From: Jamis Buck <jamis@37signals.com>
Date: 2005-04-17T00:54:51+09:00
Subject: Re: BNF-like grammar specified DIRECTLY in Ruby

On Apr 16, 2005, at 8:23 AM, Eric Mahurin wrote:

> Would it be better to put it on rubyforge after renaming?
>

That's not necessary, but it's nice if you need a CVS repository, or a 
home page, or a wiki for your project. It also gives you bug and 
feature request tracking, mailing lists, forums, and more. If any of 
that sounds appealing, you may want to apply for a new project there. 
If you have those things all hosted elsewhere, or you don't want/need 
them, then you probably won't gain anything by a RubyForge project 
(except, perhaps, better project visibility).

> Also, is it best rubygems?  Is this the ruby equivalent of cpan
> for perl?

Currently RubyGems is the de facto standard for Ruby libraries. There 
really isn't a CPAN equivalent for Ruby, yet--we've got RAA and 
RubyForge, with RubyGems as the package manager. (Another nice thing 
about RubyForge--when you add a gem file to your project file list, it 
will automatically be added to the RubyGems package list.)

- Jamis

>
> --- Jamis Buck <jamis@37signals.com> wrote:
>> Very nice! One quibble: any chance you could change the name?
>>
>> http://rubyforge.org/projects/syntax
>>
>> :) Might get confusing if someone wants to install both libs.
>>
>> - Jamis
>>
>> On Apr 15, 2005, at 10:25 PM, Eric Mahurin wrote:
>>
>>> Here is my first contribution to Ruby:
>>>
>>> http://raa.ruby-lang.org/project/syntax/
>>>
>>> There is still plenty missing in here and it is a work in
>>> progress, but I think it is ready for some of you to try it
>> out
>>> if you like it.
>>>
>>> To get an idea of what this is, there is a simple
>> expression
>>> evaluator example below.  This is pure Ruby code - no yacc
>> type
>>> compiling necessary.  That's what I love about it.
>>>
>>> Eric
>>>
>>>
>>> #!/usr/bin/ruby -d
>>>
>>> require "syntax"
>>>
>>> NULL = Syntax::NULL
>>> INF = +1.0/0
>>> LOOP0 = (0..INF)
>>> LOOP1 = (1..INF)
>>>
>>> int = (("0".."9")*LOOP1).qualify { |m| m.to_s.to_i }
>>>
>>> number = (
>>>     int +
>>>     (("."+int)|NULL) +
>>>     ((("e"|"E")+("+"|"-"|NULL)+int)|NULL)
>>> ).qualify { |m|
>>>     if (m.length>1)
>>>         m.to_s.to_f
>>>     else
>>>         m[0]
>>>     end
>>> }
>>>
>>> ws = ((" "|"\t"|"\n")*LOOP0).qualify { TRUE } # skipped
>> with
>>> TRUE
>>>
>>> expr = Syntax::Pass.new # need to predefine object for
>>> recursion
>>>
>>> atom =
>>>     (number+ws).qualify{|m|m[0]} |
>>>     ("(" + expr + ")" + ws).qualify{|m|m[1]}
>>>
>>> term = (
>>>     atom + ( ("*"|"/"|"%") + ws + atom )*LOOP0
>>> ).qualify { |m|
>>>     product = m[0]
>>>     m[1].each { |m|
>>>         case m[0]
>>>             when "*" then product *= m[1]
>>>             when "/" then product /= m[1]
>>>             when "%" then product %= m[1]
>>>         end
>>>     }
>>>     product
>>> }
>>>
>>> expr << (
>>>     ws + term + ( ("+"|"-") + ws + term )*LOOP0
>>> ).qualify { |m|
>>>     sum = m[0]
>>>     m[1].each { |m|
>>>         case m[0]
>>>             when "+" then sum += m[1]
>>>             when "-" then sum -= m[1]
>>>         end
>>>     }
>>>     sum
>>> }
>>>
>>> while (gets)
>>>     p(expr===RandomAccessStream.new($_))
>>> end
>
>
>
> 		
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