Re: [Oorexx-devel] Grammar

[Gil B. <gba...@al...>]

I seem to remember that the ANSI standard has (classic) Rexx in BNF. 
You can get a PDF here:

http://www.rexxla.org/rexxlang/standards/j18pub.pdf

Moritz Hoffmann wrote:
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> Hi,
> 
> I'm currently trying to write a grammar for ooRexx to build a workbench
> on it. However, I face some problems.
> 
> The grammar requires to be context free, and have no left recursions.
> Internally, it will use ANTLR to do the parsing, which is a LR(*).
> 
> First, I face some problem tokenizing the input, but that' snot the
> biggest issue yet. I will ask about that again.
> 
> The main issue is to parse expressions. I had a look at the ooRexx
> source code to figure out how it does it, but it's complex.
> 
> So, I'm asking for help regarding a single example in ebnf to parse some
> expression, including precedence and such.
> 
> The problem that ooRexx uses token sub-types is mostly solved. This is
> that words like "if" are keywords at some places and just symbols at
> other places. Due to this, all keywords have to be recognized as symbols
> as well.
> 
> The grammar that is currently in the SVN, has some bugs - and they're
> hard to figure out...
> 
> Kind regards,
> Moritz
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-- 
Gil Barmwater