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 unary_function_terminal.hpp 9 * \author Andrey Semashev 10 * \date 21.07.2012 11 * 12 * The header contains attribute value extractor adapter for constructing expression template terminals. 13 */ 14 15 #ifndef BOOST_LOG_DETAIL_UNARY_FUNCTION_TERMINAL_HPP_INCLUDED_ 16 #define BOOST_LOG_DETAIL_UNARY_FUNCTION_TERMINAL_HPP_INCLUDED_ 17 18 #include <boost/mpl/bool.hpp> 19 #include <boost/utility/result_of.hpp> 20 #include <boost/fusion/sequence/intrinsic/at_c.hpp> 21 #include <boost/phoenix/core/is_nullary.hpp> 22 #include <boost/phoenix/core/environment.hpp> 23 #include <boost/type_traits/remove_cv.hpp> 24 #include <boost/type_traits/remove_reference.hpp> 25 #include <boost/log/detail/config.hpp> 26 #include <boost/log/detail/copy_cv.hpp> 27 #include <boost/log/detail/custom_terminal_spec.hpp> 28 #include <boost/log/detail/header.hpp> 29 30 #ifdef BOOST_HAS_PRAGMA_ONCE 31 #pragma once 32 #endif 33 34 namespace boost { 35 36 BOOST_LOG_OPEN_NAMESPACE 37 38 namespace expressions { 39 40 namespace aux { 41 42 /*! 43 * \brief An adapter for a unary function to be used as a terminal in a Boost.Phoenix expression 44 * 45 * This class is an adapter between Boost.Phoenix expression invocation protocol and 46 * a unary function. It forwards the call to the base function, passing only the first argument 47 * from the original call. This allows to embed value extractors in template expressions. 48 */ 49 template< typename FunT > 50 class unary_function_terminal 51 { 52 private: 53 //! Adopted function type 54 typedef FunT function_type; 55 //! Self type 56 typedef unary_function_terminal< function_type > this_type; 57 58 public: 59 //! Internal typedef for type categorization 60 typedef void _is_boost_log_terminal; 61 62 //! Function result type 63 template< typename > 64 struct result; 65 66 template< typename ThisT, typename ContextT > 67 struct result< ThisT(ContextT) > 68 { 69 typedef typename remove_cv< 70 typename remove_reference< typename phoenix::result_of::env< ContextT >::type >::type 71 >::type env_type; 72 typedef typename env_type::args_type args_type; 73 typedef typename boost::log::aux::copy_cv< ThisT, function_type >::type cv_function_type; 74 75 typedef typename boost::result_of< cv_function_type(typename fusion::result_of::at_c< args_type, 0 >::type) >::type type; 76 }; 77 78 private: 79 //! Adopted function 80 function_type m_fun; 81 82 public: 83 //! Default constructor unary_function_terminal()84 BOOST_DEFAULTED_FUNCTION(unary_function_terminal(), {}) 85 //! Copy constructor 86 unary_function_terminal(unary_function_terminal const& that) : m_fun(that.m_fun) {} 87 //! Initializing constructor 88 template< typename ArgT1 > unary_function_terminal(ArgT1 const & arg1)89 explicit unary_function_terminal(ArgT1 const& arg1) : m_fun(arg1) {} 90 //! Initializing constructor 91 template< typename ArgT1, typename ArgT2 > unary_function_terminal(ArgT1 const & arg1,ArgT2 const & arg2)92 unary_function_terminal(ArgT1 const& arg1, ArgT2 const& arg2) : m_fun(arg1, arg2) {} 93 //! Initializing constructor 94 template< typename ArgT1, typename ArgT2, typename ArgT3 > unary_function_terminal(ArgT1 const & arg1,ArgT2 const & arg2,ArgT3 const & arg3)95 unary_function_terminal(ArgT1 const& arg1, ArgT2 const& arg2, ArgT3 const& arg3) : m_fun(arg1, arg2, arg3) {} 96 97 //! The operator forwards the call to the base function 98 template< typename ContextT > 99 typename result< this_type(ContextT const&) >::type operator ()(ContextT const & ctx)100 operator() (ContextT const& ctx) 101 { 102 return m_fun(fusion::at_c< 0 >(phoenix::env(ctx).args())); 103 } 104 105 //! The operator forwards the call to the base function 106 template< typename ContextT > 107 typename result< const this_type(ContextT const&) >::type operator ()(ContextT const & ctx) const108 operator() (ContextT const& ctx) const 109 { 110 return m_fun(fusion::at_c< 0 >(phoenix::env(ctx).args())); 111 } 112 }; 113 114 } // namespace aux 115 116 } // namespace expressions 117 118 BOOST_LOG_CLOSE_NAMESPACE // namespace log 119 120 #ifndef BOOST_LOG_DOXYGEN_PASS 121 122 namespace phoenix { 123 124 namespace result_of { 125 126 template< typename FunT > 127 struct is_nullary< custom_terminal< boost::log::expressions::aux::unary_function_terminal< FunT > > > : 128 public mpl::false_ 129 { 130 }; 131 132 } // namespace result_of 133 134 } // namespace phoenix 135 136 #endif // BOOST_LOG_DOXYGEN_PASS 137 138 } // namespace boost 139 140 #include <boost/log/detail/footer.hpp> 141 142 #endif // BOOST_LOG_DETAIL_UNARY_FUNCTION_TERMINAL_HPP_INCLUDED_ 143