Lex start flags performance

wim vandenhaute <wim.vandenhaute@mie.alcatel.be>
26 Nov 2001 22:02:08 -0500

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Related articles
Lex start flags performance wim.vandenhaute@mie.alcatel.be (wim vandenhaute) (2001-11-26)
Re: Lex start flags performance wim.vandenhaute@mie.alcatel.be (wim vandenhaute) (2001-12-07)
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From: wim vandenhaute <wim.vandenhaute@mie.alcatel.be>
Newsgroups: comp.compilers
Date: 26 Nov 2001 22:02:08 -0500
Organization: Alcatel
Keywords: lex
Posted-Date: 26 Nov 2001 22:02:08 EST

So far the parser i used (coded in lex and yacc) used simple int flags
for distinction between different file formats the parser has to be
capable to process After a revision we decided to replace these int
flags by the start conditions for left context sensitivity (%start
SwavParser ... )

Is there a way by which I can be sure that this will gain me
performance improvement. Is there a best way on how to do it ?

The case is that to substitute all these int flags by start conditions
it is a very big and complex work so from now we started to just
replace the biggest ones and see what it gives. After some simple
tests using /usr/bin/time we gained almost no performance.

Thanks for your help.
[As I recall, start states don't slow down lex's matcher at all. -John]

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