1 // Functor implementations -*- C++ -*- 2 3 // Copyright (C) 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2009, 2010, 2011 4 // Free Software Foundation, Inc. 5 // 6 // This file is part of the GNU ISO C++ Library. This library is free 7 // software; you can redistribute it and/or modify it under the 8 // terms of the GNU General Public License as published by the 9 // Free Software Foundation; either version 3, or (at your option) 10 // any later version. 11 12 // This library is distributed in the hope that it will be useful, 13 // but WITHOUT ANY WARRANTY; without even the implied warranty of 14 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 15 // GNU General Public License for more details. 16 17 // Under Section 7 of GPL version 3, you are granted additional 18 // permissions described in the GCC Runtime Library Exception, version 19 // 3.1, as published by the Free Software Foundation. 20 21 // You should have received a copy of the GNU General Public License and 22 // a copy of the GCC Runtime Library Exception along with this program; 23 // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see 24 // <http://www.gnu.org/licenses/>. 25 26 /* 27 * 28 * Copyright (c) 1994 29 * Hewlett-Packard Company 30 * 31 * Permission to use, copy, modify, distribute and sell this software 32 * and its documentation for any purpose is hereby granted without fee, 33 * provided that the above copyright notice appear in all copies and 34 * that both that copyright notice and this permission notice appear 35 * in supporting documentation. Hewlett-Packard Company makes no 36 * representations about the suitability of this software for any 37 * purpose. It is provided "as is" without express or implied warranty. 38 * 39 * 40 * Copyright (c) 1996-1998 41 * Silicon Graphics Computer Systems, Inc. 42 * 43 * Permission to use, copy, modify, distribute and sell this software 44 * and its documentation for any purpose is hereby granted without fee, 45 * provided that the above copyright notice appear in all copies and 46 * that both that copyright notice and this permission notice appear 47 * in supporting documentation. Silicon Graphics makes no 48 * representations about the suitability of this software for any 49 * purpose. It is provided "as is" without express or implied warranty. 50 */ 51 52 /** @file backward/binders.h 53 * This is an internal header file, included by other library headers. 54 * Do not attempt to use it directly. @headername{functional} 55 */ 56 57 #ifndef _BACKWARD_BINDERS_H 58 #define _BACKWARD_BINDERS_H 1 59 60 namespace std _GLIBCXX_VISIBILITY(default) 61 { 62 _GLIBCXX_BEGIN_NAMESPACE_VERSION 63 64 // 20.3.6 binders 65 /** @defgroup binders Binder Classes 66 * @ingroup functors 67 * 68 * Binders turn functions/functors with two arguments into functors 69 * with a single argument, storing an argument to be applied later. 70 * For example, a variable @c B of type @c binder1st is constructed 71 * from a functor @c f and an argument @c x. Later, B's @c 72 * operator() is called with a single argument @c y. The return 73 * value is the value of @c f(x,y). @c B can be @a called with 74 * various arguments (y1, y2, ...) and will in turn call @c 75 * f(x,y1), @c f(x,y2), ... 76 * 77 * The function @c bind1st is provided to save some typing. It takes the 78 * function and an argument as parameters, and returns an instance of 79 * @c binder1st. 80 * 81 * The type @c binder2nd and its creator function @c bind2nd do the same 82 * thing, but the stored argument is passed as the second parameter instead 83 * of the first, e.g., @c bind2nd(std::minus<float>(),1.3) will create a 84 * functor whose @c operator() accepts a floating-point number, subtracts 85 * 1.3 from it, and returns the result. (If @c bind1st had been used, 86 * the functor would perform <em>1.3 - x</em> instead. 87 * 88 * Creator-wrapper functions like @c bind1st are intended to be used in 89 * calling algorithms. Their return values will be temporary objects. 90 * (The goal is to not require you to type names like 91 * @c std::binder1st<std::plus<int>> for declaring a variable to hold the 92 * return value from @c bind1st(std::plus<int>(),5). 93 * 94 * These become more useful when combined with the composition functions. 95 * 96 * These functions are deprecated in C++11 and can be replaced by 97 * @c std::bind (or @c std::tr1::bind) which is more powerful and flexible, 98 * supporting functions with any number of arguments. Uses of @c bind1st 99 * can be replaced by @c std::bind(f, x, std::placeholders::_1) and 100 * @c bind2nd by @c std::bind(f, std::placeholders::_1, x). 101 * @{ 102 */ 103 /// One of the @link binders binder functors@endlink. 104 template<typename _Operation> 105 class binder1st 106 : public unary_function<typename _Operation::second_argument_type, 107 typename _Operation::result_type> 108 { 109 protected: 110 _Operation op; 111 typename _Operation::first_argument_type value; 112 113 public: 114 binder1st(const _Operation& __x, 115 const typename _Operation::first_argument_type& __y) 116 : op(__x), value(__y) { } 117 118 typename _Operation::result_type 119 operator()(const typename _Operation::second_argument_type& __x) const 120 { return op(value, __x); } 121 122 // _GLIBCXX_RESOLVE_LIB_DEFECTS 123 // 109. Missing binders for non-const sequence elements 124 typename _Operation::result_type 125 operator()(typename _Operation::second_argument_type& __x) const 126 { return op(value, __x); } 127 } _GLIBCXX_DEPRECATED; 128 129 /// One of the @link binders binder functors@endlink. 130 template<typename _Operation, typename _Tp> 131 inline binder1st<_Operation> 132 bind1st(const _Operation& __fn, const _Tp& __x) 133 { 134 typedef typename _Operation::first_argument_type _Arg1_type; 135 return binder1st<_Operation>(__fn, _Arg1_type(__x)); 136 } 137 138 /// One of the @link binders binder functors@endlink. 139 template<typename _Operation> 140 class binder2nd 141 : public unary_function<typename _Operation::first_argument_type, 142 typename _Operation::result_type> 143 { 144 protected: 145 _Operation op; 146 typename _Operation::second_argument_type value; 147 148 public: 149 binder2nd(const _Operation& __x, 150 const typename _Operation::second_argument_type& __y) 151 : op(__x), value(__y) { } 152 153 typename _Operation::result_type 154 operator()(const typename _Operation::first_argument_type& __x) const 155 { return op(__x, value); } 156 157 // _GLIBCXX_RESOLVE_LIB_DEFECTS 158 // 109. Missing binders for non-const sequence elements 159 typename _Operation::result_type 160 operator()(typename _Operation::first_argument_type& __x) const 161 { return op(__x, value); } 162 } _GLIBCXX_DEPRECATED; 163 164 /// One of the @link binders binder functors@endlink. 165 template<typename _Operation, typename _Tp> 166 inline binder2nd<_Operation> 167 bind2nd(const _Operation& __fn, const _Tp& __x) 168 { 169 typedef typename _Operation::second_argument_type _Arg2_type; 170 return binder2nd<_Operation>(__fn, _Arg2_type(__x)); 171 } 172 /** @} */ 173 174 _GLIBCXX_END_NAMESPACE_VERSION 175 } // namespace 176 177 #endif /* _BACKWARD_BINDERS_H */ 178
