From: "Florian Groß" <florgro@...>
Date: 2005-05-11T04:53:28+09:00
Subject: Re: Does any Ruby parser exist ?

Lothar Scholz wrote:

> Does any Ruby parser existother then the internal one inside the ruby
> interpreter. I found a few projects but most of them seems to be dead.
> 
> bRuby (not really a parser) and Ripper are old and not touched since
> 2003.

Ripper has been merged into 1.9 and is part of the windows one-click 
installer -- its grammar rules will thus always be up-to-date in the future.

It is used like this:

> irb(main):001:0> require 'ripper'                           
> => true                                                     
> irb(main):002:0> ripper = Ripper.new                        
> => #<Ripper:0x28e2810>                                      
> irb(main):003:0> def ripper.method_missing(*args) p args end
> => nil                                                      
> irb(main):004:0> ripper.parse "puts 'Hello World!'"         
> [:on__scan, "puts"]                                         
> [:on__IDENTIFIER, "puts"]                                   
> [:on__scan, " "]                                            
> [:on__space, " "]                                           
> [:on__scan, "'"]                                            
> [:on__new_string, "'"]                                      
> [:on__scan, "Hello World!"]                                 
> [:on__add_string, nil, "Hello World!"]                      
> [:on__scan, "'"]                                            
> [:on__string_end, nil, "'"]                                 
> [:on__argstart, "Hello World!"]                             
> [:on__fcall, :puts, nil]                                    
> => nil                                                      

> I need some positional data for the AST and a defined way to
> traverse the AST. Even the ParseTree project forgets to traverse some
> branches inside the tree.

I think that Ripper will do what you want, but I think you will have to 
build the tree by yourself.

That aside there is also a few lexers like the IRB one and the one used 
by the syntax library that does Ruby code highlighting.

I think there were other projects that generate ASTs as well, but I have 
trouble remembering their names right now... Perhaps I am wrong...