ceph/src/boost/boost/log/sinks/frontend_requirements.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   sinks/frontend_requirements.hpp
   9  * \author Andrey Semashev
  10  * \date   22.04.2007
  11  *
  12  * The header contains definition of requirement tags that sink backend may declare
  13  * with regard to frontends. These requirements ensure that a backend will not
  14  * be used with an incompatible frontend.
  15  */
  16
  17 #ifndef BOOST_LOG_SINKS_FRONTEND_REQUIREMENTS_HPP_INCLUDED_
  18 #define BOOST_LOG_SINKS_FRONTEND_REQUIREMENTS_HPP_INCLUDED_
  19
  20 #include <boost/mpl/aux_/na.hpp>
  21 #include <boost/mpl/placeholders.hpp>
  22 #include <boost/mpl/inherit.hpp>
  23 #include <boost/mpl/inherit_linearly.hpp>
  24 #include <boost/mpl/vector.hpp>
  25 #include <boost/preprocessor/repetition/enum_params.hpp>
  26 #include <boost/preprocessor/repetition/enum_params_with_a_default.hpp>
  27 #include <boost/type_traits/is_base_of.hpp>
  28 #include <boost/log/detail/config.hpp>
  29 #include <boost/log/detail/header.hpp>
  30
  31 #ifdef BOOST_HAS_PRAGMA_ONCE
  32 #pragma once
  33 #endif
  34
  35 #ifndef BOOST_LOG_COMBINE_REQUIREMENTS_LIMIT
  36 //! The macro specifies the maximum number of requirements that can be combined with the \c combine_requirements metafunction
  37 #define BOOST_LOG_COMBINE_REQUIREMENTS_LIMIT 5
  38 #endif
  39
  40 namespace boost {
  41
  42 BOOST_LOG_OPEN_NAMESPACE
  43
  44 namespace sinks {
  45
  46 /*!
  47  * The sink backend expects pre-synchronized calls, all needed synchronization is implemented
  48  * in the frontend (IOW, only one thread is feeding records to the backend concurrently, but
  49  * it is possible for several threads to write sequentially). Note that if a frontend supports
  50  * synchronized record feeding, it will also report capable of concurrent record feeding.
  51  */
  52 struct synchronized_feeding {};
  53
  54 #if !defined(BOOST_LOG_NO_THREADS)
  55
  56 /*!
  57  * The sink backend ensures all needed synchronization, it is capable to handle multithreaded calls
  58  */
  59 struct concurrent_feeding : synchronized_feeding {};
  60
  61 #else // !defined(BOOST_LOG_NO_THREADS)
  62
  63 //  If multithreading is disabled, threading models become redundant
  64 typedef synchronized_feeding concurrent_feeding;
  65
  66 #endif // !defined(BOOST_LOG_NO_THREADS)
  67
  68 /*!
  69  * The sink backend requires the frontend to perform log record formatting before feeding
  70  */
  71 struct formatted_records {};
  72
  73 /*!
  74  * The sink backend supports flushing
  75  */
  76 struct flushing {};
  77
  78 #ifdef BOOST_LOG_DOXYGEN_PASS
  79
  80 /*!
  81  * The metafunction combines multiple requirement tags into one type. The resulting type will
  82  * satisfy all specified requirements (i.e. \c has_requirement metafunction will return positive result).
  83  */
  84 template< typename... RequirementsT >
  85 struct combine_requirements;
  86
  87 #else
  88
  89 template< BOOST_PP_ENUM_PARAMS_WITH_A_DEFAULT(BOOST_LOG_COMBINE_REQUIREMENTS_LIMIT, typename ReqT, mpl::na) >
  90 struct combine_requirements :
  91     mpl::inherit_linearly<
  92         mpl::vector< BOOST_PP_ENUM_PARAMS(BOOST_LOG_COMBINE_REQUIREMENTS_LIMIT, ReqT) >,
  93         mpl::inherit2< mpl::_1, mpl::_2 >
  94     >
  95 {
  96 };
  97
  98 #endif // BOOST_LOG_DOXYGEN_PASS
  99
 100 /*!
 101  * A helper metafunction to check if a requirement is satisfied. The \c TestedT template argument
 102  * should be the type combining one or several requirements and \c RequiredT is the requirement
 103  * to test against. The metafunction will yield a positive result if \c TestedT supports \c RequiredT.
 104  */
 105 template< typename TestedT, typename RequiredT >
 106 struct has_requirement :
 107     public is_base_of< RequiredT, TestedT >
 108 {
 109 };
 110
 111 } // namespace sinks
 112
 113 BOOST_LOG_CLOSE_NAMESPACE // namespace log
 114
 115 } // namespace boost
 116
 117 #include <boost/log/detail/footer.hpp>
 118
 119 #endif // BOOST_LOG_SINKS_FRONTEND_REQUIREMENTS_HPP_INCLUDED_