class Ripper

Parent:
Object

Ripper is a Ruby script parser.

You can get information from the parser with event-based style. Information such as abstract syntax trees or simple lexical analysis of the Ruby program.

Usage

Ripper provides an easy interface for parsing your program into a symbolic expression tree (or S-expression).

Understanding the output of the parser may come as a challenge, it's recommended you use PP to format the output for legibility.

require 'ripper'
require 'pp'

pp Ripper.sexp('def hello(world) "Hello, #{world}!"; end')
  #=> [:program,
       [[:def,
         [:@ident, "hello", [1, 4]],
         [:paren,
          [:params, [[:@ident, "world", [1, 10]]], nil, nil, nil, nil, nil, nil]],
         [:bodystmt,
          [[:string_literal,
            [:string_content,
             [:@tstring_content, "Hello, ", [1, 18]],
             [:string_embexpr, [[:var_ref, [:@ident, "world", [1, 27]]]]],
             [:@tstring_content, "!", [1, 33]]]]],
          nil,
          nil,
          nil]]]]

You can see in the example above, the expression starts with :program.

From here, a method definition at :def, followed by the method's identifier :@ident. After the method's identifier comes the parentheses :paren and the method parameters under :params.

Next is the method body, starting at :bodystmt (stmt meaning statement), which contains the full definition of the method.

In our case, we're simply returning a String, so next we have the :string_literal expression.

Within our :string_literal you'll notice two @tstring_content, this is the literal part for Hello, and !. Between the two @tstring_content statements is a :string_embexpr, where embexpr is an embedded expression. Our expression consists of a local variable, or var_ref, with the identifier (@ident) of world.

Resources

Requirements

  • ruby 1.9 (support CVS HEAD only)

  • bison 1.28 or later (Other yaccs do not work)

License

Ruby License.

                                              Minero Aoki
                                      [email protected]
                                    http://i.loveruby.net

Constants

EVENTS

This array contains name of all ripper events.

PARSER_EVENTS

This array contains name of parser events.

SCANNER_EVENTS

This array contains name of scanner events.

Version

version of Ripper

Public Class Methods

lex(src, filename = '-', lineno = 1) Show source 
# File ext/ripper/lib/ripper/lexer.rb, line 42
def Ripper.lex(src, filename = '-', lineno = 1)
  Lexer.new(src, filename, lineno).lex
end

Tokenizes the Ruby program and returns an array of an array, which is formatted like [[lineno, column], type, token].

require 'ripper'
require 'pp'

pp Ripper.lex("def m(a) nil end")
  #=> [[[1,  0], :on_kw,     "def"],
       [[1,  3], :on_sp,     " "  ],
       [[1,  4], :on_ident,  "m"  ],
       [[1,  5], :on_lparen, "("  ],
       [[1,  6], :on_ident,  "a"  ],
       [[1,  7], :on_rparen, ")"  ],
       [[1,  8], :on_sp,     " "  ],
       [[1,  9], :on_kw,     "nil"],
       [[1, 12], :on_sp,     " "  ],
       [[1, 13], :on_kw,     "end"]]
new(src, filename="(ripper)", lineno=1) → ripper Show source 
static VALUE
ripper_initialize(int argc, VALUE *argv, VALUE self)
{
    struct parser_params *parser;
    VALUE src, fname, lineno;

    TypedData_Get_Struct(self, struct parser_params, &parser_data_type, parser);
    rb_scan_args(argc, argv, "12", &src, &fname, &lineno);
    if (RB_TYPE_P(src, T_FILE)) {
        parser->parser_lex_gets = ripper_lex_get_generic;
    }
    else {
        StringValue(src);
        parser->parser_lex_gets = lex_get_str;
    }
    parser->parser_lex_input = src;
    parser->eofp = Qfalse;
    if (NIL_P(fname)) {
        fname = STR_NEW2("(ripper)");
        OBJ_FREEZE(fname);
    }
    else {
        StringValue(fname);
        fname = rb_str_new_frozen(fname);
    }
    parser_initialize(parser);

    parser->parser_ruby_sourcefile_string = fname;
    parser->parser_ruby_sourcefile = RSTRING_PTR(fname);
    parser->parser_ruby_sourceline = NIL_P(lineno) ? 0 : NUM2INT(lineno) - 1;

    return Qnil;
}

Create a new Ripper object. src must be a String, an IO, or an Object which has gets method.

