From: Eric Mahurin <eric_mahurin@...>
Date: 2005-10-30T21:33:02+09:00
Subject: Re: PARSER for RUBY

--- Ryan Davis <ryand-ruby@zenspider.com> wrote:
> Below are the notes I wrote up while doing an LR to LL flip
> on an  
> ST80 grammar. ST80 is much cleaner than ruby in terms of how
> many  
> grammar rules there are in the language so it was easier to
> get my  
> head around when I was doing the work. I tried to do an LR to
> LL flip  
> on ruby a couple years back and I failed at it. Your
> professor is a  
> sadist as far as I'm concerned. I hope these notes help:
> 
>      http://www.zenspider.com/Languages/PCCTS/LR2LL.html

Ryan,

I found many links on techniques for left-recursion elimination
(including yours above).  I think the most interesting one was
this paper by Wolfgang Lohmann:

http://www.informatik.uni-rostock.de/~wlohmann/Publications/LDTA04/lohmann_ldta04_preliminary.pdf

It does sound like there is software out there for doing LR to
LL transformations from the paper.  Unfortunately, I couldn't
find anything that I could download.

Do you know of any tools out there for doing left-recursion
elimination and possibly left-factoring?

Eric



	
		
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