regex/doc/thread_safety.qbk

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Copyright 2006-2007 John Maddock.
Distributed under the Boost Software License, Version 1.0.
(See accompanying file LICENSE_1_0.txt or copy at
http://www.boost.org/LICENSE_1_0.txt).
]
[section:thread_safety Thread Safety]
The Boost.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.
Class [basic_regex] and its typedefs regex and wregex are thread safe,
in that compiled regular expressions can safely be shared between threads.
The matching algorithms [regex_match], [regex_search], and [regex_replace]
are all re-entrant and thread safe. Class [match_results] 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 [match_results] per thread.
The [link boost_regex.ref.posix POSIX API functions] are all re-entrant and thread safe, regular
expressions compiled with regcomp can also be shared between threads.
The [link boost_regex.ref.deprecated.old_regex class RegEx] 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.
Finally note that changing the global locale invalidates all compiled
regular expressions, therefore calling `set_locale` from one thread
while another uses regular expressions will produce unpredictable results.
There is also a requirement that there is only one thread executing prior
to the start of main().
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