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<title>Boost.Regex: Thread Safety</title>
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<H1 align="center">Boost.Regex</H1>
<H2 align="center">Thread Safety</H2>
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<P>The regex library is thread safe when Boost is: you can verify that Boost is in
thread safe mode by checking to see if BOOST_HAS_THREADS is defined: this macro
is set automatically by the config system when threading support is turned on
in your compiler.
</P>
<P>Class <A href="basic_regex.html">basic_regex</A><> and its typedefs regex
and wregex are thread safe, in that compiled regular expressions can safely be
shared between threads. The matching algorithms <A href="regex_match.html">regex_match</A>,
<A href="regex_search.html">regex_search</A>, <A href="regex_grep.html">regex_grep</A>,
<A href="regex_format.html">regex_format</A> and <A href="regex_merge.html">regex_merge</A>
are all re-entrant and thread safe. Class <A href="match_results.html">match_results</A>
is now thread safe, in that the results of a match can be safely copied from
one thread to another (for example one thread may find matches and push
match_results instances onto a queue, while another thread pops them off the
other end), otherwise use a separate instance of <A href="match_results.html">match_results</A>
per thread.
</P>
<P>The <A href="posix_api.html">POSIX API functions</A> are all re-entrant and
thread safe, regular expressions compiled with <I>regcomp</I> can also be
shared between threads.
</P>
<P>The class<A href="regex.html"> RegEx</A> is only thread safe if each thread
gets its own RegEx instance (apartment threading) - this is a consequence of
RegEx handling both compiling and matching regular expressions.
</P>
<P>Finally note that changing the global locale invalidates all compiled regular
expressions, therefore calling <I>set_locale</I> from one thread while another
uses regular expressions <I>will</I> produce unpredictable results.
</P>
<P>
There is also a requirement that there is only one thread executing prior to
the start of main().</P>
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<p>Revised
<!--webbot bot="Timestamp" S-Type="EDITED" S-Format="%d %B, %Y" startspan -->
24 Oct 2003
<!--webbot bot="Timestamp" endspan i-checksum="39359" --></p>
<p><i> Copyright John Maddock 1998-
<!--webbot bot="Timestamp" S-Type="EDITED" S-Format="%Y" startspan -->
2003<!--webbot bot="Timestamp" endspan i-checksum="39359" --></i></p>
<P><I>Use, modification and distribution are subject to the Boost Software License,
Version 1.0. (See accompanying file <A href="../../../LICENSE_1_0.txt">LICENSE_1_0.txt</A>
or copy at <A href="http://www.boost.org/LICENSE_1_0.txt">http://www.boost.org/LICENSE_1_0.txt</A>)</I></P>
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