regex/doc/regex_traits.qbk

[/ 
  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:regex_traits regex_traits]

   namespace boost{

   template <class charT, class implementationT = sensible_default_choice>
   struct regex_traits : public implementationT
   {
      regex_traits() : implementationT() {}
   };

   template <class charT>
   struct c_regex_traits;

   template <class charT>
   class cpp_regex_traits;

   template <class charT>
   class w32_regex_traits;

   } // namespace boost

[h4 Description]

The class `regex_traits` is just a thin wrapper around an actual implementation 
class, which may be one of:

* `c_regex_traits`: this class is deprecated, it wraps the C locale, and is used as the default implementation when the platform is not Win32, and the C++ locale is not available.
* `cpp_regex_traits`: the default traits class for non-Win32 platforms, allows the regex class to be imbued with a std::locale instance.
* `w32_regex_traits`: the default traits class implementation on Win32 platforms, allows the regex class to be imbued with an LCID.

The default behavior can be altered by defining one of the following 
configuration macros in 
[@../../../../boost/regex/user.hpp boost/regex/user.hpp]

* BOOST_REGEX_USE_C_LOCALE: makes `c_regex_traits` the default.
* BOOST_REGEX_USE_CPP_LOCALE: makes `cpp_regex_traits` the default.

All these traits classes fulfil the 
[link boost_regex.ref.concepts.traits_concept traits class requirements].
     
[endsect]