.

NOTE: the perl_ form of this function is deprecated.

PADOFFSET find_rundefsvoffset()
intro_my

"Introduce" my variables to visible status. This is called during parsing at the end of each statement to make lexical variables visible to subsequent statements.

U32     intro_my()
load_module

Loads the module whose name is pointed to by the string part of name. Note that the actual module name, not its filename, should be given. Eg, "Foo::Bar" instead of "Foo/Bar.pm". ver, if specified and not NULL, provides version semantics similar to use Foo::Bar VERSION. The optional trailing arguments can be used to specify arguments to the module's import() method, similar to use Foo::Bar VERSION LIST; their precise handling depends on the flags. The flags argument is a bitwise-ORed collection of any of PERL_LOADMOD_DENY, PERL_LOADMOD_NOIMPORT, or PERL_LOADMOD_IMPORT_OPS (or 0 for no flags).

If PERL_LOADMOD_NOIMPORT is set, the module is loaded as if with an empty import list, as in use Foo::Bar (); this is the only circumstance in which the trailing optional arguments may be omitted entirely. Otherwise, if PERL_LOADMOD_IMPORT_OPS is set, the trailing arguments must consist of exactly one OP*, containing the op tree that produces the relevant import arguments. Otherwise, the trailing arguments must all be SV* values that will be used as import arguments; and the list must be terminated with (SV*) NULL. If neither PERL_LOADMOD_NOIMPORT nor PERL_LOADMOD_IMPORT_OPS is set, the trailing NULL pointer is needed even if no import arguments are desired. The reference count for each specified SV* argument is decremented. In addition, the name argument is modified.

If PERL_LOADMOD_DENY is set, the module is loaded as if with no rather than use.

void    load_module(U32 flags, SV* name, SV* ver, ...)
newPADNAMELIST

NOTE: this function is experimental and may change or be removed without notice.

Creates a new pad name list. max is the highest index for which space is allocated.

PADNAMELIST * newPADNAMELIST(size_t max)
newPADNAMEouter

NOTE: this function is experimental and may change or be removed without notice.

Constructs and returns a new pad name. Only use this function for names that refer to outer lexicals. (See also "newPADNAMEpvn".) outer is the outer pad name that this one mirrors. The returned pad name has the PADNAMEt_OUTER flag already set.

PADNAME * newPADNAMEouter(PADNAME *outer)
newPADNAMEpvn

NOTE: this function is experimental and may change or be removed without notice.

Constructs and returns a new pad name. s must be a UTF-8 string. Do not use this for pad names that point to outer lexicals. See "newPADNAMEouter".

PADNAME * newPADNAMEpvn(const char *s, STRLEN len)
nothreadhook

Stub that provides thread hook for perl_destruct when there are no threads.

int     nothreadhook()
pad_add_anon

Allocates a place in the currently-compiling pad (via "pad_alloc") for an anonymous function that is lexically scoped inside the currently-compiling function. The function func is linked into the pad, and its CvOUTSIDE link to the outer scope is weakened to avoid a reference loop.

One reference count is stolen, so you may need to do SvREFCNT_inc(func).

optype should be an opcode indicating the type of operation that the pad entry is to support. This doesn't affect operational semantics, but is used for debugging.

PADOFFSET pad_add_anon(CV *func, I32 optype)
pad_add_name_pv

Exactly like "pad_add_name_pvn", but takes a nul-terminated string instead of a string/length pair.

PADOFFSET pad_add_name_pv(const char *name, U32 flags,
                          HV *typestash, HV *ourstash)
pad_add_name_pvn

Allocates a place in the currently-compiling pad for a named lexical variable. Stores the name and other metadata in the name part of the pad, and makes preparations to manage the variable's lexical scoping. Returns the offset of the allocated pad slot.

namepv/namelen specify the variable's name, including leading sigil. If typestash is non-null, the name is for a typed lexical, and this identifies the type. If ourstash is non-null, it's a lexical reference to a package variable, and this identifies the package. The following flags can be OR'ed together:

padadd_OUR          redundantly specifies if it's a package var
padadd_STATE        variable will retain value persistently
padadd_NO_DUP_CHECK skip check for lexical shadowing

       PADOFFSET pad_add_name_pvn(const char *namepv,
                                  STRLEN namelen, U32 flags,
                                  HV *typestash, HV *ourstash)
pad_add_name_sv

Exactly like "pad_add_name_pvn", but takes the name string in the form of an SV instead of a string/length pair.

PADOFFSET pad_add_name_sv(SV *name, U32 flags,
                          HV *typestash, HV *ourstash)
pad_alloc

NOTE: this function is experimental and may change or be removed without notice.

Allocates a place in the currently-compiling pad, returning the offset of the allocated pad slot. No name is initially attached to the pad slot. tmptype is a set of flags indicating the kind of pad entry required, which will be set in the value SV for the allocated pad entry:

SVs_PADMY    named lexical variable ("my", "our", "state")
SVs_PADTMP   unnamed temporary store
SVf_READONLY constant shared between recursion levels

SVf_READONLY has been supported here only since perl 5.20. To work with earlier versions as well, use SVf_READONLY|SVs_PADTMP. SVf_READONLY does not cause the SV in the pad slot to be marked read-only, but simply tells pad_alloc that it will be made read-only (by the caller), or at least should be treated as such.

optype should be an opcode indicating the type of operation that the pad entry is to support. This doesn't affect operational semantics, but is used for debugging.

PADOFFSET pad_alloc(I32 optype, U32 tmptype)
pad_findmy_pv

Exactly like "pad_findmy_pvn", but takes a nul-terminated string instead of a string/length pair.

PADOFFSET pad_findmy_pv(const char *name, U32 flags)
pad_findmy_pvn

Given the name of a lexical variable, find its position in the currently-compiling pad. namepv/namelen specify the variable's name, including leading sigil. flags is reserved and must be zero. If it is not in the current pad but appears in the pad of any lexically enclosing scope, then a pseudo-entry for it is added in the current pad. Returns the offset in the current pad, or NOT_IN_PAD if no such lexical is in scope.

PADOFFSET pad_findmy_pvn(const char *namepv,
                         STRLEN namelen, U32 flags)
pad_findmy_sv

Exactly like "pad_findmy_pvn", but takes the name string in the form of an SV instead of a string/length pair.

PADOFFSET pad_findmy_sv(SV *name, U32 flags)
padnamelist_fetch

NOTE: this function is experimental and may change or be removed without notice.

Fetches the pad name from the given index.

PADNAME * padnamelist_fetch(PADNAMELIST *pnl,
                            SSize_t key)
padnamelist_store

NOTE: this function is experimental and may change or be removed without notice.

Stores the pad name (which may be null) at the given index, freeing any existing pad name in that slot.

PADNAME ** padnamelist_store(PADNAMELIST *pnl,
                             SSize_t key, PADNAME *val)
pad_setsv

Set the value at offset po in the current (compiling or executing) pad. Use the macro PAD_SETSV() rather than calling this function directly.

void    pad_setsv(PADOFFSET po, SV *sv)
pad_sv

Get the value at offset po in the current (compiling or executing) pad. Use macro PAD_SV instead of calling this function directly.

SV *    pad_sv(PADOFFSET po)
pad_tidy

NOTE: this function is experimental and may change or be removed without notice.

Tidy up a pad at the end of compilation of the code to which it belongs. Jobs performed here are: remove most stuff from the pads of anonsub prototypes; give it a @_; mark temporaries as such. type indicates the kind of subroutine:

padtidy_SUB        ordinary subroutine
padtidy_SUBCLONE   prototype for lexical closure
padtidy_FORMAT     format

    void    pad_tidy(padtidy_type type)
perl_alloc

Allocates a new Perl interpreter. See perlembed.

PerlInterpreter* perl_alloc()
perl_construct

Initializes a new Perl interpreter. See perlembed.

void    perl_construct(PerlInterpreter *my_perl)
perl_destruct

Shuts down a Perl interpreter. See perlembed for a tutorial.

my_perl points to the Perl interpreter. It must have been previously created through the use of "perl_alloc" and "perl_construct". It may have been initialised through "perl_parse", and may have been used through "perl_run" and other means. This function should be called for any Perl interpreter that has been constructed with "perl_construct", even if subsequent operations on it failed, for example if "perl_parse" returned a non-zero value.

If the interpreter's PL_exit_flags word has the PERL_EXIT_DESTRUCT_END flag set, then this function will execute code in END blocks before performing the rest of destruction. If it is desired to make any use of the interpreter between "perl_parse" and "perl_destruct" other than just calling "perl_run", then this flag should be set early on. This matters if "perl_run" will not be called, or if anything else will be done in addition to calling "perl_run".

Returns a value be a suitable value to pass to the C library function exit (or to return from main), to serve as an exit code indicating the nature of the way the interpreter terminated. This takes into account any failure of "perl_parse" and any early exit from "perl_run". The exit code is of the type required by the host operating system, so because of differing exit code conventions it is not portable to interpret specific numeric values as having specific meanings.

int     perl_destruct(PerlInterpreter *my_perl)
perl_free

Releases a Perl interpreter. See perlembed.

void    perl_free(PerlInterpreter *my_perl)
perl_parse

Tells a Perl interpreter to parse a Perl script. This performs most of the initialisation of a Perl interpreter. See perlembed for a tutorial.

my_perl points to the Perl interpreter that is to parse the script. It must have been previously created through the use of "perl_alloc" and "perl_construct". xsinit points to a callback function that will be called to set up the ability for this Perl interpreter to load XS extensions, or may be null to perform no such setup.

argc and argv supply a set of command-line arguments to the Perl interpreter, as would normally be passed to the main function of a C program. argv[argc] must be null. These arguments are where the script to parse is specified, either by naming a script file or by providing a script in a -e option. If $0 will be written to in the Perl interpreter, then the argument strings must be in writable memory, and so mustn't just be string constants.

env specifies a set of environment variables that will be used by this Perl interpreter. If non-null, it must point to a null-terminated array of environment strings. If null, the Perl interpreter will use the environment supplied by the environ global variable.

This function initialises the interpreter, and parses and compiles the script specified by the command-line arguments. This includes executing code in BEGIN, UNITCHECK, and CHECK blocks. It does not execute INIT blocks or the main program.

Returns an integer of slightly tricky interpretation. The correct use of the return value is as a truth value indicating whether there was a failure in initialisation. If zero is returned, this indicates that initialisation was successful, and it is safe to proceed to call "perl_run" and make other use of it. If a non-zero value is returned, this indicates some problem that means the interpreter wants to terminate. The interpreter should not be just abandoned upon such failure; the caller should proceed to shut the interpreter down cleanly with "perl_destruct" and free it with "perl_free".

For historical reasons, the non-zero return value also attempts to be a suitable value to pass to the C library function exit (or to return from main), to serve as an exit code indicating the nature of the way initialisation terminated. However, this isn't portable, due to differing exit code conventions. A historical bug is preserved for the time being: if the Perl built-in exit is called during this function's execution, with a type of exit entailing a zero exit code under the host operating system's conventions, then this function returns zero rather than a non-zero value. This bug, [perl #2754], leads to perl_run being called (and therefore INIT blocks and the main program running) despite a call to exit. It has been preserved because a popular module-installing module has come to rely on it and needs time to be fixed. This issue is [perl #132577], and the original bug is due to be fixed in Perl 5.30.

int     perl_parse(PerlInterpreter *my_perl,
                   XSINIT_t xsinit, int argc,
                   char **argv, char **env)
perl_run

Tells a Perl interpreter to run its main program. See perlembed for a tutorial.

my_perl points to the Perl interpreter. It must have been previously created through the use of "perl_alloc" and "perl_construct", and initialised through "perl_parse". This function should not be called if "perl_parse" returned a non-zero value, indicating a failure in initialisation or compilation.

This function executes code in INIT blocks, and then executes the main program. The code to be executed is that established by the prior call to "perl_parse". If the interpreter's PL_exit_flags word does not have the PERL_EXIT_DESTRUCT_END flag set, then this function will also execute code in END blocks. If it is desired to make any further use of the interpreter after calling this function, then END blocks should be postponed to "perl_destruct" time by setting that flag.

Returns an integer of slightly tricky interpretation. The correct use of the return value is as a truth value indicating whether the program terminated non-locally. If zero is returned, this indicates that the program ran to completion, and it is safe to make other use of the interpreter (provided that the PERL_EXIT_DESTRUCT_END flag was set as described above). If a non-zero value is returned, this indicates that the interpreter wants to terminate early. The interpreter should not be just abandoned because of this desire to terminate; the caller should proceed to shut the interpreter down cleanly with "perl_destruct" and free it with "perl_free".

For historical reasons, the non-zero return value also attempts to be a suitable value to pass to the C library function exit (or to return from main), to serve as an exit code indicating the nature of the way the program terminated. However, this isn't portable, due to differing exit code conventions. An attempt is made to return an exit code of the type required by the host operating system, but because it is constrained to be non-zero, it is not necessarily possible to indicate every type of exit. It is only reliable on Unix, where a zero exit code can be augmented with a set bit that will be ignored. In any case, this function is not the correct place to acquire an exit code: one should get that from "perl_destruct".

int     perl_run(PerlInterpreter *my_perl)
require_pv

Tells Perl to require the file named by the string argument. It is analogous to the Perl code eval "require '$file'". It's even implemented that way; consider using load_module instead.

NOTE: the perl_ form of this function is deprecated.

void    require_pv(const char* pv)

Exception Handling (simple) Macros

dXCPT

Set up necessary local variables for exception handling. See "Exception Handling" in perlguts.

dXCPT;
XCPT_CATCH

Introduces a catch block. See "Exception Handling" in perlguts.

XCPT_RETHROW

Rethrows a previously caught exception. See "Exception Handling" in perlguts.

XCPT_RETHROW;
XCPT_TRY_END

Ends a try block. See "Exception Handling" in perlguts.

XCPT_TRY_START

Starts a try block. See "Exception Handling" in perlguts.

Functions in file pp_sort.c

sortsv_flags

In-place sort an array of SV pointers with the given comparison routine, with various SORTf_* flag options.

void    sortsv_flags(SV** array, size_t num_elts,
                     SVCOMPARE_t cmp, U32 flags)

Functions in file scope.c

save_gp

Saves the current GP of gv on the save stack to be restored on scope exit.

If empty is true, replace the GP with a new GP.

If empty is false, mark gv with GVf_INTRO so the next reference assigned is localized, which is how local *foo = $someref; works.

void    save_gp(GV* gv, I32 empty)

Functions in file vutil.c

new_version

Returns a new version object based on the passed in SV:

SV *sv = new_version(SV *ver);

Does not alter the passed in ver SV. See "upg_version" if you want to upgrade the SV.

SV*     new_version(SV *ver)
prescan_version

Validate that a given string can be parsed as a version object, but doesn't actually perform the parsing. Can use either strict or lax validation rules. Can optionally set a number of hint variables to save the parsing code some time when tokenizing.

const char* prescan_version(const char *s, bool strict,
                            const char** errstr,
                            bool *sqv,
                            int *ssaw_decimal,
                            int *swidth, bool *salpha)
scan_version

Returns a pointer to the next character after the parsed version string, as well as upgrading the passed in SV to an RV.

Function must be called with an already existing SV like

sv = newSV(0);
s = scan_version(s, SV *sv, bool qv);

Performs some preprocessing to the string to ensure that it has the correct characteristics of a version. Flags the object if it contains an underscore (which denotes this is an alpha version). The boolean qv denotes that the version should be interpreted as if it had multiple decimals, even if it doesn't.

const char* scan_version(const char *s, SV *rv, bool qv)
upg_version

In-place upgrade of the supplied SV to a version object.

SV *sv = upg_version(SV *sv, bool qv);

Returns a pointer to the upgraded SV. Set the boolean qv if you want to force this SV to be interpreted as an "extended" version.

SV*     upg_version(SV *ver, bool qv)
vcmp

Version object aware cmp. Both operands must already have been converted into version objects.

int     vcmp(SV *lhv, SV *rhv)
vnormal

Accepts a version object and returns the normalized string representation. Call like:

sv = vnormal(rv);

NOTE: you can pass either the object directly or the SV contained within the RV.

The SV returned has a refcount of 1.

SV*     vnormal(SV *vs)
vnumify

Accepts a version object and returns the normalized floating point representation. Call like:

sv = vnumify(rv);

NOTE: you can pass either the object directly or the SV contained within the RV.

The SV returned has a refcount of 1.

SV*     vnumify(SV *vs)
vstringify

In order to maintain maximum compatibility with earlier versions of Perl, this function will return either the floating point notation or the multiple dotted notation, depending on whether the original version contained 1 or more dots, respectively.

The SV returned has a refcount of 1.

SV*     vstringify(SV *vs)
vverify

Validates that the SV contains valid internal structure for a version object. It may be passed either the version object (RV) or the hash itself (HV). If the structure is valid, it returns the HV. If the structure is invalid, it returns NULL.

SV *hv = vverify(sv);

Note that it only confirms the bare minimum structure (so as not to get confused by derived classes which may contain additional hash entries):

  • The SV is an HV or a reference to an HV

  • The hash contains a "version" key

  • The "version" key has a reference to an AV as its value

SV*     vverify(SV *vs)

"Gimme" Values

G_ARRAY

Used to indicate list context. See "GIMME_V", "GIMME" and perlcall.

G_DISCARD

Indicates that arguments returned from a callback should be discarded. See perlcall.

G_EVAL

Used to force a Perl eval wrapper around a callback. See perlcall.

GIMME

A backward-compatible version of GIMME_V which can only return G_SCALAR or G_ARRAY; in a void context, it returns G_SCALAR. Deprecated. Use GIMME_V instead.

U32     GIMME
GIMME_V

The XSUB-writer's equivalent to Perl's wantarray. Returns G_VOID, G_SCALAR or G_ARRAY for void, scalar or list context, respectively. See perlcall for a usage example.

U32     GIMME_V
G_NOARGS

Indicates that no arguments are being sent to a callback. See perlcall.

G_SCALAR

Used to indicate scalar context. See "GIMME_V", "GIMME", and perlcall.

G_VOID

Used to indicate void context. See "GIMME_V" and perlcall.

Global Variables

These variables are global to an entire process. They are shared between all interpreters and all threads in a process. Any variables not documented here may be changed or removed without notice, so don't use them! If you feel you really do need to use an unlisted variable, first send email to [email protected]. It may be that someone there will point out a way to accomplish what you need without using an internal variable. But if not, you should get a go-ahead to document and then use the variable.

PL_check

Array, indexed by opcode, of functions that will be called for the "check" phase of optree building during compilation of Perl code. For most (but not all) types of op, once the op has been initially built and populated with child ops it will be filtered through the check function referenced by the appropriate element of this array. The new op is passed in as the sole argument to the check function, and the check function returns the completed op. The check function may (as the name suggests) check the op for validity and signal errors. It may also initialise or modify parts of the ops, or perform more radical surgery such as adding or removing child ops, or even throw the op away and return a different op in its place.

This array of function pointers is a convenient place to hook into the compilation process. An XS module can put its own custom check function in place of any of the standard ones, to influence the compilation of a particular type of op. However, a custom check function must never fully replace a standard check function (or even a custom check function from another module). A module modifying checking must instead wrap the preexisting check function. A custom check function must be selective about when to apply its custom behaviour. In the usual case where it decides not to do anything special with an op, it must chain the preexisting op function. Check functions are thus linked in a chain, with the core's base checker at the end.

For thread safety, modules should not write directly to this array. Instead, use the function "wrap_op_checker".

PL_keyword_plugin

NOTE: this function is experimental and may change or be removed without notice.

Function pointer, pointing at a function used to handle extended keywords. The function should be declared as

int keyword_plugin_function(pTHX_
        char *keyword_ptr, STRLEN keyword_len,
        OP **op_ptr)

The function is called from the tokeniser, whenever a possible keyword is seen. keyword_ptr points at the word in the parser's input buffer, and keyword_len gives its length; it is not null-terminated. The function is expected to examine the word, and possibly other state such as %^H, to decide whether it wants to handle it as an extended keyword. If it does not, the function should return KEYWORD_PLUGIN_DECLINE, and the normal parser process will continue.

If the function wants to handle the keyword, it first must parse anything following the keyword that is part of the syntax introduced by the keyword. See "Lexer interface" for details.

When a keyword is being handled, the plugin function must build a tree of OP structures, representing the code that was parsed. The root of the tree must be stored in *op_ptr. The function then returns a constant indicating the syntactic role of the construct that it has parsed: KEYWORD_PLUGIN_STMT if it is a complete statement, or KEYWORD_PLUGIN_EXPR if it is an expression. Note that a statement construct cannot be used inside an expression (except via do BLOCK and similar), and an expression is not a complete statement (it requires at least a terminating semicolon).

When a keyword is handled, the plugin function may also have (compile-time) side effects. It may modify %^H, define functions, and so on. Typically, if side effects are the main purpose of a handler, it does not wish to generate any ops to be included in the normal compilation. In this case it is still required to supply an op tree, but it suffices to generate a single null op.

That's how the *PL_keyword_plugin function needs to behave overall. Conventionally, however, one does not completely replace the existing handler function. Instead, take a copy of PL_keyword_plugin before assigning your own function pointer to it. Your handler function should look for keywords that it is interested in and handle those. Where it is not interested, it should call the saved plugin function, passing on the arguments it received. Thus PL_keyword_plugin actually points at a chain of handler functions, all of which have an opportunity to handle keywords, and only the last function in the chain (built into the Perl core) will normally return KEYWORD_PLUGIN_DECLINE.

For thread safety, modules should not set this variable directly. Instead, use the function "wrap_keyword_plugin".

GV Functions

A GV is a structure which corresponds to to a Perl typeglob, ie *foo. It is a structure that holds a pointer to a scalar, an array, a hash etc, corresponding to $foo, @foo, %foo.

GVs are usually found as values in stashes (symbol table hashes) where Perl stores its global variables.

GvAV

Return the AV from the GV.

AV*     GvAV(GV* gv)
gv_const_sv

If gv is a typeglob whose subroutine entry is a constant sub eligible for inlining, or gv is a placeholder reference that would be promoted to such a typeglob, then returns the value returned by the sub. Otherwise, returns NULL.

SV*     gv_const_sv(GV* gv)
GvCV

Return the CV from the GV.

CV*     GvCV(GV* gv)
gv_fetchmeth

Like "gv_fetchmeth_pvn", but lacks a flags parameter.

GV*     gv_fetchmeth(HV* stash, const char* name,
                     STRLEN len, I32 level)
gv_fetchmethod_autoload

Returns the glob which contains the subroutine to call to invoke the method on the stash. In fact in the presence of autoloading this may be the glob for "AUTOLOAD". In this case the corresponding variable $AUTOLOAD is already setup.

The third parameter of gv_fetchmethod_autoload determines whether AUTOLOAD lookup is performed if the given method is not present: non-zero means yes, look for AUTOLOAD; zero means no, don't look for AUTOLOAD. Calling gv_fetchmethod is equivalent to calling gv_fetchmethod_autoload with a non-zero autoload parameter.

These functions grant "SUPER" token as a prefix of the method name. Note that if you want to keep the returned glob for a long time, you need to check for it being "AUTOLOAD", since at the later time the call may load a different subroutine due to $AUTOLOAD changing its value. Use the glob created as a side effect to do this.

These functions have the same side-effects as gv_fetchmeth with level==0. The warning against passing the GV returned by gv_fetchmeth to call_sv applies equally to these functions.

GV*     gv_fetchmethod_autoload(HV* stash,
                                const char* name,
                                I32 autoload)
gv_fetchmeth_autoload

This is the old form of "gv_fetchmeth_pvn_autoload", which has no flags parameter.

GV*     gv_fetchmeth_autoload(HV* stash,
                              const char* name,
                              STRLEN len, I32 level)
gv_fetchmeth_pv

Exactly like "gv_fetchmeth_pvn", but takes a nul-terminated string instead of a string/length pair.

GV*     gv_fetchmeth_pv(HV* stash, const char* name,
                        I32 level, U32 flags)
gv_fetchmeth_pvn

Returns the glob with the given name and a defined subroutine or NULL. The glob lives in the given stash, or in the stashes accessible via @ISA and UNIVERSAL::.

The argument level should be either 0 or -1. If level==0, as a side-effect creates a glob with the given name in the given stash which in the case of success contains an alias for the subroutine, and sets up caching info for this glob.

The only significant values for flags are GV_SUPER and SVf_UTF8.

GV_SUPER indicates that we want to look up the method in the superclasses of the stash.

The GV returned from gv_fetchmeth may be a method cache entry, which is not visible to Perl code. So when calling call_sv, you should not use the GV directly; instead, you should use the method's CV, which can be obtained from the GV with the GvCV macro.

GV*     gv_fetchmeth_pvn(HV* stash, const char* name,
                         STRLEN len, I32 level,
                         U32 flags)
gv_fetchmeth_pvn_autoload

Same as gv_fetchmeth_pvn(), but looks for autoloaded subroutines too. Returns a glob for the subroutine.

For an autoloaded subroutine without a GV, will create a GV even if level < 0. For an autoloaded subroutine without a stub, GvCV() of the result may be zero.

Currently, the only significant value for flags is SVf_UTF8.

GV*     gv_fetchmeth_pvn_autoload(HV* stash,
                                  const char* name,
                                  STRLEN len, I32 level,
                                  U32 flags)
gv_fetchmeth_pv_autoload

Exactly like "gv_fetchmeth_pvn_autoload", but takes a nul-terminated string instead of a string/length pair.

GV*     gv_fetchmeth_pv_autoload(HV* stash,
                                 const char* name,
                                 I32 level, U32 flags)
gv_fetchmeth_sv

Exactly like "gv_fetchmeth_pvn", but takes the name string in the form of an SV instead of a string/length pair.

GV*     gv_fetchmeth_sv(HV* stash, SV* namesv,
                        I32 level, U32 flags)
gv_fetchmeth_sv_autoload

Exactly like "gv_fetchmeth_pvn_autoload", but takes the name string in the form of an SV instead of a string/length pair.

GV*     gv_fetchmeth_sv_autoload(HV* stash, SV* namesv,
                                 I32 level, U32 flags)
GvHV

Return the HV from the GV.

HV*     GvHV(GV* gv)
gv_init

The old form of gv_init_pvn(). It does not work with UTF-8 strings, as it has no flags parameter. If the multi parameter is set, the GV_ADDMULTI flag will be passed to gv_init_pvn().

void    gv_init(GV* gv, HV* stash, const char* name,
                STRLEN len, int multi)
gv_init_pv

Same as gv_init_pvn(), but takes a nul-terminated string for the name instead of separate char * and length parameters.

void    gv_init_pv(GV* gv, HV* stash, const char* name,
                   U32 flags)
gv_init_pvn

Converts a scalar into a typeglob. This is an incoercible typeglob; assigning a reference to it will assign to one of its slots, instead of overwriting it as happens with typeglobs created by SvSetSV. Converting any scalar that is SvOK() may produce unpredictable results and is reserved for perl's internal use.

gv is the scalar to be converted.

stash is the parent stash/package, if any.

name and len give the name. The name must be unqualified; that is, it must not include the package name. If gv is a stash element, it is the caller's responsibility to ensure that the name passed to this function matches the name of the element. If it does not match, perl's internal bookkeeping will get out of sync.

flags can be set to SVf_UTF8 if name is a UTF-8 string, or the return value of SvUTF8(sv). It can also take the GV_ADDMULTI flag, which means to pretend that the GV has been seen before (i.e., suppress "Used once" warnings).

void    gv_init_pvn(GV* gv, HV* stash, const char* name,
                    STRLEN len, U32 flags)
gv_init_sv

Same as gv_init_pvn(), but takes an SV * for the name instead of separate char * and length parameters. flags is currently unused.

void    gv_init_sv(GV* gv, HV* stash, SV* namesv,
                   U32 flags)
gv_stashpv

Returns a pointer to the stash for a specified package. Uses strlen to determine the length of name, then calls gv_stashpvn().

HV*     gv_stashpv(const char* name, I32 flags)
gv_stashpvn

Returns a pointer to the stash for a specified package. The namelen parameter indicates the length of the name, in bytes. flags is passed to gv_fetchpvn_flags(), so if set to GV_ADD then the package will be created if it does not already exist. If the package does not exist and flags is 0 (or any other setting that does not create packages) then NULL is returned.

Flags may be one of:

GV_ADD
SVf_UTF8
GV_NOADD_NOINIT
GV_NOINIT
GV_NOEXPAND
GV_ADDMG

The most important of which are probably GV_ADD and SVf_UTF8.

Note, use of gv_stashsv instead of gv_stashpvn where possible is strongly recommended for performance reasons.

HV*     gv_stashpvn(const char* name, U32 namelen,
                    I32 flags)
gv_stashpvs

Like gv_stashpvn, but takes a literal string instead of a string/length pair.

HV*     gv_stashpvs("literal string" name, I32 create)
gv_stashsv

Returns a pointer to the stash for a specified package. See "gv_stashpvn".

Note this interface is strongly preferred over gv_stashpvn for performance reasons.

HV*     gv_stashsv(SV* sv, I32 flags)
GvSV

Return the SV from the GV.

SV*     GvSV(GV* gv)
setdefout

Sets PL_defoutgv, the default file handle for output, to the passed in typeglob. As PL_defoutgv "owns" a reference on its typeglob, the reference count of the passed in typeglob is increased by one, and the reference count of the typeglob that PL_defoutgv points to is decreased by one.

void    setdefout(GV* gv)

Handy Values

Nullav

Null AV pointer.

(deprecated - use (AV *)NULL instead)

Nullch

Null character pointer. (No longer available when PERL_CORE is defined.)

Nullcv

Null CV pointer.

(deprecated - use (CV *)NULL instead)

Nullhv

Null HV pointer.

(deprecated - use (HV *)NULL instead)

Nullsv

Null SV pointer. (No longer available when PERL_CORE is defined.)

Hash Manipulation Functions

A HV structure represents a Perl hash. It consists mainly of an array of pointers, each of which points to a linked list of HE structures. The array is indexed by the hash function of the key, so each linked list represents all the hash entries with the same hash value. Each HE contains a pointer to the actual value, plus a pointer to a HEK structure which holds the key and hash value.

cop_fetch_label

NOTE: this function is experimental and may change or be removed without notice.

Returns the label attached to a cop. The flags pointer may be set to SVf_UTF8 or 0.

const char * cop_fetch_label(COP *const cop,
                             STRLEN *len, U32 *flags)
cop_store_label

NOTE: this function is experimental and may change or be removed without notice.

Save a label into a cop_hints_hash. You need to set flags to SVf_UTF8 for a UTF-8 label.

void    cop_store_label(COP *const cop,
                        const char *label, STRLEN len,
                        U32 flags)
get_hv

Returns the HV of the specified Perl hash. flags are passed to gv_fetchpv. If GV_ADD is set and the Perl variable does not exist then it will be created. If flags is zero and the variable does not exist then NULL is returned.

NOTE: the perl_ form of this function is deprecated.

HV*     get_hv(const char *name, I32 flags)
HEf_SVKEY

This flag, used in the length slot of hash entries and magic structures, specifies the structure contains an SV* pointer where a char* pointer is to be expected. (For information only--not to be used).

HeHASH

Returns the computed hash stored in the hash entry.

U32     HeHASH(HE* he)
HeKEY

Returns the actual pointer stored in the key slot of the hash entry. The pointer may be either char* or SV*, depending on the value of HeKLEN(). Can be assigned to. The HePV() or HeSVKEY() macros are usually preferable for finding the value of a key.

void*   HeKEY(HE* he)
HeKLEN

If this is negative, and amounts to HEf_SVKEY, it indicates the entry holds an SV* key. Otherwise, holds the actual length of the key. Can be assigned to. The HePV() macro is usually preferable for finding key lengths.

STRLEN  HeKLEN(HE* he)
HePV

Returns the key slot of the hash entry as a char* value, doing any necessary dereferencing of possibly SV* keys. The length of the string is placed in len (this is a macro, so do not use &len). If you do not care about what the length of the key is, you may use the global variable PL_na, though this is rather less efficient than using a local variable. Remember though, that hash keys in perl are free to contain embedded nulls, so using strlen() or similar is not a good way to find the length of hash keys. This is very similar to the SvPV() macro described elsewhere in this document. See also "HeUTF8".

If you are using HePV to get values to pass to newSVpvn() to create a new SV, you should consider using newSVhek(HeKEY_hek(he)) as it is more efficient.

char*   HePV(HE* he, STRLEN len)
HeSVKEY

Returns the key as an SV*, or NULL if the hash entry does not contain an SV* key.

SV*     HeSVKEY(HE* he)
HeSVKEY_force

Returns the key as an SV*. Will create and return a temporary mortal SV* if the hash entry contains only a char* key.

SV*     HeSVKEY_force(HE* he)
HeSVKEY_set

Sets the key to a given SV*, taking care to set the appropriate flags to indicate the presence of an SV* key, and returns the same SV*.

SV*     HeSVKEY_set(HE* he, SV* sv)
HeUTF8

Returns whether the char * value returned by HePV is encoded in UTF-8, doing any necessary dereferencing of possibly SV* keys. The value returned will be 0 or non-0, not necessarily 1 (or even a value with any low bits set), so do not blindly assign this to a bool variable, as bool may be a typedef for char.

U32     HeUTF8(HE* he)
HeVAL

Returns the value slot (type SV*) stored in the hash entry. Can be assigned to.

SV *foo= HeVAL(hv);
HeVAL(hv)= sv;


      SV*     HeVAL(HE* he)
hv_assert

Check that a hash is in an internally consistent state.

void    hv_assert(HV *hv)
hv_bucket_ratio

NOTE: this function is experimental and may change or be removed without notice.

If the hash is tied dispatches through to the SCALAR tied method, otherwise if the hash contains no keys returns 0, otherwise returns a mortal sv containing a string specifying the number of used buckets, followed by a slash, followed by the number of available buckets.

This function is expensive, it must scan all of the buckets to determine which are used, and the count is NOT cached. In a large hash this could be a lot of buckets.

SV*     hv_bucket_ratio(HV *hv)
hv_clear

Frees the all the elements of a hash, leaving it empty. The XS equivalent of %hash = (). See also "hv_undef".

See "av_clear" for a note about the hash possibly being invalid on return.

void    hv_clear(HV *hv)
hv_clear_placeholders

Clears any placeholders from a hash. If a restricted hash has any of its keys marked as readonly and the key is subsequently deleted, the key is not actually deleted but is marked by assigning it a value of &PL_sv_placeholder. This tags it so it will be ignored by future operations such as iterating over the hash, but will still allow the hash to have a value reassigned to the key at some future point. This function clears any such placeholder keys from the hash. See Hash::Util::lock_keys() for an example of its use.

void    hv_clear_placeholders(HV *hv)
hv_copy_hints_hv

A specialised version of "newHVhv" for copying %^H. ohv must be a pointer to a hash (which may have %^H magic, but should be generally non-magical), or NULL (interpreted as an empty hash). The content of ohv is copied to a new hash, which has the %^H-specific magic added to it. A pointer to the new hash is returned.

HV *    hv_copy_hints_hv(HV *ohv)
hv_delete

Deletes a key/value pair in the hash. The value's SV is removed from the hash, made mortal, and returned to the caller. The absolute value of klen is the length of the key. If klen is negative the key is assumed to be in UTF-8-encoded Unicode. The flags value will normally be zero; if set to G_DISCARD then NULL will be returned. NULL will also be returned if the key is not found.

SV*     hv_delete(HV *hv, const char *key, I32 klen,
                  I32 flags)
hv_delete_ent

Deletes a key/value pair in the hash. The value SV is removed from the hash, made mortal, and returned to the caller. The flags value will normally be zero; if set to G_DISCARD then NULL will be returned. NULL will also be returned if the key is not found. hash can be a valid precomputed hash value, or 0 to ask for it to be computed.

SV*     hv_delete_ent(HV *hv, SV *keysv, I32 flags,
                      U32 hash)
HvENAME

Returns the effective name of a stash, or NULL if there is none. The effective name represents a location in the symbol table where this stash resides. It is updated automatically when packages are aliased or deleted. A stash that is no longer in the symbol table has no effective name. This name is preferable to HvNAME for use in MRO linearisations and isa caches.

char*   HvENAME(HV* stash)
HvENAMELEN

Returns the length of the stash's effective name.

STRLEN  HvENAMELEN(HV *stash)
HvENAMEUTF8

Returns true if the effective name is in UTF-8 encoding.

unsigned char HvENAMEUTF8(HV *stash)
hv_exists

Returns a boolean indicating whether the specified hash key exists. The absolute value of klen is the length of the key. If klen is negative the key is assumed to be in UTF-8-encoded Unicode.

bool    hv_exists(HV *hv, const char *key, I32 klen)
hv_exists_ent

Returns a boolean indicating whether the specified hash key exists. hash can be a valid precomputed hash value, or 0 to ask for it to be computed.

bool    hv_exists_ent(HV *hv, SV *keysv, U32 hash)
hv_fetch

Returns the SV which corresponds to the specified key in the hash. The absolute value of klen is the length of the key. If klen is negative the key is assumed to be in UTF-8-encoded Unicode. If lval is set then the fetch will be part of a store. This means that if there is no value in the hash associated with the given key, then one is created and a pointer to it is returned. The SV* it points to can be assigned to. But always check that the return value is non-null before dereferencing it to an SV*.

See "Understanding the Magic of Tied Hashes and Arrays" in perlguts for more information on how to use this function on tied hashes.

SV**    hv_fetch(HV *hv, const char *key, I32 klen,
                 I32 lval)
hv_fetchs

Like hv_fetch, but takes a literal string instead of a string/length pair.

SV**    hv_fetchs(HV* tb, "literal string" key,
                  I32 lval)
hv_fetch_ent

Returns the hash entry which corresponds to the specified key in the hash. hash must be a valid precomputed hash number for the given key, or 0 if you want the function to compute it. IF lval is set then the fetch will be part of a store. Make sure the return value is non-null before accessing it. The return value when hv is a tied hash is a pointer to a static location, so be sure to make a copy of the structure if you need to store it somewhere.

See "Understanding the Magic of Tied Hashes and Arrays" in perlguts for more information on how to use this function on tied hashes.

HE*     hv_fetch_ent(HV *hv, SV *keysv, I32 lval,
                     U32 hash)
hv_fill

Returns the number of hash buckets that happen to be in use.

This function is wrapped by the macro HvFILL.

As of perl 5.25 this function is used only for debugging purposes, and the number of used hash buckets is not in any way cached, thus this function can be costly to execute as it must iterate over all the buckets in the hash.

STRLEN  hv_fill(HV *const hv)
hv_iterinit

Prepares a starting point to traverse a hash table. Returns the number of keys in the hash, including placeholders (i.e. the same as HvTOTALKEYS(hv)). The return value is currently only meaningful for hashes without tie magic.

