boost/log/sinks/frontend_requirements.hpp
/* * Copyright Andrey Semashev 2007 - 2015. * 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) */ /*! * \file sinks/frontend_requirements.hpp * \author Andrey Semashev * \date 22.04.2007 * * The header contains definition of requirement tags that sink backend may declare * with regard to frontends. These requirements ensure that a backend will not * be used with an incompatible frontend. */ #ifndef BOOST_LOG_SINKS_FRONTEND_REQUIREMENTS_HPP_INCLUDED_ #define BOOST_LOG_SINKS_FRONTEND_REQUIREMENTS_HPP_INCLUDED_ #include <boost/type_traits/is_base_of.hpp> #include <boost/log/detail/config.hpp> #if defined(BOOST_NO_CXX11_VARIADIC_TEMPLATES) #include <boost/mpl/aux_/na.hpp> #include <boost/mpl/placeholders.hpp> #include <boost/mpl/inherit.hpp> #include <boost/mpl/inherit_linearly.hpp> #include <boost/mpl/vector.hpp> #include <boost/preprocessor/repetition/enum_params.hpp> #include <boost/preprocessor/repetition/enum_params_with_a_default.hpp> #endif #include <boost/log/detail/header.hpp> #ifdef BOOST_HAS_PRAGMA_ONCE #pragma once #endif #ifndef BOOST_LOG_COMBINE_REQUIREMENTS_LIMIT //! The macro specifies the maximum number of requirements that can be combined with the \c combine_requirements metafunction #define BOOST_LOG_COMBINE_REQUIREMENTS_LIMIT 5 #endif namespace boost { BOOST_LOG_OPEN_NAMESPACE namespace sinks { /*! * The sink backend expects pre-synchronized calls, all needed synchronization is implemented * in the frontend (IOW, only one thread is feeding records to the backend concurrently, but * it is possible for several threads to write sequentially). Note that if a frontend supports * synchronized record feeding, it will also report capable of concurrent record feeding. */ struct synchronized_feeding {}; #if !defined(BOOST_LOG_NO_THREADS) /*! * The sink backend ensures all needed synchronization, it is capable to handle multithreaded calls */ struct concurrent_feeding : synchronized_feeding {}; #else // !defined(BOOST_LOG_NO_THREADS) // If multithreading is disabled, threading models become redundant typedef synchronized_feeding concurrent_feeding; #endif // !defined(BOOST_LOG_NO_THREADS) /*! * The sink backend requires the frontend to perform log record formatting before feeding */ struct formatted_records {}; /*! * The sink backend supports flushing */ struct flushing {}; #if defined(BOOST_LOG_DOXYGEN_PASS) /*! * The metafunction combines multiple requirement tags into one type. The resulting type will * satisfy all specified requirements (i.e. \c has_requirement metafunction will return positive result). */ template< typename... RequirementsT > struct combine_requirements; #elif !defined(BOOST_NO_CXX11_VARIADIC_TEMPLATES) namespace aux { template< typename... RequirementsT > struct combined_requirements : public RequirementsT... { }; } // namespace aux template< typename... RequirementsT > struct combine_requirements { typedef sinks::aux::combined_requirements< RequirementsT... > type; }; #else template< BOOST_PP_ENUM_PARAMS_WITH_A_DEFAULT(BOOST_LOG_COMBINE_REQUIREMENTS_LIMIT, typename ReqT, mpl::na) > struct combine_requirements : mpl::inherit_linearly< mpl::vector< BOOST_PP_ENUM_PARAMS(BOOST_LOG_COMBINE_REQUIREMENTS_LIMIT, ReqT) >, mpl::inherit2< mpl::_1, mpl::_2 > > { }; #endif // BOOST_LOG_DOXYGEN_PASS /*! * A helper metafunction to check if a requirement is satisfied. The \c TestedT template argument * should be the type combining one or several requirements and \c RequiredT is the requirement * to test against. The metafunction will yield a positive result if \c TestedT supports \c RequiredT. */ template< typename TestedT, typename RequiredT > struct has_requirement : public is_base_of< RequiredT, TestedT > { }; } // namespace sinks BOOST_LOG_CLOSE_NAMESPACE // namespace log } // namespace boost #include <boost/log/detail/footer.hpp> #endif // BOOST_LOG_SINKS_FRONTEND_REQUIREMENTS_HPP_INCLUDED_