class StringIO

Parent:: Data
Included modules:: Enumerable, IO::generic_readable, IO::generic_writable

Pseudo I/O on String object.

Commonly used to simulate `$stdio` or `$stderr`

Examples

require 'stringio'

io = StringIO.new
io.puts "Hello World"
io.string #=> "Hello World\n"

Public Class Methods

new(string=""[, mode]) Show source

static VALUE
strio_initialize(int argc, VALUE *argv, VALUE self)
{
    struct StringIO *ptr = check_strio(self);

    if (!ptr) {
        DATA_PTR(self) = ptr = strio_alloc();
    }
    rb_call_super(0, 0);
    strio_init(argc, argv, ptr, self);
    return self;
}

Creates new StringIO instance from with string and mode.

open(string=""[, mode]) {|strio| ...} Show source

static VALUE
strio_s_open(int argc, VALUE *argv, VALUE klass)
{
    VALUE obj = rb_class_new_instance(argc, argv, klass);
    if (!rb_block_given_p()) return obj;
    return rb_ensure(rb_yield, obj, strio_finalize, obj);
}

Equivalent to ::new except that when it is called with a block, it yields with the new instance and closes it, and returns the result which returned from the block.

Public Instance Methods

binmode() Show source

static VALUE
strio_binmode(VALUE self)
{
    struct StringIO *ptr = StringIO(self);
    rb_encoding *enc = rb_ascii8bit_encoding();

    ptr->enc = enc;
    if (WRITABLE(self)) {
        rb_enc_associate(ptr->string, enc);
    }
    return self;
}

bytes() Show source

static VALUE
strio_bytes(VALUE self)
{
    rb_warn("StringIO#bytes is deprecated; use #each_byte instead");
    if (!rb_block_given_p())
        return rb_enumeratorize(self, ID2SYM(rb_intern("each_byte")), 0, 0);
    return strio_each_byte(self);
}

This is a deprecated alias for each_byte.

chars() Show source

static VALUE
strio_chars(VALUE self)
{
    rb_warn("StringIO#chars is deprecated; use #each_char instead");
    if (!rb_block_given_p())
        return rb_enumeratorize(self, ID2SYM(rb_intern("each_char")), 0, 0);
    return strio_each_char(self);
}

This is a deprecated alias for each_char.

close → nil Show source

static VALUE
strio_close(VALUE self)
{
    StringIO(self);
    RBASIC(self)->flags &= ~STRIO_READWRITE;
    return Qnil;
}

Closes strio. The strio is unavailable for any further data operations; an IOError is raised if such an attempt is made.

close_read → nil Show source

static VALUE
strio_close_read(VALUE self)
{
    struct StringIO *ptr = StringIO(self);
    if (!(ptr->flags & FMODE_READABLE)) {
        rb_raise(rb_eIOError, "closing non-duplex IO for reading");
    }
    RBASIC(self)->flags &= ~STRIO_READABLE;
    return Qnil;
}

Closes the read end of a StringIO. Will raise an IOError if the strio is not readable.

close_write → nil Show source

static VALUE
strio_close_write(VALUE self)
{
    struct StringIO *ptr = StringIO(self);
    if (!(ptr->flags & FMODE_WRITABLE)) {
        rb_raise(rb_eIOError, "closing non-duplex IO for writing");
    }
    RBASIC(self)->flags &= ~STRIO_WRITABLE;
    return Qnil;
}

Closes the write end of a StringIO. Will raise an IOError if the strio is not writeable.

closed? → true or false Show source

static VALUE
strio_closed(VALUE self)
{
    StringIO(self);
    if (!CLOSED(self)) return Qfalse;
    return Qtrue;
}

Returns true if strio is completely closed, false otherwise.

closed_read? → true or false Show source

static VALUE
strio_closed_read(VALUE self)
{
    StringIO(self);
    if (READABLE(self)) return Qfalse;
    return Qtrue;
}

Returns true if strio is not readable, false otherwise.

closed_write? → true or false Show source

static VALUE
strio_closed_write(VALUE self)
{
    StringIO(self);
    if (WRITABLE(self)) return Qfalse;
    return Qtrue;
}

Returns true if strio is not writable, false otherwise.