NOTE: Before version 5.004_65, hv_iterinit used to return the number of hash buckets that happen to be in use. If you still need that esoteric value, you can get it through the macro HvFILL(hv).

I32     hv_iterinit(HV *hv)
hv_iterkey

Returns the key from the current position of the hash iterator. See "hv_iterinit".

char*   hv_iterkey(HE* entry, I32* retlen)
hv_iterkeysv

Returns the key as an SV* from the current position of the hash iterator. The return value will always be a mortal copy of the key. Also see "hv_iterinit".

SV*     hv_iterkeysv(HE* entry)
hv_iternext

Returns entries from a hash iterator. See "hv_iterinit".

You may call hv_delete or hv_delete_ent on the hash entry that the iterator currently points to, without losing your place or invalidating your iterator. Note that in this case the current entry is deleted from the hash with your iterator holding the last reference to it. Your iterator is flagged to free the entry on the next call to hv_iternext, so you must not discard your iterator immediately else the entry will leak - call hv_iternext to trigger the resource deallocation.

HE*     hv_iternext(HV *hv)
hv_iternextsv

Performs an hv_iternext, hv_iterkey, and hv_iterval in one operation.

SV*     hv_iternextsv(HV *hv, char **key, I32 *retlen)
hv_iternext_flags

NOTE: this function is experimental and may change or be removed without notice.

Returns entries from a hash iterator. See "hv_iterinit" and "hv_iternext". The flags value will normally be zero; if HV_ITERNEXT_WANTPLACEHOLDERS is set the placeholders keys (for restricted hashes) will be returned in addition to normal keys. By default placeholders are automatically skipped over. Currently a placeholder is implemented with a value that is &PL_sv_placeholder. Note that the implementation of placeholders and restricted hashes may change, and the implementation currently is insufficiently abstracted for any change to be tidy.

HE*     hv_iternext_flags(HV *hv, I32 flags)
hv_iterval

Returns the value from the current position of the hash iterator. See "hv_iterkey".

SV*     hv_iterval(HV *hv, HE *entry)
hv_magic

Adds magic to a hash. See "sv_magic".

void    hv_magic(HV *hv, GV *gv, int how)
HvNAME

Returns the package name of a stash, or NULL if stash isn't a stash. See "SvSTASH", "CvSTASH".

char*   HvNAME(HV* stash)
HvNAMELEN

Returns the length of the stash's name.

STRLEN  HvNAMELEN(HV *stash)
HvNAMEUTF8

Returns true if the name is in UTF-8 encoding.

unsigned char HvNAMEUTF8(HV *stash)
hv_scalar

Evaluates the hash in scalar context and returns the result.

When the hash is tied dispatches through to the SCALAR method, otherwise returns a mortal SV containing the number of keys in the hash.

Note, prior to 5.25 this function returned what is now returned by the hv_bucket_ratio() function.

SV*     hv_scalar(HV *hv)
hv_store

Stores an SV in a hash. The hash key is specified as key and the absolute value of klen is the length of the key. If klen is negative the key is assumed to be in UTF-8-encoded Unicode. The hash parameter is the precomputed hash value; if it is zero then Perl will compute it.

The return value will be NULL if the operation failed or if the value did not need to be actually stored within the hash (as in the case of tied hashes). Otherwise it can be dereferenced to get the original SV*. Note that the caller is responsible for suitably incrementing the reference count of val before the call, and decrementing it if the function returned NULL. Effectively a successful hv_store takes ownership of one reference to val. This is usually what you want; a newly created SV has a reference count of one, so if all your code does is create SVs then store them in a hash, hv_store will own the only reference to the new SV, and your code doesn't need to do anything further to tidy up. hv_store is not implemented as a call to hv_store_ent, and does not create a temporary SV for the key, so if your key data is not already in SV form then use hv_store in preference to hv_store_ent.

See "Understanding the Magic of Tied Hashes and Arrays" in perlguts for more information on how to use this function on tied hashes.

SV**    hv_store(HV *hv, const char *key, I32 klen,
                 SV *val, U32 hash)
hv_stores

Like hv_store, but takes a literal string instead of a string/length pair and omits the hash parameter.

SV**    hv_stores(HV* tb, "literal string" key, SV* val)
hv_store_ent

Stores val in a hash. The hash key is specified as key. The hash parameter is the precomputed hash value; if it is zero then Perl will compute it. The return value is the new hash entry so created. It will be NULL if the operation failed or if the value did not need to be actually stored within the hash (as in the case of tied hashes). Otherwise the contents of the return value can be accessed using the He? macros described here. Note that the caller is responsible for suitably incrementing the reference count of val before the call, and decrementing it if the function returned NULL. Effectively a successful hv_store_ent takes ownership of one reference to val. This is usually what you want; a newly created SV has a reference count of one, so if all your code does is create SVs then store them in a hash, hv_store will own the only reference to the new SV, and your code doesn't need to do anything further to tidy up. Note that hv_store_ent only reads the key; unlike val it does not take ownership of it, so maintaining the correct reference count on key is entirely the caller's responsibility. hv_store is not implemented as a call to hv_store_ent, and does not create a temporary SV for the key, so if your key data is not already in SV form then use hv_store in preference to hv_store_ent.

See "Understanding the Magic of Tied Hashes and Arrays" in perlguts for more information on how to use this function on tied hashes.

HE*     hv_store_ent(HV *hv, SV *key, SV *val, U32 hash)
hv_undef

Undefines the hash. The XS equivalent of undef(%hash).

As well as freeing all the elements of the hash (like hv_clear()), this also frees any auxiliary data and storage associated with the hash.

See "av_clear" for a note about the hash possibly being invalid on return.

void    hv_undef(HV *hv)
newHV

Creates a new HV. The reference count is set to 1.

HV*     newHV()

Hook manipulation

These functions provide convenient and thread-safe means of manipulating hook variables.

wrap_op_checker

Puts a C function into the chain of check functions for a specified op type. This is the preferred way to manipulate the "PL_check" array. opcode specifies which type of op is to be affected. new_checker is a pointer to the C function that is to be added to that opcode's check chain, and old_checker_p points to the storage location where a pointer to the next function in the chain will be stored. The value of new_checker is written into the "PL_check" array, while the value previously stored there is written to *old_checker_p.

"PL_check" is global to an entire process, and a module wishing to hook op checking may find itself invoked more than once per process, typically in different threads. To handle that situation, this function is idempotent. The location *old_checker_p must initially (once per process) contain a null pointer. A C variable of static duration (declared at file scope, typically also marked static to give it internal linkage) will be implicitly initialised appropriately, if it does not have an explicit initialiser. This function will only actually modify the check chain if it finds *old_checker_p to be null. This function is also thread safe on the small scale. It uses appropriate locking to avoid race conditions in accessing "PL_check".

When this function is called, the function referenced by new_checker must be ready to be called, except for *old_checker_p being unfilled. In a threading situation, new_checker may be called immediately, even before this function has returned. *old_checker_p will always be appropriately set before new_checker is called. If new_checker decides not to do anything special with an op that it is given (which is the usual case for most uses of op check hooking), it must chain the check function referenced by *old_checker_p.

Taken all together, XS code to hook an op checker should typically look something like this:

static Perl_check_t nxck_frob;
static OP *myck_frob(pTHX_ OP *op) {
    ...
    op = nxck_frob(aTHX_ op);
    ...
    return op;
}
BOOT:
    wrap_op_checker(OP_FROB, myck_frob, &nxck_frob);

If you want to influence compilation of calls to a specific subroutine, then use "cv_set_call_checker_flags" rather than hooking checking of all entersub ops.

void    wrap_op_checker(Optype opcode,
                        Perl_check_t new_checker,
                        Perl_check_t *old_checker_p)

Lexer interface

This is the lower layer of the Perl parser, managing characters and tokens.

lex_bufutf8

NOTE: this function is experimental and may change or be removed without notice.

Indicates whether the octets in the lexer buffer ("PL_parser->linestr") should be interpreted as the UTF-8 encoding of Unicode characters. If not, they should be interpreted as Latin-1 characters. This is analogous to the SvUTF8 flag for scalars.

In UTF-8 mode, it is not guaranteed that the lexer buffer actually contains valid UTF-8. Lexing code must be robust in the face of invalid encoding.

The actual SvUTF8 flag of the "PL_parser->linestr" scalar is significant, but not the whole story regarding the input character encoding. Normally, when a file is being read, the scalar contains octets and its SvUTF8 flag is off, but the octets should be interpreted as UTF-8 if the use utf8 pragma is in effect. During a string eval, however, the scalar may have the SvUTF8 flag on, and in this case its octets should be interpreted as UTF-8 unless the use bytes pragma is in effect. This logic may change in the future; use this function instead of implementing the logic yourself.

bool    lex_bufutf8()
lex_discard_to

NOTE: this function is experimental and may change or be removed without notice.

Discards the first part of the "PL_parser->linestr" buffer, up to ptr. The remaining content of the buffer will be moved, and all pointers into the buffer updated appropriately. ptr must not be later in the buffer than the position of "PL_parser->bufptr": it is not permitted to discard text that has yet to be lexed.

Normally it is not necessarily to do this directly, because it suffices to use the implicit discarding behaviour of "lex_next_chunk" and things based on it. However, if a token stretches across multiple lines, and the lexing code has kept multiple lines of text in the buffer for that purpose, then after completion of the token it would be wise to explicitly discard the now-unneeded earlier lines, to avoid future multi-line tokens growing the buffer without bound.

void    lex_discard_to(char *ptr)
lex_grow_linestr

NOTE: this function is experimental and may change or be removed without notice.

Reallocates the lexer buffer ("PL_parser->linestr") to accommodate at least len octets (including terminating NUL). Returns a pointer to the reallocated buffer. This is necessary before making any direct modification of the buffer that would increase its length. "lex_stuff_pvn" provides a more convenient way to insert text into the buffer.

Do not use SvGROW or sv_grow directly on PL_parser->linestr; this function updates all of the lexer's variables that point directly into the buffer.

char *  lex_grow_linestr(STRLEN len)
lex_next_chunk

NOTE: this function is experimental and may change or be removed without notice.

Reads in the next chunk of text to be lexed, appending it to "PL_parser->linestr". This should be called when lexing code has looked to the end of the current chunk and wants to know more. It is usual, but not necessary, for lexing to have consumed the entirety of the current chunk at this time.

If "PL_parser->bufptr" is pointing to the very end of the current chunk (i.e., the current chunk has been entirely consumed), normally the current chunk will be discarded at the same time that the new chunk is read in. If flags has the LEX_KEEP_PREVIOUS bit set, the current chunk will not be discarded. If the current chunk has not been entirely consumed, then it will not be discarded regardless of the flag.

Returns true if some new text was added to the buffer, or false if the buffer has reached the end of the input text.

bool    lex_next_chunk(U32 flags)
lex_peek_unichar

NOTE: this function is experimental and may change or be removed without notice.

Looks ahead one (Unicode) character in the text currently being lexed. Returns the codepoint (unsigned integer value) of the next character, or -1 if lexing has reached the end of the input text. To consume the peeked character, use "lex_read_unichar".

If the next character is in (or extends into) the next chunk of input text, the next chunk will be read in. Normally the current chunk will be discarded at the same time, but if flags has the LEX_KEEP_PREVIOUS bit set, then the current chunk will not be discarded.

If the input is being interpreted as UTF-8 and a UTF-8 encoding error is encountered, an exception is generated.

I32     lex_peek_unichar(U32 flags)
lex_read_space

NOTE: this function is experimental and may change or be removed without notice.

Reads optional spaces, in Perl style, in the text currently being lexed. The spaces may include ordinary whitespace characters and Perl-style comments. #line directives are processed if encountered. "PL_parser->bufptr" is moved past the spaces, so that it points at a non-space character (or the end of the input text).

If spaces extend into the next chunk of input text, the next chunk will be read in. Normally the current chunk will be discarded at the same time, but if flags has the LEX_KEEP_PREVIOUS bit set, then the current chunk will not be discarded.

void    lex_read_space(U32 flags)
lex_read_to

NOTE: this function is experimental and may change or be removed without notice.

Consume text in the lexer buffer, from "PL_parser->bufptr" up to ptr. This advances "PL_parser->bufptr" to match ptr, performing the correct bookkeeping whenever a newline character is passed. This is the normal way to consume lexed text.

Interpretation of the buffer's octets can be abstracted out by using the slightly higher-level functions "lex_peek_unichar" and "lex_read_unichar".

void    lex_read_to(char *ptr)
lex_read_unichar

NOTE: this function is experimental and may change or be removed without notice.

Reads the next (Unicode) character in the text currently being lexed. Returns the codepoint (unsigned integer value) of the character read, and moves "PL_parser->bufptr" past the character, or returns -1 if lexing has reached the end of the input text. To non-destructively examine the next character, use "lex_peek_unichar" instead.

If the next character is in (or extends into) the next chunk of input text, the next chunk will be read in. Normally the current chunk will be discarded at the same time, but if flags has the LEX_KEEP_PREVIOUS bit set, then the current chunk will not be discarded.

If the input is being interpreted as UTF-8 and a UTF-8 encoding error is encountered, an exception is generated.

I32     lex_read_unichar(U32 flags)
lex_start

NOTE: this function is experimental and may change or be removed without notice.

Creates and initialises a new lexer/parser state object, supplying a context in which to lex and parse from a new source of Perl code. A pointer to the new state object is placed in "PL_parser". An entry is made on the save stack so that upon unwinding, the new state object will be destroyed and the former value of "PL_parser" will be restored. Nothing else need be done to clean up the parsing context.

The code to be parsed comes from line and rsfp. line, if non-null, provides a string (in SV form) containing code to be parsed. A copy of the string is made, so subsequent modification of line does not affect parsing. rsfp, if non-null, provides an input stream from which code will be read to be parsed. If both are non-null, the code in line comes first and must consist of complete lines of input, and rsfp supplies the remainder of the source.

The flags parameter is reserved for future use. Currently it is only used by perl internally, so extensions should always pass zero.

void    lex_start(SV *line, PerlIO *rsfp, U32 flags)
lex_stuff_pv

NOTE: this function is experimental and may change or be removed without notice.

Insert characters into the lexer buffer ("PL_parser->linestr"), immediately after the current lexing point ("PL_parser->bufptr"), reallocating the buffer if necessary. This means that lexing code that runs later will see the characters as if they had appeared in the input. It is not recommended to do this as part of normal parsing, and most uses of this facility run the risk of the inserted characters being interpreted in an unintended manner.

The string to be inserted is represented by octets starting at pv and continuing to the first nul. These octets are interpreted as either UTF-8 or Latin-1, according to whether the LEX_STUFF_UTF8 flag is set in flags. The characters are recoded for the lexer buffer, according to how the buffer is currently being interpreted ("lex_bufutf8"). If it is not convenient to nul-terminate a string to be inserted, the "lex_stuff_pvn" function is more appropriate.

void    lex_stuff_pv(const char *pv, U32 flags)
lex_stuff_pvn

NOTE: this function is experimental and may change or be removed without notice.

Insert characters into the lexer buffer ("PL_parser->linestr"), immediately after the current lexing point ("PL_parser->bufptr"), reallocating the buffer if necessary. This means that lexing code that runs later will see the characters as if they had appeared in the input. It is not recommended to do this as part of normal parsing, and most uses of this facility run the risk of the inserted characters being interpreted in an unintended manner.

The string to be inserted is represented by len octets starting at pv. These octets are interpreted as either UTF-8 or Latin-1, according to whether the LEX_STUFF_UTF8 flag is set in flags. The characters are recoded for the lexer buffer, according to how the buffer is currently being interpreted ("lex_bufutf8"). If a string to be inserted is available as a Perl scalar, the "lex_stuff_sv" function is more convenient.

void    lex_stuff_pvn(const char *pv, STRLEN len,
                      U32 flags)
lex_stuff_pvs

NOTE: this function is experimental and may change or be removed without notice.

Like "lex_stuff_pvn", but takes a literal string instead of a string/length pair.

void    lex_stuff_pvs("literal string" pv, U32 flags)
lex_stuff_sv

NOTE: this function is experimental and may change or be removed without notice.

Insert characters into the lexer buffer ("PL_parser->linestr"), immediately after the current lexing point ("PL_parser->bufptr"), reallocating the buffer if necessary. This means that lexing code that runs later will see the characters as if they had appeared in the input. It is not recommended to do this as part of normal parsing, and most uses of this facility run the risk of the inserted characters being interpreted in an unintended manner.

The string to be inserted is the string value of sv. The characters are recoded for the lexer buffer, according to how the buffer is currently being interpreted ("lex_bufutf8"). If a string to be inserted is not already a Perl scalar, the "lex_stuff_pvn" function avoids the need to construct a scalar.

void    lex_stuff_sv(SV *sv, U32 flags)
lex_unstuff

NOTE: this function is experimental and may change or be removed without notice.

Discards text about to be lexed, from "PL_parser->bufptr" up to ptr. Text following ptr will be moved, and the buffer shortened. This hides the discarded text from any lexing code that runs later, as if the text had never appeared.

This is not the normal way to consume lexed text. For that, use "lex_read_to".

void    lex_unstuff(char *ptr)
parse_arithexpr

NOTE: this function is experimental and may change or be removed without notice.

Parse a Perl arithmetic expression. This may contain operators of precedence down to the bit shift operators. The expression must be followed (and thus terminated) either by a comparison or lower-precedence operator or by something that would normally terminate an expression such as semicolon. If flags has the PARSE_OPTIONAL bit set, then the expression is optional, otherwise it is mandatory. It is up to the caller to ensure that the dynamic parser state ("PL_parser" et al) is correctly set to reflect the source of the code to be parsed and the lexical context for the expression.

The op tree representing the expression is returned. If an optional expression is absent, a null pointer is returned, otherwise the pointer will be non-null.

If an error occurs in parsing or compilation, in most cases a valid op tree is returned anyway. The error is reflected in the parser state, normally resulting in a single exception at the top level of parsing which covers all the compilation errors that occurred. Some compilation errors, however, will throw an exception immediately.

OP *    parse_arithexpr(U32 flags)
parse_barestmt

NOTE: this function is experimental and may change or be removed without notice.

Parse a single unadorned Perl statement. This may be a normal imperative statement or a declaration that has compile-time effect. It does not include any label or other affixture. It is up to the caller to ensure that the dynamic parser state ("PL_parser" et al) is correctly set to reflect the source of the code to be parsed and the lexical context for the statement.

The op tree representing the statement is returned. This may be a null pointer if the statement is null, for example if it was actually a subroutine definition (which has compile-time side effects). If not null, it will be ops directly implementing the statement, suitable to pass to "newSTATEOP". It will not normally include a nextstate or equivalent op (except for those embedded in a scope contained entirely within the statement).

If an error occurs in parsing or compilation, in most cases a valid op tree (most likely null) is returned anyway. The error is reflected in the parser state, normally resulting in a single exception at the top level of parsing which covers all the compilation errors that occurred. Some compilation errors, however, will throw an exception immediately.

The flags parameter is reserved for future use, and must always be zero.

OP *    parse_barestmt(U32 flags)
parse_block

NOTE: this function is experimental and may change or be removed without notice.

Parse a single complete Perl code block. This consists of an opening brace, a sequence of statements, and a closing brace. The block constitutes a lexical scope, so my variables and various compile-time effects can be contained within it. It is up to the caller to ensure that the dynamic parser state ("PL_parser" et al) is correctly set to reflect the source of the code to be parsed and the lexical context for the statement.

The op tree representing the code block is returned. This is always a real op, never a null pointer. It will normally be a lineseq list, including nextstate or equivalent ops. No ops to construct any kind of runtime scope are included by virtue of it being a block.

If an error occurs in parsing or compilation, in most cases a valid op tree (most likely null) is returned anyway. The error is reflected in the parser state, normally resulting in a single exception at the top level of parsing which covers all the compilation errors that occurred. Some compilation errors, however, will throw an exception immediately.

The flags parameter is reserved for future use, and must always be zero.

OP *    parse_block(U32 flags)
parse_fullexpr

NOTE: this function is experimental and may change or be removed without notice.

Parse a single complete Perl expression. This allows the full expression grammar, including the lowest-precedence operators such as or. The expression must be followed (and thus terminated) by a token that an expression would normally be terminated by: end-of-file, closing bracketing punctuation, semicolon, or one of the keywords that signals a postfix expression-statement modifier. If flags has the PARSE_OPTIONAL bit set, then the expression is optional, otherwise it is mandatory. It is up to the caller to ensure that the dynamic parser state ("PL_parser" et al) is correctly set to reflect the source of the code to be parsed and the lexical context for the expression.

The op tree representing the expression is returned. If an optional expression is absent, a null pointer is returned, otherwise the pointer will be non-null.

If an error occurs in parsing or compilation, in most cases a valid op tree is returned anyway. The error is reflected in the parser state, normally resulting in a single exception at the top level of parsing which covers all the compilation errors that occurred. Some compilation errors, however, will throw an exception immediately.

OP *    parse_fullexpr(U32 flags)
parse_fullstmt

NOTE: this function is experimental and may change or be removed without notice.

Parse a single complete Perl statement. This may be a normal imperative statement or a declaration that has compile-time effect, and may include optional labels. It is up to the caller to ensure that the dynamic parser state ("PL_parser" et al) is correctly set to reflect the source of the code to be parsed and the lexical context for the statement.

The op tree representing the statement is returned. This may be a null pointer if the statement is null, for example if it was actually a subroutine definition (which has compile-time side effects). If not null, it will be the result of a "newSTATEOP" call, normally including a nextstate or equivalent op.

If an error occurs in parsing or compilation, in most cases a valid op tree (most likely null) is returned anyway. The error is reflected in the parser state, normally resulting in a single exception at the top level of parsing which covers all the compilation errors that occurred. Some compilation errors, however, will throw an exception immediately.

The flags parameter is reserved for future use, and must always be zero.

OP *    parse_fullstmt(U32 flags)
parse_label

NOTE: this function is experimental and may change or be removed without notice.

Parse a single label, possibly optional, of the type that may prefix a Perl statement. It is up to the caller to ensure that the dynamic parser state ("PL_parser" et al) is correctly set to reflect the source of the code to be parsed. If flags has the PARSE_OPTIONAL bit set, then the label is optional, otherwise it is mandatory.

The name of the label is returned in the form of a fresh scalar. If an optional label is absent, a null pointer is returned.

If an error occurs in parsing, which can only occur if the label is mandatory, a valid label is returned anyway. The error is reflected in the parser state, normally resulting in a single exception at the top level of parsing which covers all the compilation errors that occurred.

SV *    parse_label(U32 flags)
parse_listexpr

NOTE: this function is experimental and may change or be removed without notice.

Parse a Perl list expression. This may contain operators of precedence down to the comma operator. The expression must be followed (and thus terminated) either by a low-precedence logic operator such as or or by something that would normally terminate an expression such as semicolon. If flags has the PARSE_OPTIONAL bit set, then the expression is optional, otherwise it is mandatory. It is up to the caller to ensure that the dynamic parser state ("PL_parser" et al) is correctly set to reflect the source of the code to be parsed and the lexical context for the expression.

The op tree representing the expression is returned. If an optional expression is absent, a null pointer is returned, otherwise the pointer will be non-null.

If an error occurs in parsing or compilation, in most cases a valid op tree is returned anyway. The error is reflected in the parser state, normally resulting in a single exception at the top level of parsing which covers all the compilation errors that occurred. Some compilation errors, however, will throw an exception immediately.

OP *    parse_listexpr(U32 flags)
parse_stmtseq

NOTE: this function is experimental and may change or be removed without notice.

Parse a sequence of zero or more Perl statements. These may be normal imperative statements, including optional labels, or declarations that have compile-time effect, or any mixture thereof. The statement sequence ends when a closing brace or end-of-file is encountered in a place where a new statement could have validly started. It is up to the caller to ensure that the dynamic parser state ("PL_parser" et al) is correctly set to reflect the source of the code to be parsed and the lexical context for the statements.

The op tree representing the statement sequence is returned. This may be a null pointer if the statements were all null, for example if there were no statements or if there were only subroutine definitions (which have compile-time side effects). If not null, it will be a lineseq list, normally including nextstate or equivalent ops.

If an error occurs in parsing or compilation, in most cases a valid op tree is returned anyway. The error is reflected in the parser state, normally resulting in a single exception at the top level of parsing which covers all the compilation errors that occurred. Some compilation errors, however, will throw an exception immediately.

The flags parameter is reserved for future use, and must always be zero.

OP *    parse_stmtseq(U32 flags)
parse_termexpr

NOTE: this function is experimental and may change or be removed without notice.

Parse a Perl term expression. This may contain operators of precedence down to the assignment operators. The expression must be followed (and thus terminated) either by a comma or lower-precedence operator or by something that would normally terminate an expression such as semicolon. If flags has the PARSE_OPTIONAL bit set, then the expression is optional, otherwise it is mandatory. It is up to the caller to ensure that the dynamic parser state ("PL_parser" et al) is correctly set to reflect the source of the code to be parsed and the lexical context for the expression.

The op tree representing the expression is returned. If an optional expression is absent, a null pointer is returned, otherwise the pointer will be non-null.

If an error occurs in parsing or compilation, in most cases a valid op tree is returned anyway. The error is reflected in the parser state, normally resulting in a single exception at the top level of parsing which covers all the compilation errors that occurred. Some compilation errors, however, will throw an exception immediately.

OP *    parse_termexpr(U32 flags)
PL_parser

Pointer to a structure encapsulating the state of the parsing operation currently in progress. The pointer can be locally changed to perform a nested parse without interfering with the state of an outer parse. Individual members of PL_parser have their own documentation.

PL_parser->bufend

NOTE: this function is experimental and may change or be removed without notice.

Direct pointer to the end of the chunk of text currently being lexed, the end of the lexer buffer. This is equal to SvPVX(PL_parser->linestr) + SvCUR(PL_parser->linestr). A NUL character (zero octet) is always located at the end of the buffer, and does not count as part of the buffer's contents.

PL_parser->bufptr

NOTE: this function is experimental and may change or be removed without notice.

Points to the current position of lexing inside the lexer buffer. Characters around this point may be freely examined, within the range delimited by SvPVX("PL_parser->linestr") and "PL_parser->bufend". The octets of the buffer may be intended to be interpreted as either UTF-8 or Latin-1, as indicated by "lex_bufutf8".

Lexing code (whether in the Perl core or not) moves this pointer past the characters that it consumes. It is also expected to perform some bookkeeping whenever a newline character is consumed. This movement can be more conveniently performed by the function "lex_read_to", which handles newlines appropriately.

Interpretation of the buffer's octets can be abstracted out by using the slightly higher-level functions "lex_peek_unichar" and "lex_read_unichar".

PL_parser->linestart

NOTE: this function is experimental and may change or be removed without notice.

Points to the start of the current line inside the lexer buffer. This is useful for indicating at which column an error occurred, and not much else. This must be updated by any lexing code that consumes a newline; the function "lex_read_to" handles this detail.

PL_parser->linestr

NOTE: this function is experimental and may change or be removed without notice.

Buffer scalar containing the chunk currently under consideration of the text currently being lexed. This is always a plain string scalar (for which SvPOK is true). It is not intended to be used as a scalar by normal scalar means; instead refer to the buffer directly by the pointer variables described below.

The lexer maintains various char* pointers to things in the PL_parser->linestr buffer. If PL_parser->linestr is ever reallocated, all of these pointers must be updated. Don't attempt to do this manually, but rather use "lex_grow_linestr" if you need to reallocate the buffer.

The content of the text chunk in the buffer is commonly exactly one complete line of input, up to and including a newline terminator, but there are situations where it is otherwise. The octets of the buffer may be intended to be interpreted as either UTF-8 or Latin-1. The function "lex_bufutf8" tells you which. Do not use the SvUTF8 flag on this scalar, which may disagree with it.

For direct examination of the buffer, the variable "PL_parser->bufend" points to the end of the buffer. The current lexing position is pointed to by "PL_parser->bufptr". Direct use of these pointers is usually preferable to examination of the scalar through normal scalar means.

wrap_keyword_plugin

NOTE: this function is experimental and may change or be removed without notice.

Puts a C function into the chain of keyword plugins. This is the preferred way to manipulate the "PL_keyword_plugin" variable. new_plugin is a pointer to the C function that is to be added to the keyword plugin chain, and old_plugin_p points to the storage location where a pointer to the next function in the chain will be stored. The value of new_plugin is written into the "PL_keyword_plugin" variable, while the value previously stored there is written to *old_plugin_p.

"PL_keyword_plugin" is global to an entire process, and a module wishing to hook keyword parsing may find itself invoked more than once per process, typically in different threads. To handle that situation, this function is idempotent. The location *old_plugin_p must initially (once per process) contain a null pointer. A C variable of static duration (declared at file scope, typically also marked static to give it internal linkage) will be implicitly initialised appropriately, if it does not have an explicit initialiser. This function will only actually modify the plugin chain if it finds *old_plugin_p to be null. This function is also thread safe on the small scale. It uses appropriate locking to avoid race conditions in accessing "PL_keyword_plugin".

When this function is called, the function referenced by new_plugin must be ready to be called, except for *old_plugin_p being unfilled. In a threading situation, new_plugin may be called immediately, even before this function has returned. *old_plugin_p will always be appropriately set before new_plugin is called. If new_plugin decides not to do anything special with the identifier that it is given (which is the usual case for most calls to a keyword plugin), it must chain the plugin function referenced by *old_plugin_p.

Taken all together, XS code to install a keyword plugin should typically look something like this:

static Perl_keyword_plugin_t next_keyword_plugin;
static OP *my_keyword_plugin(pTHX_
    char *keyword_plugin, STRLEN keyword_len, OP **op_ptr)
{
    if (memEQs(keyword_ptr, keyword_len,
               "my_new_keyword")) {
        ...
    } else {
        return next_keyword_plugin(aTHX_
            keyword_ptr, keyword_len, op_ptr);
    }
}
BOOT:
    wrap_keyword_plugin(my_keyword_plugin,
                        &next_keyword_plugin);

Direct access to "PL_keyword_plugin" should be avoided.

void    wrap_keyword_plugin(
            Perl_keyword_plugin_t new_plugin,
            Perl_keyword_plugin_t *old_plugin_p
        )
DECLARATION_FOR_LC_NUMERIC_MANIPULATION

This macro should be used as a statement. It declares a private variable (whose name begins with an underscore) that is needed by the other macros in this section. Failing to include this correctly should lead to a syntax error. For compatibility with C89 C compilers it should be placed in a block before any executable statements.

void    DECLARATION_FOR_LC_NUMERIC_MANIPULATION
Perl_langinfo

This is an (almost) drop-in replacement for the system nl_langinfo(3), taking the same item parameter values, and returning the same information. But it is more thread-safe than regular nl_langinfo(), and hides the quirks of Perl's locale handling from your code, and can be used on systems that lack a native nl_langinfo.

Expanding on these:

  • The reason it isn't quite a drop-in replacement is actually an advantage. The only difference is that it returns const char *, whereas plain nl_langinfo() returns char *, but you are (only by documentation) forbidden to write into the buffer. By declaring this const, the compiler enforces this restriction, so if it is violated, you know at compilation time, rather than getting segfaults at runtime.

  • It delivers the correct results for the RADIXCHAR and THOUSEP items, without you having to write extra code. The reason for the extra code would be because these are from the LC_NUMERIC locale category, which is normally kept set by Perl so that the radix is a dot, and the separator is the empty string, no matter what the underlying locale is supposed to be, and so to get the expected results, you have to temporarily toggle into the underlying locale, and later toggle back. (You could use plain nl_langinfo and "STORE_LC_NUMERIC_FORCE_TO_UNDERLYING" for this but then you wouldn't get the other advantages of Perl_langinfo(); not keeping LC_NUMERIC in the C (or equivalent) locale would break a lot of CPAN, which is expecting the radix (decimal point) character to be a dot.)

  • The system function it replaces can have its static return buffer trashed, not only by a subesequent call to that function, but by a freelocale, setlocale, or other locale change. The returned buffer of this function is not changed until the next call to it, so the buffer is never in a trashed state.

  • Its return buffer is per-thread, so it also is never overwritten by a call to this function from another thread; unlike the function it replaces.

  • But most importantly, it works on systems that don't have nl_langinfo, such as Windows, hence makes your code more portable. Of the fifty-some possible items specified by the POSIX 2008 standard, http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/langinfo.h.html, only one is completely unimplemented, though on non-Windows platforms, another significant one is also not implemented). It uses various techniques to recover the other items, including calling localeconv(3), and strftime(3), both of which are specified in C89, so should be always be available. Later strftime() versions have additional capabilities; "" is returned for those not available on your system.

    It is important to note that when called with an item that is recovered by using localeconv, the buffer from any previous explicit call to localeconv will be overwritten. This means you must save that buffer's contents if you need to access them after a call to this function. (But note that you might not want to be using localeconv() directly anyway, because of issues like the ones listed in the second item of this list (above) for RADIXCHAR and THOUSEP. You can use the methods given in perlcall to call "localeconv" in POSIX and avoid all the issues, but then you have a hash to unpack).

    The details for those items which may deviate from what this emulation returns and what a native nl_langinfo() would return are specified in I18N::Langinfo.

When using Perl_langinfo on systems that don't have a native nl_langinfo(), you must

#include "perl_langinfo.h"

before the perl.h #include. You can replace your langinfo.h #include with this one. (Doing it this way keeps out the symbols that plain langinfo.h would try to import into the namespace for code that doesn't need it.)

The original impetus for Perl_langinfo() was so that code that needs to find out the current currency symbol, floating point radix character, or digit grouping separator can use, on all systems, the simpler and more thread-friendly nl_langinfo API instead of localeconv(3) which is a pain to make thread-friendly. For other fields returned by localeconv, it is better to use the methods given in perlcall to call POSIX::localeconv(), which is thread-friendly.

const char* Perl_langinfo(const nl_item item)
Perl_setlocale

This is an (almost) drop-in replacement for the system setlocale(3), taking the same parameters, and returning the same information, except that it returns the correct underlying LC_NUMERIC locale. Regular setlocale will instead return C if the underlying locale has a non-dot decimal point character, or a non-empty thousands separator for displaying floating point numbers. This is because perl keeps that locale category such that it has a dot and empty separator, changing the locale briefly during the operations where the underlying one is required. Perl_setlocale knows about this, and compensates; regular setlocale doesn't.

Another reason it isn't completely a drop-in replacement is that it is declared to return const char *, whereas the system setlocale omits the const (presumably because its API was specified long ago, and can't be updated; it is illegal to change the information setlocale returns; doing so leads to segfaults.)

Finally, Perl_setlocale works under all circumstances, whereas plain setlocale can be completely ineffective on some platforms under some configurations.

Perl_setlocale should not be used to change the locale except on systems where the predefined variable ${^SAFE_LOCALES} is 1. On some such systems, the system setlocale() is ineffective, returning the wrong information, and failing to actually change the locale. Perl_setlocale, however works properly in all circumstances.

The return points to a per-thread static buffer, which is overwritten the next time Perl_setlocale is called from the same thread.

const char* Perl_setlocale(const int category,
                           const char* locale)
RESTORE_LC_NUMERIC

This is used in conjunction with one of the macros "STORE_LC_NUMERIC_SET_TO_NEEDED" and "STORE_LC_NUMERIC_FORCE_TO_UNDERLYING" to properly restore the LC_NUMERIC state.

A call to "DECLARATION_FOR_LC_NUMERIC_MANIPULATION" must have been made to declare at compile time a private variable used by this macro and the two STORE ones. This macro should be called as a single statement, not an expression, but with an empty argument list, like this:

{
   DECLARATION_FOR_LC_NUMERIC_MANIPULATION;
    ...
   RESTORE_LC_NUMERIC();
    ...
}

       void    RESTORE_LC_NUMERIC()
STORE_LC_NUMERIC_FORCE_TO_UNDERLYING

This is used by XS code that that is LC_NUMERIC locale-aware to force the locale for category LC_NUMERIC to be what perl thinks is the current underlying locale. (The perl interpreter could be wrong about what the underlying locale actually is if some C or XS code has called the C library function setlocale(3) behind its back; calling "sync_locale" before calling this macro will update perl's records.)

A call to "DECLARATION_FOR_LC_NUMERIC_MANIPULATION" must have been made to declare at compile time a private variable used by this macro. This macro should be called as a single statement, not an expression, but with an empty argument list, like this:

{
   DECLARATION_FOR_LC_NUMERIC_MANIPULATION;
    ...
   STORE_LC_NUMERIC_FORCE_TO_UNDERLYING();
    ...
   RESTORE_LC_NUMERIC();
    ...
}

The private variable is used to save the current locale state, so that the requisite matching call to "RESTORE_LC_NUMERIC" can restore it.

On threaded perls not operating with thread-safe functionality, this macro uses a mutex to force a critical section. Therefore the matching RESTORE should be close by, and guaranteed to be called.

void    STORE_LC_NUMERIC_FORCE_TO_UNDERLYING()
STORE_LC_NUMERIC_SET_TO_NEEDED

This is used to help wrap XS or C code that is LC_NUMERIC locale-aware. This locale category is generally kept set to a locale where the decimal radix character is a dot, and the separator between groups of digits is empty. This is because most XS code that reads floating point numbers is expecting them to have this syntax.

This macro makes sure the current LC_NUMERIC state is set properly, to be aware of locale if the call to the XS or C code from the Perl program is from within the scope of a use locale; or to ignore locale if the call is instead from outside such scope.

This macro is the start of wrapping the C or XS code; the wrap ending is done by calling the "RESTORE_LC_NUMERIC" macro after the operation. Otherwise the state can be changed that will adversely affect other XS code.

A call to "DECLARATION_FOR_LC_NUMERIC_MANIPULATION" must have been made to declare at compile time a private variable used by this macro. This macro should be called as a single statement, not an expression, but with an empty argument list, like this:

{
   DECLARATION_FOR_LC_NUMERIC_MANIPULATION;
    ...
   STORE_LC_NUMERIC_SET_TO_NEEDED();
    ...
   RESTORE_LC_NUMERIC();
    ...
}

On threaded perls not operating with thread-safe functionality, this macro uses a mutex to force a critical section. Therefore the matching RESTORE should be close by, and guaranteed to be called.

void    STORE_LC_NUMERIC_SET_TO_NEEDED()
switch_to_global_locale

On systems without locale support, or on single-threaded builds, or on platforms that do not support per-thread locale operations, this function does nothing. On such systems that do have locale support, only a locale global to the whole program is available.

