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 attribute_value_impl.hpp 9 * \author Andrey Semashev 10 * \date 24.06.2007 11 * 12 * The header contains an implementation of a basic attribute value implementation class. 13 */ 14 15 #ifndef BOOST_LOG_ATTRIBUTES_ATTRIBUTE_VALUE_IMPL_HPP_INCLUDED_ 16 #define BOOST_LOG_ATTRIBUTES_ATTRIBUTE_VALUE_IMPL_HPP_INCLUDED_ 17 18 #include <boost/type_index.hpp> 19 #include <boost/move/core.hpp> 20 #include <boost/move/utility_core.hpp> 21 #include <boost/type_traits/remove_cv.hpp> 22 #include <boost/type_traits/is_nothrow_move_constructible.hpp> 23 #include <boost/log/detail/config.hpp> 24 #include <boost/log/attributes/attribute_value.hpp> 25 #include <boost/log/utility/type_dispatch/type_dispatcher.hpp> 26 #if !defined(BOOST_NO_CXX11_RVALUE_REFERENCES) 27 #include <boost/type_traits/remove_reference.hpp> 28 #endif 29 #include <boost/log/detail/header.hpp> 30 31 #ifdef BOOST_HAS_PRAGMA_ONCE 32 #pragma once 33 #endif 34 35 namespace boost { 36 37 BOOST_LOG_OPEN_NAMESPACE 38 39 namespace attributes { 40 41 /*! 42 * \brief Basic attribute value implementation class 43 * 44 * This class can be used as a boilerplate for simple attribute values. The class implements all needed 45 * interfaces of attribute values and allows to store a single value of the type specified as a template parameter. 46 * The stored value can be dispatched with type dispatching mechanism. 47 */ 48 template< typename T > 49 class attribute_value_impl : 50 public attribute_value::impl 51 { 52 public: 53 //! Value type 54 typedef T value_type; 55 56 private: 57 //! Attribute value 58 const value_type m_value; 59 60 public: 61 /*! 62 * Constructor with initialization of the stored value 63 */ attribute_value_impl(value_type const & v)64 explicit attribute_value_impl(value_type const& v) : m_value(v) {} 65 /*! 66 * Constructor with initialization of the stored value 67 */ BOOST_NOEXCEPT_IF(boost::is_nothrow_move_constructible<value_type>::value)68 explicit attribute_value_impl(BOOST_RV_REF(value_type) v) BOOST_NOEXCEPT_IF(boost::is_nothrow_move_constructible< value_type >::value) : 69 m_value(boost::move(v)) 70 { 71 } 72 73 /*! 74 * Attribute value dispatching method. 75 * 76 * \param dispatcher The dispatcher that receives the stored value 77 * 78 * \return \c true if the value has been dispatched, \c false otherwise 79 */ dispatch(type_dispatcher & dispatcher)80 bool dispatch(type_dispatcher& dispatcher) BOOST_OVERRIDE 81 { 82 type_dispatcher::callback< value_type > callback = dispatcher.get_callback< value_type >(); 83 if (callback) 84 { 85 callback(m_value); 86 return true; 87 } 88 else 89 return false; 90 } 91 92 /*! 93 * \return The attribute value type 94 */ get_type() const95 typeindex::type_index get_type() const BOOST_OVERRIDE { return typeindex::type_id< value_type >(); } 96 97 /*! 98 * \return Reference to the contained value. 99 */ get() const100 value_type const& get() const { return m_value; } 101 }; 102 103 /*! 104 * The function creates an attribute value from the specified object. 105 */ 106 #if !defined(BOOST_NO_CXX11_RVALUE_REFERENCES) 107 108 template< typename T > make_attribute_value(T && v)109inline attribute_value make_attribute_value(T&& v) 110 { 111 typedef typename remove_cv< typename remove_reference< T >::type >::type value_type; 112 return attribute_value(new attribute_value_impl< value_type >(boost::forward< T >(v))); 113 } 114 115 #else // !defined(BOOST_NO_CXX11_RVALUE_REFERENCES) 116 117 template< typename T > make_attribute_value(T const & v)118inline attribute_value make_attribute_value(T const& v) 119 { 120 typedef typename remove_cv< T >::type value_type; 121 return attribute_value(new attribute_value_impl< value_type >(v)); 122 } 123 124 template< typename T > make_attribute_value(rv<T> const & v)125inline attribute_value make_attribute_value(rv< T > const& v) 126 { 127 typedef typename remove_cv< T >::type value_type; 128 return attribute_value(new attribute_value_impl< value_type >(v)); 129 } 130 131 #endif // !defined(BOOST_NO_CXX11_RVALUE_REFERENCES) 132 133 } // namespace attributes 134 135 BOOST_LOG_CLOSE_NAMESPACE // namespace log 136 137 } // namespace boost 138 139 #include <boost/log/detail/footer.hpp> 140 141 #endif // BOOST_LOG_ATTRIBUTES_ATTRIBUTE_VALUE_IMPL_HPP_INCLUDED_ 142