codepoints() Show source

static VALUE
strio_codepoints(VALUE self)
{
    rb_warn("StringIO#codepoints is deprecated; use #each_codepoint instead");
    if (!rb_block_given_p())
        return rb_enumeratorize(self, ID2SYM(rb_intern("each_codepoint")), 0, 0);
    return strio_each_codepoint(self);
}

This is a deprecated alias for each_codepoint.

each(sep=$/) {|line| block } → strio Show source

each(limit) {|line| block } → strio

each(sep, limit) {|line| block } → strio

each(...) → anEnumerator

each_line(sep=$/) {|line| block } → strio

each_line(limit) {|line| block } → strio

each_line(sep,limit) {|line| block } → strio

each_line(...) → anEnumerator

static VALUE
strio_each(int argc, VALUE *argv, VALUE self)
{
    VALUE line;

    StringIO(self);
    RETURN_ENUMERATOR(self, argc, argv);

    if (argc > 0 && !NIL_P(argv[argc-1]) && NIL_P(rb_check_string_type(argv[argc-1])) &&
        NUM2LONG(argv[argc-1]) == 0) {
        rb_raise(rb_eArgError, "invalid limit: 0 for each_line");
    }

    while (!NIL_P(line = strio_getline(argc, argv, readable(self)))) {
        rb_yield(line);
    }
    return self;
}

See IO#each.

each_byte {|byte| block } → strio Show source

each_byte → anEnumerator

static VALUE
strio_each_byte(VALUE self)
{
    struct StringIO *ptr = readable(self);

    RETURN_ENUMERATOR(self, 0, 0);

    while (ptr->pos < RSTRING_LEN(ptr->string)) {
        char c = RSTRING_PTR(ptr->string)[ptr->pos++];
        rb_yield(CHR2FIX(c));
    }
    return self;
}

See IO#each_byte.

each_char {|char| block } → strio Show source

each_char → anEnumerator

static VALUE
strio_each_char(VALUE self)
{
    VALUE c;

    RETURN_ENUMERATOR(self, 0, 0);

    while (!NIL_P(c = strio_getc(self))) {
        rb_yield(c);
    }
    return self;
}

See IO#each_char.

each_codepoint {|c| block } → strio Show source

each_codepoint → anEnumerator

static VALUE
strio_each_codepoint(VALUE self)
{
    struct StringIO *ptr;
    rb_encoding *enc;
    unsigned int c;
    int n;

    RETURN_ENUMERATOR(self, 0, 0);

    ptr = readable(self);
    enc = get_enc(ptr);
    for (;;) {
        if (ptr->pos >= RSTRING_LEN(ptr->string)) {
            return self;
        }

        c = rb_enc_codepoint_len(RSTRING_PTR(ptr->string)+ptr->pos,
                                 RSTRING_END(ptr->string), &n, enc);
        rb_yield(UINT2NUM(c));
        ptr->pos += n;
    }
    return self;
}

See IO#each_codepoint.

each_line(sep=$/) {|line| block } → strio Show source

each_line(limit) {|line| block } → strio

each_line(sep,limit) {|line| block } → strio

each_line(...) → anEnumerator

static VALUE
strio_each(int argc, VALUE *argv, VALUE self)
{
    VALUE line;

    StringIO(self);
    RETURN_ENUMERATOR(self, argc, argv);

    if (argc > 0 && !NIL_P(argv[argc-1]) && NIL_P(rb_check_string_type(argv[argc-1])) &&
        NUM2LONG(argv[argc-1]) == 0) {
        rb_raise(rb_eArgError, "invalid limit: 0 for each_line");
    }

    while (!NIL_P(line = strio_getline(argc, argv, readable(self)))) {
        rb_yield(line);
    }
    return self;
}

See IO#each.

eof → true or false Show source

eof? → true or false

static VALUE
strio_eof(VALUE self)
{
    struct StringIO *ptr = readable(self);
    if (ptr->pos < RSTRING_LEN(ptr->string)) return Qfalse;
    return Qtrue;
}

Returns true if strio is at end of file. The stringio must be opened for reading or an IOError will be raised.

eof? → true or false Show source

static VALUE
strio_eof(VALUE self)
{
    struct StringIO *ptr = readable(self);
    if (ptr->pos < RSTRING_LEN(ptr->string)) return Qfalse;
    return Qtrue;
}