On multi-threaded builds on systems that do have per-thread locale operations, this function converts the thread it is running in to use the global locale. This is for code that has not yet or cannot be updated to handle multi-threaded locale operation. As long as only a single thread is so-converted, everything works fine, as all the other threads continue to ignore the global one, so only this thread looks at it.

However, on Windows systems this isn't quite true prior to Visual Studio 15, at which point Microsoft fixed a bug. A race can occur if you use the following operations on earlier Windows platforms:

POSIX::localeconv
I18N::Langinfo, items CRNCYSTR and THOUSEP
"Perl_langinfo" in perlapi, items CRNCYSTR and THOUSEP

The first item is not fixable (except by upgrading to a later Visual Studio release), but it would be possible to work around the latter two items by using the Windows API functions GetNumberFormat and GetCurrencyFormat; patches welcome.

Without this function call, threads that use the setlocale(3) system function will not work properly, as all the locale-sensitive functions will look at the per-thread locale, and setlocale will have no effect on this thread.

Perl code should convert to either call Perl_setlocale (which is a drop-in for the system setlocale) or use the methods given in perlcall to call POSIX::setlocale. Either one will transparently properly handle all cases of single- vs multi-thread, POSIX 2008-supported or not.

Non-Perl libraries, such as gtk, that call the system setlocale can continue to work if this function is called before transferring control to the library.

Upon return from the code that needs to use the global locale, sync_locale() should be called to restore the safe multi-thread operation.

void    switch_to_global_locale()
sync_locale

Perl_setlocale can be used at any time to query or change the locale (though changing the locale is antisocial and dangerous on multi-threaded systems that don't have multi-thread safe locale operations. (See "Multi-threaded operation" in perllocale). Using the system setlocale(3) should be avoided. Nevertheless, certain non-Perl libraries called from XS, such as Gtk do so, and this can't be changed. When the locale is changed by XS code that didn't use Perl_setlocale, Perl needs to be told that the locale has changed. Use this function to do so, before returning to Perl.

The return value is a boolean: TRUE if the global locale at the time of call was in effect; and FALSE if a per-thread locale was in effect. This can be used by the caller that needs to restore things as-they-were to decide whether or not to call Perl_switch_to_global_locale.

bool    sync_locale()

Magical Functions

mg_clear

Clear something magical that the SV represents. See "sv_magic".

int     mg_clear(SV* sv)
mg_copy

Copies the magic from one SV to another. See "sv_magic".

int     mg_copy(SV *sv, SV *nsv, const char *key,
                I32 klen)
mg_find

Finds the magic pointer for type matching the SV. See "sv_magic".

MAGIC*  mg_find(const SV* sv, int type)
mg_findext

Finds the magic pointer of type with the given vtbl for the SV. See "sv_magicext".

MAGIC*  mg_findext(const SV* sv, int type,
                   const MGVTBL *vtbl)
mg_free

Free any magic storage used by the SV. See "sv_magic".

int     mg_free(SV* sv)
mg_freeext

Remove any magic of type how using virtual table vtbl from the SV sv. See "sv_magic".

mg_freeext(sv, how, NULL) is equivalent to mg_free_type(sv, how).

void    mg_freeext(SV* sv, int how, const MGVTBL *vtbl)
mg_free_type

Remove any magic of type how from the SV sv. See "sv_magic".

void    mg_free_type(SV *sv, int how)
mg_get

Do magic before a value is retrieved from the SV. The type of SV must be >= SVt_PVMG. See "sv_magic".

int     mg_get(SV* sv)
mg_length

DEPRECATED! It is planned to remove this function from a future release of Perl. Do not use it for new code; remove it from existing code.

Reports on the SV's length in bytes, calling length magic if available, but does not set the UTF8 flag on sv. It will fall back to 'get' magic if there is no 'length' magic, but with no indication as to whether it called 'get' magic. It assumes sv is a PVMG or higher. Use sv_len() instead.

U32     mg_length(SV* sv)
mg_magical

Turns on the magical status of an SV. See "sv_magic".

void    mg_magical(SV* sv)
mg_set

Do magic after a value is assigned to the SV. See "sv_magic".

int     mg_set(SV* sv)
SvGETMAGIC

Invokes mg_get on an SV if it has 'get' magic. For example, this will call FETCH on a tied variable. This macro evaluates its argument more than once.

void    SvGETMAGIC(SV* sv)
SvLOCK

Arranges for a mutual exclusion lock to be obtained on sv if a suitable module has been loaded.

void    SvLOCK(SV* sv)
SvSETMAGIC

Invokes mg_set on an SV if it has 'set' magic. This is necessary after modifying a scalar, in case it is a magical variable like $| or a tied variable (it calls STORE). This macro evaluates its argument more than once.

void    SvSETMAGIC(SV* sv)
SvSetMagicSV

Like SvSetSV, but does any set magic required afterwards.

void    SvSetMagicSV(SV* dsv, SV* ssv)
SvSetMagicSV_nosteal

Like SvSetSV_nosteal, but does any set magic required afterwards.

void    SvSetMagicSV_nosteal(SV* dsv, SV* ssv)
SvSetSV

Calls sv_setsv if dsv is not the same as ssv. May evaluate arguments more than once. Does not handle 'set' magic on the destination SV.

void    SvSetSV(SV* dsv, SV* ssv)
SvSetSV_nosteal

Calls a non-destructive version of sv_setsv if dsv is not the same as ssv. May evaluate arguments more than once.

void    SvSetSV_nosteal(SV* dsv, SV* ssv)
SvSHARE

Arranges for sv to be shared between threads if a suitable module has been loaded.

void    SvSHARE(SV* sv)
sv_string_from_errnum

Generates the message string describing an OS error and returns it as an SV. errnum must be a value that errno could take, identifying the type of error.

If tgtsv is non-null then the string will be written into that SV (overwriting existing content) and it will be returned. If tgtsv is a null pointer then the string will be written into a new mortal SV which will be returned.

The message will be taken from whatever locale would be used by $!, and will be encoded in the SV in whatever manner would be used by $!. The details of this process are subject to future change. Currently, the message is taken from the C locale by default (usually producing an English message), and from the currently selected locale when in the scope of the use locale pragma. A heuristic attempt is made to decode the message from the locale's character encoding, but it will only be decoded as either UTF-8 or ISO-8859-1. It is always correctly decoded in a UTF-8 locale, usually in an ISO-8859-1 locale, and never in any other locale.

The SV is always returned containing an actual string, and with no other OK bits set. Unlike $!, a message is even yielded for errnum zero (meaning success), and if no useful message is available then a useless string (currently empty) is returned.

SV *    sv_string_from_errnum(int errnum, SV *tgtsv)
SvUNLOCK

Releases a mutual exclusion lock on sv if a suitable module has been loaded.

void    SvUNLOCK(SV* sv)

Memory Management

Copy

The XSUB-writer's interface to the C memcpy function. The src is the source, dest is the destination, nitems is the number of items, and type is the type. May fail on overlapping copies. See also "Move".

void    Copy(void* src, void* dest, int nitems, type)
CopyD

Like Copy but returns dest. Useful for encouraging compilers to tail-call optimise.

void *  CopyD(void* src, void* dest, int nitems, type)
Move

The XSUB-writer's interface to the C memmove function. The src is the source, dest is the destination, nitems is the number of items, and type is the type. Can do overlapping moves. See also "Copy".

void    Move(void* src, void* dest, int nitems, type)
MoveD

Like Move but returns dest. Useful for encouraging compilers to tail-call optimise.

void *  MoveD(void* src, void* dest, int nitems, type)
Newx

The XSUB-writer's interface to the C malloc function.

Memory obtained by this should ONLY be freed with "Safefree".

In 5.9.3, Newx() and friends replace the older New() API, and drops the first parameter, x, a debug aid which allowed callers to identify themselves. This aid has been superseded by a new build option, PERL_MEM_LOG (see "PERL_MEM_LOG" in perlhacktips). The older API is still there for use in XS modules supporting older perls.

void    Newx(void* ptr, int nitems, type)
Newxc

The XSUB-writer's interface to the C malloc function, with cast. See also "Newx".

Memory obtained by this should ONLY be freed with "Safefree".

void    Newxc(void* ptr, int nitems, type, cast)
Newxz

The XSUB-writer's interface to the C malloc function. The allocated memory is zeroed with memzero. See also "Newx".

Memory obtained by this should ONLY be freed with "Safefree".

void    Newxz(void* ptr, int nitems, type)
Poison

PoisonWith(0xEF) for catching access to freed memory.

void    Poison(void* dest, int nitems, type)
PoisonFree

PoisonWith(0xEF) for catching access to freed memory.

void    PoisonFree(void* dest, int nitems, type)
PoisonNew

PoisonWith(0xAB) for catching access to allocated but uninitialized memory.

void    PoisonNew(void* dest, int nitems, type)
PoisonWith

Fill up memory with a byte pattern (a byte repeated over and over again) that hopefully catches attempts to access uninitialized memory.

void    PoisonWith(void* dest, int nitems, type,
                   U8 byte)
Renew

The XSUB-writer's interface to the C realloc function.

Memory obtained by this should ONLY be freed with "Safefree".

void    Renew(void* ptr, int nitems, type)
Renewc

The XSUB-writer's interface to the C realloc function, with cast.

Memory obtained by this should ONLY be freed with "Safefree".

void    Renewc(void* ptr, int nitems, type, cast)
Safefree

The XSUB-writer's interface to the C free function.

This should ONLY be used on memory obtained using "Newx" and friends.

void    Safefree(void* ptr)
savepv

Perl's version of strdup(). Returns a pointer to a newly allocated string which is a duplicate of pv. The size of the string is determined by strlen(), which means it may not contain embedded NUL characters and must have a trailing NUL. The memory allocated for the new string can be freed with the Safefree() function.

On some platforms, Windows for example, all allocated memory owned by a thread is deallocated when that thread ends. So if you need that not to happen, you need to use the shared memory functions, such as "savesharedpv".

char*   savepv(const char* pv)
savepvn

Perl's version of what strndup() would be if it existed. Returns a pointer to a newly allocated string which is a duplicate of the first len bytes from pv, plus a trailing NUL byte. The memory allocated for the new string can be freed with the Safefree() function.

On some platforms, Windows for example, all allocated memory owned by a thread is deallocated when that thread ends. So if you need that not to happen, you need to use the shared memory functions, such as "savesharedpvn".

char*   savepvn(const char* pv, I32 len)
savepvs

Like savepvn, but takes a literal string instead of a string/length pair.

char*   savepvs("literal string" s)
savesharedpv

A version of savepv() which allocates the duplicate string in memory which is shared between threads.

char*   savesharedpv(const char* pv)
savesharedpvn

A version of savepvn() which allocates the duplicate string in memory which is shared between threads. (With the specific difference that a NULL pointer is not acceptable)

char*   savesharedpvn(const char *const pv,
                      const STRLEN len)
savesharedpvs

A version of savepvs() which allocates the duplicate string in memory which is shared between threads.

char*   savesharedpvs("literal string" s)
savesharedsvpv

A version of savesharedpv() which allocates the duplicate string in memory which is shared between threads.

char*   savesharedsvpv(SV *sv)
savesvpv

A version of savepv()/savepvn() which gets the string to duplicate from the passed in SV using SvPV()

On some platforms, Windows for example, all allocated memory owned by a thread is deallocated when that thread ends. So if you need that not to happen, you need to use the shared memory functions, such as "savesharedsvpv".

char*   savesvpv(SV* sv)
StructCopy

This is an architecture-independent macro to copy one structure to another.

void    StructCopy(type *src, type *dest, type)
Zero

The XSUB-writer's interface to the C memzero function. The dest is the destination, nitems is the number of items, and type is the type.

void    Zero(void* dest, int nitems, type)
ZeroD

Like Zero but returns dest. Useful for encouraging compilers to tail-call optimise.

void *  ZeroD(void* dest, int nitems, type)

Miscellaneous Functions

dump_c_backtrace

Dumps the C backtrace to the given fp.

Returns true if a backtrace could be retrieved, false if not.

bool    dump_c_backtrace(PerlIO* fp, int max_depth,
                         int skip)
fbm_compile

Analyzes the string in order to make fast searches on it using fbm_instr() -- the Boyer-Moore algorithm.

void    fbm_compile(SV* sv, U32 flags)
fbm_instr

Returns the location of the SV in the string delimited by big and bigend (bigend) is the char following the last char). It returns NULL if the string can't be found. The sv does not have to be fbm_compiled, but the search will not be as fast then.

char*   fbm_instr(unsigned char* big,
                  unsigned char* bigend, SV* littlestr,
                  U32 flags)
foldEQ

Returns true if the leading len bytes of the strings s1 and s2 are the same case-insensitively; false otherwise. Uppercase and lowercase ASCII range bytes match themselves and their opposite case counterparts. Non-cased and non-ASCII range bytes match only themselves.

I32     foldEQ(const char* a, const char* b, I32 len)
foldEQ_locale

Returns true if the leading len bytes of the strings s1 and s2 are the same case-insensitively in the current locale; false otherwise.

I32     foldEQ_locale(const char* a, const char* b,
                      I32 len)
form

Takes a sprintf-style format pattern and conventional (non-SV) arguments and returns the formatted string.

(char *) Perl_form(pTHX_ const char* pat, ...)

can be used any place a string (char *) is required:

char * s = Perl_form("%d.%d",major,minor);

Uses a single private buffer so if you want to format several strings you must explicitly copy the earlier strings away (and free the copies when you are done).

char*   form(const char* pat, ...)
getcwd_sv

Fill sv with current working directory

int     getcwd_sv(SV* sv)
get_c_backtrace_dump

Returns a SV containing a dump of depth frames of the call stack, skipping the skip innermost ones. depth of 20 is usually enough.

The appended output looks like:

... 1 10e004812:0082 Perl_croak util.c:1716 /usr/bin/perl 2 10df8d6d2:1d72 perl_parse perl.c:3975 /usr/bin/perl ...

The fields are tab-separated. The first column is the depth (zero being the innermost non-skipped frame). In the hex:offset, the hex is where the program counter was in S_parse_body, and the :offset (might be missing) tells how much inside the S_parse_body the program counter was.

The util.c:1716 is the source code file and line number.

The /usr/bin/perl is obvious (hopefully).

Unknowns are "-". Unknowns can happen unfortunately quite easily: if the platform doesn't support retrieving the information; if the binary is missing the debug information; if the optimizer has transformed the code by for example inlining.

SV*     get_c_backtrace_dump(int max_depth, int skip)
ibcmp

This is a synonym for (! foldEQ())

I32     ibcmp(const char* a, const char* b, I32 len)
ibcmp_locale

This is a synonym for (! foldEQ_locale())

I32     ibcmp_locale(const char* a, const char* b,
                     I32 len)
is_safe_syscall

Test that the given pv doesn't contain any internal NUL characters. If it does, set errno to ENOENT, optionally warn, and return FALSE.

Return TRUE if the name is safe.

Used by the IS_SAFE_SYSCALL() macro.

bool    is_safe_syscall(const char *pv, STRLEN len,
                        const char *what,
                        const char *op_name)
memEQ

Test two buffers (which may contain embedded NUL characters, to see if they are equal. The len parameter indicates the number of bytes to compare. Returns zero if equal, or non-zero if non-equal.

bool    memEQ(char* s1, char* s2, STRLEN len)
memNE

Test two buffers (which may contain embedded NUL characters, to see if they are not equal. The len parameter indicates the number of bytes to compare. Returns zero if non-equal, or non-zero if equal.

bool    memNE(char* s1, char* s2, STRLEN len)
mess

Take a sprintf-style format pattern and argument list. These are used to generate a string message. If the message does not end with a newline, then it will be extended with some indication of the current location in the code, as described for "mess_sv".

Normally, the resulting message is returned in a new mortal SV. During global destruction a single SV may be shared between uses of this function.

SV *    mess(const char *pat, ...)
mess_sv

Expands a message, intended for the user, to include an indication of the current location in the code, if the message does not already appear to be complete.

basemsg is the initial message or object. If it is a reference, it will be used as-is and will be the result of this function. Otherwise it is used as a string, and if it already ends with a newline, it is taken to be complete, and the result of this function will be the same string. If the message does not end with a newline, then a segment such as at foo.pl line 37 will be appended, and possibly other clauses indicating the current state of execution. The resulting message will end with a dot and a newline.

Normally, the resulting message is returned in a new mortal SV. During global destruction a single SV may be shared between uses of this function. If consume is true, then the function is permitted (but not required) to modify and return basemsg instead of allocating a new SV.

SV *    mess_sv(SV *basemsg, bool consume)
my_snprintf

The C library snprintf functionality, if available and standards-compliant (uses vsnprintf, actually). However, if the vsnprintf is not available, will unfortunately use the unsafe vsprintf which can overrun the buffer (there is an overrun check, but that may be too late). Consider using sv_vcatpvf instead, or getting vsnprintf.

int     my_snprintf(char *buffer, const Size_t len,
                    const char *format, ...)
my_strlcat

The C library strlcat if available, or a Perl implementation of it. This operates on C NUL-terminated strings.

my_strlcat() appends string src to the end of dst. It will append at most size - strlen(dst) - 1 characters. It will then NUL-terminate, unless size is 0 or the original dst string was longer than size (in practice this should not happen as it means that either size is incorrect or that dst is not a proper NUL-terminated string).

Note that size is the full size of the destination buffer and the result is guaranteed to be NUL-terminated if there is room. Note that room for the NUL should be included in size.

The return value is the total length that dst would have if size is sufficiently large. Thus it is the initial length of dst plus the length of src. If size is smaller than the return, the excess was not appended.

Size_t  my_strlcat(char *dst, const char *src,
                   Size_t size)
my_strlcpy

The C library strlcpy if available, or a Perl implementation of it. This operates on C NUL-terminated strings.

my_strlcpy() copies up to size - 1 characters from the string src to dst, NUL-terminating the result if size is not 0.

The return value is the total length src would be if the copy completely succeeded. If it is larger than size, the excess was not copied.

Size_t  my_strlcpy(char *dst, const char *src,
                   Size_t size)
my_strnlen

The C library strnlen if available, or a Perl implementation of it.

my_strnlen() computes the length of the string, up to maxlen characters. It will will never attempt to address more than maxlen characters, making it suitable for use with strings that are not guaranteed to be NUL-terminated.

Size_t  my_strnlen(const char *str, Size_t maxlen)
my_vsnprintf

The C library vsnprintf if available and standards-compliant. However, if if the vsnprintf is not available, will unfortunately use the unsafe vsprintf which can overrun the buffer (there is an overrun check, but that may be too late). Consider using sv_vcatpvf instead, or getting vsnprintf.

int     my_vsnprintf(char *buffer, const Size_t len,
                     const char *format, va_list ap)
ninstr

Find the first (leftmost) occurrence of a sequence of bytes within another sequence. This is the Perl version of strstr(), extended to handle arbitrary sequences, potentially containing embedded NUL characters (NUL is what the initial n in the function name stands for; some systems have an equivalent, memmem(), but with a somewhat different API).

Another way of thinking about this function is finding a needle in a haystack. big points to the first byte in the haystack. big_end points to one byte beyond the final byte in the haystack. little points to the first byte in the needle. little_end points to one byte beyond the final byte in the needle. All the parameters must be non-NULL.

The function returns NULL if there is no occurrence of little within big. If little is the empty string, big is returned.

Because this function operates at the byte level, and because of the inherent characteristics of UTF-8 (or UTF-EBCDIC), it will work properly if both the needle and the haystack are strings with the same UTF-8ness, but not if the UTF-8ness differs.

char *  ninstr(char * big, char * bigend, char * little,
               char * little_end)
PERL_SYS_INIT

Provides system-specific tune up of the C runtime environment necessary to run Perl interpreters. This should be called only once, before creating any Perl interpreters.

void    PERL_SYS_INIT(int *argc, char*** argv)
PERL_SYS_INIT3

Provides system-specific tune up of the C runtime environment necessary to run Perl interpreters. This should be called only once, before creating any Perl interpreters.

void    PERL_SYS_INIT3(int *argc, char*** argv,
                       char*** env)
PERL_SYS_TERM

Provides system-specific clean up of the C runtime environment after running Perl interpreters. This should be called only once, after freeing any remaining Perl interpreters.

void    PERL_SYS_TERM()
quadmath_format_needed

quadmath_format_needed() returns true if the format string seems to contain at least one non-Q-prefixed %[efgaEFGA] format specifier, or returns false otherwise.

The format specifier detection is not complete printf-syntax detection, but it should catch most common cases.

If true is returned, those arguments should in theory be processed with quadmath_snprintf(), but in case there is more than one such format specifier (see "quadmath_format_single"), and if there is anything else beyond that one (even just a single byte), they cannot be processed because quadmath_snprintf() is very strict, accepting only one format spec, and nothing else. In this case, the code should probably fail.

bool    quadmath_format_needed(const char* format)
quadmath_format_single

quadmath_snprintf() is very strict about its format string and will fail, returning -1, if the format is invalid. It accepts exactly one format spec.

quadmath_format_single() checks that the intended single spec looks sane: begins with %, has only one %, ends with [efgaEFGA], and has Q before it. This is not a full "printf syntax check", just the basics.

Returns the format if it is valid, NULL if not.

quadmath_format_single() can and will actually patch in the missing Q, if necessary. In this case it will return the modified copy of the format, which the caller will need to free.

See also "quadmath_format_needed".

const char* quadmath_format_single(const char* format)
READ_XDIGIT

Returns the value of an ASCII-range hex digit and advances the string pointer. Behaviour is only well defined when isXDIGIT(*str) is true.

U8      READ_XDIGIT(char str*)
rninstr

Like "ninstr", but instead finds the final (rightmost) occurrence of a sequence of bytes within another sequence, returning NULL if there is no such occurrence.

char *  rninstr(char * big, char * bigend,
                char * little, char * little_end)
strEQ

Test two NUL-terminated strings to see if they are equal. Returns true or false.

bool    strEQ(char* s1, char* s2)
strGE

Test two NUL-terminated strings to see if the first, s1, is greater than or equal to the second, s2. Returns true or false.

bool    strGE(char* s1, char* s2)
strGT

Test two NUL-terminated strings to see if the first, s1, is greater than the second, s2. Returns true or false.

bool    strGT(char* s1, char* s2)
strLE

Test two NUL-terminated strings to see if the first, s1, is less than or equal to the second, s2. Returns true or false.

bool    strLE(char* s1, char* s2)
strLT

Test two NUL-terminated strings to see if the first, s1, is less than the second, s2. Returns true or false.

bool    strLT(char* s1, char* s2)
strNE

Test two NUL-terminated strings to see if they are different. Returns true or false.

bool    strNE(char* s1, char* s2)
strnEQ

Test two NUL-terminated strings to see if they are equal. The len parameter indicates the number of bytes to compare. Returns true or false. (A wrapper for strncmp).

bool    strnEQ(char* s1, char* s2, STRLEN len)
strnNE

Test two NUL-terminated strings to see if they are different. The len parameter indicates the number of bytes to compare. Returns true or false. (A wrapper for strncmp).

bool    strnNE(char* s1, char* s2, STRLEN len)
sv_destroyable

Dummy routine which reports that object can be destroyed when there is no sharing module present. It ignores its single SV argument, and returns 'true'. Exists to avoid test for a NULL function pointer and because it could potentially warn under some level of strict-ness.

bool    sv_destroyable(SV *sv)
sv_nosharing

Dummy routine which "shares" an SV when there is no sharing module present. Or "locks" it. Or "unlocks" it. In other words, ignores its single SV argument. Exists to avoid test for a NULL function pointer and because it could potentially warn under some level of strict-ness.

void    sv_nosharing(SV *sv)
vmess

pat and args are a sprintf-style format pattern and encapsulated argument list, respectively. These are used to generate a string message. If the message does not end with a newline, then it will be extended with some indication of the current location in the code, as described for "mess_sv".

Normally, the resulting message is returned in a new mortal SV. During global destruction a single SV may be shared between uses of this function.

SV *    vmess(const char *pat, va_list *args)

MRO Functions

These functions are related to the method resolution order of perl classes

mro_get_linear_isa

Returns the mro linearisation for the given stash. By default, this will be whatever mro_get_linear_isa_dfs returns unless some other MRO is in effect for the stash. The return value is a read-only AV*.

You are responsible for SvREFCNT_inc() on the return value if you plan to store it anywhere semi-permanently (otherwise it might be deleted out from under you the next time the cache is invalidated).

AV*     mro_get_linear_isa(HV* stash)
mro_method_changed_in

Invalidates method caching on any child classes of the given stash, so that they might notice the changes in this one.

Ideally, all instances of PL_sub_generation++ in perl source outside of mro.c should be replaced by calls to this.

Perl automatically handles most of the common ways a method might be redefined. However, there are a few ways you could change a method in a stash without the cache code noticing, in which case you need to call this method afterwards:

1) Directly manipulating the stash HV entries from XS code.

2) Assigning a reference to a readonly scalar constant into a stash entry in order to create a constant subroutine (like constant.pm does).

This same method is available from pure perl via, mro::method_changed_in(classname).

void    mro_method_changed_in(HV* stash)
mro_register

Registers a custom mro plugin. See perlmroapi for details.

void    mro_register(const struct mro_alg *mro)

Multicall Functions

dMULTICALL

Declare local variables for a multicall. See "LIGHTWEIGHT CALLBACKS" in perlcall.

dMULTICALL;
MULTICALL

Make a lightweight callback. See "LIGHTWEIGHT CALLBACKS" in perlcall.

MULTICALL;
POP_MULTICALL

Closing bracket for a lightweight callback. See "LIGHTWEIGHT CALLBACKS" in perlcall.

POP_MULTICALL;
PUSH_MULTICALL

Opening bracket for a lightweight callback. See "LIGHTWEIGHT CALLBACKS" in perlcall.

PUSH_MULTICALL;

Numeric functions

grok_bin

converts a string representing a binary number to numeric form.

On entry start and *len give the string to scan, *flags gives conversion flags, and result should be NULL or a pointer to an NV. The scan stops at the end of the string, or the first invalid character. Unless PERL_SCAN_SILENT_ILLDIGIT is set in *flags, encountering an invalid character will also trigger a warning. On return *len is set to the length of the scanned string, and *flags gives output flags.

If the value is <= UV_MAX it is returned as a UV, the output flags are clear, and nothing is written to *result. If the value is > UV_MAX, grok_bin returns UV_MAX, sets PERL_SCAN_GREATER_THAN_UV_MAX in the output flags, and writes the value to *result (or the value is discarded if result is NULL).

The binary number may optionally be prefixed with "0b" or "b" unless PERL_SCAN_DISALLOW_PREFIX is set in *flags on entry. If PERL_SCAN_ALLOW_UNDERSCORES is set in *flags then the binary number may use "_" characters to separate digits.

UV      grok_bin(const char* start, STRLEN* len_p,
                 I32* flags, NV *result)
grok_hex

converts a string representing a hex number to numeric form.

On entry start and *len_p give the string to scan, *flags gives conversion flags, and result should be NULL or a pointer to an NV. The scan stops at the end of the string, or the first invalid character. Unless PERL_SCAN_SILENT_ILLDIGIT is set in *flags, encountering an invalid character will also trigger a warning. On return *len is set to the length of the scanned string, and *flags gives output flags.

If the value is <= UV_MAX it is returned as a UV, the output flags are clear, and nothing is written to *result. If the value is > UV_MAX, grok_hex returns UV_MAX, sets PERL_SCAN_GREATER_THAN_UV_MAX in the output flags, and writes the value to *result (or the value is discarded if result is NULL).

The hex number may optionally be prefixed with "0x" or "x" unless PERL_SCAN_DISALLOW_PREFIX is set in *flags on entry. If PERL_SCAN_ALLOW_UNDERSCORES is set in *flags then the hex number may use "_" characters to separate digits.

UV      grok_hex(const char* start, STRLEN* len_p,
                 I32* flags, NV *result)
grok_infnan

Helper for grok_number(), accepts various ways of spelling "infinity" or "not a number", and returns one of the following flag combinations:

IS_NUMBER_INFINITY
IS_NUMBER_NAN
IS_NUMBER_INFINITY | IS_NUMBER_NEG
IS_NUMBER_NAN | IS_NUMBER_NEG
0

possibly |-ed with IS_NUMBER_TRAILING.

If an infinity or a not-a-number is recognized, *sp will point to one byte past the end of the recognized string. If the recognition fails, zero is returned, and *sp will not move.

int     grok_infnan(const char** sp, const char *send)
grok_number

Identical to grok_number_flags() with flags set to zero.

int     grok_number(const char *pv, STRLEN len,
                    UV *valuep)
grok_number_flags

Recognise (or not) a number. The type of the number is returned (0 if unrecognised), otherwise it is a bit-ORed combination of IS_NUMBER_IN_UV, IS_NUMBER_GREATER_THAN_UV_MAX, IS_NUMBER_NOT_INT, IS_NUMBER_NEG, IS_NUMBER_INFINITY, IS_NUMBER_NAN (defined in perl.h).

If the value of the number can fit in a UV, it is returned in *valuep. IS_NUMBER_IN_UV will be set to indicate that *valuep is valid, IS_NUMBER_IN_UV will never be set unless *valuep is valid, but *valuep may have been assigned to during processing even though IS_NUMBER_IN_UV is not set on return. If valuep is NULL, IS_NUMBER_IN_UV will be set for the same cases as when valuep is non-NULL, but no actual assignment (or SEGV) will occur.

IS_NUMBER_NOT_INT will be set with IS_NUMBER_IN_UV if trailing decimals were seen (in which case *valuep gives the true value truncated to an integer), and IS_NUMBER_NEG if the number is negative (in which case *valuep holds the absolute value). IS_NUMBER_IN_UV is not set if e notation was used or the number is larger than a UV.

flags allows only PERL_SCAN_TRAILING, which allows for trailing non-numeric text on an otherwise successful grok, setting IS_NUMBER_TRAILING on the result.

int     grok_number_flags(const char *pv, STRLEN len,
                          UV *valuep, U32 flags)
grok_numeric_radix

Scan and skip for a numeric decimal separator (radix).

bool    grok_numeric_radix(const char **sp,
                           const char *send)
grok_oct

converts a string representing an octal number to numeric form.

On entry start and *len give the string to scan, *flags gives conversion flags, and result should be NULL or a pointer to an NV. The scan stops at the end of the string, or the first invalid character. Unless PERL_SCAN_SILENT_ILLDIGIT is set in *flags, encountering an 8 or 9 will also trigger a warning. On return *len is set to the length of the scanned string, and *flags gives output flags.

If the value is <= UV_MAX it is returned as a UV, the output flags are clear, and nothing is written to *result. If the value is > UV_MAX, grok_oct returns UV_MAX, sets PERL_SCAN_GREATER_THAN_UV_MAX in the output flags, and writes the value to *result (or the value is discarded if result is NULL).

If PERL_SCAN_ALLOW_UNDERSCORES is set in *flags then the octal number may use "_" characters to separate digits.

UV      grok_oct(const char* start, STRLEN* len_p,
                 I32* flags, NV *result)
isinfnan

Perl_isinfnan() is utility function that returns true if the NV argument is either an infinity or a NaN, false otherwise. To test in more detail, use Perl_isinf() and Perl_isnan().

This is also the logical inverse of Perl_isfinite().

bool    isinfnan(NV nv)
Perl_signbit

NOTE: this function is experimental and may change or be removed without notice.

Return a non-zero integer if the sign bit on an NV is set, and 0 if it is not.

If Configure detects this system has a signbit() that will work with our NVs, then we just use it via the #define in perl.h. Otherwise, fall back on this implementation. The main use of this function is catching -0.0.

Configure notes: This function is called 'Perl_signbit' instead of a plain 'signbit' because it is easy to imagine a system having a signbit() function or macro that doesn't happen to work with our particular choice of NVs. We shouldn't just re-#define signbit as Perl_signbit and expect the standard system headers to be happy. Also, this is a no-context function (no pTHX_) because Perl_signbit() is usually re-#defined in perl.h as a simple macro call to the system's signbit(). Users should just always call Perl_signbit().

int     Perl_signbit(NV f)
scan_bin

For backwards compatibility. Use grok_bin instead.

NV      scan_bin(const char* start, STRLEN len,
                 STRLEN* retlen)
scan_hex

For backwards compatibility. Use grok_hex instead.

NV      scan_hex(const char* start, STRLEN len,
                 STRLEN* retlen)
scan_oct

For backwards compatibility. Use grok_oct instead.

NV      scan_oct(const char* start, STRLEN len,
                 STRLEN* retlen)

Obsolete backwards compatibility functions

Some of these are also deprecated. You can exclude these from your compiled Perl by adding this option to Configure: -Accflags='-DNO_MATHOMS'

custom_op_desc

Return the description of a given custom op. This was once used by the OP_DESC macro, but is no longer: it has only been kept for compatibility, and should not be used.

const char * custom_op_desc(const OP *o)
custom_op_name

Return the name for a given custom op. This was once used by the OP_NAME macro, but is no longer: it has only been kept for compatibility, and should not be used.

const char * custom_op_name(const OP *o)
gv_fetchmethod

See "gv_fetchmethod_autoload".

GV*     gv_fetchmethod(HV* stash, const char* name)
is_utf8_char

DEPRECATED! It is planned to remove this function from a future release of Perl. Do not use it for new code; remove it from existing code.

Tests if some arbitrary number of bytes begins in a valid UTF-8 character. Note that an INVARIANT (i.e. ASCII on non-EBCDIC machines) character is a valid UTF-8 character. The actual number of bytes in the UTF-8 character will be returned if it is valid, otherwise 0.

This function is deprecated due to the possibility that malformed input could cause reading beyond the end of the input buffer. Use "isUTF8_CHAR" instead.

STRLEN  is_utf8_char(const U8 *s)
is_utf8_char_buf

This is identical to the macro "isUTF8_CHAR".

STRLEN  is_utf8_char_buf(const U8 *buf,
                         const U8 *buf_end)
pack_cat

The engine implementing pack() Perl function. Note: parameters next_in_list and flags are not used. This call should not be used; use packlist instead.

void    pack_cat(SV *cat, const char *pat,
                 const char *patend, SV **beglist,
                 SV **endlist, SV ***next_in_list,
                 U32 flags)
pad_compname_type

Looks up the type of the lexical variable at position po in the currently-compiling pad. If the variable is typed, the stash of the class to which it is typed is returned. If not, NULL is returned.

HV *    pad_compname_type(PADOFFSET po)
sv_2pvbyte_nolen

Return a pointer to the byte-encoded representation of the SV. May cause the SV to be downgraded from UTF-8 as a side-effect.

Usually accessed via the SvPVbyte_nolen macro.

char*   sv_2pvbyte_nolen(SV* sv)
sv_2pvutf8_nolen

Return a pointer to the UTF-8-encoded representation of the SV. May cause the SV to be upgraded to UTF-8 as a side-effect.

Usually accessed via the SvPVutf8_nolen macro.

char*   sv_2pvutf8_nolen(SV* sv)
sv_2pv_nolen

Like sv_2pv(), but doesn't return the length too. You should usually use the macro wrapper SvPV_nolen(sv) instead.

char*   sv_2pv_nolen(SV* sv)
sv_catpvn_mg

Like sv_catpvn, but also handles 'set' magic.

void    sv_catpvn_mg(SV *sv, const char *ptr,
                     STRLEN len)
sv_catsv_mg

Like sv_catsv, but also handles 'set' magic.

void    sv_catsv_mg(SV *dsv, SV *ssv)
sv_force_normal

Undo various types of fakery on an SV: if the PV is a shared string, make a private copy; if we're a ref, stop refing; if we're a glob, downgrade to an xpvmg. See also "sv_force_normal_flags".

void    sv_force_normal(SV *sv)
sv_iv

A private implementation of the SvIVx macro for compilers which can't cope with complex macro expressions. Always use the macro instead.

IV      sv_iv(SV* sv)
sv_nolocking

Dummy routine which "locks" an SV when there is no locking module present. Exists to avoid test for a NULL function pointer and because it could potentially warn under some level of strict-ness.

"Superseded" by sv_nosharing().

void    sv_nolocking(SV *sv)
sv_nounlocking

Dummy routine which "unlocks" an SV when there is no locking module present. Exists to avoid test for a NULL function pointer and because it could potentially warn under some level of strict-ness.

"Superseded" by sv_nosharing().

void    sv_nounlocking(SV *sv)
sv_nv

A private implementation of the SvNVx macro for compilers which can't cope with complex macro expressions. Always use the macro instead.

NV      sv_nv(SV* sv)
sv_pv

Use the SvPV_nolen macro instead

char*   sv_pv(SV *sv)
sv_pvbyte

Use SvPVbyte_nolen instead.

char*   sv_pvbyte(SV *sv)
sv_pvbyten

A private implementation of the SvPVbyte macro for compilers which can't cope with complex macro expressions. Always use the macro instead.

char*   sv_pvbyten(SV *sv, STRLEN *lp)
sv_pvn

A private implementation of the SvPV macro for compilers which can't cope with complex macro expressions. Always use the macro instead.

char*   sv_pvn(SV *sv, STRLEN *lp)
sv_pvutf8

Use the SvPVutf8_nolen macro instead

char*   sv_pvutf8(SV *sv)
sv_pvutf8n

A private implementation of the SvPVutf8 macro for compilers which can't cope with complex macro expressions. Always use the macro instead.

char*   sv_pvutf8n(SV *sv, STRLEN *lp)
sv_taint

Taint an SV. Use SvTAINTED_on instead.

void    sv_taint(SV* sv)
sv_unref

Unsets the RV status of the SV, and decrements the reference count of whatever was being referenced by the RV. This can almost be thought of as a reversal of newSVrv. This is sv_unref_flags with the flag being zero. See "SvROK_off".

void    sv_unref(SV* sv)
sv_usepvn

Tells an SV to use ptr to find its string value. Implemented by calling sv_usepvn_flags with flags of 0, hence does not handle 'set' magic. See "sv_usepvn_flags".

void    sv_usepvn(SV* sv, char* ptr, STRLEN len)
sv_usepvn_mg

Like sv_usepvn, but also handles 'set' magic.

void    sv_usepvn_mg(SV *sv, char *ptr, STRLEN len)
sv_uv

A private implementation of the SvUVx macro for compilers which can't cope with complex macro expressions. Always use the macro instead.

UV      sv_uv(SV* sv)
unpack_str

The engine implementing unpack() Perl function. Note: parameters strbeg, new_s and ocnt are not used. This call should not be used, use unpackstring instead.

SSize_t unpack_str(const char *pat, const char *patend,
                   const char *s, const char *strbeg,
                   const char *strend, char **new_s,
                   I32 ocnt, U32 flags)
utf8_to_uvuni

DEPRECATED! It is planned to remove this function from a future release of Perl. Do not use it for new code; remove it from existing code.