This method does not starts parsing. See also #parse and ::parse.

parse(src, filename = '(ripper)', lineno = 1) Show source 
# File ext/ripper/lib/ripper/core.rb, line 17
def Ripper.parse(src, filename = '(ripper)', lineno = 1)
  new(src, filename, lineno).parse
end

Parses the given Ruby program read from src. src must be a String or an IO or a object with a gets method.

sexp(src, filename = '-', lineno = 1) Show source 
# File ext/ripper/lib/ripper/sexp.rb, line 30
def Ripper.sexp(src, filename = '-', lineno = 1)
  builder = SexpBuilderPP.new(src, filename, lineno)
  sexp = builder.parse
  sexp unless builder.error?
end
EXPERIMENTAL

Parses src and create S-exp tree. Returns more readable tree rather than ::sexp_raw. This method is mainly for developer use.

require 'ripper'
require 'pp'

pp Ripper.sexp("def m(a) nil end")
  #=> [:program,
       [[:def,
        [:@ident, "m", [1, 4]],
        [:paren, [:params, [[:@ident, "a", [1, 6]]], nil, nil, nil, nil]],
        [:bodystmt, [[:var_ref, [:@kw, "nil", [1, 9]]]], nil, nil, nil]]]]
sexp_raw(src, filename = '-', lineno = 1) Show source 
# File ext/ripper/lib/ripper/sexp.rb, line 56
def Ripper.sexp_raw(src, filename = '-', lineno = 1)
  builder = SexpBuilder.new(src, filename, lineno)
  sexp = builder.parse
  sexp unless builder.error?
end
EXPERIMENTAL

Parses src and create S-exp tree. This method is mainly for developer use.

require 'ripper'
require 'pp'

pp Ripper.sexp_raw("def m(a) nil end")
  #=> [:program,
       [:stmts_add,
        [:stmts_new],
        [:def,
         [:@ident, "m", [1, 4]],
         [:paren, [:params, [[:@ident, "a", [1, 6]]], nil, nil, nil]],
         [:bodystmt,
          [:stmts_add, [:stmts_new], [:var_ref, [:@kw, "nil", [1, 9]]]],
          nil,
          nil,
          nil]]]]
slice(src, pattern, n = 0) Show source 
# File ext/ripper/lib/ripper/lexer.rb, line 84
def Ripper.slice(src, pattern, n = 0)
  if m = token_match(src, pattern)
  then m.string(n)
  else nil
  end
end
EXPERIMENTAL

Parses src and return a string which was matched to pattern. pattern should be described as Regexp.

require 'ripper'

p Ripper.slice('def m(a) nil end', 'ident')                   #=> "m"
p Ripper.slice('def m(a) nil end', '[ident lparen rparen]+')  #=> "m(a)"
p Ripper.slice("<<EOS\nstring\nEOS",
               'heredoc_beg nl $(tstring_content*) heredoc_end', 1)
    #=> "string\n"
tokenize(src, filename = '-', lineno = 1) Show source 
# File ext/ripper/lib/ripper/lexer.rb, line 20
def Ripper.tokenize(src, filename = '-', lineno = 1)
  Lexer.new(src, filename, lineno).tokenize
end

Tokenizes the Ruby program and returns an array of strings.

p Ripper.tokenize("def m(a) nil end")
   # => ["def", " ", "m", "(", "a", ")", " ", "nil", " ", "end"]

Public Instance Methods

ripper#column → Integer Show source 
static VALUE
ripper_column(VALUE self)
{
    struct parser_params *parser;
    long col;

    TypedData_Get_Struct(self, struct parser_params, &parser_data_type, parser);
    if (!ripper_initialized_p(parser)) {
        rb_raise(rb_eArgError, "method called for uninitialized object");
    }
    if (NIL_P(parser->parsing_thread)) return Qnil;
    col = parser->tokp - parser->parser_lex_pbeg;
    return LONG2NUM(col);
}

