1ANTLR 3 for Ruby
2    by Kyle Yetter (kcy5b@yahoo.com)
3    http://antlr.ohboyohboyohboy.org
4    http://github.com/ohboyohboyohboy/antlr3
5
6== DESCRIPTION:
7
8Fully-featured ANTLR 3 parser generation for Ruby.
9
10ANTLR (ANother Tool for Language Recognition) is a tool that is used to generate
11code for performing a variety of language recognition tasks: lexing, parsing,
12abstract syntax tree construction and manipulation, tree structure recognition,
13and input translation. The tool operates similarly to other parser generators,
14taking in a grammar specification written in the special ANTLR metalanguage and
15producing source code that implements the recognition functionality.
16
17While the tool itself is implemented in Java, it has an extensible design that
18allows for code generation in other programming languages. To implement an
19ANTLR language target, a developer may supply a set of templates written in the
20StringTemplate (http://www.stringtemplate.org) language.
21
22ANTLR is currently distributed with a fairly limited Ruby target implementation.
23While it does provide implementation for basic lexer and parser classes, the
24target does not provide any implementation for abstract syntax tree
25construction, tree parser class generation, input translation, or a number of
26the other ANTLR features that give the program an edge over traditional code
27generators.
28
29This gem packages together a complete implementation of the majority of features
30ANTLR provides for other language targets, such as Java and Python. It contains:
31
32* A customized version of the latest ANTLR program, bundling all necessary
33  java code and templates for producing fully featured language recognition
34  in ruby code
35
36* a ruby run-time library that collects classes used throughout the code that
37  ANTLR generates
38  
39* a wrapper script, `antlr4ruby', which executes the ANTLR command line tool
40  after ensuring the ANTLR jar is Java's class path
41
42== FEATURES
43
441. generates ruby code capable of:
45   * lexing text input
46   * parsing lexical output and responding with arbitrary actions 
47   * constructing Abstract Syntax Trees (ASTs)
48   * parsing AST structure and responding with arbitrary actions
49   * translating input source to some desired output format
50
512. This package can serve as a powerful assistant when performing tasks
52   such as:
53   * code compilation
54   * source code highlighting and formatting
55   * domain-specific language implementation
56   * source code extraction and analysis
57
58== USAGE
59
601. Write an ANTLR grammar specification for a language
61
62   grammar SomeLanguage;
63   
64   options {
65     language = Ruby;    // <- this option must be set to Ruby
66     output   = AST;
67   }
68   
69   top: expr ( ',' expr )*
70      ;
71    
72   and so on...
73   
74
752. Run the ANTLR tool with the antlr4ruby command to generate output:
76   
77   antlr4ruby SomeLanguage.g
78   # creates:
79   #   SomeLanguageParser.rb
80   #   SomeLanguageLexer.rb
81   #   SomeLanguage.g
82
833. Try out the results directly, if you like:
84
85  # see how the lexer tokenizes some input
86  ruby SomeLanguageLexer.rb < path/to/source-code.xyz
87  
88  # check whether the parser successfully matches some input
89  ruby SomeLanguageParser.rb --rule=top < path/to/source-code.xyz
90
91-> Read up on the package documentation for more specific details
92   about loading the recognizers and using their class definitions
93
94== ISSUES
95
96* Currently, there are a few nuanced ways in which using the ruby output differs
97  from the conventions and examples covered in the ANTLR standard documentation.
98  I am still working on documenting these details.
99
100* So far, this has only been tested on Linux with ruby 1.8.7 and ruby 1.9.1.
101  I'm currently working on verifying behavior on other systems and with
102  slightly older versions of ruby. 
103
104== LICENSE
105
106[The "BSD license"]
107Copyright (c) 2009-2010 Kyle Yetter
108All rights reserved.
109
110Redistribution and use in source and binary forms, with or without
111modification, are permitted provided that the following conditions
112are met:
113
114 1. Redistributions of source code must retain the above copyright
115    notice, this list of conditions and the following disclaimer.
116 2. Redistributions in binary form must reproduce the above copyright
117    notice, this list of conditions and the following disclaimer in the
118    documentation and/or other materials provided with the distribution.
119 3. The name of the author may not be used to endorse or promote products
120    derived from this software without specific prior written permission.
121
122THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
123IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
124OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
125IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
126INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
127NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
128DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
129THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
130(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
131THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
132
133