Returns the Unicode code point of the first character in the string s which is assumed to be in UTF-8 encoding; retlen will be set to the length, in bytes, of that character.

Some, but not all, UTF-8 malformations are detected, and in fact, some malformed input could cause reading beyond the end of the input buffer, which is one reason why this function is deprecated. The other is that only in extremely limited circumstances should the Unicode versus native code point be of any interest to you. See "utf8_to_uvuni_buf" for alternatives.

If s points to one of the detected malformations, and UTF8 warnings are enabled, zero is returned and *retlen is set (if retlen doesn't point to NULL) to -1. If those warnings are off, the computed value if well-defined (or the Unicode REPLACEMENT CHARACTER, if not) is silently returned, and *retlen is set (if retlen isn't NULL) so that (s + *retlen) is the next possible position in s that could begin a non-malformed character. See "utf8n_to_uvchr" for details on when the REPLACEMENT CHARACTER is returned.

UV      utf8_to_uvuni(const U8 *s, STRLEN *retlen)

Optree construction

newASSIGNOP

Constructs, checks, and returns an assignment op. left and right supply the parameters of the assignment; they are consumed by this function and become part of the constructed op tree.

If optype is OP_ANDASSIGN, OP_ORASSIGN, or OP_DORASSIGN, then a suitable conditional optree is constructed. If optype is the opcode of a binary operator, such as OP_BIT_OR, then an op is constructed that performs the binary operation and assigns the result to the left argument. Either way, if optype is non-zero then flags has no effect.

If optype is zero, then a plain scalar or list assignment is constructed. Which type of assignment it is is automatically determined. flags gives the eight bits of op_flags, except that OPf_KIDS will be set automatically, and, shifted up eight bits, the eight bits of op_private, except that the bit with value 1 or 2 is automatically set as required.

OP *    newASSIGNOP(I32 flags, OP *left, I32 optype,
                    OP *right)
newBINOP

Constructs, checks, and returns an op of any binary type. type is the opcode. flags gives the eight bits of op_flags, except that OPf_KIDS will be set automatically, and, shifted up eight bits, the eight bits of op_private, except that the bit with value 1 or 2 is automatically set as required. first and last supply up to two ops to be the direct children of the binary op; they are consumed by this function and become part of the constructed op tree.

OP *    newBINOP(I32 type, I32 flags, OP *first,
                 OP *last)
newCONDOP

Constructs, checks, and returns a conditional-expression (cond_expr) op. flags gives the eight bits of op_flags, except that OPf_KIDS will be set automatically, and, shifted up eight bits, the eight bits of op_private, except that the bit with value 1 is automatically set. first supplies the expression selecting between the two branches, and trueop and falseop supply the branches; they are consumed by this function and become part of the constructed op tree.

OP *    newCONDOP(I32 flags, OP *first, OP *trueop,
                  OP *falseop)
newDEFSVOP

Constructs and returns an op to access $_.

OP *    newDEFSVOP()
newFOROP

Constructs, checks, and returns an op tree expressing a foreach loop (iteration through a list of values). This is a heavyweight loop, with structure that allows exiting the loop by last and suchlike.

sv optionally supplies the variable that will be aliased to each item in turn; if null, it defaults to $_. expr supplies the list of values to iterate over. block supplies the main body of the loop, and cont optionally supplies a continue block that operates as a second half of the body. All of these optree inputs are consumed by this function and become part of the constructed op tree.

flags gives the eight bits of op_flags for the leaveloop op and, shifted up eight bits, the eight bits of op_private for the leaveloop op, except that (in both cases) some bits will be set automatically.

OP *    newFOROP(I32 flags, OP *sv, OP *expr, OP *block,
                 OP *cont)
newGIVENOP

Constructs, checks, and returns an op tree expressing a given block. cond supplies the expression to whose value $_ will be locally aliased, and block supplies the body of the given construct; they are consumed by this function and become part of the constructed op tree. defsv_off must be zero (it used to identity the pad slot of lexical $_).

OP *    newGIVENOP(OP *cond, OP *block,
                   PADOFFSET defsv_off)
newGVOP

Constructs, checks, and returns an op of any type that involves an embedded reference to a GV. type is the opcode. flags gives the eight bits of op_flags. gv identifies the GV that the op should reference; calling this function does not transfer ownership of any reference to it.

OP *    newGVOP(I32 type, I32 flags, GV *gv)
newLISTOP

Constructs, checks, and returns an op of any list type. type is the opcode. flags gives the eight bits of op_flags, except that OPf_KIDS will be set automatically if required. first and last supply up to two ops to be direct children of the list op; they are consumed by this function and become part of the constructed op tree.

For most list operators, the check function expects all the kid ops to be present already, so calling newLISTOP(OP_JOIN, ...) (e.g.) is not appropriate. What you want to do in that case is create an op of type OP_LIST, append more children to it, and then call "op_convert_list". See "op_convert_list" for more information.

OP *    newLISTOP(I32 type, I32 flags, OP *first,
                  OP *last)
newLOGOP

Constructs, checks, and returns a logical (flow control) op. type is the opcode. flags gives the eight bits of op_flags, except that OPf_KIDS will be set automatically, and, shifted up eight bits, the eight bits of op_private, except that the bit with value 1 is automatically set. first supplies the expression controlling the flow, and other supplies the side (alternate) chain of ops; they are consumed by this function and become part of the constructed op tree.

OP *    newLOGOP(I32 type, I32 flags, OP *first,
                 OP *other)
newLOOPEX

Constructs, checks, and returns a loop-exiting op (such as goto or last). type is the opcode. label supplies the parameter determining the target of the op; it is consumed by this function and becomes part of the constructed op tree.

OP *    newLOOPEX(I32 type, OP *label)
newLOOPOP

Constructs, checks, and returns an op tree expressing a loop. This is only a loop in the control flow through the op tree; it does not have the heavyweight loop structure that allows exiting the loop by last and suchlike. flags gives the eight bits of op_flags for the top-level op, except that some bits will be set automatically as required. expr supplies the expression controlling loop iteration, and block supplies the body of the loop; they are consumed by this function and become part of the constructed op tree. debuggable is currently unused and should always be 1.

OP *    newLOOPOP(I32 flags, I32 debuggable, OP *expr,
                  OP *block)
newMETHOP

Constructs, checks, and returns an op of method type with a method name evaluated at runtime. type is the opcode. flags gives the eight bits of op_flags, except that OPf_KIDS will be set automatically, and, shifted up eight bits, the eight bits of op_private, except that the bit with value 1 is automatically set. dynamic_meth supplies an op which evaluates method name; it is consumed by this function and become part of the constructed op tree. Supported optypes: OP_METHOD.

OP *    newMETHOP(I32 type, I32 flags, OP *first)
newMETHOP_named

Constructs, checks, and returns an op of method type with a constant method name. type is the opcode. flags gives the eight bits of op_flags, and, shifted up eight bits, the eight bits of op_private. const_meth supplies a constant method name; it must be a shared COW string. Supported optypes: OP_METHOD_NAMED.

OP *    newMETHOP_named(I32 type, I32 flags,
                        SV *const_meth)
newNULLLIST

Constructs, checks, and returns a new stub op, which represents an empty list expression.

OP *    newNULLLIST()
newOP

Constructs, checks, and returns an op of any base type (any type that has no extra fields). type is the opcode. flags gives the eight bits of op_flags, and, shifted up eight bits, the eight bits of op_private.

OP *    newOP(I32 type, I32 flags)
newPADOP

Constructs, checks, and returns an op of any type that involves a reference to a pad element. type is the opcode. flags gives the eight bits of op_flags. A pad slot is automatically allocated, and is populated with sv; this function takes ownership of one reference to it.

This function only exists if Perl has been compiled to use ithreads.

OP *    newPADOP(I32 type, I32 flags, SV *sv)
newPMOP

Constructs, checks, and returns an op of any pattern matching type. type is the opcode. flags gives the eight bits of op_flags and, shifted up eight bits, the eight bits of op_private.

OP *    newPMOP(I32 type, I32 flags)
newPVOP

Constructs, checks, and returns an op of any type that involves an embedded C-level pointer (PV). type is the opcode. flags gives the eight bits of op_flags. pv supplies the C-level pointer. Depending on the op type, the memory referenced by pv may be freed when the op is destroyed. If the op is of a freeing type, pv must have been allocated using PerlMemShared_malloc.

OP *    newPVOP(I32 type, I32 flags, char *pv)
newRANGE

Constructs and returns a range op, with subordinate flip and flop ops. flags gives the eight bits of op_flags for the flip op and, shifted up eight bits, the eight bits of op_private for both the flip and range ops, except that the bit with value 1 is automatically set. left and right supply the expressions controlling the endpoints of the range; they are consumed by this function and become part of the constructed op tree.

OP *    newRANGE(I32 flags, OP *left, OP *right)
newSLICEOP

Constructs, checks, and returns an lslice (list slice) op. flags gives the eight bits of op_flags, except that OPf_KIDS will be set automatically, and, shifted up eight bits, the eight bits of op_private, except that the bit with value 1 or 2 is automatically set as required. listval and subscript supply the parameters of the slice; they are consumed by this function and become part of the constructed op tree.

OP *    newSLICEOP(I32 flags, OP *subscript,
                   OP *listval)
newSTATEOP

Constructs a state op (COP). The state op is normally a nextstate op, but will be a dbstate op if debugging is enabled for currently-compiled code. The state op is populated from PL_curcop (or PL_compiling). If label is non-null, it supplies the name of a label to attach to the state op; this function takes ownership of the memory pointed at by label, and will free it. flags gives the eight bits of op_flags for the state op.

If o is null, the state op is returned. Otherwise the state op is combined with o into a lineseq list op, which is returned. o is consumed by this function and becomes part of the returned op tree.

OP *    newSTATEOP(I32 flags, char *label, OP *o)
newSVOP

Constructs, checks, and returns an op of any type that involves an embedded SV. type is the opcode. flags gives the eight bits of op_flags. sv gives the SV to embed in the op; this function takes ownership of one reference to it.

OP *    newSVOP(I32 type, I32 flags, SV *sv)
newUNOP

Constructs, checks, and returns an op of any unary type. type is the opcode. flags gives the eight bits of op_flags, except that OPf_KIDS will be set automatically if required, and, shifted up eight bits, the eight bits of op_private, except that the bit with value 1 is automatically set. first supplies an optional op to be the direct child of the unary op; it is consumed by this function and become part of the constructed op tree.

OP *    newUNOP(I32 type, I32 flags, OP *first)
newUNOP_AUX

Similar to newUNOP, but creates an UNOP_AUX struct instead, with op_aux initialised to aux

OP*     newUNOP_AUX(I32 type, I32 flags, OP* first,
                    UNOP_AUX_item *aux)
newWHENOP

Constructs, checks, and returns an op tree expressing a when block. cond supplies the test expression, and block supplies the block that will be executed if the test evaluates to true; they are consumed by this function and become part of the constructed op tree. cond will be interpreted DWIMically, often as a comparison against $_, and may be null to generate a default block.

OP *    newWHENOP(OP *cond, OP *block)
newWHILEOP

Constructs, checks, and returns an op tree expressing a while loop. This is a heavyweight loop, with structure that allows exiting the loop by last and suchlike.

loop is an optional preconstructed enterloop op to use in the loop; if it is null then a suitable op will be constructed automatically. expr supplies the loop's controlling expression. block supplies the main body of the loop, and cont optionally supplies a continue block that operates as a second half of the body. All of these optree inputs are consumed by this function and become part of the constructed op tree.

flags gives the eight bits of op_flags for the leaveloop op and, shifted up eight bits, the eight bits of op_private for the leaveloop op, except that (in both cases) some bits will be set automatically. debuggable is currently unused and should always be 1. has_my can be supplied as true to force the loop body to be enclosed in its own scope.

OP *    newWHILEOP(I32 flags, I32 debuggable,
                   LOOP *loop, OP *expr, OP *block,
                   OP *cont, I32 has_my)

Optree Manipulation Functions

alloccopstash

NOTE: this function is experimental and may change or be removed without notice.

Available only under threaded builds, this function allocates an entry in PL_stashpad for the stash passed to it.

PADOFFSET alloccopstash(HV *hv)
block_end

Handles compile-time scope exit. floor is the savestack index returned by block_start, and seq is the body of the block. Returns the block, possibly modified.

OP *    block_end(I32 floor, OP *seq)
block_start

Handles compile-time scope entry. Arranges for hints to be restored on block exit and also handles pad sequence numbers to make lexical variables scope right. Returns a savestack index for use with block_end.

int     block_start(int full)
ck_entersub_args_list

Performs the default fixup of the arguments part of an entersub op tree. This consists of applying list context to each of the argument ops. This is the standard treatment used on a call marked with &, or a method call, or a call through a subroutine reference, or any other call where the callee can't be identified at compile time, or a call where the callee has no prototype.

OP *    ck_entersub_args_list(OP *entersubop)
ck_entersub_args_proto

Performs the fixup of the arguments part of an entersub op tree based on a subroutine prototype. This makes various modifications to the argument ops, from applying context up to inserting refgen ops, and checking the number and syntactic types of arguments, as directed by the prototype. This is the standard treatment used on a subroutine call, not marked with &, where the callee can be identified at compile time and has a prototype.

protosv supplies the subroutine prototype to be applied to the call. It may be a normal defined scalar, of which the string value will be used. Alternatively, for convenience, it may be a subroutine object (a CV* that has been cast to SV*) which has a prototype. The prototype supplied, in whichever form, does not need to match the actual callee referenced by the op tree.

If the argument ops disagree with the prototype, for example by having an unacceptable number of arguments, a valid op tree is returned anyway. The error is reflected in the parser state, normally resulting in a single exception at the top level of parsing which covers all the compilation errors that occurred. In the error message, the callee is referred to by the name defined by the namegv parameter.

OP *    ck_entersub_args_proto(OP *entersubop,
                               GV *namegv, SV *protosv)
ck_entersub_args_proto_or_list

Performs the fixup of the arguments part of an entersub op tree either based on a subroutine prototype or using default list-context processing. This is the standard treatment used on a subroutine call, not marked with &, where the callee can be identified at compile time.

protosv supplies the subroutine prototype to be applied to the call, or indicates that there is no prototype. It may be a normal scalar, in which case if it is defined then the string value will be used as a prototype, and if it is undefined then there is no prototype. Alternatively, for convenience, it may be a subroutine object (a CV* that has been cast to SV*), of which the prototype will be used if it has one. The prototype (or lack thereof) supplied, in whichever form, does not need to match the actual callee referenced by the op tree.

If the argument ops disagree with the prototype, for example by having an unacceptable number of arguments, a valid op tree is returned anyway. The error is reflected in the parser state, normally resulting in a single exception at the top level of parsing which covers all the compilation errors that occurred. In the error message, the callee is referred to by the name defined by the namegv parameter.

OP *    ck_entersub_args_proto_or_list(OP *entersubop,
                                       GV *namegv,
                                       SV *protosv)
cv_const_sv

If cv is a constant sub eligible for inlining, returns the constant value returned by the sub. Otherwise, returns NULL.

Constant subs can be created with newCONSTSUB or as described in "Constant Functions" in perlsub.

SV*     cv_const_sv(const CV *const cv)
cv_get_call_checker

The original form of "cv_get_call_checker_flags", which does not return checker flags. When using a checker function returned by this function, it is only safe to call it with a genuine GV as its namegv argument.

void    cv_get_call_checker(CV *cv,
                            Perl_call_checker *ckfun_p,
                            SV **ckobj_p)
cv_get_call_checker_flags

Retrieves the function that will be used to fix up a call to cv. Specifically, the function is applied to an entersub op tree for a subroutine call, not marked with &, where the callee can be identified at compile time as cv.

The C-level function pointer is returned in *ckfun_p, an SV argument for it is returned in *ckobj_p, and control flags are returned in *ckflags_p. The function is intended to be called in this manner:

entersubop = (*ckfun_p)(aTHX_ entersubop, namegv, (*ckobj_p));

In this call, entersubop is a pointer to the entersub op, which may be replaced by the check function, and namegv supplies the name that should be used by the check function to refer to the callee of the entersub op if it needs to emit any diagnostics. It is permitted to apply the check function in non-standard situations, such as to a call to a different subroutine or to a method call.

namegv may not actually be a GV. If the CALL_CHECKER_REQUIRE_GV bit is clear in *ckflags_p, it is permitted to pass a CV or other SV instead, anything that can be used as the first argument to "cv_name". If the CALL_CHECKER_REQUIRE_GV bit is set in *ckflags_p then the check function requires namegv to be a genuine GV.

By default, the check function is Perl_ck_entersub_args_proto_or_list, the SV parameter is cv itself, and the CALL_CHECKER_REQUIRE_GV flag is clear. This implements standard prototype processing. It can be changed, for a particular subroutine, by "cv_set_call_checker_flags".

If the CALL_CHECKER_REQUIRE_GV bit is set in gflags then it indicates that the caller only knows about the genuine GV version of namegv, and accordingly the corresponding bit will always be set in *ckflags_p, regardless of the check function's recorded requirements. If the CALL_CHECKER_REQUIRE_GV bit is clear in gflags then it indicates the caller knows about the possibility of passing something other than a GV as namegv, and accordingly the corresponding bit may be either set or clear in *ckflags_p, indicating the check function's recorded requirements.

gflags is a bitset passed into cv_get_call_checker_flags, in which only the CALL_CHECKER_REQUIRE_GV bit currently has a defined meaning (for which see above). All other bits should be clear.

void    cv_get_call_checker_flags(
            CV *cv, U32 gflags,
            Perl_call_checker *ckfun_p, SV **ckobj_p,
            U32 *ckflags_p
        )
cv_set_call_checker

The original form of "cv_set_call_checker_flags", which passes it the CALL_CHECKER_REQUIRE_GV flag for backward-compatibility. The effect of that flag setting is that the check function is guaranteed to get a genuine GV as its namegv argument.

void    cv_set_call_checker(CV *cv,
                            Perl_call_checker ckfun,
                            SV *ckobj)
cv_set_call_checker_flags

Sets the function that will be used to fix up a call to cv. Specifically, the function is applied to an entersub op tree for a subroutine call, not marked with &, where the callee can be identified at compile time as cv.

The C-level function pointer is supplied in ckfun, an SV argument for it is supplied in ckobj, and control flags are supplied in ckflags. The function should be defined like this:

STATIC OP * ckfun(pTHX_ OP *op, GV *namegv, SV *ckobj)

It is intended to be called in this manner:

entersubop = ckfun(aTHX_ entersubop, namegv, ckobj);

In this call, entersubop is a pointer to the entersub op, which may be replaced by the check function, and namegv supplies the name that should be used by the check function to refer to the callee of the entersub op if it needs to emit any diagnostics. It is permitted to apply the check function in non-standard situations, such as to a call to a different subroutine or to a method call.

namegv may not actually be a GV. For efficiency, perl may pass a CV or other SV instead. Whatever is passed can be used as the first argument to "cv_name". You can force perl to pass a GV by including CALL_CHECKER_REQUIRE_GV in the ckflags.

ckflags is a bitset, in which only the CALL_CHECKER_REQUIRE_GV bit currently has a defined meaning (for which see above). All other bits should be clear.

The current setting for a particular CV can be retrieved by "cv_get_call_checker_flags".

void    cv_set_call_checker_flags(
            CV *cv, Perl_call_checker ckfun, SV *ckobj,
            U32 ckflags
        )

Given the root of an optree, link the tree in execution order using the op_next pointers and return the first op executed. If this has already been done, it will not be redone, and o->op_next will be returned. If o->op_next is not already set, o should be at least an UNOP.

OP*     LINKLIST(OP *o)
newCONSTSUB

Behaves like "newCONSTSUB_flags", except that name is nul-terminated rather than of counted length, and no flags are set. (This means that name is always interpreted as Latin-1.)

CV *    newCONSTSUB(HV *stash, const char *name, SV *sv)
newCONSTSUB_flags

Construct a constant subroutine, also performing some surrounding jobs. A scalar constant-valued subroutine is eligible for inlining at compile-time, and in Perl code can be created by sub FOO () { 123 }. Other kinds of constant subroutine have other treatment.

The subroutine will have an empty prototype and will ignore any arguments when called. Its constant behaviour is determined by sv. If sv is null, the subroutine will yield an empty list. If sv points to a scalar, the subroutine will always yield that scalar. If sv points to an array, the subroutine will always yield a list of the elements of that array in list context, or the number of elements in the array in scalar context. This function takes ownership of one counted reference to the scalar or array, and will arrange for the object to live as long as the subroutine does. If sv points to a scalar then the inlining assumes that the value of the scalar will never change, so the caller must ensure that the scalar is not subsequently written to. If sv points to an array then no such assumption is made, so it is ostensibly safe to mutate the array or its elements, but whether this is really supported has not been determined.

The subroutine will have CvFILE set according to PL_curcop. Other aspects of the subroutine will be left in their default state. The caller is free to mutate the subroutine beyond its initial state after this function has returned.

If name is null then the subroutine will be anonymous, with its CvGV referring to an __ANON__ glob. If name is non-null then the subroutine will be named accordingly, referenced by the appropriate glob. name is a string of length len bytes giving a sigilless symbol name, in UTF-8 if flags has the SVf_UTF8 bit set and in Latin-1 otherwise. The name may be either qualified or unqualified. If the name is unqualified then it defaults to being in the stash specified by stash if that is non-null, or to PL_curstash if stash is null. The symbol is always added to the stash if necessary, with GV_ADDMULTI semantics.

flags should not have bits set other than SVf_UTF8.

If there is already a subroutine of the specified name, then the new sub will replace the existing one in the glob. A warning may be generated about the redefinition.

If the subroutine has one of a few special names, such as BEGIN or END, then it will be claimed by the appropriate queue for automatic running of phase-related subroutines. In this case the relevant glob will be left not containing any subroutine, even if it did contain one before. Execution of the subroutine will likely be a no-op, unless sv was a tied array or the caller modified the subroutine in some interesting way before it was executed. In the case of BEGIN, the treatment is buggy: the sub will be executed when only half built, and may be deleted prematurely, possibly causing a crash.

The function returns a pointer to the constructed subroutine. If the sub is anonymous then ownership of one counted reference to the subroutine is transferred to the caller. If the sub is named then the caller does not get ownership of a reference. In most such cases, where the sub has a non-phase name, the sub will be alive at the point it is returned by virtue of being contained in the glob that names it. A phase-named subroutine will usually be alive by virtue of the reference owned by the phase's automatic run queue. A BEGIN subroutine may have been destroyed already by the time this function returns, but currently bugs occur in that case before the caller gets control. It is the caller's responsibility to ensure that it knows which of these situations applies.

CV *    newCONSTSUB_flags(HV *stash, const char *name,
                          STRLEN len, U32 flags, SV *sv)
newXS

Used by xsubpp to hook up XSUBs as Perl subs. filename needs to be static storage, as it is used directly as CvFILE(), without a copy being made.

op_append_elem

Append an item to the list of ops contained directly within a list-type op, returning the lengthened list. first is the list-type op, and last is the op to append to the list. optype specifies the intended opcode for the list. If first is not already a list of the right type, it will be upgraded into one. If either first or last is null, the other is returned unchanged.

OP *    op_append_elem(I32 optype, OP *first, OP *last)
op_append_list

Concatenate the lists of ops contained directly within two list-type ops, returning the combined list. first and last are the list-type ops to concatenate. optype specifies the intended opcode for the list. If either first or last is not already a list of the right type, it will be upgraded into one. If either first or last is null, the other is returned unchanged.

OP *    op_append_list(I32 optype, OP *first, OP *last)
OP_CLASS

Return the class of the provided OP: that is, which of the *OP structures it uses. For core ops this currently gets the information out of PL_opargs, which does not always accurately reflect the type used; in v5.26 onwards, see also the function "op_class" which can do a better job of determining the used type.

For custom ops the type is returned from the registration, and it is up to the registree to ensure it is accurate. The value returned will be one of the OA_* constants from op.h.

U32     OP_CLASS(OP *o)
op_contextualize

Applies a syntactic context to an op tree representing an expression. o is the op tree, and context must be G_SCALAR, G_ARRAY, or G_VOID to specify the context to apply. The modified op tree is returned.

OP *    op_contextualize(OP *o, I32 context)
op_convert_list

Converts o into a list op if it is not one already, and then converts it into the specified type, calling its check function, allocating a target if it needs one, and folding constants.

A list-type op is usually constructed one kid at a time via newLISTOP, op_prepend_elem and op_append_elem. Then finally it is passed to op_convert_list to make it the right type.

OP *    op_convert_list(I32 type, I32 flags, OP *o)
OP_DESC

Return a short description of the provided OP.

const char * OP_DESC(OP *o)
op_free

Free an op. Only use this when an op is no longer linked to from any optree.

void    op_free(OP *o)
OpHAS_SIBLING

Returns true if o has a sibling

bool    OpHAS_SIBLING(OP *o)
OpLASTSIB_set

Marks o as having no further siblings. On PERL_OP_PARENT builds, marks o as having the specified parent. See also "OpMORESIB_set" and OpMAYBESIB_set. For a higher-level interface, see "op_sibling_splice".

void    OpLASTSIB_set(OP *o, OP *parent)

This function is the implementation of the "LINKLIST" macro. It should not be called directly.

OP*     op_linklist(OP *o)
op_lvalue

NOTE: this function is experimental and may change or be removed without notice.

Propagate lvalue ("modifiable") context to an op and its children. type represents the context type, roughly based on the type of op that would do the modifying, although local() is represented by OP_NULL, because it has no op type of its own (it is signalled by a flag on the lvalue op).

This function detects things that can't be modified, such as $x+1, and generates errors for them. For example, $x+1 = 2 would cause it to be called with an op of type OP_ADD and a type argument of OP_SASSIGN.

It also flags things that need to behave specially in an lvalue context, such as $$x = 5 which might have to vivify a reference in $x.

OP *    op_lvalue(OP *o, I32 type)
OpMAYBESIB_set

Conditionally does OpMORESIB_set or OpLASTSIB_set depending on whether sib is non-null. For a higher-level interface, see "op_sibling_splice".

void    OpMAYBESIB_set(OP *o, OP *sib, OP *parent)
OpMORESIB_set

Sets the sibling of o to the non-zero value sib. See also "OpLASTSIB_set" and "OpMAYBESIB_set". For a higher-level interface, see "op_sibling_splice".

void    OpMORESIB_set(OP *o, OP *sib)
OP_NAME

Return the name of the provided OP. For core ops this looks up the name from the op_type; for custom ops from the op_ppaddr.

const char * OP_NAME(OP *o)
op_null

Neutralizes an op when it is no longer needed, but is still linked to from other ops.

void    op_null(OP *o)
op_parent

Returns the parent OP of o, if it has a parent. Returns NULL otherwise. This function is only available on perls built with -DPERL_OP_PARENT.

OP*     op_parent(OP *o)
op_prepend_elem

Prepend an item to the list of ops contained directly within a list-type op, returning the lengthened list. first is the op to prepend to the list, and last is the list-type op. optype specifies the intended opcode for the list. If last is not already a list of the right type, it will be upgraded into one. If either first or last is null, the other is returned unchanged.

OP *    op_prepend_elem(I32 optype, OP *first, OP *last)
op_scope

NOTE: this function is experimental and may change or be removed without notice.

Wraps up an op tree with some additional ops so that at runtime a dynamic scope will be created. The original ops run in the new dynamic scope, and then, provided that they exit normally, the scope will be unwound. The additional ops used to create and unwind the dynamic scope will normally be an enter/leave pair, but a scope op may be used instead if the ops are simple enough to not need the full dynamic scope structure.

OP *    op_scope(OP *o)
OpSIBLING

Returns the sibling of o, or NULL if there is no sibling

OP*     OpSIBLING(OP *o)
op_sibling_splice

A general function for editing the structure of an existing chain of op_sibling nodes. By analogy with the perl-level splice() function, allows you to delete zero or more sequential nodes, replacing them with zero or more different nodes. Performs the necessary op_first/op_last housekeeping on the parent node and op_sibling manipulation on the children. The last deleted node will be marked as as the last node by updating the op_sibling/op_sibparent or op_moresib field as appropriate.

Note that op_next is not manipulated, and nodes are not freed; that is the responsibility of the caller. It also won't create a new list op for an empty list etc; use higher-level functions like op_append_elem() for that.

parent is the parent node of the sibling chain. It may passed as NULL if the splicing doesn't affect the first or last op in the chain.

start is the node preceding the first node to be spliced. Node(s) following it will be deleted, and ops will be inserted after it. If it is NULL, the first node onwards is deleted, and nodes are inserted at the beginning.

del_count is the number of nodes to delete. If zero, no nodes are deleted. If -1 or greater than or equal to the number of remaining kids, all remaining kids are deleted.

insert is the first of a chain of nodes to be inserted in place of the nodes. If NULL, no nodes are inserted.

The head of the chain of deleted ops is returned, or NULL if no ops were deleted.

For example:

action                    before      after         returns
------                    -----       -----         -------

                          P           P
splice(P, A, 2, X-Y-Z)    |           |             B-C
                          A-B-C-D     A-X-Y-Z-D

                          P           P
splice(P, NULL, 1, X-Y)   |           |             A
                          A-B-C-D     X-Y-B-C-D

                          P           P
splice(P, NULL, 3, NULL)  |           |             A-B-C
                          A-B-C-D     D

                          P           P
splice(P, B, 0, X-Y)      |           |             NULL
                          A-B-C-D     A-B-X-Y-C-D

For lower-level direct manipulation of op_sibparent and op_moresib, see "OpMORESIB_set", "OpLASTSIB_set", "OpMAYBESIB_set".

OP*     op_sibling_splice(OP *parent, OP *start,
                          int del_count, OP* insert)
OP_TYPE_IS

Returns true if the given OP is not a NULL pointer and if it is of the given type.

The negation of this macro, OP_TYPE_ISNT is also available as well as OP_TYPE_IS_NN and OP_TYPE_ISNT_NN which elide the NULL pointer check.

bool    OP_TYPE_IS(OP *o, Optype type)
OP_TYPE_IS_OR_WAS

Returns true if the given OP is not a NULL pointer and if it is of the given type or used to be before being replaced by an OP of type OP_NULL.

The negation of this macro, OP_TYPE_ISNT_AND_WASNT is also available as well as OP_TYPE_IS_OR_WAS_NN and OP_TYPE_ISNT_AND_WASNT_NN which elide the NULL pointer check.

bool    OP_TYPE_IS_OR_WAS(OP *o, Optype type)
rv2cv_op_cv

Examines an op, which is expected to identify a subroutine at runtime, and attempts to determine at compile time which subroutine it identifies. This is normally used during Perl compilation to determine whether a prototype can be applied to a function call. cvop is the op being considered, normally an rv2cv op. A pointer to the identified subroutine is returned, if it could be determined statically, and a null pointer is returned if it was not possible to determine statically.

Currently, the subroutine can be identified statically if the RV that the rv2cv is to operate on is provided by a suitable gv or const op. A gv op is suitable if the GV's CV slot is populated. A const op is suitable if the constant value must be an RV pointing to a CV. Details of this process may change in future versions of Perl. If the rv2cv op has the OPpENTERSUB_AMPER flag set then no attempt is made to identify the subroutine statically: this flag is used to suppress compile-time magic on a subroutine call, forcing it to use default runtime behaviour.

If flags has the bit RV2CVOPCV_MARK_EARLY set, then the handling of a GV reference is modified. If a GV was examined and its CV slot was found to be empty, then the gv op has the OPpEARLY_CV flag set. If the op is not optimised away, and the CV slot is later populated with a subroutine having a prototype, that flag eventually triggers the warning "called too early to check prototype".

If flags has the bit RV2CVOPCV_RETURN_NAME_GV set, then instead of returning a pointer to the subroutine it returns a pointer to the GV giving the most appropriate name for the subroutine in this context. Normally this is just the CvGV of the subroutine, but for an anonymous (CvANON) subroutine that is referenced through a GV it will be the referencing GV. The resulting GV* is cast to CV* to be returned. A null pointer is returned as usual if there is no statically-determinable subroutine.

CV *    rv2cv_op_cv(OP *cvop, U32 flags)

Pack and Unpack

packlist

The engine implementing pack() Perl function.

void    packlist(SV *cat, const char *pat,
                 const char *patend, SV **beglist,
                 SV **endlist)
unpackstring

The engine implementing the unpack() Perl function.

Using the template pat..patend, this function unpacks the string s..strend into a number of mortal SVs, which it pushes onto the perl argument (@_) stack (so you will need to issue a PUTBACK before and SPAGAIN after the call to this function). It returns the number of pushed elements.

The strend and patend pointers should point to the byte following the last character of each string.

Although this function returns its values on the perl argument stack, it doesn't take any parameters from that stack (and thus in particular there's no need to do a PUSHMARK before calling it, unlike "call_pv" for example).

SSize_t unpackstring(const char *pat,
                     const char *patend, const char *s,
                     const char *strend, U32 flags)

Pad Data Structures

CvPADLIST

NOTE: this function is experimental and may change or be removed without notice.

CV's can have CvPADLIST(cv) set to point to a PADLIST. This is the CV's scratchpad, which stores lexical variables and opcode temporary and per-thread values.

For these purposes "formats" are a kind-of CV; eval""s are too (except they're not callable at will and are always thrown away after the eval"" is done executing). Require'd files are simply evals without any outer lexical scope.

XSUBs do not have a CvPADLIST. dXSTARG fetches values from PL_curpad, but that is really the callers pad (a slot of which is allocated by every entersub). Do not get or set CvPADLIST if a CV is an XSUB (as determined by CvISXSUB()), CvPADLIST slot is reused for a different internal purpose in XSUBs.

The PADLIST has a C array where pads are stored.

The 0th entry of the PADLIST is a PADNAMELIST which represents the "names" or rather the "static type information" for lexicals. The individual elements of a PADNAMELIST are PADNAMEs. Future refactorings might stop the PADNAMELIST from being stored in the PADLIST's array, so don't rely on it. See "PadlistNAMES".

The CvDEPTH'th entry of a PADLIST is a PAD (an AV) which is the stack frame at that depth of recursion into the CV. The 0th slot of a frame AV is an AV which is @_. Other entries are storage for variables and op targets.

Iterating over the PADNAMELIST iterates over all possible pad items. Pad slots for targets (SVs_PADTMP) and GVs end up having &PL_padname_undef "names", while slots for constants have &PL_padname_const "names" (see "pad_alloc"). That &PL_padname_undef and &PL_padname_const are used is an implementation detail subject to change. To test for them, use !PadnamePV(name) and PadnamePV(name) && !PadnameLEN(name), respectively.

Only my/our variable slots get valid names. The rest are op targets/GVs/constants which are statically allocated or resolved at compile time. These don't have names by which they can be looked up from Perl code at run time through eval"" the way my/our variables can be. Since they can't be looked up by "name" but only by their index allocated at compile time (which is usually in PL_op->op_targ), wasting a name SV for them doesn't make sense.

The pad names in the PADNAMELIST have their PV holding the name of the variable. The COP_SEQ_RANGE_LOW and _HIGH fields form a range (low+1..high inclusive) of cop_seq numbers for which the name is valid. During compilation, these fields may hold the special value PERL_PADSEQ_INTRO to indicate various stages:

COP_SEQ_RANGE_LOW        _HIGH
-----------------        -----
PERL_PADSEQ_INTRO            0   variable not yet introduced:
                                 { my ($x
valid-seq#   PERL_PADSEQ_INTRO   variable in scope:
                                 { my ($x);
valid-seq#          valid-seq#   compilation of scope complete:
                                 { my ($x); .... }

When a lexical var hasn't yet been introduced, it already exists from the perspective of duplicate declarations, but not for variable lookups, e.g.

my ($x, $x); # '"my" variable $x masks earlier declaration'
my $x = $x;  # equal to my $x = $::x;

For typed lexicals PadnameTYPE points at the type stash. For our lexicals, PadnameOURSTASH points at the stash of the associated global (so that duplicate our declarations in the same package can be detected). PadnameGEN is sometimes used to store the generation number during compilation.

If PadnameOUTER is set on the pad name, then that slot in the frame AV is a REFCNT'ed reference to a lexical from "outside". Such entries are sometimes referred to as 'fake'. In this case, the name does not use 'low' and 'high' to store a cop_seq range, since it is in scope throughout. Instead 'high' stores some flags containing info about the real lexical (is it declared in an anon, and is it capable of being instantiated multiple times?), and for fake ANONs, 'low' contains the index within the parent's pad where the lexical's value is stored, to make cloning quicker.

If the 'name' is & the corresponding entry in the PAD is a CV representing a possible closure.

Note that formats are treated as anon subs, and are cloned each time write is called (if necessary).

The flag SVs_PADSTALE is cleared on lexicals each time the my() is executed, and set on scope exit. This allows the "Variable $x is not available" warning to be generated in evals, such as

{ my $x = 1; sub f { eval '$x'} } f();

For state vars, SVs_PADSTALE is overloaded to mean 'not yet initialised', but this internal state is stored in a separate pad entry.

PADLIST * CvPADLIST(CV *cv)
pad_add_name_pvs

Exactly like "pad_add_name_pvn", but takes a literal string instead of a string/length pair.

PADOFFSET pad_add_name_pvs("literal string" name,
                           U32 flags, HV *typestash,
                           HV *ourstash)
PadARRAY

NOTE: this function is experimental and may change or be removed without notice.

The C array of pad entries.

SV **   PadARRAY(PAD pad)
pad_findmy_pvs

Exactly like "pad_findmy_pvn", but takes a literal string instead of a string/length pair.

PADOFFSET pad_findmy_pvs("literal string" name,
                         U32 flags)
PadlistARRAY

NOTE: this function is experimental and may change or be removed without notice.

The C array of a padlist, containing the pads. Only subscript it with numbers >= 1, as the 0th entry is not guaranteed to remain usable.

PAD **  PadlistARRAY(PADLIST padlist)
PadlistMAX

NOTE: this function is experimental and may change or be removed without notice.

The index of the last allocated space in the padlist. Note that the last pad may be in an earlier slot. Any entries following it will be NULL in that case.

SSize_t PadlistMAX(PADLIST padlist)
PadlistNAMES

NOTE: this function is experimental and may change or be removed without notice.

The names associated with pad entries.

PADNAMELIST * PadlistNAMES(PADLIST padlist)
PadlistNAMESARRAY

NOTE: this function is experimental and may change or be removed without notice.

The C array of pad names.

PADNAME ** PadlistNAMESARRAY(PADLIST padlist)
PadlistNAMESMAX

NOTE: this function is experimental and may change or be removed without notice.

The index of the last pad name.

SSize_t PadlistNAMESMAX(PADLIST padlist)
PadlistREFCNT

NOTE: this function is experimental and may change or be removed without notice.

