Re: [Pyparsing] parsing an operator-precedence-based grammar with reasonable performance?

[Gre7g L. <haf...@ya...>]

You'll need to enable Packrat. It makes a huge difference, especially with operatorPrecedence.

Gre7g

----- Original Message ----
From: Andrew Warkentin <and...@gm...>
To: pyp...@li...
Sent: Friday, July 4, 2008 9:43:10 PM
Subject: [Pyparsing] parsing an operator-precedence-based grammar with reasonable performance?

I am trying to write a parser for a regexp-like matching language using 
pyparsing. It can be implemented in terms of operator precedence. I 
tried using the operatorPrecedence function, but the performance is 
unacceptable for expressions containing nested parentheses.

Parsing time appears to increase exponentially with the number of nested 
parentheses, and the parsing time for each set of nested parentheses 
appears to increase exponentially with the number of operators in the 
grammar.

Even parsing something as simple as "(foo(bar))" with a grammar of 4 
binary and 2 unary operators takes ridiculously long (about 2 minutes).

Is there any way to parse operator-precedence-based grammars using 
pypasing that doesn't increase exponentially in run time with the number 
of nested parentheses?

-------------------------------------------------------------------------
Sponsored by: SourceForge.net Community Choice Awards: VOTE NOW!
Studies have shown that voting for your favorite open source project,
along with a healthy diet, reduces your potential for chronic lameness
and boredom. Vote Now at http://www.sourceforge.net/community/cca08
_______________________________________________
Pyparsing-users mailing list
Pyp...@li...
https://lists.sourceforge.net/lists/listinfo/pyparsing-users