1 // (C) Copyright Steve Cleary, Beman Dawes, Howard Hinnant & John Maddock 2000. 2 // Use, modification and distribution are subject to the Boost Software License, 3 // Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at 4 // http://www.boost.org/LICENSE_1_0.txt). 5 // 6 // See http://www.boost.org/libs/utility for most recent version including documentation. 7 8 // call_traits: defines typedefs for function usage 9 // (see libs/utility/call_traits.htm) 10 11 /* Release notes: 12 23rd July 2000: 13 Fixed array specialization. (JM) 14 Added Borland specific fixes for reference types 15 (issue raised by Steve Cleary). 16 */ 17 18 #ifndef BOOST_DETAIL_CALL_TRAITS_HPP 19 #define BOOST_DETAIL_CALL_TRAITS_HPP 20 21 #ifndef BOOST_CONFIG_HPP 22 #include <boost/config.hpp> 23 #endif 24 #include <cstddef> 25 26 #include <boost/type_traits/is_arithmetic.hpp> 27 #include <boost/type_traits/is_enum.hpp> 28 #include <boost/type_traits/is_pointer.hpp> 29 #include <boost/detail/workaround.hpp> 30 31 namespace boost{ 32 33 namespace detail{ 34 35 template <typename T, bool small_> 36 struct ct_imp2 37 { 38 typedef const T& param_type; 39 }; 40 41 template <typename T> 42 struct ct_imp2<T, true> 43 { 44 typedef const T param_type; 45 }; 46 47 template <typename T, bool isp, bool b1, bool b2> 48 struct ct_imp 49 { 50 typedef const T& param_type; 51 }; 52 53 template <typename T, bool isp, bool b2> 54 struct ct_imp<T, isp, true, b2> 55 { 56 typedef typename ct_imp2<T, sizeof(T) <= sizeof(void*)>::param_type param_type; 57 }; 58 59 template <typename T, bool isp, bool b1> 60 struct ct_imp<T, isp, b1, true> 61 { 62 typedef typename ct_imp2<T, sizeof(T) <= sizeof(void*)>::param_type param_type; 63 }; 64 65 template <typename T, bool b1, bool b2> 66 struct ct_imp<T, true, b1, b2> 67 { 68 typedef const T param_type; 69 }; 70 71 } 72 73 template <typename T> 74 struct call_traits 75 { 76 public: 77 typedef T value_type; 78 typedef T& reference; 79 typedef const T& const_reference; 80 // 81 // C++ Builder workaround: we should be able to define a compile time 82 // constant and pass that as a single template parameter to ct_imp<T,bool>, 83 // however compiler bugs prevent this - instead pass three bool's to 84 // ct_imp<T,bool,bool,bool> and add an extra partial specialisation 85 // of ct_imp to handle the logic. (JM) 86 typedef typename boost::detail::ct_imp< 87 T, 88 ::boost::is_pointer<T>::value, 89 ::boost::is_arithmetic<T>::value, 90 ::boost::is_enum<T>::value 91 >::param_type param_type; 92 }; 93 94 template <typename T> 95 struct call_traits<T&> 96 { 97 typedef T& value_type; 98 typedef T& reference; 99 typedef const T& const_reference; 100 typedef T& param_type; // hh removed const 101 }; 102 103 #if BOOST_WORKAROUND( __BORLANDC__, < 0x5A0 ) 104 // these are illegal specialisations; cv-qualifies applied to 105 // references have no effect according to [8.3.2p1], 106 // C++ Builder requires them though as it treats cv-qualified 107 // references as distinct types... 108 template <typename T> 109 struct call_traits<T&const> 110 { 111 typedef T& value_type; 112 typedef T& reference; 113 typedef const T& const_reference; 114 typedef T& param_type; // hh removed const 115 }; 116 template <typename T> 117 struct call_traits<T&volatile> 118 { 119 typedef T& value_type; 120 typedef T& reference; 121 typedef const T& const_reference; 122 typedef T& param_type; // hh removed const 123 }; 124 template <typename T> 125 struct call_traits<T&const volatile> 126 { 127 typedef T& value_type; 128 typedef T& reference; 129 typedef const T& const_reference; 130 typedef T& param_type; // hh removed const 131 }; 132 133 template <typename T> 134 struct call_traits< T * > 135 { 136 typedef T * value_type; 137 typedef T * & reference; 138 typedef T * const & const_reference; 139 typedef T * const param_type; // hh removed const 140 }; 141 #endif 142 #if !defined(BOOST_NO_ARRAY_TYPE_SPECIALIZATIONS) 143 template <typename T, std::size_t N> 144 struct call_traits<T [N]> 145 { 146 private: 147 typedef T array_type[N]; 148 public: 149 // degrades array to pointer: 150 typedef const T* value_type; 151 typedef array_type& reference; 152 typedef const array_type& const_reference; 153 typedef const T* const param_type; 154 }; 155 156 template <typename T, std::size_t N> 157 struct call_traits<const T [N]> 158 { 159 private: 160 typedef const T array_type[N]; 161 public: 162 // degrades array to pointer: 163 typedef const T* value_type; 164 typedef array_type& reference; 165 typedef const array_type& const_reference; 166 typedef const T* const param_type; 167 }; 168 #endif 169 170 } 171 172 #endif // BOOST_DETAIL_CALL_TRAITS_HPP 173