The reference count of the padlist. Currently this is always 1.

U32     PadlistREFCNT(PADLIST padlist)
PadMAX

NOTE: this function is experimental and may change or be removed without notice.

The index of the last pad entry.

SSize_t PadMAX(PAD pad)
PadnameLEN

NOTE: this function is experimental and may change or be removed without notice.

The length of the name.

STRLEN  PadnameLEN(PADNAME pn)
PadnamelistARRAY

NOTE: this function is experimental and may change or be removed without notice.

The C array of pad names.

PADNAME ** PadnamelistARRAY(PADNAMELIST pnl)
PadnamelistMAX

NOTE: this function is experimental and may change or be removed without notice.

The index of the last pad name.

SSize_t PadnamelistMAX(PADNAMELIST pnl)
PadnamelistREFCNT

NOTE: this function is experimental and may change or be removed without notice.

The reference count of the pad name list.

SSize_t PadnamelistREFCNT(PADNAMELIST pnl)
PadnamelistREFCNT_dec

NOTE: this function is experimental and may change or be removed without notice.

Lowers the reference count of the pad name list.

void    PadnamelistREFCNT_dec(PADNAMELIST pnl)
PadnamePV

NOTE: this function is experimental and may change or be removed without notice.

The name stored in the pad name struct. This returns NULL for a target slot.

char *  PadnamePV(PADNAME pn)
PadnameREFCNT

NOTE: this function is experimental and may change or be removed without notice.

The reference count of the pad name.

SSize_t PadnameREFCNT(PADNAME pn)
PadnameREFCNT_dec

NOTE: this function is experimental and may change or be removed without notice.

Lowers the reference count of the pad name.

void    PadnameREFCNT_dec(PADNAME pn)
PadnameSV

NOTE: this function is experimental and may change or be removed without notice.

Returns the pad name as a mortal SV.

SV *    PadnameSV(PADNAME pn)
PadnameUTF8

NOTE: this function is experimental and may change or be removed without notice.

Whether PadnamePV is in UTF-8. Currently, this is always true.

bool    PadnameUTF8(PADNAME pn)
pad_new

Create a new padlist, updating the global variables for the currently-compiling padlist to point to the new padlist. The following flags can be OR'ed together:

padnew_CLONE        this pad is for a cloned CV
padnew_SAVE         save old globals on the save stack
padnew_SAVESUB      also save extra stuff for start of sub

    PADLIST * pad_new(int flags)
PL_comppad

NOTE: this function is experimental and may change or be removed without notice.

During compilation, this points to the array containing the values part of the pad for the currently-compiling code. (At runtime a CV may have many such value arrays; at compile time just one is constructed.) At runtime, this points to the array containing the currently-relevant values for the pad for the currently-executing code.

PL_comppad_name

NOTE: this function is experimental and may change or be removed without notice.

During compilation, this points to the array containing the names part of the pad for the currently-compiling code.

PL_curpad

NOTE: this function is experimental and may change or be removed without notice.

Points directly to the body of the "PL_comppad" array. (I.e., this is PadARRAY(PL_comppad).)

Per-Interpreter Variables

PL_modglobal

PL_modglobal is a general purpose, interpreter global HV for use by extensions that need to keep information on a per-interpreter basis. In a pinch, it can also be used as a symbol table for extensions to share data among each other. It is a good idea to use keys prefixed by the package name of the extension that owns the data.

HV*     PL_modglobal
PL_na

A convenience variable which is typically used with SvPV when one doesn't care about the length of the string. It is usually more efficient to either declare a local variable and use that instead or to use the SvPV_nolen macro.

STRLEN  PL_na
PL_opfreehook

When non-NULL, the function pointed by this variable will be called each time an OP is freed with the corresponding OP as the argument. This allows extensions to free any extra attribute they have locally attached to an OP. It is also assured to first fire for the parent OP and then for its kids.

When you replace this variable, it is considered a good practice to store the possibly previously installed hook and that you recall it inside your own.

Perl_ophook_t   PL_opfreehook
PL_peepp

Pointer to the per-subroutine peephole optimiser. This is a function that gets called at the end of compilation of a Perl subroutine (or equivalently independent piece of Perl code) to perform fixups of some ops and to perform small-scale optimisations. The function is called once for each subroutine that is compiled, and is passed, as sole parameter, a pointer to the op that is the entry point to the subroutine. It modifies the op tree in place.

The peephole optimiser should never be completely replaced. Rather, add code to it by wrapping the existing optimiser. The basic way to do this can be seen in "Compile pass 3: peephole optimization" in perlguts. If the new code wishes to operate on ops throughout the subroutine's structure, rather than just at the top level, it is likely to be more convenient to wrap the "PL_rpeepp" hook.

peep_t  PL_peepp
PL_rpeepp

Pointer to the recursive peephole optimiser. This is a function that gets called at the end of compilation of a Perl subroutine (or equivalently independent piece of Perl code) to perform fixups of some ops and to perform small-scale optimisations. The function is called once for each chain of ops linked through their op_next fields; it is recursively called to handle each side chain. It is passed, as sole parameter, a pointer to the op that is at the head of the chain. It modifies the op tree in place.

The peephole optimiser should never be completely replaced. Rather, add code to it by wrapping the existing optimiser. The basic way to do this can be seen in "Compile pass 3: peephole optimization" in perlguts. If the new code wishes to operate only on ops at a subroutine's top level, rather than throughout the structure, it is likely to be more convenient to wrap the "PL_peepp" hook.

peep_t  PL_rpeepp
PL_sv_no

This is the false SV. See "PL_sv_yes". Always refer to this as &PL_sv_no.

SV      PL_sv_no
PL_sv_undef

This is the undef SV. Always refer to this as &PL_sv_undef.

SV      PL_sv_undef
PL_sv_yes

This is the true SV. See "PL_sv_no". Always refer to this as &PL_sv_yes.

SV      PL_sv_yes
PL_sv_zero

This readonly SV has a zero numeric value and a "0" string value. It's similar to "PL_sv_no" except for its string value. Can be used as a cheap alternative to mXPUSHi(0) for example. Always refer to this as &PL_sv_zero. Introduced in 5.28.

SV      PL_sv_zero

REGEXP Functions

SvRX

Convenience macro to get the REGEXP from a SV. This is approximately equivalent to the following snippet:

if (SvMAGICAL(sv))
    mg_get(sv);
if (SvROK(sv))
    sv = MUTABLE_SV(SvRV(sv));
if (SvTYPE(sv) == SVt_REGEXP)
    return (REGEXP*) sv;

NULL will be returned if a REGEXP* is not found.

REGEXP * SvRX(SV *sv)
SvRXOK

Returns a boolean indicating whether the SV (or the one it references) is a REGEXP.

If you want to do something with the REGEXP* later use SvRX instead and check for NULL.

bool    SvRXOK(SV* sv)

Stack Manipulation Macros

dMARK

Declare a stack marker variable, mark, for the XSUB. See "MARK" and "dORIGMARK".

dMARK;
dORIGMARK

Saves the original stack mark for the XSUB. See "ORIGMARK".

dORIGMARK;
dSP

Declares a local copy of perl's stack pointer for the XSUB, available via the SP macro. See "SP".

dSP;
EXTEND

Used to extend the argument stack for an XSUB's return values. Once used, guarantees that there is room for at least nitems to be pushed onto the stack.

void    EXTEND(SP, SSize_t nitems)
MARK

Stack marker variable for the XSUB. See "dMARK".

mPUSHi

Push an integer onto the stack. The stack must have room for this element. Does not use TARG. See also "PUSHi", "mXPUSHi" and "XPUSHi".

void    mPUSHi(IV iv)
mPUSHn

Push a double onto the stack. The stack must have room for this element. Does not use TARG. See also "PUSHn", "mXPUSHn" and "XPUSHn".

void    mPUSHn(NV nv)
mPUSHp

Push a string onto the stack. The stack must have room for this element. The len indicates the length of the string. Does not use TARG. See also "PUSHp", "mXPUSHp" and "XPUSHp".

void    mPUSHp(char* str, STRLEN len)
mPUSHs

Push an SV onto the stack and mortalizes the SV. The stack must have room for this element. Does not use TARG. See also "PUSHs" and "mXPUSHs".

void    mPUSHs(SV* sv)
mPUSHu

Push an unsigned integer onto the stack. The stack must have room for this element. Does not use TARG. See also "PUSHu", "mXPUSHu" and "XPUSHu".

void    mPUSHu(UV uv)
mXPUSHi

Push an integer onto the stack, extending the stack if necessary. Does not use TARG. See also "XPUSHi", "mPUSHi" and "PUSHi".

void    mXPUSHi(IV iv)
mXPUSHn

Push a double onto the stack, extending the stack if necessary. Does not use TARG. See also "XPUSHn", "mPUSHn" and "PUSHn".

void    mXPUSHn(NV nv)
mXPUSHp

Push a string onto the stack, extending the stack if necessary. The len indicates the length of the string. Does not use TARG. See also "XPUSHp", mPUSHp and PUSHp.

void    mXPUSHp(char* str, STRLEN len)
mXPUSHs

Push an SV onto the stack, extending the stack if necessary and mortalizes the SV. Does not use TARG. See also "XPUSHs" and "mPUSHs".

void    mXPUSHs(SV* sv)
mXPUSHu

Push an unsigned integer onto the stack, extending the stack if necessary. Does not use TARG. See also "XPUSHu", "mPUSHu" and "PUSHu".

void    mXPUSHu(UV uv)
ORIGMARK

The original stack mark for the XSUB. See "dORIGMARK".

POPi

Pops an integer off the stack.

IV      POPi
POPl

Pops a long off the stack.

long    POPl
POPn

Pops a double off the stack.

NV      POPn
POPp

Pops a string off the stack.

char*   POPp
POPpbytex

Pops a string off the stack which must consist of bytes i.e. characters < 256.

char*   POPpbytex
POPpx

Pops a string off the stack. Identical to POPp. There are two names for historical reasons.

char*   POPpx
POPs

Pops an SV off the stack.

SV*     POPs
POPu

Pops an unsigned integer off the stack.

UV      POPu
POPul

Pops an unsigned long off the stack.

long    POPul
PUSHi

Push an integer onto the stack. The stack must have room for this element. Handles 'set' magic. Uses TARG, so dTARGET or dXSTARG should be called to declare it. Do not call multiple TARG-oriented macros to return lists from XSUB's - see "mPUSHi" instead. See also "XPUSHi" and "mXPUSHi".

void    PUSHi(IV iv)
PUSHMARK

Opening bracket for arguments on a callback. See "PUTBACK" and perlcall.

void    PUSHMARK(SP)
PUSHmortal

Push a new mortal SV onto the stack. The stack must have room for this element. Does not use TARG. See also "PUSHs", "XPUSHmortal" and "XPUSHs".

void    PUSHmortal()
PUSHn

Push a double onto the stack. The stack must have room for this element. Handles 'set' magic. Uses TARG, so dTARGET or dXSTARG should be called to declare it. Do not call multiple TARG-oriented macros to return lists from XSUB's - see "mPUSHn" instead. See also "XPUSHn" and "mXPUSHn".

void    PUSHn(NV nv)
PUSHp

Push a string onto the stack. The stack must have room for this element. The len indicates the length of the string. Handles 'set' magic. Uses TARG, so dTARGET or dXSTARG should be called to declare it. Do not call multiple TARG-oriented macros to return lists from XSUB's - see "mPUSHp" instead. See also "XPUSHp" and "mXPUSHp".

void    PUSHp(char* str, STRLEN len)
PUSHs

Push an SV onto the stack. The stack must have room for this element. Does not handle 'set' magic. Does not use TARG. See also "PUSHmortal", "XPUSHs", and "XPUSHmortal".

void    PUSHs(SV* sv)
PUSHu

Push an unsigned integer onto the stack. The stack must have room for this element. Handles 'set' magic. Uses TARG, so dTARGET or dXSTARG should be called to declare it. Do not call multiple TARG-oriented macros to return lists from XSUB's - see "mPUSHu" instead. See also "XPUSHu" and "mXPUSHu".

void    PUSHu(UV uv)
PUTBACK

Closing bracket for XSUB arguments. This is usually handled by xsubpp. See "PUSHMARK" and perlcall for other uses.

PUTBACK;
SP

Stack pointer. This is usually handled by xsubpp. See "dSP" and SPAGAIN.

SPAGAIN

Refetch the stack pointer. Used after a callback. See perlcall.

SPAGAIN;
XPUSHi

Push an integer onto the stack, extending the stack if necessary. Handles 'set' magic. Uses TARG, so dTARGET or dXSTARG should be called to declare it. Do not call multiple TARG-oriented macros to return lists from XSUB's - see "mXPUSHi" instead. See also "PUSHi" and "mPUSHi".

void    XPUSHi(IV iv)
XPUSHmortal

Push a new mortal SV onto the stack, extending the stack if necessary. Does not use TARG. See also "XPUSHs", "PUSHmortal" and "PUSHs".

void    XPUSHmortal()
XPUSHn

Push a double onto the stack, extending the stack if necessary. Handles 'set' magic. Uses TARG, so dTARGET or dXSTARG should be called to declare it. Do not call multiple TARG-oriented macros to return lists from XSUB's - see "mXPUSHn" instead. See also "PUSHn" and "mPUSHn".

void    XPUSHn(NV nv)
XPUSHp

Push a string onto the stack, extending the stack if necessary. The len indicates the length of the string. Handles 'set' magic. Uses TARG, so dTARGET or dXSTARG should be called to declare it. Do not call multiple TARG-oriented macros to return lists from XSUB's - see "mXPUSHp" instead. See also "PUSHp" and "mPUSHp".

void    XPUSHp(char* str, STRLEN len)
XPUSHs

Push an SV onto the stack, extending the stack if necessary. Does not handle 'set' magic. Does not use TARG. See also "XPUSHmortal", PUSHs and PUSHmortal.

void    XPUSHs(SV* sv)
XPUSHu

Push an unsigned integer onto the stack, extending the stack if necessary. Handles 'set' magic. Uses TARG, so dTARGET or dXSTARG should be called to declare it. Do not call multiple TARG-oriented macros to return lists from XSUB's - see "mXPUSHu" instead. See also "PUSHu" and "mPUSHu".

void    XPUSHu(UV uv)
XSRETURN

Return from XSUB, indicating number of items on the stack. This is usually handled by xsubpp.

void    XSRETURN(int nitems)
XSRETURN_EMPTY

Return an empty list from an XSUB immediately.

XSRETURN_EMPTY;
XSRETURN_IV

Return an integer from an XSUB immediately. Uses XST_mIV.

void    XSRETURN_IV(IV iv)
XSRETURN_NO

Return &PL_sv_no from an XSUB immediately. Uses XST_mNO.

XSRETURN_NO;
XSRETURN_NV

Return a double from an XSUB immediately. Uses XST_mNV.

void    XSRETURN_NV(NV nv)
XSRETURN_PV

Return a copy of a string from an XSUB immediately. Uses XST_mPV.

void    XSRETURN_PV(char* str)
XSRETURN_UNDEF

Return &PL_sv_undef from an XSUB immediately. Uses XST_mUNDEF.

XSRETURN_UNDEF;
XSRETURN_UV

Return an integer from an XSUB immediately. Uses XST_mUV.

void    XSRETURN_UV(IV uv)
XSRETURN_YES

Return &PL_sv_yes from an XSUB immediately. Uses XST_mYES.

XSRETURN_YES;
XST_mIV

Place an integer into the specified position pos on the stack. The value is stored in a new mortal SV.

void    XST_mIV(int pos, IV iv)
XST_mNO

Place &PL_sv_no into the specified position pos on the stack.

void    XST_mNO(int pos)
XST_mNV

Place a double into the specified position pos on the stack. The value is stored in a new mortal SV.

void    XST_mNV(int pos, NV nv)
XST_mPV

Place a copy of a string into the specified position pos on the stack. The value is stored in a new mortal SV.

void    XST_mPV(int pos, char* str)
XST_mUNDEF

Place &PL_sv_undef into the specified position pos on the stack.

void    XST_mUNDEF(int pos)
XST_mYES

Place &PL_sv_yes into the specified position pos on the stack.

void    XST_mYES(int pos)

SV-Body Allocation

looks_like_number

Test if the content of an SV looks like a number (or is a number). Inf and Infinity are treated as numbers (so will not issue a non-numeric warning), even if your atof() doesn't grok them. Get-magic is ignored.

I32     looks_like_number(SV *const sv)
newRV_noinc

Creates an RV wrapper for an SV. The reference count for the original SV is not incremented.

SV*     newRV_noinc(SV *const tmpRef)
newSV

Creates a new SV. A non-zero len parameter indicates the number of bytes of preallocated string space the SV should have. An extra byte for a trailing NUL is also reserved. (SvPOK is not set for the SV even if string space is allocated.) The reference count for the new SV is set to 1.

In 5.9.3, newSV() replaces the older NEWSV() API, and drops the first parameter, x, a debug aid which allowed callers to identify themselves. This aid has been superseded by a new build option, PERL_MEM_LOG (see "PERL_MEM_LOG" in perlhacktips). The older API is still there for use in XS modules supporting older perls.

SV*     newSV(const STRLEN len)
newSVhek

Creates a new SV from the hash key structure. It will generate scalars that point to the shared string table where possible. Returns a new (undefined) SV if hek is NULL.

SV*     newSVhek(const HEK *const hek)
newSViv

Creates a new SV and copies an integer into it. The reference count for the SV is set to 1.

SV*     newSViv(const IV i)
newSVnv

Creates a new SV and copies a floating point value into it. The reference count for the SV is set to 1.

SV*     newSVnv(const NV n)
newSVpv

Creates a new SV and copies a string (which may contain NUL (\0) characters) into it. The reference count for the SV is set to 1. If len is zero, Perl will compute the length using strlen(), (which means if you use this option, that s can't have embedded NUL characters and has to have a terminating NUL byte).

This function can cause reliability issues if you are likely to pass in empty strings that are not null terminated, because it will run strlen on the string and potentially run past valid memory.

Using "newSVpvn" is a safer alternative for non NUL terminated strings. For string literals use "newSVpvs" instead. This function will work fine for NUL terminated strings, but if you want to avoid the if statement on whether to call strlen use newSVpvn instead (calling strlen yourself).

SV*     newSVpv(const char *const s, const STRLEN len)
newSVpvf

Creates a new SV and initializes it with the string formatted like sv_catpvf.

SV*     newSVpvf(const char *const pat, ...)
newSVpvn

Creates a new SV and copies a string into it, which may contain NUL characters (\0) and other binary data. The reference count for the SV is set to 1. Note that if len is zero, Perl will create a zero length (Perl) string. You are responsible for ensuring that the source buffer is at least len bytes long. If the s argument is NULL the new SV will be undefined.

SV*     newSVpvn(const char *const buffer,
                 const STRLEN len)
newSVpvn_flags

Creates a new SV and copies a string (which may contain NUL (\0) characters) into it. The reference count for the SV is set to 1. Note that if len is zero, Perl will create a zero length string. You are responsible for ensuring that the source string is at least len bytes long. If the s argument is NULL the new SV will be undefined. Currently the only flag bits accepted are SVf_UTF8 and SVs_TEMP. If SVs_TEMP is set, then sv_2mortal() is called on the result before returning. If SVf_UTF8 is set, s is considered to be in UTF-8 and the SVf_UTF8 flag will be set on the new SV. newSVpvn_utf8() is a convenience wrapper for this function, defined as

#define newSVpvn_utf8(s, len, u)                    \
    newSVpvn_flags((s), (len), (u) ? SVf_UTF8 : 0)

    SV*     newSVpvn_flags(const char *const s,
                           const STRLEN len,
                           const U32 flags)
newSVpvn_share

Creates a new SV with its SvPVX_const pointing to a shared string in the string table. If the string does not already exist in the table, it is created first. Turns on the SvIsCOW flag (or READONLY and FAKE in 5.16 and earlier). If the hash parameter is non-zero, that value is used; otherwise the hash is computed. The string's hash can later be retrieved from the SV with the SvSHARED_HASH() macro. The idea here is that as the string table is used for shared hash keys these strings will have SvPVX_const == HeKEY and hash lookup will avoid string compare.

SV*     newSVpvn_share(const char* s, I32 len, U32 hash)
newSVpvs

Like newSVpvn, but takes a literal string instead of a string/length pair.

SV*     newSVpvs("literal string" s)
newSVpvs_flags

Like newSVpvn_flags, but takes a literal string instead of a string/length pair.

SV*     newSVpvs_flags("literal string" s, U32 flags)
newSVpv_share

Like newSVpvn_share, but takes a NUL-terminated string instead of a string/length pair.

SV*     newSVpv_share(const char* s, U32 hash)
newSVpvs_share

Like newSVpvn_share, but takes a literal string instead of a string/length pair and omits the hash parameter.

SV*     newSVpvs_share("literal string" s)
newSVrv

Creates a new SV for the existing RV, rv, to point to. If rv is not an RV then it will be upgraded to one. If classname is non-null then the new SV will be blessed in the specified package. The new SV is returned and its reference count is 1. The reference count 1 is owned by rv.

SV*     newSVrv(SV *const rv,
                const char *const classname)
newSVsv

Creates a new SV which is an exact duplicate of the original SV. (Uses sv_setsv.)

SV*     newSVsv(SV *const old)
newSV_type

Creates a new SV, of the type specified. The reference count for the new SV is set to 1.

SV*     newSV_type(const svtype type)
newSVuv

Creates a new SV and copies an unsigned integer into it. The reference count for the SV is set to 1.

SV*     newSVuv(const UV u)
sv_2bool

This macro is only used by sv_true() or its macro equivalent, and only if the latter's argument is neither SvPOK, SvIOK nor SvNOK. It calls sv_2bool_flags with the SV_GMAGIC flag.

bool    sv_2bool(SV *const sv)
sv_2bool_flags

This function is only used by sv_true() and friends, and only if the latter's argument is neither SvPOK, SvIOK nor SvNOK. If the flags contain SV_GMAGIC, then it does an mg_get() first.

bool    sv_2bool_flags(SV *sv, I32 flags)
sv_2cv

Using various gambits, try to get a CV from an SV; in addition, try if possible to set *st and *gvp to the stash and GV associated with it. The flags in lref are passed to gv_fetchsv.

CV*     sv_2cv(SV* sv, HV **const st, GV **const gvp,
               const I32 lref)
sv_2io

Using various gambits, try to get an IO from an SV: the IO slot if its a GV; or the recursive result if we're an RV; or the IO slot of the symbol named after the PV if we're a string.

'Get' magic is ignored on the sv passed in, but will be called on SvRV(sv) if sv is an RV.

IO*     sv_2io(SV *const sv)
sv_2iv_flags

Return the integer value of an SV, doing any necessary string conversion. If flags has the SV_GMAGIC bit set, does an mg_get() first. Normally used via the SvIV(sv) and SvIVx(sv) macros.

IV      sv_2iv_flags(SV *const sv, const I32 flags)
sv_2mortal

Marks an existing SV as mortal. The SV will be destroyed "soon", either by an explicit call to FREETMPS, or by an implicit call at places such as statement boundaries. SvTEMP() is turned on which means that the SV's string buffer can be "stolen" if this SV is copied. See also "sv_newmortal" and "sv_mortalcopy".

SV*     sv_2mortal(SV *const sv)
sv_2nv_flags

Return the num value of an SV, doing any necessary string or integer conversion. If flags has the SV_GMAGIC bit set, does an mg_get() first. Normally used via the SvNV(sv) and SvNVx(sv) macros.

NV      sv_2nv_flags(SV *const sv, const I32 flags)
sv_2pvbyte

Return a pointer to the byte-encoded representation of the SV, and set *lp to its length. May cause the SV to be downgraded from UTF-8 as a side-effect.

Usually accessed via the SvPVbyte macro.

char*   sv_2pvbyte(SV *sv, STRLEN *const lp)
sv_2pvutf8

Return a pointer to the UTF-8-encoded representation of the SV, and set *lp to its length. May cause the SV to be upgraded to UTF-8 as a side-effect.

Usually accessed via the SvPVutf8 macro.

char*   sv_2pvutf8(SV *sv, STRLEN *const lp)
sv_2pv_flags

Returns a pointer to the string value of an SV, and sets *lp to its length. If flags has the SV_GMAGIC bit set, does an mg_get() first. Coerces sv to a string if necessary. Normally invoked via the SvPV_flags macro. sv_2pv() and sv_2pv_nomg usually end up here too.

char*   sv_2pv_flags(SV *const sv, STRLEN *const lp,
                     const I32 flags)
sv_2uv_flags

Return the unsigned integer value of an SV, doing any necessary string conversion. If flags has the SV_GMAGIC bit set, does an mg_get() first. Normally used via the SvUV(sv) and SvUVx(sv) macros.

UV      sv_2uv_flags(SV *const sv, const I32 flags)
sv_backoff

Remove any string offset. You should normally use the SvOOK_off macro wrapper instead.

void    sv_backoff(SV *const sv)
sv_bless

Blesses an SV into a specified package. The SV must be an RV. The package must be designated by its stash (see "gv_stashpv"). The reference count of the SV is unaffected.

SV*     sv_bless(SV *const sv, HV *const stash)
sv_catpv

Concatenates the NUL-terminated string onto the end of the string which is in the SV. If the SV has the UTF-8 status set, then the bytes appended should be valid UTF-8. Handles 'get' magic, but not 'set' magic. See "sv_catpv_mg".

void    sv_catpv(SV *const sv, const char* ptr)
sv_catpvf

Processes its arguments like sprintf, and appends the formatted output to an SV. As with sv_vcatpvfn called with a non-null C-style variable argument list, argument reordering is not supported. If the appended data contains "wide" characters (including, but not limited to, SVs with a UTF-8 PV formatted with %s, and characters >255 formatted with %c), the original SV might get upgraded to UTF-8. Handles 'get' magic, but not 'set' magic. See "sv_catpvf_mg". If the original SV was UTF-8, the pattern should be valid UTF-8; if the original SV was bytes, the pattern should be too.

void    sv_catpvf(SV *const sv, const char *const pat,
                  ...)
sv_catpvf_mg

Like sv_catpvf, but also handles 'set' magic.

void    sv_catpvf_mg(SV *const sv,
                     const char *const pat, ...)
sv_catpvn

Concatenates the string onto the end of the string which is in the SV. len indicates number of bytes to copy. If the SV has the UTF-8 status set, then the bytes appended should be valid UTF-8. Handles 'get' magic, but not 'set' magic. See "sv_catpvn_mg".

void    sv_catpvn(SV *dsv, const char *sstr, STRLEN len)
sv_catpvn_flags

Concatenates the string onto the end of the string which is in the SV. The len indicates number of bytes to copy.

By default, the string appended is assumed to be valid UTF-8 if the SV has the UTF-8 status set, and a string of bytes otherwise. One can force the appended string to be interpreted as UTF-8 by supplying the SV_CATUTF8 flag, and as bytes by supplying the SV_CATBYTES flag; the SV or the string appended will be upgraded to UTF-8 if necessary.

If flags has the SV_SMAGIC bit set, will mg_set on dsv afterwards if appropriate. sv_catpvn and sv_catpvn_nomg are implemented in terms of this function.

void    sv_catpvn_flags(SV *const dstr,
                        const char *sstr,
                        const STRLEN len,
                        const I32 flags)
sv_catpvs

Like sv_catpvn, but takes a literal string instead of a string/length pair.

void    sv_catpvs(SV* sv, "literal string" s)
sv_catpvs_flags

Like sv_catpvn_flags, but takes a literal string instead of a string/length pair.

void    sv_catpvs_flags(SV* sv, "literal string" s,
                        I32 flags)
sv_catpvs_mg

Like sv_catpvn_mg, but takes a literal string instead of a string/length pair.

void    sv_catpvs_mg(SV* sv, "literal string" s)
sv_catpvs_nomg

Like sv_catpvn_nomg, but takes a literal string instead of a string/length pair.

void    sv_catpvs_nomg(SV* sv, "literal string" s)
sv_catpv_flags

Concatenates the NUL-terminated string onto the end of the string which is in the SV. If the SV has the UTF-8 status set, then the bytes appended should be valid UTF-8. If flags has the SV_SMAGIC bit set, will mg_set on the modified SV if appropriate.

void    sv_catpv_flags(SV *dstr, const char *sstr,
                       const I32 flags)
sv_catpv_mg

Like sv_catpv, but also handles 'set' magic.

void    sv_catpv_mg(SV *const sv, const char *const ptr)
sv_catsv

Concatenates the string from SV ssv onto the end of the string in SV dsv. If ssv is null, does nothing; otherwise modifies only dsv. Handles 'get' magic on both SVs, but no 'set' magic. See "sv_catsv_mg" and "sv_catsv_nomg".

void    sv_catsv(SV *dstr, SV *sstr)
sv_catsv_flags

Concatenates the string from SV ssv onto the end of the string in SV dsv. If ssv is null, does nothing; otherwise modifies only dsv. If flags has the SV_GMAGIC bit set, will call mg_get on both SVs if appropriate. If flags has the SV_SMAGIC bit set, mg_set will be called on the modified SV afterward, if appropriate. sv_catsv, sv_catsv_nomg, and sv_catsv_mg are implemented in terms of this function.

void    sv_catsv_flags(SV *const dsv, SV *const ssv,
                       const I32 flags)
sv_chop

Efficient removal of characters from the beginning of the string buffer. SvPOK(sv), or at least SvPOKp(sv), must be true and ptr must be a pointer to somewhere inside the string buffer. ptr becomes the first character of the adjusted string. Uses the OOK hack. On return, only SvPOK(sv) and SvPOKp(sv) among the OK flags will be true.

Beware: after this function returns, ptr and SvPVX_const(sv) may no longer refer to the same chunk of data.

The unfortunate similarity of this function's name to that of Perl's chop operator is strictly coincidental. This function works from the left; chop works from the right.

void    sv_chop(SV *const sv, const char *const ptr)
sv_clear

Clear an SV: call any destructors, free up any memory used by the body, and free the body itself. The SV's head is not freed, although its type is set to all 1's so that it won't inadvertently be assumed to be live during global destruction etc. This function should only be called when REFCNT is zero. Most of the time you'll want to call sv_free() (or its macro wrapper SvREFCNT_dec) instead.

void    sv_clear(SV *const orig_sv)
sv_cmp

Compares the strings in two SVs. Returns -1, 0, or 1 indicating whether the string in sv1 is less than, equal to, or greater than the string in sv2. Is UTF-8 and 'use bytes' aware, handles get magic, and will coerce its args to strings if necessary. See also "sv_cmp_locale".

I32     sv_cmp(SV *const sv1, SV *const sv2)
sv_cmp_flags

Compares the strings in two SVs. Returns -1, 0, or 1 indicating whether the string in sv1 is less than, equal to, or greater than the string in sv2. Is UTF-8 and 'use bytes' aware and will coerce its args to strings if necessary. If the flags has the SV_GMAGIC bit set, it handles get magic. See also "sv_cmp_locale_flags".

I32     sv_cmp_flags(SV *const sv1, SV *const sv2,
                     const U32 flags)
sv_cmp_locale

Compares the strings in two SVs in a locale-aware manner. Is UTF-8 and 'use bytes' aware, handles get magic, and will coerce its args to strings if necessary. See also "sv_cmp".

I32     sv_cmp_locale(SV *const sv1, SV *const sv2)
sv_cmp_locale_flags

Compares the strings in two SVs in a locale-aware manner. Is UTF-8 and 'use bytes' aware and will coerce its args to strings if necessary. If the flags contain SV_GMAGIC, it handles get magic. See also "sv_cmp_flags".

I32     sv_cmp_locale_flags(SV *const sv1,
                            SV *const sv2,
                            const U32 flags)
sv_collxfrm

This calls sv_collxfrm_flags with the SV_GMAGIC flag. See "sv_collxfrm_flags".

char*   sv_collxfrm(SV *const sv, STRLEN *const nxp)
sv_collxfrm_flags

Add Collate Transform magic to an SV if it doesn't already have it. If the flags contain SV_GMAGIC, it handles get-magic.

Any scalar variable may carry PERL_MAGIC_collxfrm magic that contains the scalar data of the variable, but transformed to such a format that a normal memory comparison can be used to compare the data according to the locale settings.

char*   sv_collxfrm_flags(SV *const sv,
                          STRLEN *const nxp,
                          I32 const flags)
sv_copypv

Copies a stringified representation of the source SV into the destination SV. Automatically performs any necessary mg_get and coercion of numeric values into strings. Guaranteed to preserve UTF8 flag even from overloaded objects. Similar in nature to sv_2pv[_flags] but operates directly on an SV instead of just the string. Mostly uses sv_2pv_flags to do its work, except when that would lose the UTF-8'ness of the PV.

void    sv_copypv(SV *const dsv, SV *const ssv)
sv_copypv_flags

Implementation of sv_copypv and sv_copypv_nomg. Calls get magic iff flags has the SV_GMAGIC bit set.

void    sv_copypv_flags(SV *const dsv, SV *const ssv,
                        const I32 flags)
sv_copypv_nomg

Like sv_copypv, but doesn't invoke get magic first.

void    sv_copypv_nomg(SV *const dsv, SV *const ssv)
sv_dec

Auto-decrement of the value in the SV, doing string to numeric conversion if necessary. Handles 'get' magic and operator overloading.

void    sv_dec(SV *const sv)
sv_dec_nomg

Auto-decrement of the value in the SV, doing string to numeric conversion if necessary. Handles operator overloading. Skips handling 'get' magic.

void    sv_dec_nomg(SV *const sv)
sv_eq

Returns a boolean indicating whether the strings in the two SVs are identical. Is UTF-8 and 'use bytes' aware, handles get magic, and will coerce its args to strings if necessary.

I32     sv_eq(SV* sv1, SV* sv2)
sv_eq_flags

Returns a boolean indicating whether the strings in the two SVs are identical. Is UTF-8 and 'use bytes' aware and coerces its args to strings if necessary. If the flags has the SV_GMAGIC bit set, it handles get-magic, too.

I32     sv_eq_flags(SV* sv1, SV* sv2, const U32 flags)
sv_force_normal_flags

Undo various types of fakery on an SV, where fakery means "more than" a string: if the PV is a shared string, make a private copy; if we're a ref, stop refing; if we're a glob, downgrade to an xpvmg; if we're a copy-on-write scalar, this is the on-write time when we do the copy, and is also used locally; if this is a vstring, drop the vstring magic. If SV_COW_DROP_PV is set then a copy-on-write scalar drops its PV buffer (if any) and becomes SvPOK_off rather than making a copy. (Used where this scalar is about to be set to some other value.) In addition, the flags parameter gets passed to sv_unref_flags() when unreffing. sv_force_normal calls this function with flags set to 0.

This function is expected to be used to signal to perl that this SV is about to be written to, and any extra book-keeping needs to be taken care of. Hence, it croaks on read-only values.

void    sv_force_normal_flags(SV *const sv,
                              const U32 flags)
sv_free

Decrement an SV's reference count, and if it drops to zero, call sv_clear to invoke destructors and free up any memory used by the body; finally, deallocating the SV's head itself. Normally called via a wrapper macro SvREFCNT_dec.

void    sv_free(SV *const sv)
sv_gets

Get a line from the filehandle and store it into the SV, optionally appending to the currently-stored string. If append is not 0, the line is appended to the SV instead of overwriting it. append should be set to the byte offset that the appended string should start at in the SV (typically, SvCUR(sv) is a suitable choice).

char*   sv_gets(SV *const sv, PerlIO *const fp,
                I32 append)
sv_get_backrefs

NOTE: this function is experimental and may change or be removed without notice.

If sv is the target of a weak reference then it returns the back references structure associated with the sv; otherwise return NULL.

When returning a non-null result the type of the return is relevant. If it is an AV then the elements of the AV are the weak reference RVs which point at this item. If it is any other type then the item itself is the weak reference.

See also Perl_sv_add_backref(), Perl_sv_del_backref(), Perl_sv_kill_backrefs()

SV*     sv_get_backrefs(SV *const sv)
sv_grow

Expands the character buffer in the SV. If necessary, uses sv_unref and upgrades the SV to SVt_PV. Returns a pointer to the character buffer. Use the SvGROW wrapper instead.

char*   sv_grow(SV *const sv, STRLEN newlen)
sv_inc

Auto-increment of the value in the SV, doing string to numeric conversion if necessary. Handles 'get' magic and operator overloading.

void    sv_inc(SV *const sv)
sv_inc_nomg

Auto-increment of the value in the SV, doing string to numeric conversion if necessary. Handles operator overloading. Skips handling 'get' magic.

void    sv_inc_nomg(SV *const sv)
sv_insert

Inserts a string at the specified offset/length within the SV. Similar to the Perl substr() function. Handles get magic.

void    sv_insert(SV *const bigstr, const STRLEN offset,
                  const STRLEN len,
                  const char *const little,
                  const STRLEN littlelen)
sv_insert_flags

Same as sv_insert, but the extra flags are passed to the SvPV_force_flags that applies to bigstr.

void    sv_insert_flags(SV *const bigstr,
                        const STRLEN offset,
                        const STRLEN len,
                        const char *little,
                        const STRLEN littlelen,
                        const U32 flags)
sv_isa

Returns a boolean indicating whether the SV is blessed into the specified class. This does not check for subtypes; use sv_derived_from to verify an inheritance relationship.

int     sv_isa(SV* sv, const char *const name)
sv_isobject

Returns a boolean indicating whether the SV is an RV pointing to a blessed object. If the SV is not an RV, or if the object is not blessed, then this will return false.

int     sv_isobject(SV* sv)
sv_len

Returns the length of the string in the SV. Handles magic and type coercion and sets the UTF8 flag appropriately. See also "SvCUR", which gives raw access to the xpv_cur slot.

STRLEN  sv_len(SV *const sv)
sv_len_utf8

Returns the number of characters in the string in an SV, counting wide UTF-8 bytes as a single character. Handles magic and type coercion.

STRLEN  sv_len_utf8(SV *const sv)
sv_magic

Adds magic to an SV. First upgrades sv to type SVt_PVMG if necessary, then adds a new magic item of type how to the head of the magic list.

See "sv_magicext" (which sv_magic now calls) for a description of the handling of the name and namlen arguments.

You need to use sv_magicext to add magic to SvREADONLY SVs and also to add more than one instance of the same how.

void    sv_magic(SV *const sv, SV *const obj,
                 const int how, const char *const name,
                 const I32 namlen)
sv_magicext

Adds magic to an SV, upgrading it if necessary. Applies the supplied vtable and returns a pointer to the magic added.

Note that sv_magicext will allow things that sv_magic will not. In particular, you can add magic to SvREADONLY SVs, and add more than one instance of the same how.

