Re: [Pyparsing] A newbie w/nested structures

[Tim C. <tim...@gm...>]

Hi Paul,

On Sun, 2007-09-09 at 04:30 -0500, Paul McGuire wrote:
> Here are some suggestions on getting started:
> - pick a part of the sample ADL (I would suggest working section by section)
> - develop a simple BNF for this grammar
> 
> Here is a sample parser for the ontology section. 

This is exactly what I started with.  Well, it's what I dropped back to
when I realized how difficult it would be. :-)

>  It is a recursive
> example, defining a valueDef that is defined in terms of component
> valueDefs.  It also shows the comment format, and the mechanism for skipping
> comments.  I hope this sample gives you a jump start on a more complete ADL
> parser.

Thank you so very much for your prompt and informative reply.  


> valueDef = Forward()
> valueDef << ( key + EQ + LT + ZeroOrMore( Group(valueDef | quotedString )) +
> GT )

I am certain that my problem is that I still do not have a good grasp of
Forward().

Is this the meaning of the valueDef assignment?

"valueDefs are composed of a key followed by an = followed by < and then
zero or more embedded valueDefs or quoted strings. The key is composed
of an attribute name or a bracketed and quoted string"

BTW: The example you sent raises ParseException;
pyparsing.ParseException: Expected ">" (at char 55), (line:4, col:17)

Thanks.
Tim
 


-- 
Timothy Cook, MSc
Health Informatics Research & Development Services
http://timothywayne.cook.googlepages.com/home
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