ceph/src/boost/libs/log/include/boost/log/attributes/value_extraction_fwd.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   value_extraction_fwd.hpp
   9  * \author Andrey Semashev
  10  * \date   01.03.2008
  11  *
  12  * The header contains forward declaration of tools for extracting attribute values
  13  * from the view.
  14  */
  15
  16 #ifndef BOOST_LOG_ATTRIBUTES_VALUE_EXTRACTION_FWD_HPP_INCLUDED_
  17 #define BOOST_LOG_ATTRIBUTES_VALUE_EXTRACTION_FWD_HPP_INCLUDED_
  18
  19 #include <boost/log/detail/config.hpp>
  20 #include <boost/log/attributes/fallback_policy_fwd.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 result_of {
  31
  32 /*!
  33  * \brief A metafunction that allows to acquire the result of the value extraction
  34  */
  35 template< typename T, typename DefaultT = T, typename TagT = void >
  36 struct extract_or_default;
  37
  38 /*!
  39  * \brief A metafunction that allows to acquire the result of the value extraction
  40  */
  41 template< typename T, typename TagT = void >
  42 struct extract_or_throw;
  43
  44 /*!
  45  * \brief A metafunction that allows to acquire the result of the value extraction
  46  */
  47 template< typename T, typename TagT = void >
  48 struct extract;
  49
  50 } // namespace result_of
  51
  52 /*!
  53  * \brief Generic attribute value extractor
  54  */
  55 template< typename T, typename FallbackPolicyT = fallback_to_none, typename TagT = void >
  56 class value_extractor;
  57
  58 BOOST_LOG_CLOSE_NAMESPACE // namespace log
  59
  60 } // namespace boost
  61
  62 #endif // BOOST_LOG_ATTRIBUTES_VALUE_EXTRACTION_FWD_HPP_INCLUDED_