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