If namlen is greater than zero then a savepvn copy of name is stored, if namlen is zero then name is stored as-is and - as another special case - if (name && namlen == HEf_SVKEY) then name is assumed to contain an SV* and is stored as-is with its REFCNT incremented.

(This is now used as a subroutine by sv_magic.)

MAGIC * sv_magicext(SV *const sv, SV *const obj,
                    const int how,
                    const MGVTBL *const vtbl,
                    const char *const name,
                    const I32 namlen)
sv_mortalcopy

Creates a new SV which is a copy of the original SV (using sv_setsv). The new SV is marked as mortal. It will be destroyed "soon", either by an explicit call to FREETMPS, or by an implicit call at places such as statement boundaries. See also "sv_newmortal" and "sv_2mortal".

SV*     sv_mortalcopy(SV *const oldsv)
sv_newmortal

Creates a new null SV which is mortal. The reference count of the SV is set to 1. It will be destroyed "soon", either by an explicit call to FREETMPS, or by an implicit call at places such as statement boundaries. See also "sv_mortalcopy" and "sv_2mortal".

SV*     sv_newmortal()
sv_newref

Increment an SV's reference count. Use the SvREFCNT_inc() wrapper instead.

SV*     sv_newref(SV *const sv)
sv_pos_b2u

Converts the value pointed to by offsetp from a count of bytes from the start of the string, to a count of the equivalent number of UTF-8 chars. Handles magic and type coercion.

Use sv_pos_b2u_flags in preference, which correctly handles strings longer than 2Gb.

void    sv_pos_b2u(SV *const sv, I32 *const offsetp)
sv_pos_b2u_flags

Converts offset from a count of bytes from the start of the string, to a count of the equivalent number of UTF-8 chars. Handles type coercion. flags is passed to SvPV_flags, and usually should be SV_GMAGIC|SV_CONST_RETURN to handle magic.

STRLEN  sv_pos_b2u_flags(SV *const sv,
                         STRLEN const offset, U32 flags)
sv_pos_u2b

Converts the value pointed to by offsetp from a count of UTF-8 chars from the start of the string, to a count of the equivalent number of bytes; if lenp is non-zero, it does the same to lenp, but this time starting from the offset, rather than from the start of the string. Handles magic and type coercion.

Use sv_pos_u2b_flags in preference, which correctly handles strings longer than 2Gb.

void    sv_pos_u2b(SV *const sv, I32 *const offsetp,
                   I32 *const lenp)
sv_pos_u2b_flags

Converts the offset from a count of UTF-8 chars from the start of the string, to a count of the equivalent number of bytes; if lenp is non-zero, it does the same to lenp, but this time starting from offset, rather than from the start of the string. Handles type coercion. flags is passed to SvPV_flags, and usually should be SV_GMAGIC|SV_CONST_RETURN to handle magic.

STRLEN  sv_pos_u2b_flags(SV *const sv, STRLEN uoffset,
                         STRLEN *const lenp, U32 flags)
sv_pvbyten_force

The backend for the SvPVbytex_force macro. Always use the macro instead.

char*   sv_pvbyten_force(SV *const sv, STRLEN *const lp)
sv_pvn_force

Get a sensible string out of the SV somehow. A private implementation of the SvPV_force macro for compilers which can't cope with complex macro expressions. Always use the macro instead.

char*   sv_pvn_force(SV* sv, STRLEN* lp)
sv_pvn_force_flags

Get a sensible string out of the SV somehow. If flags has the SV_GMAGIC bit set, will mg_get on sv if appropriate, else not. sv_pvn_force and sv_pvn_force_nomg are implemented in terms of this function. You normally want to use the various wrapper macros instead: see "SvPV_force" and "SvPV_force_nomg".

char*   sv_pvn_force_flags(SV *const sv,
                           STRLEN *const lp,
                           const I32 flags)
sv_pvutf8n_force

The backend for the SvPVutf8x_force macro. Always use the macro instead.

char*   sv_pvutf8n_force(SV *const sv, STRLEN *const lp)
sv_ref

Returns a SV describing what the SV passed in is a reference to.

dst can be a SV to be set to the description or NULL, in which case a mortal SV is returned.

If ob is true and the SV is blessed, the description is the class name, otherwise it is the type of the SV, "SCALAR", "ARRAY" etc.

SV*     sv_ref(SV *dst, const SV *const sv,
               const int ob)
sv_reftype

Returns a string describing what the SV is a reference to.

If ob is true and the SV is blessed, the string is the class name, otherwise it is the type of the SV, "SCALAR", "ARRAY" etc.

const char* sv_reftype(const SV *const sv, const int ob)
sv_replace

Make the first argument a copy of the second, then delete the original. The target SV physically takes over ownership of the body of the source SV and inherits its flags; however, the target keeps any magic it owns, and any magic in the source is discarded. Note that this is a rather specialist SV copying operation; most of the time you'll want to use sv_setsv or one of its many macro front-ends.

void    sv_replace(SV *const sv, SV *const nsv)
sv_reset

Underlying implementation for the reset Perl function. Note that the perl-level function is vaguely deprecated.

void    sv_reset(const char* s, HV *const stash)
sv_rvunweaken

Unweaken a reference: Clear the SvWEAKREF flag on this RV; remove the backreference to this RV from the array of backreferences associated with the target SV, increment the refcount of the target. Silently ignores undef and warns on non-weak references.

SV*     sv_rvunweaken(SV *const sv)
sv_rvweaken

Weaken a reference: set the SvWEAKREF flag on this RV; give the referred-to SV PERL_MAGIC_backref magic if it hasn't already; and push a back-reference to this RV onto the array of backreferences associated with that magic. If the RV is magical, set magic will be called after the RV is cleared. Silently ignores undef and warns on already-weak references.

SV*     sv_rvweaken(SV *const sv)
sv_setiv

Copies an integer into the given SV, upgrading first if necessary. Does not handle 'set' magic. See also "sv_setiv_mg".

void    sv_setiv(SV *const sv, const IV num)
sv_setiv_mg

Like sv_setiv, but also handles 'set' magic.

void    sv_setiv_mg(SV *const sv, const IV i)
sv_setnv

Copies a double into the given SV, upgrading first if necessary. Does not handle 'set' magic. See also "sv_setnv_mg".

void    sv_setnv(SV *const sv, const NV num)
sv_setnv_mg

Like sv_setnv, but also handles 'set' magic.

void    sv_setnv_mg(SV *const sv, const NV num)
sv_setpv

Copies a string into an SV. The string must be terminated with a NUL character, and not contain embeded NUL's. Does not handle 'set' magic. See "sv_setpv_mg".

void    sv_setpv(SV *const sv, const char *const ptr)
sv_setpvf

Works like sv_catpvf but copies the text into the SV instead of appending it. Does not handle 'set' magic. See "sv_setpvf_mg".

void    sv_setpvf(SV *const sv, const char *const pat,
                  ...)
sv_setpvf_mg

Like sv_setpvf, but also handles 'set' magic.

void    sv_setpvf_mg(SV *const sv,
                     const char *const pat, ...)
sv_setpviv

Copies an integer into the given SV, also updating its string value. Does not handle 'set' magic. See "sv_setpviv_mg".

void    sv_setpviv(SV *const sv, const IV num)
sv_setpviv_mg

Like sv_setpviv, but also handles 'set' magic.

void    sv_setpviv_mg(SV *const sv, const IV iv)
sv_setpvn

Copies a string (possibly containing embedded NUL characters) into an SV. The len parameter indicates the number of bytes to be copied. If the ptr argument is NULL the SV will become undefined. Does not handle 'set' magic. See "sv_setpvn_mg".

void    sv_setpvn(SV *const sv, const char *const ptr,
                  const STRLEN len)
sv_setpvn_mg

Like sv_setpvn, but also handles 'set' magic.

void    sv_setpvn_mg(SV *const sv,
                     const char *const ptr,
                     const STRLEN len)
sv_setpvs

Like sv_setpvn, but takes a literal string instead of a string/length pair.

void    sv_setpvs(SV* sv, "literal string" s)
sv_setpvs_mg

Like sv_setpvn_mg, but takes a literal string instead of a string/length pair.

void    sv_setpvs_mg(SV* sv, "literal string" s)
sv_setpv_bufsize

Sets the SV to be a string of cur bytes length, with at least len bytes available. Ensures that there is a null byte at SvEND. Returns a char * pointer to the SvPV buffer.

char  * sv_setpv_bufsize(SV *const sv, const STRLEN cur,
                         const STRLEN len)
sv_setpv_mg

Like sv_setpv, but also handles 'set' magic.

void    sv_setpv_mg(SV *const sv, const char *const ptr)
sv_setref_iv

Copies an integer into a new SV, optionally blessing the SV. The rv argument will be upgraded to an RV. That RV will be modified to point to the new SV. The classname argument indicates the package for the blessing. Set classname to NULL to avoid the blessing. The new SV will have a reference count of 1, and the RV will be returned.

SV*     sv_setref_iv(SV *const rv,
                     const char *const classname,
                     const IV iv)
sv_setref_nv

Copies a double into a new SV, optionally blessing the SV. The rv argument will be upgraded to an RV. That RV will be modified to point to the new SV. The classname argument indicates the package for the blessing. Set classname to NULL to avoid the blessing. The new SV will have a reference count of 1, and the RV will be returned.

SV*     sv_setref_nv(SV *const rv,
                     const char *const classname,
                     const NV nv)
sv_setref_pv

Copies a pointer into a new SV, optionally blessing the SV. The rv argument will be upgraded to an RV. That RV will be modified to point to the new SV. If the pv argument is NULL, then PL_sv_undef will be placed into the SV. The classname argument indicates the package for the blessing. Set classname to NULL to avoid the blessing. The new SV will have a reference count of 1, and the RV will be returned.

Do not use with other Perl types such as HV, AV, SV, CV, because those objects will become corrupted by the pointer copy process.

Note that sv_setref_pvn copies the string while this copies the pointer.

SV*     sv_setref_pv(SV *const rv,
                     const char *const classname,
                     void *const pv)
sv_setref_pvn

Copies a string into a new SV, optionally blessing the SV. The length of the string must be specified with n. The rv argument will be upgraded to an RV. That RV will be modified to point to the new SV. The classname argument indicates the package for the blessing. Set classname to NULL to avoid the blessing. The new SV will have a reference count of 1, and the RV will be returned.

Note that sv_setref_pv copies the pointer while this copies the string.

SV*     sv_setref_pvn(SV *const rv,
                      const char *const classname,
                      const char *const pv,
                      const STRLEN n)
sv_setref_pvs

Like sv_setref_pvn, but takes a literal string instead of a string/length pair.

SV *    sv_setref_pvs("literal string" s)
sv_setref_uv

Copies an unsigned integer into a new SV, optionally blessing the SV. The rv argument will be upgraded to an RV. That RV will be modified to point to the new SV. The classname argument indicates the package for the blessing. Set classname to NULL to avoid the blessing. The new SV will have a reference count of 1, and the RV will be returned.

SV*     sv_setref_uv(SV *const rv,
                     const char *const classname,
                     const UV uv)
sv_setsv

Copies the contents of the source SV ssv into the destination SV dsv. The source SV may be destroyed if it is mortal, so don't use this function if the source SV needs to be reused. Does not handle 'set' magic on destination SV. Calls 'get' magic on source SV. Loosely speaking, it performs a copy-by-value, obliterating any previous content of the destination.

You probably want to use one of the assortment of wrappers, such as SvSetSV, SvSetSV_nosteal, SvSetMagicSV and SvSetMagicSV_nosteal.

void    sv_setsv(SV *dstr, SV *sstr)
sv_setsv_flags

Copies the contents of the source SV ssv into the destination SV dsv. The source SV may be destroyed if it is mortal, so don't use this function if the source SV needs to be reused. Does not handle 'set' magic. Loosely speaking, it performs a copy-by-value, obliterating any previous content of the destination. If the flags parameter has the SV_GMAGIC bit set, will mg_get on ssv if appropriate, else not. If the flags parameter has the SV_NOSTEAL bit set then the buffers of temps will not be stolen. sv_setsv and sv_setsv_nomg are implemented in terms of this function.

You probably want to use one of the assortment of wrappers, such as SvSetSV, SvSetSV_nosteal, SvSetMagicSV and SvSetMagicSV_nosteal.

This is the primary function for copying scalars, and most other copy-ish functions and macros use this underneath.

void    sv_setsv_flags(SV *dstr, SV *sstr,
                       const I32 flags)
sv_setsv_mg

Like sv_setsv, but also handles 'set' magic.

void    sv_setsv_mg(SV *const dstr, SV *const sstr)
sv_setuv

Copies an unsigned integer into the given SV, upgrading first if necessary. Does not handle 'set' magic. See also "sv_setuv_mg".

void    sv_setuv(SV *const sv, const UV num)
sv_setuv_mg

Like sv_setuv, but also handles 'set' magic.

void    sv_setuv_mg(SV *const sv, const UV u)
sv_set_undef

Equivalent to sv_setsv(sv, &PL_sv_undef), but more efficient. Doesn't handle set magic.

The perl equivalent is $sv = undef;. Note that it doesn't free any string buffer, unlike undef $sv.

Introduced in perl 5.25.12.

void    sv_set_undef(SV *sv)
sv_tainted

Test an SV for taintedness. Use SvTAINTED instead.

bool    sv_tainted(SV *const sv)
sv_true

Returns true if the SV has a true value by Perl's rules. Use the SvTRUE macro instead, which may call sv_true() or may instead use an in-line version.

I32     sv_true(SV *const sv)
sv_unmagic

Removes all magic of type type from an SV.

int     sv_unmagic(SV *const sv, const int type)
sv_unmagicext

Removes all magic of type type with the specified vtbl from an SV.

int     sv_unmagicext(SV *const sv, const int type,
                      MGVTBL *vtbl)
sv_unref_flags

Unsets the RV status of the SV, and decrements the reference count of whatever was being referenced by the RV. This can almost be thought of as a reversal of newSVrv. The cflags argument can contain SV_IMMEDIATE_UNREF to force the reference count to be decremented (otherwise the decrementing is conditional on the reference count being different from one or the reference being a readonly SV). See "SvROK_off".

void    sv_unref_flags(SV *const ref, const U32 flags)
sv_untaint

Untaint an SV. Use SvTAINTED_off instead.

void    sv_untaint(SV *const sv)
sv_upgrade

Upgrade an SV to a more complex form. Generally adds a new body type to the SV, then copies across as much information as possible from the old body. It croaks if the SV is already in a more complex form than requested. You generally want to use the SvUPGRADE macro wrapper, which checks the type before calling sv_upgrade, and hence does not croak. See also "svtype".

void    sv_upgrade(SV *const sv, svtype new_type)
sv_usepvn_flags

Tells an SV to use ptr to find its string value. Normally the string is stored inside the SV, but sv_usepvn allows the SV to use an outside string. ptr should point to memory that was allocated by Newx. It must be the start of a Newx-ed block of memory, and not a pointer to the middle of it (beware of OOK and copy-on-write), and not be from a non-Newx memory allocator like malloc. The string length, len, must be supplied. By default this function will Renew (i.e. realloc, move) the memory pointed to by ptr, so that pointer should not be freed or used by the programmer after giving it to sv_usepvn, and neither should any pointers from "behind" that pointer (e.g. ptr + 1) be used.

If flags & SV_SMAGIC is true, will call SvSETMAGIC. If flags & SV_HAS_TRAILING_NUL is true, then ptr[len] must be NUL, and the realloc will be skipped (i.e. the buffer is actually at least 1 byte longer than len, and already meets the requirements for storing in SvPVX).

void    sv_usepvn_flags(SV *const sv, char* ptr,
                        const STRLEN len,
                        const U32 flags)
sv_utf8_decode

NOTE: this function is experimental and may change or be removed without notice.

If the PV of the SV is an octet sequence in Perl's extended UTF-8 and contains a multiple-byte character, the SvUTF8 flag is turned on so that it looks like a character. If the PV contains only single-byte characters, the SvUTF8 flag stays off. Scans PV for validity and returns FALSE if the PV is invalid UTF-8.

bool    sv_utf8_decode(SV *const sv)
sv_utf8_downgrade

NOTE: this function is experimental and may change or be removed without notice.

Attempts to convert the PV of an SV from characters to bytes. If the PV contains a character that cannot fit in a byte, this conversion will fail; in this case, either returns false or, if fail_ok is not true, croaks.

This is not a general purpose Unicode to byte encoding interface: use the Encode extension for that.

bool    sv_utf8_downgrade(SV *const sv,
                          const bool fail_ok)
sv_utf8_encode

Converts the PV of an SV to UTF-8, but then turns the SvUTF8 flag off so that it looks like octets again.

void    sv_utf8_encode(SV *const sv)
sv_utf8_upgrade

Converts the PV of an SV to its UTF-8-encoded form. Forces the SV to string form if it is not already. Will mg_get on sv if appropriate. Always sets the SvUTF8 flag to avoid future validity checks even if the whole string is the same in UTF-8 as not. Returns the number of bytes in the converted string

This is not a general purpose byte encoding to Unicode interface: use the Encode extension for that.

STRLEN  sv_utf8_upgrade(SV *sv)
sv_utf8_upgrade_flags

Converts the PV of an SV to its UTF-8-encoded form. Forces the SV to string form if it is not already. Always sets the SvUTF8 flag to avoid future validity checks even if all the bytes are invariant in UTF-8. If flags has SV_GMAGIC bit set, will mg_get on sv if appropriate, else not.

The SV_FORCE_UTF8_UPGRADE flag is now ignored.

Returns the number of bytes in the converted string.

This is not a general purpose byte encoding to Unicode interface: use the Encode extension for that.

STRLEN  sv_utf8_upgrade_flags(SV *const sv,
                              const I32 flags)
sv_utf8_upgrade_flags_grow

Like sv_utf8_upgrade_flags, but has an additional parameter extra, which is the number of unused bytes the string of sv is guaranteed to have free after it upon return. This allows the caller to reserve extra space that it intends to fill, to avoid extra grows.

sv_utf8_upgrade, sv_utf8_upgrade_nomg, and sv_utf8_upgrade_flags are implemented in terms of this function.

Returns the number of bytes in the converted string (not including the spares).

STRLEN  sv_utf8_upgrade_flags_grow(SV *const sv,
                                   const I32 flags,
                                   STRLEN extra)
sv_utf8_upgrade_nomg

Like sv_utf8_upgrade, but doesn't do magic on sv.

STRLEN  sv_utf8_upgrade_nomg(SV *sv)
sv_vcatpvf

Processes its arguments like sv_vcatpvfn called with a non-null C-style variable argument list, and appends the formatted output to an SV. Does not handle 'set' magic. See "sv_vcatpvf_mg".

Usually used via its frontend sv_catpvf.

void    sv_vcatpvf(SV *const sv, const char *const pat,
                   va_list *const args)
sv_vcatpvfn 
void    sv_vcatpvfn(SV *const sv, const char *const pat,
                    const STRLEN patlen,
                    va_list *const args,
                    SV **const svargs,
                    const Size_t sv_count,
                    bool *const maybe_tainted)
sv_vcatpvfn_flags

Processes its arguments like vsprintf and appends the formatted output to an SV. Uses an array of SVs if the C-style variable argument list is missing (NULL). Argument reordering (using format specifiers like %2$d or %*2$d) is supported only when using an array of SVs; using a C-style va_list argument list with a format string that uses argument reordering will yield an exception.

When running with taint checks enabled, indicates via maybe_tainted if results are untrustworthy (often due to the use of locales).

If called as sv_vcatpvfn or flags has the SV_GMAGIC bit set, calls get magic.

It assumes that pat has the same utf8-ness as sv. It's the caller's responsibility to ensure that this is so.

Usually used via one of its frontends sv_vcatpvf and sv_vcatpvf_mg.

void    sv_vcatpvfn_flags(SV *const sv,
                          const char *const pat,
                          const STRLEN patlen,
                          va_list *const args,
                          SV **const svargs,
                          const Size_t sv_count,
                          bool *const maybe_tainted,
                          const U32 flags)
sv_vcatpvf_mg

Like sv_vcatpvf, but also handles 'set' magic.

Usually used via its frontend sv_catpvf_mg.

void    sv_vcatpvf_mg(SV *const sv,
                      const char *const pat,
                      va_list *const args)
sv_vsetpvf

Works like sv_vcatpvf but copies the text into the SV instead of appending it. Does not handle 'set' magic. See "sv_vsetpvf_mg".

Usually used via its frontend sv_setpvf.

void    sv_vsetpvf(SV *const sv, const char *const pat,
                   va_list *const args)
sv_vsetpvfn

Works like sv_vcatpvfn but copies the text into the SV instead of appending it.

Usually used via one of its frontends sv_vsetpvf and sv_vsetpvf_mg.

void    sv_vsetpvfn(SV *const sv, const char *const pat,
                    const STRLEN patlen,
                    va_list *const args,
                    SV **const svargs,
                    const Size_t sv_count,
                    bool *const maybe_tainted)
sv_vsetpvf_mg

Like sv_vsetpvf, but also handles 'set' magic.

Usually used via its frontend sv_setpvf_mg.

void    sv_vsetpvf_mg(SV *const sv,
                      const char *const pat,
                      va_list *const args)

SV Flags

SVt_INVLIST

Type flag for scalars. See "svtype".

SVt_IV

Type flag for scalars. See "svtype".

SVt_NULL

Type flag for scalars. See "svtype".

SVt_NV

Type flag for scalars. See "svtype".

SVt_PV

Type flag for scalars. See "svtype".

SVt_PVAV

Type flag for arrays. See "svtype".

SVt_PVCV

Type flag for subroutines. See "svtype".

SVt_PVFM

Type flag for formats. See "svtype".

SVt_PVGV

Type flag for typeglobs. See "svtype".

SVt_PVHV

Type flag for hashes. See "svtype".

SVt_PVIO

Type flag for I/O objects. See "svtype".

SVt_PVIV

Type flag for scalars. See "svtype".

SVt_PVLV

Type flag for scalars. See "svtype".

SVt_PVMG

Type flag for scalars. See "svtype".

SVt_PVNV

Type flag for scalars. See "svtype".

SVt_REGEXP

Type flag for regular expressions. See "svtype".

svtype

An enum of flags for Perl types. These are found in the file sv.h in the svtype enum. Test these flags with the SvTYPE macro.

The types are:

SVt_NULL
SVt_IV
SVt_NV
SVt_RV
SVt_PV
SVt_PVIV
SVt_PVNV
SVt_PVMG
SVt_INVLIST
SVt_REGEXP
SVt_PVGV
SVt_PVLV
SVt_PVAV
SVt_PVHV
SVt_PVCV
SVt_PVFM
SVt_PVIO

These are most easily explained from the bottom up.

SVt_PVIO is for I/O objects, SVt_PVFM for formats, SVt_PVCV for subroutines, SVt_PVHV for hashes and SVt_PVAV for arrays.

All the others are scalar types, that is, things that can be bound to a $ variable. For these, the internal types are mostly orthogonal to types in the Perl language.

Hence, checking SvTYPE(sv) < SVt_PVAV is the best way to see whether something is a scalar.

SVt_PVGV represents a typeglob. If !SvFAKE(sv), then it is a real, incoercible typeglob. If SvFAKE(sv), then it is a scalar to which a typeglob has been assigned. Assigning to it again will stop it from being a typeglob. SVt_PVLV represents a scalar that delegates to another scalar behind the scenes. It is used, e.g., for the return value of substr and for tied hash and array elements. It can hold any scalar value, including a typeglob. SVt_REGEXP is for regular expressions. SVt_INVLIST is for Perl core internal use only.

SVt_PVMG represents a "normal" scalar (not a typeglob, regular expression, or delegate). Since most scalars do not need all the internal fields of a PVMG, we save memory by allocating smaller structs when possible. All the other types are just simpler forms of SVt_PVMG, with fewer internal fields. SVt_NULL can only hold undef. SVt_IV can hold undef, an integer, or a reference. (SVt_RV is an alias for SVt_IV, which exists for backward compatibility.) SVt_NV can hold any of those or a double. SVt_PV can only hold undef or a string. SVt_PVIV is a superset of SVt_PV and SVt_IV. SVt_PVNV is similar. SVt_PVMG can hold anything SVt_PVNV can hold, but it can, but does not have to, be blessed or magical.

SV Manipulation Functions

boolSV

Returns a true SV if b is a true value, or a false SV if b is 0.

See also "PL_sv_yes" and "PL_sv_no".

SV *    boolSV(bool b)
croak_xs_usage

A specialised variant of croak() for emitting the usage message for xsubs

croak_xs_usage(cv, "eee_yow");

works out the package name and subroutine name from cv, and then calls croak(). Hence if cv is &ouch::awk, it would call croak as:

Perl_croak(aTHX_ "Usage: %" SVf "::%" SVf "(%s)", "ouch" "awk",
                                                    "eee_yow");

       void    croak_xs_usage(const CV *const cv,
                              const char *const params)
get_sv

Returns the SV of the specified Perl scalar. flags are passed to gv_fetchpv. If GV_ADD is set and the Perl variable does not exist then it will be created. If flags is zero and the variable does not exist then NULL is returned.

NOTE: the perl_ form of this function is deprecated.

SV*     get_sv(const char *name, I32 flags)
newRV_inc

Creates an RV wrapper for an SV. The reference count for the original SV is incremented.

SV*     newRV_inc(SV* sv)
newSVpadname

NOTE: this function is experimental and may change or be removed without notice.

Creates a new SV containing the pad name.

SV*     newSVpadname(PADNAME *pn)
newSVpvn_utf8

Creates a new SV and copies a string (which may contain NUL (\0) characters) into it. If utf8 is true, calls SvUTF8_on on the new SV. Implemented as a wrapper around newSVpvn_flags.

SV*     newSVpvn_utf8(const char* s, STRLEN len,
                      U32 utf8)
sv_catpvn_nomg

Like sv_catpvn but doesn't process magic.

void    sv_catpvn_nomg(SV* sv, const char* ptr,
                       STRLEN len)
sv_catpv_nomg

Like sv_catpv but doesn't process magic.

void    sv_catpv_nomg(SV* sv, const char* ptr)
sv_catsv_nomg

Like sv_catsv but doesn't process magic.

void    sv_catsv_nomg(SV* dsv, SV* ssv)
SvCUR

Returns the length of the string which is in the SV. See "SvLEN".

STRLEN  SvCUR(SV* sv)
SvCUR_set

Set the current length of the string which is in the SV. See "SvCUR" and SvIV_set>.

void    SvCUR_set(SV* sv, STRLEN len)
sv_derived_from

Exactly like "sv_derived_from_pv", but doesn't take a flags parameter.

bool    sv_derived_from(SV* sv, const char *const name)
sv_derived_from_pv

Exactly like "sv_derived_from_pvn", but takes a nul-terminated string instead of a string/length pair.

bool    sv_derived_from_pv(SV* sv,
                           const char *const name,
                           U32 flags)
sv_derived_from_pvn

Returns a boolean indicating whether the SV is derived from the specified class at the C level. To check derivation at the Perl level, call isa() as a normal Perl method.

Currently, the only significant value for flags is SVf_UTF8.

bool    sv_derived_from_pvn(SV* sv,
                            const char *const name,
                            const STRLEN len, U32 flags)
sv_derived_from_sv

Exactly like "sv_derived_from_pvn", but takes the name string in the form of an SV instead of a string/length pair.

bool    sv_derived_from_sv(SV* sv, SV *namesv,
                           U32 flags)
sv_does

Like "sv_does_pv", but doesn't take a flags parameter.

bool    sv_does(SV* sv, const char *const name)
sv_does_pv

Like "sv_does_sv", but takes a nul-terminated string instead of an SV.

bool    sv_does_pv(SV* sv, const char *const name,
                   U32 flags)
sv_does_pvn

Like "sv_does_sv", but takes a string/length pair instead of an SV.

bool    sv_does_pvn(SV* sv, const char *const name,
                    const STRLEN len, U32 flags)
sv_does_sv

Returns a boolean indicating whether the SV performs a specific, named role. The SV can be a Perl object or the name of a Perl class.

bool    sv_does_sv(SV* sv, SV* namesv, U32 flags)
SvEND

Returns a pointer to the spot just after the last character in the string which is in the SV, where there is usually a trailing NUL character (even though Perl scalars do not strictly require it). See "SvCUR". Access the character as *(SvEND(sv)).

Warning: If SvCUR is equal to SvLEN, then SvEND points to unallocated memory.

char*   SvEND(SV* sv)
SvGAMAGIC

Returns true if the SV has get magic or overloading. If either is true then the scalar is active data, and has the potential to return a new value every time it is accessed. Hence you must be careful to only read it once per user logical operation and work with that returned value. If neither is true then the scalar's value cannot change unless written to.

U32     SvGAMAGIC(SV* sv)
SvGROW

Expands the character buffer in the SV so that it has room for the indicated number of bytes (remember to reserve space for an extra trailing NUL character). Calls sv_grow to perform the expansion if necessary. Returns a pointer to the character buffer. SV must be of type >= SVt_PV. One alternative is to call sv_grow if you are not sure of the type of SV.

You might mistakenly think that len is the number of bytes to add to the existing size, but instead it is the total size sv should be.

char *  SvGROW(SV* sv, STRLEN len)
SvIOK

Returns a U32 value indicating whether the SV contains an integer.

U32     SvIOK(SV* sv)
SvIOK_notUV

Returns a boolean indicating whether the SV contains a signed integer.

bool    SvIOK_notUV(SV* sv)
SvIOK_off

Unsets the IV status of an SV.

void    SvIOK_off(SV* sv)
SvIOK_on

Tells an SV that it is an integer.

void    SvIOK_on(SV* sv)
SvIOK_only

Tells an SV that it is an integer and disables all other OK bits.

void    SvIOK_only(SV* sv)
SvIOK_only_UV

Tells an SV that it is an unsigned integer and disables all other OK bits.

void    SvIOK_only_UV(SV* sv)
SvIOKp

Returns a U32 value indicating whether the SV contains an integer. Checks the private setting. Use SvIOK instead.

U32     SvIOKp(SV* sv)
SvIOK_UV

Returns a boolean indicating whether the SV contains an integer that must be interpreted as unsigned. A non-negative integer whose value is within the range of both an IV and a UV may be be flagged as either SvUOK or SVIOK.

bool    SvIOK_UV(SV* sv)
SvIsCOW

Returns a U32 value indicating whether the SV is Copy-On-Write (either shared hash key scalars, or full Copy On Write scalars if 5.9.0 is configured for COW).

U32     SvIsCOW(SV* sv)
SvIsCOW_shared_hash

Returns a boolean indicating whether the SV is Copy-On-Write shared hash key scalar.

bool    SvIsCOW_shared_hash(SV* sv)
SvIV

Coerces the given SV to IV and returns it. The returned value in many circumstances will get stored in sv's IV slot, but not in all cases. (Use "sv_setiv" to make sure it does).

See "SvIVx" for a version which guarantees to evaluate sv only once.

IV      SvIV(SV* sv)
SvIV_nomg

Like SvIV but doesn't process magic.

IV      SvIV_nomg(SV* sv)
SvIV_set

Set the value of the IV pointer in sv to val. It is possible to perform the same function of this macro with an lvalue assignment to SvIVX. With future Perls, however, it will be more efficient to use SvIV_set instead of the lvalue assignment to SvIVX.

void    SvIV_set(SV* sv, IV val)
SvIVX

Returns the raw value in the SV's IV slot, without checks or conversions. Only use when you are sure SvIOK is true. See also "SvIV".

IV      SvIVX(SV* sv)
SvIVx

Coerces the given SV to IV and returns it. The returned value in many circumstances will get stored in sv's IV slot, but not in all cases. (Use "sv_setiv" to make sure it does).

This form guarantees to evaluate sv only once. Only use this if sv is an expression with side effects, otherwise use the more efficient SvIV.

IV      SvIVx(SV* sv)
SvLEN

Returns the size of the string buffer in the SV, not including any part attributable to SvOOK. See "SvCUR".

STRLEN  SvLEN(SV* sv)
SvLEN_set

Set the size of the string buffer for the SV. See "SvLEN".

void    SvLEN_set(SV* sv, STRLEN len)
SvMAGIC_set

Set the value of the MAGIC pointer in sv to val. See "SvIV_set".

void    SvMAGIC_set(SV* sv, MAGIC* val)
SvNIOK

Returns a U32 value indicating whether the SV contains a number, integer or double.

U32     SvNIOK(SV* sv)
SvNIOK_off

Unsets the NV/IV status of an SV.

void    SvNIOK_off(SV* sv)
SvNIOKp

Returns a U32 value indicating whether the SV contains a number, integer or double. Checks the private setting. Use SvNIOK instead.

U32     SvNIOKp(SV* sv)
SvNOK

Returns a U32 value indicating whether the SV contains a double.

U32     SvNOK(SV* sv)
SvNOK_off

Unsets the NV status of an SV.

void    SvNOK_off(SV* sv)
SvNOK_on

Tells an SV that it is a double.

void    SvNOK_on(SV* sv)
SvNOK_only

Tells an SV that it is a double and disables all other OK bits.

void    SvNOK_only(SV* sv)
SvNOKp

Returns a U32 value indicating whether the SV contains a double. Checks the private setting. Use SvNOK instead.

U32     SvNOKp(SV* sv)
SvNV

Coerces the given SV to NV and returns it. The returned value in many circumstances will get stored in sv's NV slot, but not in all cases. (Use "sv_setnv" to make sure it does).

See "SvNVx" for a version which guarantees to evaluate sv only once.

NV      SvNV(SV* sv)
SvNV_nomg

Like SvNV but doesn't process magic.

NV      SvNV_nomg(SV* sv)
SvNV_set

Set the value of the NV pointer in sv to val. See "SvIV_set".

void    SvNV_set(SV* sv, NV val)
SvNVX

Returns the raw value in the SV's NV slot, without checks or conversions. Only use when you are sure SvNOK is true. See also "SvNV".

NV      SvNVX(SV* sv)
SvNVx

Coerces the given SV to NV and returns it. The returned value in many circumstances will get stored in sv's NV slot, but not in all cases. (Use "sv_setnv" to make sure it does).

This form guarantees to evaluate sv only once. Only use this if sv is an expression with side effects, otherwise use the more efficient SvNV.

NV      SvNVx(SV* sv)
SvOK

Returns a U32 value indicating whether the value is defined. This is only meaningful for scalars.

U32     SvOK(SV* sv)
SvOOK

Returns a U32 indicating whether the pointer to the string buffer is offset. This hack is used internally to speed up removal of characters from the beginning of a SvPV. When SvOOK is true, then the start of the allocated string buffer is actually SvOOK_offset() bytes before SvPVX. This offset used to be stored in SvIVX, but is now stored within the spare part of the buffer.

U32     SvOOK(SV* sv)
SvOOK_offset

Reads into len the offset from SvPVX back to the true start of the allocated buffer, which will be non-zero if sv_chop has been used to efficiently remove characters from start of the buffer. Implemented as a macro, which takes the address of len, which must be of type STRLEN. Evaluates sv more than once. Sets len to 0 if SvOOK(sv) is false.

void    SvOOK_offset(SV*sv, STRLEN len)
SvPOK

Returns a U32 value indicating whether the SV contains a character string.

U32     SvPOK(SV* sv)
SvPOK_off

Unsets the PV status of an SV.

void    SvPOK_off(SV* sv)
SvPOK_on

Tells an SV that it is a string.

void    SvPOK_on(SV* sv)
SvPOK_only

Tells an SV that it is a string and disables all other OK bits. Will also turn off the UTF-8 status.

void    SvPOK_only(SV* sv)
SvPOK_only_UTF8

Tells an SV that it is a string and disables all other OK bits, and leaves the UTF-8 status as it was.

void    SvPOK_only_UTF8(SV* sv)
SvPOKp

Returns a U32 value indicating whether the SV contains a character string. Checks the private setting. Use SvPOK instead.

U32     SvPOKp(SV* sv)
SvPV

Returns a pointer to the string in the SV, or a stringified form of the SV if the SV does not contain a string. The SV may cache the stringified version becoming SvPOK. Handles 'get' magic. The len variable will be set to the length of the string (this is a macro, so don't use &len). See also "SvPVx" for a version which guarantees to evaluate sv only once.

Note that there is no guarantee that the return value of SvPV() is equal to SvPVX(sv), or that SvPVX(sv) contains valid data, or that successive calls to SvPV(sv) will return the same pointer value each time. This is due to the way that things like overloading and Copy-On-Write are handled. In these cases, the return value may point to a temporary buffer or similar. If you absolutely need the SvPVX field to be valid (for example, if you intend to write to it), then see "SvPV_force".

char*   SvPV(SV* sv, STRLEN len)
SvPVbyte

Like SvPV, but converts sv to byte representation first if necessary.

char*   SvPVbyte(SV* sv, STRLEN len)
SvPVbyte_force

Like SvPV_force, but converts sv to byte representation first if necessary.

char*   SvPVbyte_force(SV* sv, STRLEN len)
SvPVbyte_nolen

Like SvPV_nolen, but converts sv to byte representation first if necessary.

char*   SvPVbyte_nolen(SV* sv)
SvPVbytex

Like SvPV, but converts sv to byte representation first if necessary. Guarantees to evaluate sv only once; use the more efficient SvPVbyte otherwise.

char*   SvPVbytex(SV* sv, STRLEN len)
SvPVbytex_force

Like SvPV_force, but converts sv to byte representation first if necessary. Guarantees to evaluate sv only once; use the more efficient SvPVbyte_force otherwise.

char*   SvPVbytex_force(SV* sv, STRLEN len)
SvPVCLEAR

Ensures that sv is a SVt_PV and that its SvCUR is 0, and that it is properly null terminated. Equivalent to sv_setpvs(""), but more efficient.

char *  SvPVCLEAR(SV* sv)
SvPV_force

Like SvPV but will force the SV into containing a string (SvPOK), and only a string (SvPOK_only), by hook or by crook. You need force if you are going to update the SvPVX directly. Processes get magic.

Note that coercing an arbitrary scalar into a plain PV will potentially strip useful data from it. For example if the SV was SvROK, then the referent will have its reference count decremented, and the SV itself may be converted to an SvPOK scalar with a string buffer containing a value such as "ARRAY(0x1234)".

char*   SvPV_force(SV* sv, STRLEN len)
SvPV_force_nomg

Like SvPV_force, but doesn't process get magic.

char*   SvPV_force_nomg(SV* sv, STRLEN len)
SvPV_nolen

Like SvPV but doesn't set a length variable.

char*   SvPV_nolen(SV* sv)
SvPV_nomg

Like SvPV but doesn't process magic.

char*   SvPV_nomg(SV* sv, STRLEN len)
SvPV_nomg_nolen

Like SvPV_nolen but doesn't process magic.

char*   SvPV_nomg_nolen(SV* sv)
SvPV_set

This is probably not what you want to use, you probably wanted "sv_usepvn_flags" or "sv_setpvn" or "sv_setpvs".

