boost/log/attributes/value_extraction_fwd.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 value_extraction_fwd.hpp * \author Andrey Semashev * \date 01.03.2008 * * The header contains forward declaration of tools for extracting attribute values * from the view. */ #ifndef BOOST_LOG_ATTRIBUTES_VALUE_EXTRACTION_FWD_HPP_INCLUDED_ #define BOOST_LOG_ATTRIBUTES_VALUE_EXTRACTION_FWD_HPP_INCLUDED_ #include <boost/log/detail/config.hpp> #include <boost/log/attributes/fallback_policy_fwd.hpp> #ifdef BOOST_HAS_PRAGMA_ONCE #pragma once #endif namespace boost { BOOST_LOG_OPEN_NAMESPACE namespace result_of { /*! * \brief A metafunction that allows to acquire the result of the value extraction */ template< typename T, typename DefaultT = T, typename TagT = void > struct extract_or_default; /*! * \brief A metafunction that allows to acquire the result of the value extraction */ template< typename T, typename TagT = void > struct extract_or_throw; /*! * \brief A metafunction that allows to acquire the result of the value extraction */ template< typename T, typename TagT = void > struct extract; } // namespace result_of /*! * \brief Generic attribute value extractor */ template< typename T, typename FallbackPolicyT = fallback_to_none, typename TagT = void > class value_extractor; BOOST_LOG_CLOSE_NAMESPACE // namespace log } // namespace boost #endif // BOOST_LOG_ATTRIBUTES_VALUE_EXTRACTION_FWD_HPP_INCLUDED_