Returns true if strio is at end of file. The stringio must be opened for reading or an IOError will be raised.

external_encoding → encoding Show source

static VALUE
strio_external_encoding(VALUE self)
{
    struct StringIO *ptr = StringIO(self);
    return rb_enc_from_encoding(get_enc(ptr));
}

Returns the Encoding object that represents the encoding of the file. If strio is write mode and no encoding is specified, returns nil.

fcntl(*args) Show source

static VALUE
strio_unimpl(int argc, VALUE *argv, VALUE self)
{
    StringIO(self);
    rb_notimplement();

    UNREACHABLE;
}

Raises NotImplementedError.

fileno() Show source

static VALUE
strio_nil(VALUE self)
{
    StringIO(self);
    return Qnil;
}

Returns nil. Just for compatibility to IO.

flush() Show source

static VALUE
strio_self(VALUE self)
{
    StringIO(self);
    return self;
}

Returns strio itself. Just for compatibility to IO.

fsync() Show source

static VALUE
strio_0(VALUE self)
{
    StringIO(self);
    return INT2FIX(0);
}

Returns 0. Just for compatibility to IO.

getbyte → fixnum or nil Show source

static VALUE
strio_getbyte(VALUE self)
{
    struct StringIO *ptr = readable(self);
    int c;
    if (ptr->pos >= RSTRING_LEN(ptr->string)) {
        return Qnil;
    }
    c = RSTRING_PTR(ptr->string)[ptr->pos++];
    return CHR2FIX(c);
}

See IO#getbyte.

getc → string or nil Show source

static VALUE
strio_getc(VALUE self)
{
    struct StringIO *ptr = readable(self);
    rb_encoding *enc = get_enc(ptr);
    int len;
    char *p;

    if (ptr->pos >= RSTRING_LEN(ptr->string)) {
        return Qnil;
    }
    p = RSTRING_PTR(ptr->string)+ptr->pos;
    len = rb_enc_mbclen(p, RSTRING_END(ptr->string), enc);
    ptr->pos += len;
    return rb_enc_str_new(p, len, enc);
}

See IO#getc.

gets(sep=$/) → string or nil Show source

gets(limit) → string or nil

gets(sep, limit) → string or nil

static VALUE
strio_gets(int argc, VALUE *argv, VALUE self)
{
    VALUE str = strio_getline(argc, argv, readable(self));

    rb_lastline_set(str);
    return str;
}

See IO#gets.

internal_encoding → encoding Show source

static VALUE
strio_internal_encoding(VALUE self)
{
     return Qnil;
}

Returns the Encoding of the internal string if conversion is specified. Otherwise returns nil.

isatty() Show source

static VALUE
strio_false(VALUE self)
{
    StringIO(self);
    return Qfalse;
}

Returns false. Just for compatibility to IO.

length → integer Show source

static VALUE
strio_size(VALUE self)
{
    VALUE string = StringIO(self)->string;
    if (NIL_P(string)) {
        rb_raise(rb_eIOError, "not opened");
    }
    return ULONG2NUM(RSTRING_LEN(string));
}

Returns the size of the buffer string.

lineno → integer Show source

static VALUE
strio_get_lineno(VALUE self)
{
    return LONG2NUM(StringIO(self)->lineno);
}

Returns the current line number in strio. The stringio must be opened for reading. lineno counts the number of times gets is called, rather than the number of newlines encountered. The two values will differ if gets is called with a separator other than newline. See also the $. variable.

lineno = integer → integer Show source

static VALUE
strio_set_lineno(VALUE self, VALUE lineno)
{
    StringIO(self)->lineno = NUM2LONG(lineno);
    return lineno;
}

Manually sets the current line number to the given value. $. is updated only on the next read.

lines(*args) Show source

static VALUE
strio_lines(int argc, VALUE *argv, VALUE self)
{
    rb_warn("StringIO#lines is deprecated; use #each_line instead");
    if (!rb_block_given_p())
        return rb_enumeratorize(self, ID2SYM(rb_intern("each_line")), argc, argv);
    return strio_each(argc, argv, self);
}

This is a deprecated alias for each_line.

