1 // Functor implementations -*- C++ -*- 2 3 // Copyright (C) 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2009, 2010 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 * You should not attempt to use it directly. 55 */ 56 57 #ifndef _BACKWARD_BINDERS_H 58 #define _BACKWARD_BINDERS_H 1 59 60 _GLIBCXX_BEGIN_NAMESPACE(std) 61 62 // 20.3.6 binders 63 /** @defgroup binders Binder Classes 64 * @ingroup functors 65 * 66 * Binders turn functions/functors with two arguments into functors 67 * with a single argument, storing an argument to be applied later. 68 * For example, a variable @c B of type @c binder1st is constructed 69 * from a functor @c f and an argument @c x. Later, B's @c 70 * operator() is called with a single argument @c y. The return 71 * value is the value of @c f(x,y). @c B can be @a called with 72 * various arguments (y1, y2, ...) and will in turn call @c 73 * f(x,y1), @c f(x,y2), ... 74 * 75 * The function @c bind1st is provided to save some typing. It takes the 76 * function and an argument as parameters, and returns an instance of 77 * @c binder1st. 78 * 79 * The type @c binder2nd and its creator function @c bind2nd do the same 80 * thing, but the stored argument is passed as the second parameter instead 81 * of the first, e.g., @c bind2nd(std::minus<float>,1.3) will create a 82 * functor whose @c operator() accepts a floating-point number, subtracts 83 * 1.3 from it, and returns the result. (If @c bind1st had been used, 84 * the functor would perform <em>1.3 - x</em> instead. 85 * 86 * Creator-wrapper functions like @c bind1st are intended to be used in 87 * calling algorithms. Their return values will be temporary objects. 88 * (The goal is to not require you to type names like 89 * @c std::binder1st<std::plus<int>> for declaring a variable to hold the 90 * return value from @c bind1st(std::plus<int>,5). 91 * 92 * These become more useful when combined with the composition functions. 93 * 94 * @{ 95 */ 96 /// One of the @link binders binder functors@endlink. 97 template<typename _Operation> 98 class binder1st 99 : public unary_function<typename _Operation::second_argument_type, 100 typename _Operation::result_type> 101 { 102 protected: 103 _Operation op; 104 typename _Operation::first_argument_type value; 105 106 public: 107 binder1st(const _Operation& __x, 108 const typename _Operation::first_argument_type& __y) 109 : op(__x), value(__y) { } 110 111 typename _Operation::result_type 112 operator()(const typename _Operation::second_argument_type& __x) const 113 { return op(value, __x); } 114 115 // _GLIBCXX_RESOLVE_LIB_DEFECTS 116 // 109. Missing binders for non-const sequence elements 117 typename _Operation::result_type 118 operator()(typename _Operation::second_argument_type& __x) const 119 { return op(value, __x); } 120 } _GLIBCXX_DEPRECATED_ATTR; 121 122 /// One of the @link binders binder functors@endlink. 123 template<typename _Operation, typename _Tp> 124 inline binder1st<_Operation> 125 bind1st(const _Operation& __fn, const _Tp& __x) 126 { 127 typedef typename _Operation::first_argument_type _Arg1_type; 128 return binder1st<_Operation>(__fn, _Arg1_type(__x)); 129 } 130 131 /// One of the @link binders binder functors@endlink. 132 template<typename _Operation> 133 class binder2nd 134 : public unary_function<typename _Operation::first_argument_type, 135 typename _Operation::result_type> 136 { 137 protected: 138 _Operation op; 139 typename _Operation::second_argument_type value; 140 141 public: 142 binder2nd(const _Operation& __x, 143 const typename _Operation::second_argument_type& __y) 144 : op(__x), value(__y) { } 145 146 typename _Operation::result_type 147 operator()(const typename _Operation::first_argument_type& __x) const 148 { return op(__x, value); } 149 150 // _GLIBCXX_RESOLVE_LIB_DEFECTS 151 // 109. Missing binders for non-const sequence elements 152 typename _Operation::result_type 153 operator()(typename _Operation::first_argument_type& __x) const 154 { return op(__x, value); } 155 } _GLIBCXX_DEPRECATED_ATTR; 156 157 /// One of the @link binders binder functors@endlink. 158 template<typename _Operation, typename _Tp> 159 inline binder2nd<_Operation> 160 bind2nd(const _Operation& __fn, const _Tp& __x) 161 { 162 typedef typename _Operation::second_argument_type _Arg2_type; 163 return binder2nd<_Operation>(__fn, _Arg2_type(__x)); 164 } 165 /** @} */ 166 167 _GLIBCXX_END_NAMESPACE 168 169 #endif /* _BACKWARD_BINDERS_H */ 170