Set the value of the PV pointer in sv to the Perl allocated NUL-terminated string val. See also "SvIV_set".

Remember to free the previous PV buffer. There are many things to check. Beware that the existing pointer may be involved in copy-on-write or other mischief, so do SvOOK_off(sv) and use sv_force_normal or SvPV_force (or check the SvIsCOW flag) first to make sure this modification is safe. Then finally, if it is not a COW, call SvPV_free to free the previous PV buffer.

void    SvPV_set(SV* sv, char* val)
SvPVutf8

Like SvPV, but converts sv to UTF-8 first if necessary.

char*   SvPVutf8(SV* sv, STRLEN len)
SvPVutf8x

Like SvPV, but converts sv to UTF-8 first if necessary. Guarantees to evaluate sv only once; use the more efficient SvPVutf8 otherwise.

char*   SvPVutf8x(SV* sv, STRLEN len)
SvPVutf8x_force

Like SvPV_force, but converts sv to UTF-8 first if necessary. Guarantees to evaluate sv only once; use the more efficient SvPVutf8_force otherwise.

char*   SvPVutf8x_force(SV* sv, STRLEN len)
SvPVutf8_force

Like SvPV_force, but converts sv to UTF-8 first if necessary.

char*   SvPVutf8_force(SV* sv, STRLEN len)
SvPVutf8_nolen

Like SvPV_nolen, but converts sv to UTF-8 first if necessary.

char*   SvPVutf8_nolen(SV* sv)
SvPVX

Returns a pointer to the physical string in the SV. The SV must contain a string. Prior to 5.9.3 it is not safe to execute this macro unless the SV's type >= SVt_PV.

This is also used to store the name of an autoloaded subroutine in an XS AUTOLOAD routine. See "Autoloading with XSUBs" in perlguts.

char*   SvPVX(SV* sv)
SvPVx

A version of SvPV which guarantees to evaluate sv only once. Only use this if sv is an expression with side effects, otherwise use the more efficient SvPV.

char*   SvPVx(SV* sv, STRLEN len)
SvREADONLY

Returns true if the argument is readonly, otherwise returns false. Exposed to to perl code via Internals::SvREADONLY().

U32     SvREADONLY(SV* sv)
SvREADONLY_off

Mark an object as not-readonly. Exactly what this mean depends on the object type. Exposed to perl code via Internals::SvREADONLY().

U32     SvREADONLY_off(SV* sv)
SvREADONLY_on

Mark an object as readonly. Exactly what this means depends on the object type. Exposed to perl code via Internals::SvREADONLY().

U32     SvREADONLY_on(SV* sv)
SvREFCNT

Returns the value of the object's reference count. Exposed to perl code via Internals::SvREFCNT().

U32     SvREFCNT(SV* sv)
SvREFCNT_dec

Decrements the reference count of the given SV. sv may be NULL.

void    SvREFCNT_dec(SV* sv)
SvREFCNT_dec_NN

Same as SvREFCNT_dec, but can only be used if you know sv is not NULL. Since we don't have to check the NULLness, it's faster and smaller.

void    SvREFCNT_dec_NN(SV* sv)
SvREFCNT_inc

Increments the reference count of the given SV, returning the SV.

All of the following SvREFCNT_inc* macros are optimized versions of SvREFCNT_inc, and can be replaced with SvREFCNT_inc.

SV*     SvREFCNT_inc(SV* sv)
SvREFCNT_inc_NN

Same as SvREFCNT_inc, but can only be used if you know sv is not NULL. Since we don't have to check the NULLness, it's faster and smaller.

SV*     SvREFCNT_inc_NN(SV* sv)
SvREFCNT_inc_simple

Same as SvREFCNT_inc, but can only be used with expressions without side effects. Since we don't have to store a temporary value, it's faster.

SV*     SvREFCNT_inc_simple(SV* sv)
SvREFCNT_inc_simple_NN

Same as SvREFCNT_inc_simple, but can only be used if you know sv is not NULL. Since we don't have to check the NULLness, it's faster and smaller.

SV*     SvREFCNT_inc_simple_NN(SV* sv)
SvREFCNT_inc_simple_void

Same as SvREFCNT_inc_simple, but can only be used if you don't need the return value. The macro doesn't need to return a meaningful value.

void    SvREFCNT_inc_simple_void(SV* sv)
SvREFCNT_inc_simple_void_NN

Same as SvREFCNT_inc, but can only be used if you don't need the return value, and you know that sv is not NULL. The macro doesn't need to return a meaningful value, or check for NULLness, so it's smaller and faster.

void    SvREFCNT_inc_simple_void_NN(SV* sv)
SvREFCNT_inc_void

Same as SvREFCNT_inc, but can only be used if you don't need the return value. The macro doesn't need to return a meaningful value.

void    SvREFCNT_inc_void(SV* sv)
SvREFCNT_inc_void_NN

Same as SvREFCNT_inc, but can only be used if you don't need the return value, and you know that sv is not NULL. The macro doesn't need to return a meaningful value, or check for NULLness, so it's smaller and faster.

void    SvREFCNT_inc_void_NN(SV* sv)
sv_report_used

Dump the contents of all SVs not yet freed (debugging aid).

void    sv_report_used()
SvROK

Tests if the SV is an RV.

U32     SvROK(SV* sv)
SvROK_off

Unsets the RV status of an SV.

void    SvROK_off(SV* sv)
SvROK_on

Tells an SV that it is an RV.

void    SvROK_on(SV* sv)
SvRV

Dereferences an RV to return the SV.

SV*     SvRV(SV* sv)
SvRV_set

Set the value of the RV pointer in sv to val. See "SvIV_set".

void    SvRV_set(SV* sv, SV* val)
sv_setsv_nomg

Like sv_setsv but doesn't process magic.

void    sv_setsv_nomg(SV* dsv, SV* ssv)
SvSTASH

Returns the stash of the SV.

HV*     SvSTASH(SV* sv)
SvSTASH_set

Set the value of the STASH pointer in sv to val. See "SvIV_set".

void    SvSTASH_set(SV* sv, HV* val)
SvTAINT

Taints an SV if tainting is enabled, and if some input to the current expression is tainted--usually a variable, but possibly also implicit inputs such as locale settings. SvTAINT propagates that taintedness to the outputs of an expression in a pessimistic fashion; i.e., without paying attention to precisely which outputs are influenced by which inputs.

void    SvTAINT(SV* sv)
SvTAINTED

Checks to see if an SV is tainted. Returns TRUE if it is, FALSE if not.

bool    SvTAINTED(SV* sv)
SvTAINTED_off

Untaints an SV. Be very careful with this routine, as it short-circuits some of Perl's fundamental security features. XS module authors should not use this function unless they fully understand all the implications of unconditionally untainting the value. Untainting should be done in the standard perl fashion, via a carefully crafted regexp, rather than directly untainting variables.

void    SvTAINTED_off(SV* sv)
SvTAINTED_on

Marks an SV as tainted if tainting is enabled.

void    SvTAINTED_on(SV* sv)
SvTRUE

Returns a boolean indicating whether Perl would evaluate the SV as true or false. See "SvOK" for a defined/undefined test. Handles 'get' magic unless the scalar is already SvPOK, SvIOK or SvNOK (the public, not the private flags).

bool    SvTRUE(SV* sv)
SvTRUE_nomg

Returns a boolean indicating whether Perl would evaluate the SV as true or false. See "SvOK" for a defined/undefined test. Does not handle 'get' magic.

bool    SvTRUE_nomg(SV* sv)
SvTYPE

Returns the type of the SV. See "svtype".

svtype  SvTYPE(SV* sv)
SvUOK

Returns a boolean indicating whether the SV contains an integer that must be interpreted as unsigned. A non-negative integer whose value is within the range of both an IV and a UV may be be flagged as either SvUOK or SVIOK.

bool    SvUOK(SV* sv)
SvUPGRADE

Used to upgrade an SV to a more complex form. Uses sv_upgrade to perform the upgrade if necessary. See "svtype".

void    SvUPGRADE(SV* sv, svtype type)
SvUTF8

Returns a U32 value indicating the UTF-8 status of an SV. If things are set-up properly, this indicates whether or not the SV contains UTF-8 encoded data. You should use this after a call to SvPV() or one of its variants, in case any call to string overloading updates the internal flag.

If you want to take into account the bytes pragma, use "DO_UTF8" instead.

U32     SvUTF8(SV* sv)
sv_utf8_upgrade_nomg

Like sv_utf8_upgrade, but doesn't do magic on sv.

STRLEN  sv_utf8_upgrade_nomg(SV *sv)
SvUTF8_off

Unsets the UTF-8 status of an SV (the data is not changed, just the flag). Do not use frivolously.

void    SvUTF8_off(SV *sv)
SvUTF8_on

Turn on the UTF-8 status of an SV (the data is not changed, just the flag). Do not use frivolously.

void    SvUTF8_on(SV *sv)
SvUV

Coerces the given SV to UV and returns it. The returned value in many circumstances will get stored in sv's UV slot, but not in all cases. (Use "sv_setuv" to make sure it does).

See "SvUVx" for a version which guarantees to evaluate sv only once.

UV      SvUV(SV* sv)
SvUV_nomg

Like SvUV but doesn't process magic.

UV      SvUV_nomg(SV* sv)
SvUV_set

Set the value of the UV pointer in sv to val. See "SvIV_set".

void    SvUV_set(SV* sv, UV val)
SvUVX

Returns the raw value in the SV's UV slot, without checks or conversions. Only use when you are sure SvIOK is true. See also "SvUV".

UV      SvUVX(SV* sv)
SvUVx

Coerces the given SV to UV and returns it. The returned value in many circumstances will get stored in sv's UV slot, but not in all cases. (Use "sv_setuv" to make sure it does).

This form guarantees to evaluate sv only once. Only use this if sv is an expression with side effects, otherwise use the more efficient SvUV.

UV      SvUVx(SV* sv)
SvVOK

Returns a boolean indicating whether the SV contains a v-string.

bool    SvVOK(SV* sv)

Unicode Support

"Unicode Support" in perlguts has an introduction to this API.

See also "Character classification", and "Character case changing". Various functions outside this section also work specially with Unicode. Search for the string "utf8" in this document.

BOM_UTF8

This is a macro that evaluates to a string constant of the UTF-8 bytes that define the Unicode BYTE ORDER MARK (U+FEFF) for the platform that perl is compiled on. This allows code to use a mnemonic for this character that works on both ASCII and EBCDIC platforms. sizeof(BOM_UTF8) - 1 can be used to get its length in bytes.

bytes_cmp_utf8

Compares the sequence of characters (stored as octets) in b, blen with the sequence of characters (stored as UTF-8) in u, ulen. Returns 0 if they are equal, -1 or -2 if the first string is less than the second string, +1 or +2 if the first string is greater than the second string.

-1 or +1 is returned if the shorter string was identical to the start of the longer string. -2 or +2 is returned if there was a difference between characters within the strings.

int     bytes_cmp_utf8(const U8 *b, STRLEN blen,
                       const U8 *u, STRLEN ulen)
bytes_from_utf8

NOTE: this function is experimental and may change or be removed without notice.

Converts a potentially UTF-8 encoded string s of length *lenp into native byte encoding. On input, the boolean *is_utf8p gives whether or not s is actually encoded in UTF-8.

Unlike "utf8_to_bytes" but like "bytes_to_utf8", this is non-destructive of the input string.

Do nothing if *is_utf8p is 0, or if there are code points in the string not expressible in native byte encoding. In these cases, *is_utf8p and *lenp are unchanged, and the return value is the original s.

Otherwise, *is_utf8p is set to 0, and the return value is a pointer to a newly created string containing a downgraded copy of s, and whose length is returned in *lenp, updated. The new string is NUL-terminated. The caller is responsible for arranging for the memory used by this string to get freed.

Upon successful return, the number of variants in the string can be computed by having saved the value of *lenp before the call, and subtracting the after-call value of *lenp from it.

U8*     bytes_from_utf8(const U8 *s, STRLEN *lenp,
                        bool *is_utf8p)
bytes_to_utf8

NOTE: this function is experimental and may change or be removed without notice.

Converts a string s of length *lenp bytes from the native encoding into UTF-8. Returns a pointer to the newly-created string, and sets *lenp to reflect the new length in bytes. The caller is responsible for arranging for the memory used by this string to get freed.

Upon successful return, the number of variants in the string can be computed by having saved the value of *lenp before the call, and subtracting it from the after-call value of *lenp.

A NUL character will be written after the end of the string.

If you want to convert to UTF-8 from encodings other than the native (Latin1 or EBCDIC), see "sv_recode_to_utf8"().

U8*     bytes_to_utf8(const U8 *s, STRLEN *lenp)
DO_UTF8

Returns a bool giving whether or not the PV in sv is to be treated as being encoded in UTF-8.

You should use this after a call to SvPV() or one of its variants, in case any call to string overloading updates the internal UTF-8 encoding flag.

bool    DO_UTF8(SV* sv)
foldEQ_utf8

Returns true if the leading portions of the strings s1 and s2 (either or both of which may be in UTF-8) are the same case-insensitively; false otherwise. How far into the strings to compare is determined by other input parameters.

If u1 is true, the string s1 is assumed to be in UTF-8-encoded Unicode; otherwise it is assumed to be in native 8-bit encoding. Correspondingly for u2 with respect to s2.

If the byte length l1 is non-zero, it says how far into s1 to check for fold equality. In other words, s1+l1 will be used as a goal to reach. The scan will not be considered to be a match unless the goal is reached, and scanning won't continue past that goal. Correspondingly for l2 with respect to s2.

If pe1 is non-NULL and the pointer it points to is not NULL, that pointer is considered an end pointer to the position 1 byte past the maximum point in s1 beyond which scanning will not continue under any circumstances. (This routine assumes that UTF-8 encoded input strings are not malformed; malformed input can cause it to read past pe1). This means that if both l1 and pe1 are specified, and pe1 is less than s1+l1, the match will never be successful because it can never get as far as its goal (and in fact is asserted against). Correspondingly for pe2 with respect to s2.

At least one of s1 and s2 must have a goal (at least one of l1 and l2 must be non-zero), and if both do, both have to be reached for a successful match. Also, if the fold of a character is multiple characters, all of them must be matched (see tr21 reference below for 'folding').

Upon a successful match, if pe1 is non-NULL, it will be set to point to the beginning of the next character of s1 beyond what was matched. Correspondingly for pe2 and s2.

For case-insensitiveness, the "casefolding" of Unicode is used instead of upper/lowercasing both the characters, see http://www.unicode.org/unicode/reports/tr21/ (Case Mappings).

I32     foldEQ_utf8(const char *s1, char **pe1, UV l1,
                    bool u1, const char *s2, char **pe2,
                    UV l2, bool u2)
is_ascii_string

This is a misleadingly-named synonym for "is_utf8_invariant_string". On ASCII-ish platforms, the name isn't misleading: the ASCII-range characters are exactly the UTF-8 invariants. But EBCDIC machines have more invariants than just the ASCII characters, so is_utf8_invariant_string is preferred.

bool    is_ascii_string(const U8* const s, STRLEN len)
is_c9strict_utf8_string

Returns TRUE if the first len bytes of string s form a valid UTF-8-encoded string that conforms to Unicode Corrigendum #9; otherwise it returns FALSE. If len is 0, it will be calculated using strlen(s) (which means if you use this option, that s can't have embedded NUL characters and has to have a terminating NUL byte). Note that all characters being ASCII constitute 'a valid UTF-8 string'.

This function returns FALSE for strings containing any code points above the Unicode max of 0x10FFFF or surrogate code points, but accepts non-character code points per Corrigendum #9.

See also "is_utf8_invariant_string", "is_utf8_invariant_string_loc", "is_utf8_string", "is_utf8_string_flags", "is_utf8_string_loc", "is_utf8_string_loc_flags", "is_utf8_string_loclen", "is_utf8_string_loclen_flags", "is_utf8_fixed_width_buf_flags", "is_utf8_fixed_width_buf_loc_flags", "is_utf8_fixed_width_buf_loclen_flags", "is_strict_utf8_string", "is_strict_utf8_string_loc", "is_strict_utf8_string_loclen", "is_c9strict_utf8_string_loc", and "is_c9strict_utf8_string_loclen".

bool    is_c9strict_utf8_string(const U8 *s, STRLEN len)
is_c9strict_utf8_string_loc

Like "is_c9strict_utf8_string" but stores the location of the failure (in the case of "utf8ness failure") or the location s+len (in the case of "utf8ness success") in the ep pointer.

See also "is_c9strict_utf8_string_loclen".

bool    is_c9strict_utf8_string_loc(const U8 *s,
                                    STRLEN len,
                                    const U8 **ep)
is_c9strict_utf8_string_loclen

Like "is_c9strict_utf8_string" but stores the location of the failure (in the case of "utf8ness failure") or the location s+len (in the case of "utf8ness success") in the ep pointer, and the number of UTF-8 encoded characters in the el pointer.

See also "is_c9strict_utf8_string_loc".

bool    is_c9strict_utf8_string_loclen(const U8 *s,
                                       STRLEN len,
                                       const U8 **ep,
                                       STRLEN *el)
isC9_STRICT_UTF8_CHAR

Evaluates to non-zero if the first few bytes of the string starting at s and looking no further than e - 1 are well-formed UTF-8 that represents some Unicode non-surrogate code point; otherwise it evaluates to 0. If non-zero, the value gives how many bytes starting at s comprise the code point's representation. Any bytes remaining before e, but beyond the ones needed to form the first code point in s, are not examined.

The largest acceptable code point is the Unicode maximum 0x10FFFF. This differs from "isSTRICT_UTF8_CHAR" only in that it accepts non-character code points. This corresponds to Unicode Corrigendum #9. which said that non-character code points are merely discouraged rather than completely forbidden in open interchange. See "Noncharacter code points" in perlunicode.

Use "isUTF8_CHAR" to check for Perl's extended UTF-8; and "isUTF8_CHAR_flags" for a more customized definition.

Use "is_c9strict_utf8_string", "is_c9strict_utf8_string_loc", and "is_c9strict_utf8_string_loclen" to check entire strings.

STRLEN  isC9_STRICT_UTF8_CHAR(const U8 *s, const U8 *e)
is_invariant_string

This is a somewhat misleadingly-named synonym for "is_utf8_invariant_string". is_utf8_invariant_string is preferred, as it indicates under what conditions the string is invariant.

bool    is_invariant_string(const U8* const s,
                            STRLEN len)
isSTRICT_UTF8_CHAR

Evaluates to non-zero if the first few bytes of the string starting at s and looking no further than e - 1 are well-formed UTF-8 that represents some Unicode code point completely acceptable for open interchange between all applications; otherwise it evaluates to 0. If non-zero, the value gives how many bytes starting at s comprise the code point's representation. Any bytes remaining before e, but beyond the ones needed to form the first code point in s, are not examined.

The largest acceptable code point is the Unicode maximum 0x10FFFF, and must not be a surrogate nor a non-character code point. Thus this excludes any code point from Perl's extended UTF-8.

This is used to efficiently decide if the next few bytes in s is legal Unicode-acceptable UTF-8 for a single character.

Use "isC9_STRICT_UTF8_CHAR" to use the Unicode Corrigendum #9 definition of allowable code points; "isUTF8_CHAR" to check for Perl's extended UTF-8; and "isUTF8_CHAR_flags" for a more customized definition.

Use "is_strict_utf8_string", "is_strict_utf8_string_loc", and "is_strict_utf8_string_loclen" to check entire strings.

STRLEN  isSTRICT_UTF8_CHAR(const U8 *s, const U8 *e)
is_strict_utf8_string

Returns TRUE if the first len bytes of string s form a valid UTF-8-encoded string that is fully interchangeable by any application using Unicode rules; otherwise it returns FALSE. If len is 0, it will be calculated using strlen(s) (which means if you use this option, that s can't have embedded NUL characters and has to have a terminating NUL byte). Note that all characters being ASCII constitute 'a valid UTF-8 string'.

This function returns FALSE for strings containing any code points above the Unicode max of 0x10FFFF, surrogate code points, or non-character code points.

See also "is_utf8_invariant_string", "is_utf8_invariant_string_loc", "is_utf8_string", "is_utf8_string_flags", "is_utf8_string_loc", "is_utf8_string_loc_flags", "is_utf8_string_loclen", "is_utf8_string_loclen_flags", "is_utf8_fixed_width_buf_flags", "is_utf8_fixed_width_buf_loc_flags", "is_utf8_fixed_width_buf_loclen_flags", "is_strict_utf8_string_loc", "is_strict_utf8_string_loclen", "is_c9strict_utf8_string", "is_c9strict_utf8_string_loc", and "is_c9strict_utf8_string_loclen".

bool    is_strict_utf8_string(const U8 *s, STRLEN len)
is_strict_utf8_string_loc

Like "is_strict_utf8_string" but stores the location of the failure (in the case of "utf8ness failure") or the location s+len (in the case of "utf8ness success") in the ep pointer.

See also "is_strict_utf8_string_loclen".

bool    is_strict_utf8_string_loc(const U8 *s,
                                  STRLEN len,
                                  const U8 **ep)
is_strict_utf8_string_loclen

Like "is_strict_utf8_string" but stores the location of the failure (in the case of "utf8ness failure") or the location s+len (in the case of "utf8ness success") in the ep pointer, and the number of UTF-8 encoded characters in the el pointer.

See also "is_strict_utf8_string_loc".

bool    is_strict_utf8_string_loclen(const U8 *s,
                                     STRLEN len,
                                     const U8 **ep,
                                     STRLEN *el)
is_utf8_fixed_width_buf_flags

Returns TRUE if the fixed-width buffer starting at s with length len is entirely valid UTF-8, subject to the restrictions given by flags; otherwise it returns FALSE.

If flags is 0, any well-formed UTF-8, as extended by Perl, is accepted without restriction. If the final few bytes of the buffer do not form a complete code point, this will return TRUE anyway, provided that "is_utf8_valid_partial_char_flags" returns TRUE for them.

If flags in non-zero, it can be any combination of the UTF8_DISALLOW_foo flags accepted by "utf8n_to_uvchr", and with the same meanings.

This function differs from "is_utf8_string_flags" only in that the latter returns FALSE if the final few bytes of the string don't form a complete code point.

bool    is_utf8_fixed_width_buf_flags(
            const U8 * const s, STRLEN len,
            const U32 flags
        )
is_utf8_fixed_width_buf_loclen_flags

Like "is_utf8_fixed_width_buf_loc_flags" but stores the number of complete, valid characters found in the el pointer.

bool    is_utf8_fixed_width_buf_loclen_flags(
            const U8 * const s, STRLEN len,
            const U8 **ep, STRLEN *el, const U32 flags
        )
is_utf8_fixed_width_buf_loc_flags

Like "is_utf8_fixed_width_buf_flags" but stores the location of the failure in the ep pointer. If the function returns TRUE, *ep will point to the beginning of any partial character at the end of the buffer; if there is no partial character *ep will contain s+len.

See also "is_utf8_fixed_width_buf_loclen_flags".

bool    is_utf8_fixed_width_buf_loc_flags(
            const U8 * const s, STRLEN len,
            const U8 **ep, const U32 flags
        )
is_utf8_invariant_string

Returns TRUE if the first len bytes of the string s are the same regardless of the UTF-8 encoding of the string (or UTF-EBCDIC encoding on EBCDIC machines); otherwise it returns FALSE. That is, it returns TRUE if they are UTF-8 invariant. On ASCII-ish machines, all the ASCII characters and only the ASCII characters fit this definition. On EBCDIC machines, the ASCII-range characters are invariant, but so also are the C1 controls.

If len is 0, it will be calculated using strlen(s), (which means if you use this option, that s can't have embedded NUL characters and has to have a terminating NUL byte).

See also "is_utf8_string", "is_utf8_string_flags", "is_utf8_string_loc", "is_utf8_string_loc_flags", "is_utf8_string_loclen", "is_utf8_string_loclen_flags", "is_utf8_fixed_width_buf_flags", "is_utf8_fixed_width_buf_loc_flags", "is_utf8_fixed_width_buf_loclen_flags", "is_strict_utf8_string", "is_strict_utf8_string_loc", "is_strict_utf8_string_loclen", "is_c9strict_utf8_string", "is_c9strict_utf8_string_loc", and "is_c9strict_utf8_string_loclen".

bool    is_utf8_invariant_string(const U8* const s,
                                 STRLEN len)
is_utf8_invariant_string_loc

Like "is_utf8_invariant_string" but upon failure, stores the location of the first UTF-8 variant character in the ep pointer; if all characters are UTF-8 invariant, this function does not change the contents of *ep.

bool    is_utf8_invariant_string_loc(const U8* const s,
                                     STRLEN len,
                                     const U8 ** ep)
is_utf8_string

Returns TRUE if the first len bytes of string s form a valid Perl-extended-UTF-8 string; returns FALSE otherwise. If len is 0, it will be calculated using strlen(s) (which means if you use this option, that s can't have embedded NUL characters and has to have a terminating NUL byte). Note that all characters being ASCII constitute 'a valid UTF-8 string'.

This function considers Perl's extended UTF-8 to be valid. That means that code points above Unicode, surrogates, and non-character code points are considered valid by this function. Use "is_strict_utf8_string", "is_c9strict_utf8_string", or "is_utf8_string_flags" to restrict what code points are considered valid.

See also "is_utf8_invariant_string", "is_utf8_invariant_string_loc", "is_utf8_string_loc", "is_utf8_string_loclen", "is_utf8_fixed_width_buf_flags", "is_utf8_fixed_width_buf_loc_flags", "is_utf8_fixed_width_buf_loclen_flags",

bool    is_utf8_string(const U8 *s, STRLEN len)
is_utf8_string_flags

Returns TRUE if the first len bytes of string s form a valid UTF-8 string, subject to the restrictions imposed by flags; returns FALSE otherwise. If len is 0, it will be calculated using strlen(s) (which means if you use this option, that s can't have embedded NUL characters and has to have a terminating NUL byte). Note that all characters being ASCII constitute 'a valid UTF-8 string'.

If flags is 0, this gives the same results as "is_utf8_string"; if flags is UTF8_DISALLOW_ILLEGAL_INTERCHANGE, this gives the same results as "is_strict_utf8_string"; and if flags is UTF8_DISALLOW_ILLEGAL_C9_INTERCHANGE, this gives the same results as "is_c9strict_utf8_string". Otherwise flags may be any combination of the UTF8_DISALLOW_foo flags understood by "utf8n_to_uvchr", with the same meanings.

See also "is_utf8_invariant_string", "is_utf8_invariant_string_loc", "is_utf8_string", "is_utf8_string_loc", "is_utf8_string_loc_flags", "is_utf8_string_loclen", "is_utf8_string_loclen_flags", "is_utf8_fixed_width_buf_flags", "is_utf8_fixed_width_buf_loc_flags", "is_utf8_fixed_width_buf_loclen_flags", "is_strict_utf8_string", "is_strict_utf8_string_loc", "is_strict_utf8_string_loclen", "is_c9strict_utf8_string", "is_c9strict_utf8_string_loc", and "is_c9strict_utf8_string_loclen".

bool    is_utf8_string_flags(const U8 *s, STRLEN len,
                             const U32 flags)
is_utf8_string_loc

Like "is_utf8_string" but stores the location of the failure (in the case of "utf8ness failure") or the location s+len (in the case of "utf8ness success") in the ep pointer.

See also "is_utf8_string_loclen".

bool    is_utf8_string_loc(const U8 *s,
                           const STRLEN len,
                           const U8 **ep)
is_utf8_string_loclen

Like "is_utf8_string" but stores the location of the failure (in the case of "utf8ness failure") or the location s+len (in the case of "utf8ness success") in the ep pointer, and the number of UTF-8 encoded characters in the el pointer.

See also "is_utf8_string_loc".

bool    is_utf8_string_loclen(const U8 *s, STRLEN len,
                              const U8 **ep, STRLEN *el)
is_utf8_string_loclen_flags

Like "is_utf8_string_flags" but stores the location of the failure (in the case of "utf8ness failure") or the location s+len (in the case of "utf8ness success") in the ep pointer, and the number of UTF-8 encoded characters in the el pointer.

See also "is_utf8_string_loc_flags".

bool    is_utf8_string_loclen_flags(const U8 *s,
                                    STRLEN len,
                                    const U8 **ep,
                                    STRLEN *el,
                                    const U32 flags)
is_utf8_string_loc_flags

Like "is_utf8_string_flags" but stores the location of the failure (in the case of "utf8ness failure") or the location s+len (in the case of "utf8ness success") in the ep pointer.

See also "is_utf8_string_loclen_flags".

bool    is_utf8_string_loc_flags(const U8 *s,
                                 STRLEN len,
                                 const U8 **ep,
                                 const U32 flags)
is_utf8_valid_partial_char

Returns 0 if the sequence of bytes starting at s and looking no further than e - 1 is the UTF-8 encoding, as extended by Perl, for one or more code points. Otherwise, it returns 1 if there exists at least one non-empty sequence of bytes that when appended to sequence s, starting at position e causes the entire sequence to be the well-formed UTF-8 of some code point; otherwise returns 0.

In other words this returns TRUE if s points to a partial UTF-8-encoded code point.

This is useful when a fixed-length buffer is being tested for being well-formed UTF-8, but the final few bytes in it don't comprise a full character; that is, it is split somewhere in the middle of the final code point's UTF-8 representation. (Presumably when the buffer is refreshed with the next chunk of data, the new first bytes will complete the partial code point.) This function is used to verify that the final bytes in the current buffer are in fact the legal beginning of some code point, so that if they aren't, the failure can be signalled without having to wait for the next read.

bool    is_utf8_valid_partial_char(const U8 * const s,
                                   const U8 * const e)
is_utf8_valid_partial_char_flags

Like "is_utf8_valid_partial_char", it returns a boolean giving whether or not the input is a valid UTF-8 encoded partial character, but it takes an extra parameter, flags, which can further restrict which code points are considered valid.

If flags is 0, this behaves identically to "is_utf8_valid_partial_char". Otherwise flags can be any combination of the UTF8_DISALLOW_foo flags accepted by "utf8n_to_uvchr". If there is any sequence of bytes that can complete the input partial character in such a way that a non-prohibited character is formed, the function returns TRUE; otherwise FALSE. Non character code points cannot be determined based on partial character input. But many of the other possible excluded types can be determined from just the first one or two bytes.

bool    is_utf8_valid_partial_char_flags(
            const U8 * const s, const U8 * const e,
            const U32 flags
        )
isUTF8_CHAR

Evaluates to non-zero if the first few bytes of the string starting at s and looking no further than e - 1 are well-formed UTF-8, as extended by Perl, that represents some code point; otherwise it evaluates to 0. If non-zero, the value gives how many bytes starting at s comprise the code point's representation. Any bytes remaining before e, but beyond the ones needed to form the first code point in s, are not examined.

The code point can be any that will fit in a UV on this machine, using Perl's extension to official UTF-8 to represent those higher than the Unicode maximum of 0x10FFFF. That means that this macro is used to efficiently decide if the next few bytes in s is legal UTF-8 for a single character.

Use "isSTRICT_UTF8_CHAR" to restrict the acceptable code points to those defined by Unicode to be fully interchangeable across applications; "isC9_STRICT_UTF8_CHAR" to use the Unicode Corrigendum #9 definition of allowable code points; and "isUTF8_CHAR_flags" for a more customized definition.

Use "is_utf8_string", "is_utf8_string_loc", and "is_utf8_string_loclen" to check entire strings.

Note that it is deprecated to use code points higher than what will fit in an IV. This macro does not raise any warnings for such code points, treating them as valid.

Note also that a UTF-8 INVARIANT character (i.e. ASCII on non-EBCDIC machines) is a valid UTF-8 character.

STRLEN  isUTF8_CHAR(const U8 *s, const U8 *e)
isUTF8_CHAR_flags

Evaluates to non-zero if the first few bytes of the string starting at s and looking no further than e - 1 are well-formed UTF-8, as extended by Perl, that represents some code point, subject to the restrictions given by flags; otherwise it evaluates to 0. If non-zero, the value gives how many bytes starting at s comprise the code point's representation. Any bytes remaining before e, but beyond the ones needed to form the first code point in s, are not examined.

If flags is 0, this gives the same results as "isUTF8_CHAR"; if flags is UTF8_DISALLOW_ILLEGAL_INTERCHANGE, this gives the same results as "isSTRICT_UTF8_CHAR"; and if flags is UTF8_DISALLOW_ILLEGAL_C9_INTERCHANGE, this gives the same results as "isC9_STRICT_UTF8_CHAR". Otherwise flags may be any combination of the UTF8_DISALLOW_foo flags understood by "utf8n_to_uvchr", with the same meanings.

The three alternative macros are for the most commonly needed validations; they are likely to run somewhat faster than this more general one, as they can be inlined into your code.

Use "is_utf8_string_flags", "is_utf8_string_loc_flags", and "is_utf8_string_loclen_flags" to check entire strings.

STRLEN  isUTF8_CHAR_flags(const U8 *s, const U8 *e,
                           const U32 flags)
pv_uni_display

Build to the scalar dsv a displayable version of the string spv, length len, the displayable version being at most pvlim bytes long (if longer, the rest is truncated and "..." will be appended).

The flags argument can have UNI_DISPLAY_ISPRINT set to display isPRINT()able characters as themselves, UNI_DISPLAY_BACKSLASH to display the \\[nrfta\\] as the backslashed versions (like "\n") (UNI_DISPLAY_BACKSLASH is preferred over UNI_DISPLAY_ISPRINT for "\\"). UNI_DISPLAY_QQ (and its alias UNI_DISPLAY_REGEX) have both UNI_DISPLAY_BACKSLASH and UNI_DISPLAY_ISPRINT turned on.

The pointer to the PV of the dsv is returned.

See also "sv_uni_display".

char*   pv_uni_display(SV *dsv, const U8 *spv,
                       STRLEN len, STRLEN pvlim,
                       UV flags)
REPLACEMENT_CHARACTER_UTF8

This is a macro that evaluates to a string constant of the UTF-8 bytes that define the Unicode REPLACEMENT CHARACTER (U+FFFD) for the platform that perl is compiled on. This allows code to use a mnemonic for this character that works on both ASCII and EBCDIC platforms. sizeof(REPLACEMENT_CHARACTER_UTF8) - 1 can be used to get its length in bytes.

sv_cat_decode

encoding is assumed to be an Encode object, the PV of ssv is assumed to be octets in that encoding and decoding the input starts from the position which (PV + *offset) pointed to. dsv will be concatenated with the decoded UTF-8 string from ssv. Decoding will terminate when the string tstr appears in decoding output or the input ends on the PV of ssv. The value which offset points will be modified to the last input position on ssv.

Returns TRUE if the terminator was found, else returns FALSE.

bool    sv_cat_decode(SV* dsv, SV *encoding, SV *ssv,
                      int *offset, char* tstr, int tlen)
sv_recode_to_utf8

encoding is assumed to be an Encode object, on entry the PV of sv is assumed to be octets in that encoding, and sv will be converted into Unicode (and UTF-8).

If sv already is UTF-8 (or if it is not POK), or if encoding is not a reference, nothing is done to sv. If encoding is not an Encode::XS Encoding object, bad things will happen. (See cpan/Encode/encoding.pm and Encode.)

The PV of sv is returned.

char*   sv_recode_to_utf8(SV* sv, SV *encoding)
sv_uni_display

Build to the scalar dsv a displayable version of the scalar sv, the displayable version being at most pvlim bytes long (if longer, the rest is truncated and "..." will be appended).

The flags argument is as in "pv_uni_display"().

The pointer to the PV of the dsv is returned.

char*   sv_uni_display(SV *dsv, SV *ssv, STRLEN pvlim,
                       UV flags)
to_utf8_fold

DEPRECATED! It is planned to remove this function from a future release of Perl. Do not use it for new code; remove it from existing code.

Instead use "toFOLD_utf8_safe".

UV      to_utf8_fold(const U8 *p, U8* ustrp,
                     STRLEN *lenp)
to_utf8_lower

DEPRECATED! It is planned to remove this function from a future release of Perl. Do not use it for new code; remove it from existing code.

Instead use "toLOWER_utf8_safe".

UV      to_utf8_lower(const U8 *p, U8* ustrp,
                      STRLEN *lenp)
to_utf8_title

DEPRECATED! It is planned to remove this function from a future release of Perl. Do not use it for new code; remove it from existing code.

Instead use "toTITLE_utf8_safe".

UV      to_utf8_title(const U8 *p, U8* ustrp,
                      STRLEN *lenp)
to_utf8_upper

DEPRECATED! It is planned to remove this function from a future release of Perl. Do not use it for new code; remove it from existing code.

Instead use "toUPPER_utf8_safe".

UV      to_utf8_upper(const U8 *p, U8* ustrp,
                      STRLEN *lenp)
utf8n_to_uvchr

THIS FUNCTION SHOULD BE USED IN ONLY VERY SPECIALIZED CIRCUMSTANCES. Most code should use "utf8_to_uvchr_buf"() rather than call this directly.

Bottom level UTF-8 decode routine. Returns the native code point value of the first character in the string s, which is assumed to be in UTF-8 (or UTF-EBCDIC) encoding, and no longer than curlen bytes; *retlen (if retlen isn't NULL) will be set to the length, in bytes, of that character.

The value of flags determines the behavior when s does not point to a well-formed UTF-8 character. If flags is 0, encountering a malformation causes zero to be returned and *retlen is set so that (s + *retlen) is the next possible position in s that could begin a non-malformed character. Also, if UTF-8 warnings haven't been lexically disabled, a warning is raised. Some UTF-8 input sequences may contain multiple malformations. This function tries to find every possible one in each call, so multiple warnings can be raised for the same sequence.

Various ALLOW flags can be set in flags to allow (and not warn on) individual types of malformations, such as the sequence being overlong (that is, when there is a shorter sequence that can express the same code point; overlong sequences are expressly forbidden in the UTF-8 standard due to potential security issues). Another malformation example is the first byte of a character not being a legal first byte. See utf8.h for the list of such flags. Even if allowed, this function generally returns the Unicode REPLACEMENT CHARACTER when it encounters a malformation. There are flags in utf8.h to override this behavior for the overlong malformations, but don't do that except for very specialized purposes.

The UTF8_CHECK_ONLY flag overrides the behavior when a non-allowed (by other flags) malformation is found. If this flag is set, the routine assumes that the caller will raise a warning, and this function will silently just set retlen to -1 (cast to STRLEN) and return zero.