pid() Show source

static VALUE
strio_nil(VALUE self)
{
    StringIO(self);
    return Qnil;
}

Returns nil. Just for compatibility to IO.

pos → integer Show source

tell → integer

static VALUE
strio_get_pos(VALUE self)
{
    return LONG2NUM(StringIO(self)->pos);
}

Returns the current offset (in bytes) of strio.

pos = integer → integer Show source

static VALUE
strio_set_pos(VALUE self, VALUE pos)
{
    struct StringIO *ptr = StringIO(self);
    long p = NUM2LONG(pos);
    if (p < 0) {
        error_inval(0);
    }
    ptr->pos = p;
    return pos;
}

Seeks to the given position (in bytes) in strio.

putc(obj) → obj Show source

static VALUE
strio_putc(VALUE self, VALUE ch)
{
    struct StringIO *ptr = writable(self);
    VALUE str;

    check_modifiable(ptr);
    if (RB_TYPE_P(ch, T_STRING)) {
        str = rb_str_substr(ch, 0, 1);
    }
    else {
        char c = NUM2CHR(ch);
        str = rb_str_new(&c, 1);
    }
    strio_write(self, str);
    return ch;
}

See IO#putc.

read([length [, outbuf]]) → string, outbuf, or nil Show source

static VALUE
strio_read(int argc, VALUE *argv, VALUE self)
{
    struct StringIO *ptr = readable(self);
    VALUE str = Qnil;
    long len;
    int binary = 0;

    rb_check_arity(argc, 0, 2);
    switch (argc) {
      case 2:
        str = argv[1];
        if (!NIL_P(str)) {
            StringValue(str);
            rb_str_modify(str);
        }
      case 1:
        if (!NIL_P(argv[0])) {
            len = NUM2LONG(argv[0]);
            if (len < 0) {
                rb_raise(rb_eArgError, "negative length %ld given", len);
            }
            if (len > 0 && ptr->pos >= RSTRING_LEN(ptr->string)) {
                if (!NIL_P(str)) rb_str_resize(str, 0);
                return Qnil;
            }
            binary = 1;
            break;
        }
        /* fall through */
      case 0:
        len = RSTRING_LEN(ptr->string);
        if (len <= ptr->pos) {
            if (NIL_P(str)) {
                str = rb_str_new(0, 0);
            }
            else {
                rb_str_resize(str, 0);
            }
            return str;
        }
        else {
            len -= ptr->pos;
        }
        break;
    }
    if (NIL_P(str)) {
        str = strio_substr(ptr, ptr->pos, len);
        if (binary) rb_enc_associate(str, rb_ascii8bit_encoding());
    }
    else {
        long rest = RSTRING_LEN(ptr->string) - ptr->pos;
        if (len > rest) len = rest;
        rb_str_resize(str, len);
        MEMCPY(RSTRING_PTR(str), RSTRING_PTR(ptr->string) + ptr->pos, char, len);
        if (binary)
            rb_enc_associate(str, rb_ascii8bit_encoding());
        else
            rb_enc_copy(str, ptr->string);
    }
    ptr->pos += RSTRING_LEN(str);
    return str;
}

See IO#read.

readlines(sep=$/) → array Show source

readlines(limit) → array

readlines(sep,limit) → array

static VALUE
strio_readlines(int argc, VALUE *argv, VALUE self)
{
    VALUE ary, line;

    StringIO(self);
    ary = rb_ary_new();
    if (argc > 0 && !NIL_P(argv[argc-1]) && NIL_P(rb_check_string_type(argv[argc-1])) &&
        NUM2LONG(argv[argc-1]) == 0) {
        rb_raise(rb_eArgError, "invalid limit: 0 for readlines");
    }

    while (!NIL_P(line = strio_getline(argc, argv, readable(self)))) {
        rb_ary_push(ary, line);
    }
    return ary;
}

See IO#readlines.

reopen(other_StrIO) → strio Show source

reopen(string, mode) → strio

static VALUE
strio_reopen(int argc, VALUE *argv, VALUE self)
{
    rb_io_taint_check(self);
    if (argc == 1 && !RB_TYPE_P(*argv, T_STRING)) {
        return strio_copy(self, *argv);
    }
    strio_init(argc, argv, StringIO(self), self);
    return self;
}