Return column number of current parsing line. This number starts from 0.

ripper#encoding → encoding Show source 
VALUE
rb_parser_encoding(VALUE vparser)
{
    struct parser_params *parser;

    TypedData_Get_Struct(vparser, struct parser_params, &parser_data_type, parser);
    return rb_enc_from_encoding(current_enc);
}

Return encoding of the source.

ripper#end_seen? → Boolean Show source 
VALUE
rb_parser_end_seen_p(VALUE vparser)
{
    struct parser_params *parser;

    TypedData_Get_Struct(vparser, struct parser_params, &parser_data_type, parser);
    return ruby__end__seen ? Qtrue : Qfalse;
}

Return true if parsed source ended by +_END_+.

ripper#error? → Boolean Show source 
static VALUE
ripper_error_p(VALUE vparser)
{
    struct parser_params *parser;

    TypedData_Get_Struct(vparser, struct parser_params, &parser_data_type, parser);
    return parser->error_p ? Qtrue : Qfalse;
}

Return true if parsed source has errors.

ripper#filename → String Show source 
static VALUE
ripper_filename(VALUE self)
{
    struct parser_params *parser;

    TypedData_Get_Struct(self, struct parser_params, &parser_data_type, parser);
    if (!ripper_initialized_p(parser)) {
        rb_raise(rb_eArgError, "method called for uninitialized object");
    }
    return parser->parser_ruby_sourcefile_string;
}

Return current parsing filename.

ripper#lineno → Integer Show source 
static VALUE
ripper_lineno(VALUE self)
{
    struct parser_params *parser;

    TypedData_Get_Struct(self, struct parser_params, &parser_data_type, parser);
    if (!ripper_initialized_p(parser)) {
        rb_raise(rb_eArgError, "method called for uninitialized object");
    }
    if (NIL_P(parser->parsing_thread)) return Qnil;
    return INT2NUM(parser->parser_ruby_sourceline);
}

Return line number of current parsing line. This number starts from 1.

ripper#parse Show source 
static VALUE
ripper_parse(VALUE self)
{
    struct parser_params *parser;

    TypedData_Get_Struct(self, struct parser_params, &parser_data_type, parser);
    if (!ripper_initialized_p(parser)) {
        rb_raise(rb_eArgError, "method called for uninitialized object");
    }
    if (!NIL_P(parser->parsing_thread)) {
        if (parser->parsing_thread == rb_thread_current())
            rb_raise(rb_eArgError, "Ripper#parse is not reentrant");
        else
            rb_raise(rb_eArgError, "Ripper#parse is not multithread-safe");
    }
    parser->parsing_thread = rb_thread_current();
    rb_ensure(ripper_parse0, self, ripper_ensure, self);

    return parser->result;
}

Start parsing and returns the value of the root action.

yydebug → true or false Show source 
VALUE
rb_parser_get_yydebug(VALUE self)
{
    struct parser_params *parser;

    TypedData_Get_Struct(self, struct parser_params, &parser_data_type, parser);
    return yydebug ? Qtrue : Qfalse;
}

Get yydebug.

yydebug = flag Show source 
VALUE
rb_parser_set_yydebug(VALUE self, VALUE flag)
{
    struct parser_params *parser;

    TypedData_Get_Struct(self, struct parser_params, &parser_data_type, parser);
    yydebug = RTEST(flag);
    return flag;
}

Set yydebug.

Private Instance Methods

compile_error(msg) Show source 
# File ext/ripper/lib/ripper/core.rb, line 55
def compile_error(msg)
end

This method is called when the parser found syntax error.

warn(fmt, *args) Show source 
# File ext/ripper/lib/ripper/core.rb, line 46
def warn(fmt, *args)
end

This method is called when weak warning is produced by the parser. fmt and args is printf style.

warning(fmt, *args) Show source 
# File ext/ripper/lib/ripper/core.rb, line 51
def warning(fmt, *args)
end

This method is called when strong warning is produced by the parser. fmt and args is printf style.

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