I'm sure someone has mentioned it already but what about the lexer support in 


ANTLR is available under the BSD license, which seems to be one with no strings 


Best Regards,
Jonathan S. Levinson

-----Original Message-----
From: Vincent Hennebert [mailto:vhenneb...@gmail.com] 
Sent: Wednesday, October 07, 2009 6:51 AM
To: fop-dev@xmlgraphics.apache.org
Subject: Re: Regular expression use

Hi Jonathan,

Jonathan Levinson wrote:
> I noticed that if one is not careful in one's regular expression use,
> the compilation for a regular expression can take minutes.  I'm not
> talking about applying the pattern just compiling it!
> Should regular expressions be avoided altogether and should one use
> hand-crafted state machines for parsing, and tokenizing, or can regular
> expressions be used as long as one is careful?  

I’d say, use regular expressions as long as they are not too complex.
But I guess you’re mentioning that in the context of property parsing,
in which case I don’t think regular expressions are the ultimate answer.
A proper lexer is likely to be needed, either generated or written by
hand. As the latter solution quickly becomes a maintenance nightmare,
some lexer generator will probably be needed. Question remains, which
one, and I’m not even sure there’s one that exists whose license is
ASLv2-compatible. Plus there are some issues specific to property
parsing, like shorthands (which should ideally re-use the parsers of the
individual properties), sub-properties, etc.


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