Reinitializes strio with the given other_StrIO or string and mode (see StringIO#new).

rewind → 0 Show source

static VALUE
strio_rewind(VALUE self)
{
    struct StringIO *ptr = StringIO(self);
    ptr->pos = 0;
    ptr->lineno = 0;
    return INT2FIX(0);
}

Positions strio to the beginning of input, resetting lineno to zero.

seek(amount, whence=SEEK_SET) → 0 Show source

static VALUE
strio_seek(int argc, VALUE *argv, VALUE self)
{
    VALUE whence;
    struct StringIO *ptr = StringIO(self);
    long offset;

    rb_scan_args(argc, argv, "11", NULL, &whence);
    offset = NUM2LONG(argv[0]);
    if (CLOSED(self)) {
        rb_raise(rb_eIOError, "closed stream");
    }
    switch (NIL_P(whence) ? 0 : NUM2LONG(whence)) {
      case 0:
        break;
      case 1:
        offset += ptr->pos;
        break;
      case 2:
        offset += RSTRING_LEN(ptr->string);
        break;
      default:
        error_inval("invalid whence");
    }
    if (offset < 0) {
        error_inval(0);
    }
    ptr->pos = offset;
    return INT2FIX(0);
}

Seeks to a given offset amount in the stream according to the value of whence (see IO#seek).

set_encoding(ext_enc, [int_enc[, opt]]) → strio Show source

static VALUE
strio_set_encoding(int argc, VALUE *argv, VALUE self)
{
    rb_encoding* enc;
    struct StringIO *ptr = StringIO(self);
    VALUE ext_enc, int_enc, opt;

    argc = rb_scan_args(argc, argv, "11:", &ext_enc, &int_enc, &opt);

    if (NIL_P(ext_enc)) {
        enc = rb_default_external_encoding();
    }
    else {
        enc = rb_to_encoding(ext_enc);
    }
    ptr->enc = enc;
    if (WRITABLE(self)) {
        rb_enc_associate(ptr->string, enc);
    }

    return self;
}

Specify the encoding of the StringIO as ext_enc. Use the default external encoding if ext_enc is nil. 2nd argument int_enc and optional hash opt argument are ignored; they are for API compatibility to IO.

size → integer Show source

static VALUE
strio_size(VALUE self)
{
    VALUE string = StringIO(self)->string;
    if (NIL_P(string)) {
        rb_raise(rb_eIOError, "not opened");
    }
    return ULONG2NUM(RSTRING_LEN(string));
}

Returns the size of the buffer string.

string → string Show source

static VALUE
strio_get_string(VALUE self)
{
    return StringIO(self)->string;
}

Returns underlying String object, the subject of IO.

string = string → string Show source

static VALUE
strio_set_string(VALUE self, VALUE string)
{
    struct StringIO *ptr = StringIO(self);

    rb_io_taint_check(self);
    ptr->flags &= ~FMODE_READWRITE;
    StringValue(string);
    ptr->flags = OBJ_FROZEN(string) ? FMODE_READABLE : FMODE_READWRITE;
    ptr->pos = 0;
    ptr->lineno = 0;
    return ptr->string = string;
}

Changes underlying String object, the subject of IO.

sync → true Show source

static VALUE
strio_get_sync(VALUE self)
{
    StringIO(self);
    return Qtrue;
}

Returns true always.

sync=(p1) Show source

static VALUE
strio_first(VALUE self, VALUE arg)
{
    StringIO(self);
    return arg;
}

Returns the argument unchanged. Just for compatibility to IO.

pos → integer Show source

tell → integer

static VALUE
strio_get_pos(VALUE self)
{
    return LONG2NUM(StringIO(self)->pos);
}

Returns the current offset (in bytes) of strio.

truncate(integer) → 0 Show source

static VALUE
strio_truncate(VALUE self, VALUE len)
{
    VALUE string = writable(self)->string;
    long l = NUM2LONG(len);
    long plen = RSTRING_LEN(string);
    if (l < 0) {
        error_inval("negative length");
    }
    rb_str_resize(string, l);
    if (plen < l) {
        MEMZERO(RSTRING_PTR(string) + plen, char, l - plen);
    }
    return len;
}

Truncates the buffer string to at most integer bytes. The strio must be opened for writing.

