Class: Ripper

Inherits:

Object

Object
Ripper

show all

Defined in:: lib/ripper.rb,
lib/ripper/core.rb,
lib/ripper/sexp.rb,
lib/ripper/lexer.rb,
lib/ripper/filter.rb

Overview

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

Ruby Inside

Requirements

ruby 1.9 (support CVS HEAD only)
bison 1.28 or later (Other yaccs do not work)

License

Ruby License.

Direct Known Subclasses

Lexer, SexpBuilder

Defined Under Namespace

Classes: Filter, Lexer, SexpBuilder, SexpBuilderPP, TokenPattern

Constant Summary collapse

PARSER_EVENTS = This array contains name of parser events.

PARSER_EVENT_TABLE.keys

SCANNER_EVENTS = This array contains name of scanner events.

SCANNER_EVENT_TABLE.keys

EVENTS = This array contains name of all ripper events.

PARSER_EVENTS + SCANNER_EVENTS