From: Logan Capaldo <logancapaldo@...>
Date: 2006-09-09T10:49:59+09:00
Subject: Re: [ANN] Wirble 0.1.1: Irb Enhancements for the Masses


On Sep 8, 2006, at 8:01 PM, Hal Fulton wrote:

> Paul Duncan wrote:
>> I looked into highlighting the input in Irb, too.  It's a lot more  
>> work,
>> but it might be doable.  At a minimum, I'd need to write, borrow, or
>> steal a full-blown Ruby lexer.  I'd probably need a more terminal-
>> friendly replacement for readlines (probably curses).
>
> You can use the lexer built into irb. I forget how it's
> done, but I did it two years ago. ;)
>

You certainly can steal irb's lexer. Here's an example from some code  
I've been kicking around for a while, so you can see how it works:

(This code understands a very minimal set of ruby and turns it into a  
sort of Sexpr)

require 'irb/ruby-lex'
module RubyMerge
   class ParseSkeleton
     def initialize(io)
       @io = io
     end

     def skeleton
       lexer = RubyLex.new
       stack = []
       results = []
       lexer.set_input( @io )
       while current = lexer.token
         case current
         when RubyLex::TkDEF, RubyLex::TkMODULE
           if stack.empty?
             results << current.name.to_sym
             ident = nil
             1 while ( ident = lexer.token ).kind_of? RubyLex::TkSPACE
             results << ident.name
           else
             if results.last.kind_of? Array
               results.last << current.name.to_sym
               ident = nil
               1 while ( ident = lexer.token ).kind_of? RubyLex::TkSPACE
               results.last << ident.name
             else
               results << []
               results.last << current.name.to_sym
               ident = nil
               1 while ( ident = lexer.token ).kind_of? RubyLex::TkSPACE
               results.last << ident.name
             end
           end
           stack.push current
         when RubyLex::TkEND
           stack.pop
         end
       end
       results
     end
   end
end



>
> Hal
>