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Subject: [Boost-users] How about easiest to use? RE: How efficient is the boost::regex library?
From: Harelick, Matthew (MHarelick_at_[hidden])
Date: 2011-10-27 14:49:28


So which of these libraries is easiest to develop against?


-----Original Message-----
From: boost-users-bounces_at_[hidden] [mailto:boost-users-bounces_at_[hidden]] On Behalf Of John Maddock
Sent: Thursday, October 27, 2011 2:11 PM
To: boost-users_at_[hidden]
Subject: Re: [Boost-users] How efficient is the boost::regex library?

> I am looking for the most efficient open-source C++ regex library.
> Reading this article: - It
> seems that GNU awk is the best overall:

This is all true, but also completely irrelevant. DFA's have good worst
case behaviour, but can be many times slower for common cases. It's also
impossible to implement a DFA matcher that offers the full range of Perl
regular expression features (if you think it can be done, congratulations,
you've just proved that P==NP).

It's also possible to protect the regex engine against runaway "bad"
expressions and bail out in those cases (this is what Boost.Regex does, it
throws an exception if the complexity of obtaining a match grows too fast).

> How does the boost::regex library compare?
> Would you recommend boost::regex as the most efficient one, or would
> you suggest another?

There's no such thing as best - it all depends on the data being searched
and the particular regular expression. In addition since most
Perl-compatible libraries use much the same algorithm they're all broadly
similar albeit with different quirks.

HTH, John.

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