Note that this API requires disambiguation between successful decoding a NUL character, and an error return (unless the UTF8_CHECK_ONLY flag is set), as in both cases, 0 is returned, and, depending on the malformation, retlen may be set to 1. To disambiguate, upon a zero return, see if the first byte of s is 0 as well. If so, the input was a NUL; if not, the input had an error. Or you can use "utf8n_to_uvchr_error".

Certain code points are considered problematic. These are Unicode surrogates, Unicode non-characters, and code points above the Unicode maximum of 0x10FFFF. By default these are considered regular code points, but certain situations warrant special handling for them, which can be specified using the flags parameter. If flags contains UTF8_DISALLOW_ILLEGAL_INTERCHANGE, all three classes are treated as malformations and handled as such. The flags UTF8_DISALLOW_SURROGATE, UTF8_DISALLOW_NONCHAR, and UTF8_DISALLOW_SUPER (meaning above the legal Unicode maximum) can be set to disallow these categories individually. UTF8_DISALLOW_ILLEGAL_INTERCHANGE restricts the allowed inputs to the strict UTF-8 traditionally defined by Unicode. Use UTF8_DISALLOW_ILLEGAL_C9_INTERCHANGE to use the strictness definition given by Unicode Corrigendum #9. The difference between traditional strictness and C9 strictness is that the latter does not forbid non-character code points. (They are still discouraged, however.) For more discussion see "Noncharacter code points" in perlunicode.

The flags UTF8_WARN_ILLEGAL_INTERCHANGE, UTF8_WARN_ILLEGAL_C9_INTERCHANGE, UTF8_WARN_SURROGATE, UTF8_WARN_NONCHAR, and UTF8_WARN_SUPER will cause warning messages to be raised for their respective categories, but otherwise the code points are considered valid (not malformations). To get a category to both be treated as a malformation and raise a warning, specify both the WARN and DISALLOW flags. (But note that warnings are not raised if lexically disabled nor if UTF8_CHECK_ONLY is also specified.)

Extremely high code points were never specified in any standard, and require an extension to UTF-8 to express, which Perl does. It is likely that programs written in something other than Perl would not be able to read files that contain these; nor would Perl understand files written by something that uses a different extension. For these reasons, there is a separate set of flags that can warn and/or disallow these extremely high code points, even if other above-Unicode ones are accepted. They are the UTF8_WARN_PERL_EXTENDED and UTF8_DISALLOW_PERL_EXTENDED flags. For more information see "UTF8_GOT_PERL_EXTENDED". Of course UTF8_DISALLOW_SUPER will treat all above-Unicode code points, including these, as malformations. (Note that the Unicode standard considers anything above 0x10FFFF to be illegal, but there are standards predating it that allow up to 0x7FFF_FFFF (2**31 -1))

A somewhat misleadingly named synonym for UTF8_WARN_PERL_EXTENDED is retained for backward compatibility: UTF8_WARN_ABOVE_31_BIT. Similarly, UTF8_DISALLOW_ABOVE_31_BIT is usable instead of the more accurately named UTF8_DISALLOW_PERL_EXTENDED. The names are misleading because these flags can apply to code points that actually do fit in 31 bits. This happens on EBCDIC platforms, and sometimes when the overlong malformation is also present. The new names accurately describe the situation in all cases.

All other code points corresponding to Unicode characters, including private use and those yet to be assigned, are never considered malformed and never warn.

UV      utf8n_to_uvchr(const U8 *s, STRLEN curlen,
                       STRLEN *retlen, const U32 flags)
utf8n_to_uvchr_error

THIS FUNCTION SHOULD BE USED IN ONLY VERY SPECIALIZED CIRCUMSTANCES. Most code should use "utf8_to_uvchr_buf"() rather than call this directly.

This function is for code that needs to know what the precise malformation(s) are when an error is found. If you also need to know the generated warning messages, use "utf8n_to_uvchr_msgs"() instead.

It is like "utf8n_to_uvchr" but it takes an extra parameter placed after all the others, errors. If this parameter is 0, this function behaves identically to "utf8n_to_uvchr". Otherwise, errors should be a pointer to a U32 variable, which this function sets to indicate any errors found. Upon return, if *errors is 0, there were no errors found. Otherwise, *errors is the bit-wise OR of the bits described in the list below. Some of these bits will be set if a malformation is found, even if the input flags parameter indicates that the given malformation is allowed; those exceptions are noted:

UTF8_GOT_PERL_EXTENDED

The input sequence is not standard UTF-8, but a Perl extension. This bit is set only if the input flags parameter contains either the UTF8_DISALLOW_PERL_EXTENDED or the UTF8_WARN_PERL_EXTENDED flags.

Code points above 0x7FFF_FFFF (2**31 - 1) were never specified in any standard, and so some extension must be used to express them. Perl uses a natural extension to UTF-8 to represent the ones up to 2**36-1, and invented a further extension to represent even higher ones, so that any code point that fits in a 64-bit word can be represented. Text using these extensions is not likely to be portable to non-Perl code. We lump both of these extensions together and refer to them as Perl extended UTF-8. There exist other extensions that people have invented, incompatible with Perl's.

On EBCDIC platforms starting in Perl v5.24, the Perl extension for representing extremely high code points kicks in at 0x3FFF_FFFF (2**30 -1), which is lower than on ASCII. Prior to that, code points 2**31 and higher were simply unrepresentable, and a different, incompatible method was used to represent code points between 2**30 and 2**31 - 1.

On both platforms, ASCII and EBCDIC, UTF8_GOT_PERL_EXTENDED is set if Perl extended UTF-8 is used.

In earlier Perls, this bit was named UTF8_GOT_ABOVE_31_BIT, which you still may use for backward compatibility. That name is misleading, as this flag may be set when the code point actually does fit in 31 bits. This happens on EBCDIC platforms, and sometimes when the overlong malformation is also present. The new name accurately describes the situation in all cases.

UTF8_GOT_CONTINUATION

The input sequence was malformed in that the first byte was a a UTF-8 continuation byte.

UTF8_GOT_EMPTY

The input curlen parameter was 0.

UTF8_GOT_LONG

The input sequence was malformed in that there is some other sequence that evaluates to the same code point, but that sequence is shorter than this one.

Until Unicode 3.1, it was legal for programs to accept this malformation, but it was discovered that this created security issues.

UTF8_GOT_NONCHAR

The code point represented by the input UTF-8 sequence is for a Unicode non-character code point. This bit is set only if the input flags parameter contains either the UTF8_DISALLOW_NONCHAR or the UTF8_WARN_NONCHAR flags.

UTF8_GOT_NON_CONTINUATION

The input sequence was malformed in that a non-continuation type byte was found in a position where only a continuation type one should be.

UTF8_GOT_OVERFLOW

The input sequence was malformed in that it is for a code point that is not representable in the number of bits available in an IV on the current platform.

UTF8_GOT_SHORT

The input sequence was malformed in that curlen is smaller than required for a complete sequence. In other words, the input is for a partial character sequence.

UTF8_GOT_SUPER

The input sequence was malformed in that it is for a non-Unicode code point; that is, one above the legal Unicode maximum. This bit is set only if the input flags parameter contains either the UTF8_DISALLOW_SUPER or the UTF8_WARN_SUPER flags.

UTF8_GOT_SURROGATE

The input sequence was malformed in that it is for a -Unicode UTF-16 surrogate code point. This bit is set only if the input flags parameter contains either the UTF8_DISALLOW_SURROGATE or the UTF8_WARN_SURROGATE flags.

To do your own error handling, call this function with the UTF8_CHECK_ONLY flag to suppress any warnings, and then examine the *errors return.

UV      utf8n_to_uvchr_error(const U8 *s, STRLEN curlen,
                             STRLEN *retlen,
                             const U32 flags,
                             U32 * errors)
utf8n_to_uvchr_msgs

NOTE: this function is experimental and may change or be removed without notice.

THIS FUNCTION SHOULD BE USED IN ONLY VERY SPECIALIZED CIRCUMSTANCES. Most code should use "utf8_to_uvchr_buf"() rather than call this directly.

This function is for code that needs to know what the precise malformation(s) are when an error is found, and wants the corresponding warning and/or error messages to be returned to the caller rather than be displayed. All messages that would have been displayed if all lexcial warnings are enabled will be returned.

It is just like "utf8n_to_uvchr_error" but it takes an extra parameter placed after all the others, msgs. If this parameter is 0, this function behaves identically to "utf8n_to_uvchr_error". Otherwise, msgs should be a pointer to an AV * variable, in which this function creates a new AV to contain any appropriate messages. The elements of the array are ordered so that the first message that would have been displayed is in the 0th element, and so on. Each element is a hash with three key-value pairs, as follows:

text

The text of the message as a SVpv.

warn_categories

The warning category (or categories) packed into a SVuv.

flag

A single flag bit associated with this message, in a SVuv. The bit corresponds to some bit in the *errors return value, such as UTF8_GOT_LONG.

It's important to note that specifying this parameter as non-null will cause any warnings this function would otherwise generate to be suppressed, and instead be placed in *msgs. The caller can check the lexical warnings state (or not) when choosing what to do with the returned messages.

If the flag UTF8_CHECK_ONLY is passed, no warnings are generated, and hence no AV is created.

The caller, of course, is responsible for freeing any returned AV.

UV      utf8n_to_uvchr_msgs(const U8 *s, STRLEN curlen,
                            STRLEN *retlen,
                            const U32 flags,
                            U32 * errors, AV ** msgs)
utf8n_to_uvuni

Instead use "utf8_to_uvchr_buf", or rarely, "utf8n_to_uvchr".

This function was useful for code that wanted to handle both EBCDIC and ASCII platforms with Unicode properties, but starting in Perl v5.20, the distinctions between the platforms have mostly been made invisible to most code, so this function is quite unlikely to be what you want. If you do need this precise functionality, use instead NATIVE_TO_UNI(utf8_to_uvchr_buf(...)) or NATIVE_TO_UNI(utf8n_to_uvchr(...)).

UV      utf8n_to_uvuni(const U8 *s, STRLEN curlen,
                       STRLEN *retlen, U32 flags)
UTF8SKIP

returns the number of bytes in the UTF-8 encoded character whose first (perhaps only) byte is pointed to by s.

STRLEN  UTF8SKIP(char* s)
utf8_distance

Returns the number of UTF-8 characters between the UTF-8 pointers a and b.

WARNING: use only if you *know* that the pointers point inside the same UTF-8 buffer.

IV      utf8_distance(const U8 *a, const U8 *b)
utf8_hop

Return the UTF-8 pointer s displaced by off characters, either forward or backward.

WARNING: do not use the following unless you *know* off is within the UTF-8 data pointed to by s *and* that on entry s is aligned on the first byte of character or just after the last byte of a character.

U8*     utf8_hop(const U8 *s, SSize_t off)
utf8_hop_back

Return the UTF-8 pointer s displaced by up to off characters, backward.

off must be non-positive.

s must be after or equal to start.

When moving backward it will not move before start.

Will not exceed this limit even if the string is not valid "UTF-8".

U8*     utf8_hop_back(const U8 *s, SSize_t off,
                      const U8 *start)
utf8_hop_forward

Return the UTF-8 pointer s displaced by up to off characters, forward.

off must be non-negative.

s must be before or equal to end.

When moving forward it will not move beyond end.

Will not exceed this limit even if the string is not valid "UTF-8".

U8*     utf8_hop_forward(const U8 *s, SSize_t off,
                         const U8 *end)
utf8_hop_safe

Return the UTF-8 pointer s displaced by up to off characters, either forward or backward.

When moving backward it will not move before start.

When moving forward it will not move beyond end.

Will not exceed those limits even if the string is not valid "UTF-8".

U8*     utf8_hop_safe(const U8 *s, SSize_t off,
                      const U8 *start, const U8 *end)
UTF8_IS_INVARIANT

Evaluates to 1 if the byte c represents the same character when encoded in UTF-8 as when not; otherwise evaluates to 0. UTF-8 invariant characters can be copied as-is when converting to/from UTF-8, saving time.

In spite of the name, this macro gives the correct result if the input string from which c comes is not encoded in UTF-8.

See "UVCHR_IS_INVARIANT" for checking if a UV is invariant.

bool    UTF8_IS_INVARIANT(char c)
UTF8_IS_NONCHAR

Evaluates to non-zero if the first few bytes of the string starting at s and looking no further than e - 1 are well-formed UTF-8 that represents one of the Unicode non-character code points; otherwise it evaluates to 0. If non-zero, the value gives how many bytes starting at s comprise the code point's representation.

bool    UTF8_IS_NONCHAR(const U8 *s, const U8 *e)
UTF8_IS_SUPER

Recall that Perl recognizes an extension to UTF-8 that can encode code points larger than the ones defined by Unicode, which are 0..0x10FFFF.

This macro evaluates to non-zero if the first few bytes of the string starting at s and looking no further than e - 1 are from this UTF-8 extension; otherwise it evaluates to 0. If non-zero, the value gives how many bytes starting at s comprise the code point's representation.

0 is returned if the bytes are not well-formed extended UTF-8, or if they represent a code point that cannot fit in a UV on the current platform. Hence this macro can give different results when run on a 64-bit word machine than on one with a 32-bit word size.

Note that it is deprecated to have code points that are larger than what can fit in an IV on the current machine.

bool    UTF8_IS_SUPER(const U8 *s, const U8 *e)
UTF8_IS_SURROGATE

Evaluates to non-zero if the first few bytes of the string starting at s and looking no further than e - 1 are well-formed UTF-8 that represents one of the Unicode surrogate code points; otherwise it evaluates to 0. If non-zero, the value gives how many bytes starting at s comprise the code point's representation.

bool    UTF8_IS_SURROGATE(const U8 *s, const U8 *e)
utf8_length

Returns the number of characters in the sequence of UTF-8-encoded bytes starting at s and ending at the byte just before e. If <s> and <e> point to the same place, it returns 0 with no warning raised.

If e < s or if the scan would end up past e, it raises a UTF8 warning and returns the number of valid characters.

STRLEN  utf8_length(const U8* s, const U8 *e)
utf8_to_bytes

NOTE: this function is experimental and may change or be removed without notice.

Converts a string "s" of length *lenp from UTF-8 into native byte encoding. Unlike "bytes_to_utf8", this over-writes the original string, and updates *lenp to contain the new length. Returns zero on failure (leaving "s" unchanged) setting *lenp to -1.

Upon successful return, the number of variants in the string can be computed by having saved the value of *lenp before the call, and subtracting the after-call value of *lenp from it.

If you need a copy of the string, see "bytes_from_utf8".

U8*     utf8_to_bytes(U8 *s, STRLEN *lenp)
utf8_to_uvchr

DEPRECATED! It is planned to remove this function from a future release of Perl. Do not use it for new code; remove it from existing code.

Returns the native code point of the first character in the string s which is assumed to be in UTF-8 encoding; retlen will be set to the length, in bytes, of that character.

Some, but not all, UTF-8 malformations are detected, and in fact, some malformed input could cause reading beyond the end of the input buffer, which is why this function is deprecated. Use "utf8_to_uvchr_buf" instead.

If s points to one of the detected malformations, and UTF8 warnings are enabled, zero is returned and *retlen is set (if retlen isn't NULL) to -1. If those warnings are off, the computed value if well-defined (or the Unicode REPLACEMENT CHARACTER, if not) is silently returned, and *retlen is set (if retlen isn't NULL) so that (s + *retlen) is the next possible position in s that could begin a non-malformed character. See "utf8n_to_uvchr" for details on when the REPLACEMENT CHARACTER is returned.

UV      utf8_to_uvchr(const U8 *s, STRLEN *retlen)
utf8_to_uvchr_buf

Returns the native code point of the first character in the string s which is assumed to be in UTF-8 encoding; send points to 1 beyond the end of s. *retlen will be set to the length, in bytes, of that character.

If s does not point to a well-formed UTF-8 character and UTF8 warnings are enabled, zero is returned and *retlen is set (if retlen isn't NULL) to -1. If those warnings are off, the computed value, if well-defined (or the Unicode REPLACEMENT CHARACTER if not), is silently returned, and *retlen is set (if retlen isn't NULL) so that (s + *retlen) is the next possible position in s that could begin a non-malformed character. See "utf8n_to_uvchr" for details on when the REPLACEMENT CHARACTER is returned.

UV      utf8_to_uvchr_buf(const U8 *s, const U8 *send,
                          STRLEN *retlen)
utf8_to_uvuni_buf

DEPRECATED! It is planned to remove this function from a future release of Perl. Do not use it for new code; remove it from existing code.

Only in very rare circumstances should code need to be dealing in Unicode (as opposed to native) code points. In those few cases, use NATIVE_TO_UNI(utf8_to_uvchr_buf(...)) instead. If you are not absolutely sure this is one of those cases, then assume it isn't and use plain utf8_to_uvchr_buf instead.

Returns the Unicode (not-native) code point of the first character in the string s which is assumed to be in UTF-8 encoding; send points to 1 beyond the end of s. retlen will be set to the length, in bytes, of that character.

If s does not point to a well-formed UTF-8 character and UTF8 warnings are enabled, zero is returned and *retlen is set (if retlen isn't NULL) to -1. If those warnings are off, the computed value if well-defined (or the Unicode REPLACEMENT CHARACTER, if not) is silently returned, and *retlen is set (if retlen isn't NULL) so that (s + *retlen) is the next possible position in s that could begin a non-malformed character. See "utf8n_to_uvchr" for details on when the REPLACEMENT CHARACTER is returned.

UV      utf8_to_uvuni_buf(const U8 *s, const U8 *send,
                          STRLEN *retlen)
UVCHR_IS_INVARIANT

Evaluates to 1 if the representation of code point cp is the same whether or not it is encoded in UTF-8; otherwise evaluates to 0. UTF-8 invariant characters can be copied as-is when converting to/from UTF-8, saving time. cp is Unicode if above 255; otherwise is platform-native.

bool    UVCHR_IS_INVARIANT(UV cp)
UVCHR_SKIP

returns the number of bytes required to represent the code point cp when encoded as UTF-8. cp is a native (ASCII or EBCDIC) code point if less than 255; a Unicode code point otherwise.

STRLEN  UVCHR_SKIP(UV cp)
uvchr_to_utf8

Adds the UTF-8 representation of the native code point uv to the end of the string d; d should have at least UVCHR_SKIP(uv)+1 (up to UTF8_MAXBYTES+1) free bytes available. The return value is the pointer to the byte after the end of the new character. In other words,

d = uvchr_to_utf8(d, uv);

is the recommended wide native character-aware way of saying

*(d++) = uv;

This function accepts any code point from 0..IV_MAX as input. IV_MAX is typically 0x7FFF_FFFF in a 32-bit word.

It is possible to forbid or warn on non-Unicode code points, or those that may be problematic by using "uvchr_to_utf8_flags".

U8*     uvchr_to_utf8(U8 *d, UV uv)
uvchr_to_utf8_flags

Adds the UTF-8 representation of the native code point uv to the end of the string d; d should have at least UVCHR_SKIP(uv)+1 (up to UTF8_MAXBYTES+1) free bytes available. The return value is the pointer to the byte after the end of the new character. In other words,

d = uvchr_to_utf8_flags(d, uv, flags);

or, in most cases,

d = uvchr_to_utf8_flags(d, uv, 0);

This is the Unicode-aware way of saying

*(d++) = uv;

If flags is 0, this function accepts any code point from 0..IV_MAX as input. IV_MAX is typically 0x7FFF_FFFF in a 32-bit word.

Specifying flags can further restrict what is allowed and not warned on, as follows:

If uv is a Unicode surrogate code point and UNICODE_WARN_SURROGATE is set, the function will raise a warning, provided UTF8 warnings are enabled. If instead UNICODE_DISALLOW_SURROGATE is set, the function will fail and return NULL. If both flags are set, the function will both warn and return NULL.

Similarly, the UNICODE_WARN_NONCHAR and UNICODE_DISALLOW_NONCHAR flags affect how the function handles a Unicode non-character.

And likewise, the UNICODE_WARN_SUPER and UNICODE_DISALLOW_SUPER flags affect the handling of code points that are above the Unicode maximum of 0x10FFFF. Languages other than Perl may not be able to accept files that contain these.

The flag UNICODE_WARN_ILLEGAL_INTERCHANGE selects all three of the above WARN flags; and UNICODE_DISALLOW_ILLEGAL_INTERCHANGE selects all three DISALLOW flags. UNICODE_DISALLOW_ILLEGAL_INTERCHANGE restricts the allowed inputs to the strict UTF-8 traditionally defined by Unicode. Similarly, UNICODE_WARN_ILLEGAL_C9_INTERCHANGE and UNICODE_DISALLOW_ILLEGAL_C9_INTERCHANGE are shortcuts to select the above-Unicode and surrogate flags, but not the non-character ones, as defined in Unicode Corrigendum #9. See "Noncharacter code points" in perlunicode.

Extremely high code points were never specified in any standard, and require an extension to UTF-8 to express, which Perl does. It is likely that programs written in something other than Perl would not be able to read files that contain these; nor would Perl understand files written by something that uses a different extension. For these reasons, there is a separate set of flags that can warn and/or disallow these extremely high code points, even if other above-Unicode ones are accepted. They are the UNICODE_WARN_PERL_EXTENDED and UNICODE_DISALLOW_PERL_EXTENDED flags. For more information see "UTF8_GOT_PERL_EXTENDED". Of course UNICODE_DISALLOW_SUPER will treat all above-Unicode code points, including these, as malformations. (Note that the Unicode standard considers anything above 0x10FFFF to be illegal, but there are standards predating it that allow up to 0x7FFF_FFFF (2**31 -1))

A somewhat misleadingly named synonym for UNICODE_WARN_PERL_EXTENDED is retained for backward compatibility: UNICODE_WARN_ABOVE_31_BIT. Similarly, UNICODE_DISALLOW_ABOVE_31_BIT is usable instead of the more accurately named UNICODE_DISALLOW_PERL_EXTENDED. The names are misleading because on EBCDIC platforms,these flags can apply to code points that actually do fit in 31 bits. The new names accurately describe the situation in all cases.

U8*     uvchr_to_utf8_flags(U8 *d, UV uv, UV flags)
uvchr_to_utf8_flags_msgs

NOTE: this function is experimental and may change or be removed without notice.

THIS FUNCTION SHOULD BE USED IN ONLY VERY SPECIALIZED CIRCUMSTANCES.

Most code should use "uvchr_to_utf8_flags"() rather than call this directly.

This function is for code that wants any warning and/or error messages to be returned to the caller rather than be displayed. All messages that would have been displayed if all lexcial warnings are enabled will be returned.

It is just like "uvchr_to_utf8_flags" but it takes an extra parameter placed after all the others, msgs. If this parameter is 0, this function behaves identically to "uvchr_to_utf8_flags". Otherwise, msgs should be a pointer to an HV * variable, in which this function creates a new HV to contain any appropriate messages. The hash has three key-value pairs, as follows:

text

The text of the message as a SVpv.

warn_categories

The warning category (or categories) packed into a SVuv.

flag

A single flag bit associated with this message, in a SVuv. The bit corresponds to some bit in the *errors return value, such as UNICODE_GOT_SURROGATE.

It's important to note that specifying this parameter as non-null will cause any warnings this function would otherwise generate to be suppressed, and instead be placed in *msgs. The caller can check the lexical warnings state (or not) when choosing what to do with the returned messages.

The caller, of course, is responsible for freeing any returned HV.

U8*     uvchr_to_utf8_flags_msgs(U8 *d, UV uv, UV flags,
                                 HV ** msgs)
uvoffuni_to_utf8_flags

THIS FUNCTION SHOULD BE USED IN ONLY VERY SPECIALIZED CIRCUMSTANCES. Instead, Almost all code should use "uvchr_to_utf8" or "uvchr_to_utf8_flags".

This function is like them, but the input is a strict Unicode (as opposed to native) code point. Only in very rare circumstances should code not be using the native code point.

For details, see the description for "uvchr_to_utf8_flags".

U8*     uvoffuni_to_utf8_flags(U8 *d, UV uv,
                               const UV flags)
uvuni_to_utf8_flags

Instead you almost certainly want to use "uvchr_to_utf8" or "uvchr_to_utf8_flags".

This function is a deprecated synonym for "uvoffuni_to_utf8_flags", which itself, while not deprecated, should be used only in isolated circumstances. These functions were useful for code that wanted to handle both EBCDIC and ASCII platforms with Unicode properties, but starting in Perl v5.20, the distinctions between the platforms have mostly been made invisible to most code, so this function is quite unlikely to be what you want.

U8*     uvuni_to_utf8_flags(U8 *d, UV uv, UV flags)
valid_utf8_to_uvchr

Like "utf8_to_uvchr_buf", but should only be called when it is known that the next character in the input UTF-8 string s is well-formed (e.g., it passes "isUTF8_CHAR". Surrogates, non-character code points, and non-Unicode code points are allowed.

UV      valid_utf8_to_uvchr(const U8 *s, STRLEN *retlen)

Variables created by xsubpp and xsubpp internal functions

newXSproto

Used by xsubpp to hook up XSUBs as Perl subs. Adds Perl prototypes to the subs.

XS_APIVERSION_BOOTCHECK

Macro to verify that the perl api version an XS module has been compiled against matches the api version of the perl interpreter it's being loaded into.

XS_APIVERSION_BOOTCHECK;
XS_VERSION

The version identifier for an XS module. This is usually handled automatically by ExtUtils::MakeMaker. See "XS_VERSION_BOOTCHECK".

XS_VERSION_BOOTCHECK

Macro to verify that a PM module's $VERSION variable matches the XS module's XS_VERSION variable. This is usually handled automatically by xsubpp. See "The VERSIONCHECK: Keyword" in perlxs.

XS_VERSION_BOOTCHECK;

Warning and Dieing

ckWARN

Returns a boolean as to whether or not warnings are enabled for the warning category w. If the category is by default enabled even if not within the scope of use warnings, instead use the "ckWARN_d" macro.

bool    ckWARN(U32 w)
ckWARN2

Like "ckWARN", but takes two warnings categories as input, and returns TRUE if either is enabled. If either category is by default enabled even if not within the scope of use warnings, instead use the "ckWARN2_d" macro. The categories must be completely independent, one may not be subclassed from the other.

bool    ckWARN2(U32 w1, U32 w2)
ckWARN3

Like "ckWARN2", but takes three warnings categories as input, and returns TRUE if any is enabled. If any of the categories is by default enabled even if not within the scope of use warnings, instead use the "ckWARN3_d" macro. The categories must be completely independent, one may not be subclassed from any other.

bool    ckWARN3(U32 w1, U32 w2, U32 w3)
ckWARN4

Like "ckWARN3", but takes four warnings categories as input, and returns TRUE if any is enabled. If any of the categories is by default enabled even if not within the scope of use warnings, instead use the "ckWARN4_d" macro. The categories must be completely independent, one may not be subclassed from any other.

bool    ckWARN4(U32 w1, U32 w2, U32 w3, U32 w4)
ckWARN_d

Like "ckWARN", but for use if and only if the warning category is by default enabled even if not within the scope of use warnings.

bool    ckWARN_d(U32 w)
ckWARN2_d

Like "ckWARN2", but for use if and only if either warning category is by default enabled even if not within the scope of use warnings.

bool    ckWARN2_d(U32 w1, U32 w2)
ckWARN3_d

Like "ckWARN3", but for use if and only if any of the warning categories is by default enabled even if not within the scope of use warnings.

bool    ckWARN3_d(U32 w1, U32 w2, U32 w3)
ckWARN4_d

Like "ckWARN4", but for use if and only if any of the warning categories is by default enabled even if not within the scope of use warnings.

bool    ckWARN4_d(U32 w1, U32 w2, U32 w3, U32 w4)
croak

This is an XS interface to Perl's die function.

Take a sprintf-style format pattern and argument list. These are used to generate a string message. If the message does not end with a newline, then it will be extended with some indication of the current location in the code, as described for "mess_sv".

The error message will be used as an exception, by default returning control to the nearest enclosing eval, but subject to modification by a $SIG{__DIE__} handler. In any case, the croak function never returns normally.

For historical reasons, if pat is null then the contents of ERRSV ($@) will be used as an error message or object instead of building an error message from arguments. If you want to throw a non-string object, or build an error message in an SV yourself, it is preferable to use the "croak_sv" function, which does not involve clobbering ERRSV.

void    croak(const char *pat, ...)
croak_no_modify

Exactly equivalent to Perl_croak(aTHX_ "%s", PL_no_modify), but generates terser object code than using Perl_croak. Less code used on exception code paths reduces CPU cache pressure.

void    croak_no_modify()
croak_sv

This is an XS interface to Perl's die function.

baseex is the error message or object. If it is a reference, it will be used as-is. Otherwise it is used as a string, and if it does not end with a newline then it will be extended with some indication of the current location in the code, as described for "mess_sv".

The error message or object will be used as an exception, by default returning control to the nearest enclosing eval, but subject to modification by a $SIG{__DIE__} handler. In any case, the croak_sv function never returns normally.

To die with a simple string message, the "croak" function may be more convenient.

void    croak_sv(SV *baseex)
die

Behaves the same as "croak", except for the return type. It should be used only where the OP * return type is required. The function never actually returns.

OP *    die(const char *pat, ...)
die_sv

Behaves the same as "croak_sv", except for the return type. It should be used only where the OP * return type is required. The function never actually returns.

OP *    die_sv(SV *baseex)
vcroak

This is an XS interface to Perl's die function.

pat and args are a sprintf-style format pattern and encapsulated argument list. These are used to generate a string message. If the message does not end with a newline, then it will be extended with some indication of the current location in the code, as described for "mess_sv".

The error message will be used as an exception, by default returning control to the nearest enclosing eval, but subject to modification by a $SIG{__DIE__} handler. In any case, the croak function never returns normally.

For historical reasons, if pat is null then the contents of ERRSV ($@) will be used as an error message or object instead of building an error message from arguments. If you want to throw a non-string object, or build an error message in an SV yourself, it is preferable to use the "croak_sv" function, which does not involve clobbering ERRSV.

void    vcroak(const char *pat, va_list *args)
vwarn

This is an XS interface to Perl's warn function.

pat and args are a sprintf-style format pattern and encapsulated argument list. These are used to generate a string message. If the message does not end with a newline, then it will be extended with some indication of the current location in the code, as described for "mess_sv".

The error message or object will by default be written to standard error, but this is subject to modification by a $SIG{__WARN__} handler.

Unlike with "vcroak", pat is not permitted to be null.

void    vwarn(const char *pat, va_list *args)
warn

This is an XS interface to Perl's warn function.

Take a sprintf-style format pattern and argument list. These are used to generate a string message. If the message does not end with a newline, then it will be extended with some indication of the current location in the code, as described for "mess_sv".

The error message or object will by default be written to standard error, but this is subject to modification by a $SIG{__WARN__} handler.

Unlike with "croak", pat is not permitted to be null.

void    warn(const char *pat, ...)
warn_sv

This is an XS interface to Perl's warn function.

baseex is the error message or object. If it is a reference, it will be used as-is. Otherwise it is used as a string, and if it does not end with a newline then it will be extended with some indication of the current location in the code, as described for "mess_sv".

The error message or object will by default be written to standard error, but this is subject to modification by a $SIG{__WARN__} handler.

To warn with a simple string message, the "warn" function may be more convenient.

void    warn_sv(SV *baseex)

Undocumented functions

The following functions have been flagged as part of the public API, but are currently undocumented. Use them at your own risk, as the interfaces are subject to change. Functions that are not listed in this document are not intended for public use, and should NOT be used under any circumstances.

If you feel you need to use one of these functions, first send email to [email protected]. It may be that there is a good reason for the function not being documented, and it should be removed from this list; or it may just be that no one has gotten around to documenting it. In the latter case, you will be asked to submit a patch to document the function. Once your patch is accepted, it will indicate that the interface is stable (unless it is explicitly marked otherwise) and usable by you.

GetVars
Gv_AMupdate
PerlIO_clearerr
PerlIO_close
PerlIO_context_layers
PerlIO_eof
PerlIO_error
PerlIO_fileno
PerlIO_fill
PerlIO_flush
PerlIO_get_base
PerlIO_get_bufsiz
PerlIO_get_cnt
PerlIO_get_ptr
PerlIO_read
PerlIO_seek
PerlIO_set_cnt
PerlIO_set_ptrcnt
PerlIO_setlinebuf
PerlIO_stderr
PerlIO_stdin
PerlIO_stdout
PerlIO_tell
PerlIO_unread
PerlIO_write
_variant_byte_number
amagic_call
amagic_deref_call
any_dup
atfork_lock
atfork_unlock
av_arylen_p
av_iter_p
block_gimme
call_atexit
call_list
calloc
cast_i32
cast_iv
cast_ulong
cast_uv
ck_warner
ck_warner_d
ckwarn
ckwarn_d
clear_defarray
clone_params_del
clone_params_new
croak_memory_wrap
croak_nocontext
csighandler
cx_dump
cx_dup
cxinc
deb
deb_nocontext
debop
debprofdump
debstack
debstackptrs
delimcpy
despatch_signals
die_nocontext
dirp_dup
do_aspawn
do_binmode
do_close
do_gv_dump
do_gvgv_dump
do_hv_dump
do_join
do_magic_dump
do_op_dump
do_open
do_open9
do_openn
do_pmop_dump
do_spawn
do_spawn_nowait
do_sprintf
do_sv_dump
doing_taint
doref
dounwind
dowantarray
dump_eval
dump_form
dump_indent
dump_mstats
dump_sub
dump_vindent
filter_add
filter_del
filter_read
foldEQ_latin1
form_nocontext
fp_dup
fprintf_nocontext
free_global_struct
free_tmps
get_context
get_mstats
get_op_descs
get_op_names
get_ppaddr
get_vtbl
gp_dup
gp_free
gp_ref
gv_AVadd
gv_HVadd
gv_IOadd
gv_SVadd
gv_add_by_type
gv_autoload4
gv_autoload_pv
gv_autoload_pvn
gv_autoload_sv
gv_check
gv_dump
gv_efullname
gv_efullname3
gv_efullname4
gv_fetchfile
gv_fetchfile_flags
gv_fetchpv
gv_fetchpvn_flags
gv_fetchsv
gv_fullname
gv_fullname3
gv_fullname4
gv_handler
gv_name_set
he_dup
hek_dup
hv_common
hv_common_key_len
hv_delayfree_ent
hv_eiter_p
hv_eiter_set
hv_free_ent
hv_ksplit
hv_name_set
hv_placeholders_get
hv_placeholders_set
hv_rand_set
hv_riter_p
hv_riter_set
ibcmp_utf8
init_global_struct
init_stacks
init_tm
instr
is_lvalue_sub
leave_scope
load_module_nocontext
magic_dump
malloc
markstack_grow
mess_nocontext
mfree
mg_dup
mg_size
mini_mktime
moreswitches
mro_get_from_name
mro_get_private_data
mro_set_mro
mro_set_private_data
my_atof
my_atof2
my_chsize
my_cxt_index
my_cxt_init
my_dirfd
my_exit
my_failure_exit
my_fflush_all
my_fork
my_lstat
my_pclose
my_popen
my_popen_list
my_setenv
my_socketpair
my_stat
my_strftime
newANONATTRSUB
newANONHASH
newANONLIST
newANONSUB
newATTRSUB
newAVREF
newCVREF
newFORM
newGVREF
newGVgen
newGVgen_flags
newHVREF
newHVhv
newIO
newMYSUB
newPROG
newRV
newSUB
newSVREF
newSVpvf_nocontext
new_stackinfo
op_refcnt_lock
op_refcnt_unlock
parser_dup
perl_alloc_using
perl_clone_using
pmop_dump
pop_scope
pregcomp
pregexec
pregfree
pregfree2
printf_nocontext
ptr_table_fetch
ptr_table_free
ptr_table_new
ptr_table_split
ptr_table_store
push_scope
re_compile
re_dup_guts
re_intuit_start
re_intuit_string
realloc
reentrant_free
reentrant_init
reentrant_retry
reentrant_size
ref
reg_named_buff_all
reg_named_buff_exists
reg_named_buff_fetch
reg_named_buff_firstkey
reg_named_buff_nextkey
reg_named_buff_scalar
regdump
regdupe_internal
regexec_flags
regfree_internal
reginitcolors
regnext
repeatcpy
rsignal
rsignal_state
runops_debug
runops_standard
rvpv_dup
safesyscalloc
safesysfree
safesysmalloc
safesysrealloc
save_I16
save_I32
save_I8
save_adelete
save_aelem
save_aelem_flags
save_alloc
save_aptr
save_ary
save_bool
save_clearsv
save_delete
save_destructor
save_destructor_x
save_freeop
save_freepv
save_freesv
save_generic_pvref
save_generic_svref
save_hash
save_hdelete
save_helem
save_helem_flags
save_hints
save_hptr
save_int
save_item
save_iv
save_list
save_long
save_mortalizesv
save_nogv
save_op
save_padsv_and_mortalize
save_pptr
save_pushi32ptr
save_pushptr
save_pushptrptr
save_re_context
save_scalar
save_set_svflags
save_shared_pvref
save_sptr
save_svref
save_vptr
savestack_grow
savestack_grow_cnt
scan_num
scan_vstring
seed
set_context
share_hek
si_dup
ss_dup
stack_grow
start_subparse
str_to_version
sv_2iv
sv_2pv
sv_2uv
sv_catpvf_mg_nocontext
sv_catpvf_nocontext
sv_dup
sv_dup_inc
sv_peek
sv_pvn_nomg
sv_setpvf_mg_nocontext
sv_setpvf_nocontext
sys_init
sys_init3
sys_intern_clear
sys_intern_dup
sys_intern_init
sys_term
taint_env
taint_proper
unlnk
unsharepvn
uvuni_to_utf8
vdeb
vform
vload_module
vnewSVpvf
vwarner
warn_nocontext
warner
warner_nocontext
whichsig
whichsig_pv
whichsig_pvn
whichsig_sv

AUTHORS

Until May 1997, this document was maintained by Jeff Okamoto <[email protected]>. It is now maintained as part of Perl itself.

With lots of help and suggestions from Dean Roehrich, Malcolm Beattie, Andreas Koenig, Paul Hudson, Ilya Zakharevich, Paul Marquess, Neil Bowers, Matthew Green, Tim Bunce, Spider Boardman, Ulrich Pfeifer, Stephen McCamant, and Gurusamy Sarathy.

API Listing originally by Dean Roehrich <[email protected]>.

Updated to be autogenerated from comments in the source by Benjamin Stuhl.

SEE ALSO

perlguts, perlxs, perlxstut, perlintern

© 1993–2020 Larry Wall and others
Licensed under the GNU General Public License version 1 or later, or the Artistic License.
The Perl logo is a trademark of the Perl Foundation.
https://perldoc.perl.org/5.28.3/perlapi