1 // Functor implementations -*- C++ -*- 2 3 // Copyright (C) 2001-2013 Free Software Foundation, Inc. 4 // 5 // This file is part of the GNU ISO C++ Library. This library is free 6 // software; you can redistribute it and/or modify it under the 7 // terms of the GNU General Public License as published by the 8 // Free Software Foundation; either version 3, or (at your option) 9 // any later version. 10 11 // This library is distributed in the hope that it will be useful, 12 // but WITHOUT ANY WARRANTY; without even the implied warranty of 13 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 14 // GNU General Public License for more details. 15 16 // Under Section 7 of GPL version 3, you are granted additional 17 // permissions described in the GCC Runtime Library Exception, version 18 // 3.1, as published by the Free Software Foundation. 19 20 // You should have received a copy of the GNU General Public License and 21 // a copy of the GCC Runtime Library Exception along with this program; 22 // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see 23 // <http://www.gnu.org/licenses/>. 24 25 /* 26 * 27 * Copyright (c) 1994 28 * Hewlett-Packard Company 29 * 30 * Permission to use, copy, modify, distribute and sell this software 31 * and its documentation for any purpose is hereby granted without fee, 32 * provided that the above copyright notice appear in all copies and 33 * that both that copyright notice and this permission notice appear 34 * in supporting documentation. Hewlett-Packard Company makes no 35 * representations about the suitability of this software for any 36 * purpose. It is provided "as is" without express or implied warranty. 37 * 38 * 39 * Copyright (c) 1996-1998 40 * Silicon Graphics Computer Systems, Inc. 41 * 42 * Permission to use, copy, modify, distribute and sell this software 43 * and its documentation for any purpose is hereby granted without fee, 44 * provided that the above copyright notice appear in all copies and 45 * that both that copyright notice and this permission notice appear 46 * in supporting documentation. Silicon Graphics makes no 47 * representations about the suitability of this software for any 48 * purpose. It is provided "as is" without express or implied warranty. 49 */ 50 51 /** @file backward/binders.h 52 * This is an internal header file, included by other library headers. 53 * Do not attempt to use it directly. @headername{functional} 54 */ 55 56 #ifndef _BACKWARD_BINDERS_H 57 #define _BACKWARD_BINDERS_H 1 58 59 namespace std _GLIBCXX_VISIBILITY(default) 60 { 61 _GLIBCXX_BEGIN_NAMESPACE_VERSION 62 63 // 20.3.6 binders 64 /** @defgroup binders Binder Classes 65 * @ingroup functors 66 * 67 * Binders turn functions/functors with two arguments into functors 68 * with a single argument, storing an argument to be applied later. 69 * For example, a variable @c B of type @c binder1st is constructed 70 * from a functor @c f and an argument @c x. Later, B's @c 71 * operator() is called with a single argument @c y. The return 72 * value is the value of @c f(x,y). @c B can be @a called with 73 * various arguments (y1, y2, ...) and will in turn call @c 74 * f(x,y1), @c f(x,y2), ... 75 * 76 * The function @c bind1st is provided to save some typing. It takes the 77 * function and an argument as parameters, and returns an instance of 78 * @c binder1st. 79 * 80 * The type @c binder2nd and its creator function @c bind2nd do the same 81 * thing, but the stored argument is passed as the second parameter instead 82 * of the first, e.g., @c bind2nd(std::minus<float>(),1.3) will create a 83 * functor whose @c operator() accepts a floating-point number, subtracts 84 * 1.3 from it, and returns the result. (If @c bind1st had been used, 85 * the functor would perform <em>1.3 - x</em> instead. 86 * 87 * Creator-wrapper functions like @c bind1st are intended to be used in 88 * calling algorithms. Their return values will be temporary objects. 89 * (The goal is to not require you to type names like 90 * @c std::binder1st<std::plus<int>> for declaring a variable to hold the 91 * return value from @c bind1st(std::plus<int>(),5). 92 * 93 * These become more useful when combined with the composition functions. 94 * 95 * These functions are deprecated in C++11 and can be replaced by 96 * @c std::bind (or @c std::tr1::bind) which is more powerful and flexible, 97 * supporting functions with any number of arguments. Uses of @c bind1st 98 * can be replaced by @c std::bind(f, x, std::placeholders::_1) and 99 * @c bind2nd by @c std::bind(f, std::placeholders::_1, x). 100 * @{ 101 */ 102 /// One of the @link binders binder functors@endlink. 103 template<typename _Operation> 104 class binder1st 105 : public unary_function<typename _Operation::second_argument_type, 106 typename _Operation::result_type> 107 { 108 protected: 109 _Operation op; 110 typename _Operation::first_argument_type value; 111 112 public: 113 binder1st(const _Operation& __x, 114 const typename _Operation::first_argument_type& __y) 115 : op(__x), value(__y) { } 116 117 typename _Operation::result_type 118 operator()(const typename _Operation::second_argument_type& __x) const 119 { return op(value, __x); } 120 121 // _GLIBCXX_RESOLVE_LIB_DEFECTS 122 // 109. Missing binders for non-const sequence elements 123 typename _Operation::result_type 124 operator()(typename _Operation::second_argument_type& __x) const 125 { return op(value, __x); } 126 } _GLIBCXX_DEPRECATED; 127 128 /// One of the @link binders binder functors@endlink. 129 template<typename _Operation, typename _Tp> 130 inline binder1st<_Operation> 131 bind1st(const _Operation& __fn, const _Tp& __x) 132 { 133 typedef typename _Operation::first_argument_type _Arg1_type; 134 return binder1st<_Operation>(__fn, _Arg1_type(__x)); 135 } 136 137 /// One of the @link binders binder functors@endlink. 138 template<typename _Operation> 139 class binder2nd 140 : public unary_function<typename _Operation::first_argument_type, 141 typename _Operation::result_type> 142 { 143 protected: 144 _Operation op; 145 typename _Operation::second_argument_type value; 146 147 public: 148 binder2nd(const _Operation& __x, 149 const typename _Operation::second_argument_type& __y) 150 : op(__x), value(__y) { } 151 152 typename _Operation::result_type 153 operator()(const typename _Operation::first_argument_type& __x) const 154 { return op(__x, value); } 155 156 // _GLIBCXX_RESOLVE_LIB_DEFECTS 157 // 109. Missing binders for non-const sequence elements 158 typename _Operation::result_type 159 operator()(typename _Operation::first_argument_type& __x) const 160 { return op(__x, value); } 161 } _GLIBCXX_DEPRECATED; 162 163 /// One of the @link binders binder functors@endlink. 164 template<typename _Operation, typename _Tp> 165 inline binder2nd<_Operation> 166 bind2nd(const _Operation& __fn, const _Tp& __x) 167 { 168 typedef typename _Operation::second_argument_type _Arg2_type; 169 return binder2nd<_Operation>(__fn, _Arg2_type(__x)); 170 } 171 /** @} */ 172 173 _GLIBCXX_END_NAMESPACE_VERSION 174 } // namespace 175 176 #endif /* _BACKWARD_BINDERS_H */ 177
