Re: Regular expression implementations ? (Henry Spencer)
Sat, 7 Aug 1993 23:14:02 GMT

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Newsgroups: comp.compilers
From: (Henry Spencer)
Keywords: lex, DFA
Organization: U of Toronto Zoology
References: 93-08-031 93-08-035
Date: Sat, 7 Aug 1993 23:14:02 GMT (Arnold Robbins) writes:
>>Where can I find information on regular expressions implementations in C?
>Two and a half choices.
>1) Flex, which is a lex clone...
>2) Gnu regex, (slow)
>3) Gnu RX, a regex re-implementation...
>[There's more regexps than that. What about Henry Spencer's package? -John]

In fact, there are at least two more, because I wrote them both. :-)

There's my old package, dating back to 1986 or thereabouts, which is in
widespread use (including several commercial products -- it helps that
its copyright terms are much more liberal than the GNU ones). A slightly
updated version of that will appear in a few months, in conjunction with
a new book -- Software Solutions In C, ed. Dale Schumacher, Academic
Press -- which will have a chapter (by me) that walks through the code
explaining how it works. Meanwhile, you can find the old code lots of
places, including .

Then there's my new one, which is the regular-expression implementation
shipping with 4.4BSD. The good news is that it's completely POSIX.2
compliant. The bad news is that it's pretty slow; it's basically an
alpha release, and I'd really hoped to get at least to a beta before
4.4 shipped, but that didn't happen. Eventually there will be a faster
release, but don't ask me to set a date just yet.
Henry Spencer @ U of Toronto Zoology, utzoo!henry

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