tty?() Show source

static VALUE
strio_false(VALUE self)
{
    StringIO(self);
    return Qfalse;
}

Returns false. Just for compatibility to IO.

ungetbyte(fixnum) → nil Show source

static VALUE
strio_ungetbyte(VALUE self, VALUE c)
{
    struct StringIO *ptr = readable(self);
    char buf[1], *cp = buf;
    long cl = 1;

    check_modifiable(ptr);
    if (NIL_P(c)) return Qnil;
    if (FIXNUM_P(c)) {
        buf[0] = (char)FIX2INT(c);
        return strio_unget_bytes(ptr, buf, 1);
    }
    else {
        SafeStringValue(c);
        cp = RSTRING_PTR(c);
        cl = RSTRING_LEN(c);
        if (cl == 0) return Qnil;
        strio_unget_bytes(ptr, cp, cl);
        RB_GC_GUARD(c);
        return Qnil;
    }
}

See IO#ungetbyte

ungetc(string) → nil Show source

static VALUE
strio_ungetc(VALUE self, VALUE c)
{
    struct StringIO *ptr = readable(self);
    rb_encoding *enc, *enc2;

    check_modifiable(ptr);
    if (NIL_P(c)) return Qnil;
    if (RB_INTEGER_TYPE_P(c)) {
        int len, cc = NUM2INT(c);
        char buf[16];

        enc = rb_enc_get(ptr->string);
        len = rb_enc_codelen(cc, enc);
        if (len <= 0) rb_enc_uint_chr(cc, enc);
        rb_enc_mbcput(cc, buf, enc);
        return strio_unget_bytes(ptr, buf, len);
    }
    else {
        SafeStringValue(c);
        enc = rb_enc_get(ptr->string);
        enc2 = rb_enc_get(c);
        if (enc != enc2 && enc != rb_ascii8bit_encoding()) {
            c = rb_str_conv_enc(c, enc2, enc);
        }
        strio_unget_bytes(ptr, RSTRING_PTR(c), RSTRING_LEN(c));
        RB_GC_GUARD(c);
        return Qnil;
    }
}

Pushes back one character (passed as a parameter) onto strio such that a subsequent buffered read will return it. There is no limitation for multiple pushbacks including pushing back behind the beginning of the buffer string.

write(string) → integer Show source

syswrite(string) → integer

static VALUE
strio_write(VALUE self, VALUE str)
{
    struct StringIO *ptr = writable(self);
    long len, olen;
    rb_encoding *enc, *enc2;
    rb_encoding *const ascii8bit = rb_ascii8bit_encoding();

    if (!RB_TYPE_P(str, T_STRING))
        str = rb_obj_as_string(str);
    enc = get_enc(ptr);
    enc2 = rb_enc_get(str);
    if (enc != enc2 && enc != ascii8bit) {
        str = rb_str_conv_enc(str, enc2, enc);
    }
    len = RSTRING_LEN(str);
    if (len == 0) return INT2FIX(0);
    check_modifiable(ptr);
    olen = RSTRING_LEN(ptr->string);
    if (ptr->flags & FMODE_APPEND) {
        ptr->pos = olen;
    }
    if (ptr->pos == olen) {
        if (enc == ascii8bit || enc2 == ascii8bit) {
            rb_enc_str_buf_cat(ptr->string, RSTRING_PTR(str), len, enc);
            OBJ_INFECT(ptr->string, str);
        }
        else {
            rb_str_buf_append(ptr->string, str);
        }
    }
    else {
        strio_extend(ptr, ptr->pos, len);
        memmove(RSTRING_PTR(ptr->string)+ptr->pos, RSTRING_PTR(str), len);
        OBJ_INFECT(ptr->string, str);
    }
    OBJ_INFECT(ptr->string, self);
    RB_GC_GUARD(str);
    ptr->pos += len;
    return LONG2NUM(len);
}

Appends the given string to the underlying buffer string of strio. The stream must be opened for writing. If the argument is not a string, it will be converted to a string using to_s. Returns the number of bytes written. See IO#write.

Ruby Core © 1993–2017 Yukihiro Matsumoto
Licensed under the Ruby License.
Ruby Standard Library © contributors
Licensed under their own licenses.