ceph/src/boost/boost/log/expressions/is_keyword_descriptor.hpp

   1 /*
   2  *          Copyright Andrey Semashev 2007 - 2015.
   3  * Distributed under the Boost Software License, Version 1.0.
   4  *    (See accompanying file LICENSE_1_0.txt or copy at
   5  *          http://www.boost.org/LICENSE_1_0.txt)
   6  */
   7 /*!
   8  * \file   is_keyword_descriptor.hpp
   9  * \author Andrey Semashev
  10  * \date   14.07.2012
  11  *
  12  * The header contains attribute keyword descriptor detection trait.
  13  */
  14
  15 #ifndef BOOST_LOG_EXPRESSIONS_IS_KEYWORD_DESCRIPTOR_HPP_INCLUDED_
  16 #define BOOST_LOG_EXPRESSIONS_IS_KEYWORD_DESCRIPTOR_HPP_INCLUDED_
  17
  18 #include <boost/mpl/bool.hpp>
  19 #include <boost/log/detail/config.hpp>
  20 #include <boost/log/detail/header.hpp>
  21
  22 #ifdef BOOST_HAS_PRAGMA_ONCE
  23 #pragma once
  24 #endif
  25
  26 namespace boost {
  27
  28 BOOST_LOG_OPEN_NAMESPACE
  29
  30 namespace expressions {
  31
  32 /*!
  33  * Base class for keyword descriptors. All keyword descriptors must derive from this class to support the \c is_keyword_descriptor trait.
  34  */
  35 struct keyword_descriptor
  36 {
  37 #ifndef BOOST_LOG_DOXYGEN_PASS
  38     typedef void _is_boost_log_keyword_descriptor;
  39 #endif // BOOST_LOG_DOXYGEN_PASS
  40 };
  41
  42 /*!
  43  * The metafunction detects if the type \c T is a keyword descriptor
  44  */
  45 template< typename T, typename VoidT = void >
  46 struct is_keyword_descriptor :
  47     public mpl::false_
  48 {
  49 };
  50
  51 #ifndef BOOST_LOG_DOXYGEN_PASS
  52 template< typename T >
  53 struct is_keyword_descriptor< T, typename T::_is_boost_log_keyword_descriptor > :
  54     public mpl::true_
  55 {
  56 };
  57 #endif
  58
  59 } // namespace expressions
  60
  61 BOOST_LOG_CLOSE_NAMESPACE // namespace log
  62
  63 } // namespace boost
  64
  65 #include <boost/log/detail/footer.hpp>
  66
  67 #endif // BOOST_LOG_EXPRESSIONS_IS_KEYWORD_DESCRIPTOR_HPP_INCLUDED_