libstdc++
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00001 // Functor implementations -*- C++ -*- 00002 00003 // Copyright (C) 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2009, 2010, 2011 00004 // Free Software Foundation, Inc. 00005 // 00006 // This file is part of the GNU ISO C++ Library. This library is free 00007 // software; you can redistribute it and/or modify it under the 00008 // terms of the GNU General Public License as published by the 00009 // Free Software Foundation; either version 3, or (at your option) 00010 // any later version. 00011 00012 // This library is distributed in the hope that it will be useful, 00013 // but WITHOUT ANY WARRANTY; without even the implied warranty of 00014 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 00015 // GNU General Public License for more details. 00016 00017 // Under Section 7 of GPL version 3, you are granted additional 00018 // permissions described in the GCC Runtime Library Exception, version 00019 // 3.1, as published by the Free Software Foundation. 00020 00021 // You should have received a copy of the GNU General Public License and 00022 // a copy of the GCC Runtime Library Exception along with this program; 00023 // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see 00024 // <http://www.gnu.org/licenses/>. 00025 00026 /* 00027 * 00028 * Copyright (c) 1994 00029 * Hewlett-Packard Company 00030 * 00031 * Permission to use, copy, modify, distribute and sell this software 00032 * and its documentation for any purpose is hereby granted without fee, 00033 * provided that the above copyright notice appear in all copies and 00034 * that both that copyright notice and this permission notice appear 00035 * in supporting documentation. Hewlett-Packard Company makes no 00036 * representations about the suitability of this software for any 00037 * purpose. It is provided "as is" without express or implied warranty. 00038 * 00039 * 00040 * Copyright (c) 1996-1998 00041 * Silicon Graphics Computer Systems, Inc. 00042 * 00043 * Permission to use, copy, modify, distribute and sell this software 00044 * and its documentation for any purpose is hereby granted without fee, 00045 * provided that the above copyright notice appear in all copies and 00046 * that both that copyright notice and this permission notice appear 00047 * in supporting documentation. Silicon Graphics makes no 00048 * representations about the suitability of this software for any 00049 * purpose. It is provided "as is" without express or implied warranty. 00050 */ 00051 00052 /** @file backward/binders.h 00053 * This is an internal header file, included by other library headers. 00054 * Do not attempt to use it directly. @headername{functional} 00055 */ 00056 00057 #ifndef _BACKWARD_BINDERS_H 00058 #define _BACKWARD_BINDERS_H 1 00059 00060 namespace std _GLIBCXX_VISIBILITY(default) 00061 { 00062 _GLIBCXX_BEGIN_NAMESPACE_VERSION 00063 00064 // 20.3.6 binders 00065 /** @defgroup binders Binder Classes 00066 * @ingroup functors 00067 * 00068 * Binders turn functions/functors with two arguments into functors 00069 * with a single argument, storing an argument to be applied later. 00070 * For example, a variable @c B of type @c binder1st is constructed 00071 * from a functor @c f and an argument @c x. Later, B's @c 00072 * operator() is called with a single argument @c y. The return 00073 * value is the value of @c f(x,y). @c B can be @a called with 00074 * various arguments (y1, y2, ...) and will in turn call @c 00075 * f(x,y1), @c f(x,y2), ... 00076 * 00077 * The function @c bind1st is provided to save some typing. It takes the 00078 * function and an argument as parameters, and returns an instance of 00079 * @c binder1st. 00080 * 00081 * The type @c binder2nd and its creator function @c bind2nd do the same 00082 * thing, but the stored argument is passed as the second parameter instead 00083 * of the first, e.g., @c bind2nd(std::minus<float>(),1.3) will create a 00084 * functor whose @c operator() accepts a floating-point number, subtracts 00085 * 1.3 from it, and returns the result. (If @c bind1st had been used, 00086 * the functor would perform <em>1.3 - x</em> instead. 00087 * 00088 * Creator-wrapper functions like @c bind1st are intended to be used in 00089 * calling algorithms. Their return values will be temporary objects. 00090 * (The goal is to not require you to type names like 00091 * @c std::binder1st<std::plus<int>> for declaring a variable to hold the 00092 * return value from @c bind1st(std::plus<int>(),5). 00093 * 00094 * These become more useful when combined with the composition functions. 00095 * 00096 * These functions are deprecated in C++11 and can be replaced by 00097 * @c std::bind (or @c std::tr1::bind) which is more powerful and flexible, 00098 * supporting functions with any number of arguments. Uses of @c bind1st 00099 * can be replaced by @c std::bind(f, x, std::placeholders::_1) and 00100 * @c bind2nd by @c std::bind(f, std::placeholders::_1, x). 00101 * @{ 00102 */ 00103 /// One of the @link binders binder functors@endlink. 00104 template<typename _Operation> 00105 class binder1st 00106 : public unary_function<typename _Operation::second_argument_type, 00107 typename _Operation::result_type> 00108 { 00109 protected: 00110 _Operation op; 00111 typename _Operation::first_argument_type value; 00112 00113 public: 00114 binder1st(const _Operation& __x, 00115 const typename _Operation::first_argument_type& __y) 00116 : op(__x), value(__y) { } 00117 00118 typename _Operation::result_type 00119 operator()(const typename _Operation::second_argument_type& __x) const 00120 { return op(value, __x); } 00121 00122 // _GLIBCXX_RESOLVE_LIB_DEFECTS 00123 // 109. Missing binders for non-const sequence elements 00124 typename _Operation::result_type 00125 operator()(typename _Operation::second_argument_type& __x) const 00126 { return op(value, __x); } 00127 } _GLIBCXX_DEPRECATED; 00128 00129 /// One of the @link binders binder functors@endlink. 00130 template<typename _Operation, typename _Tp> 00131 inline binder1st<_Operation> 00132 bind1st(const _Operation& __fn, const _Tp& __x) 00133 { 00134 typedef typename _Operation::first_argument_type _Arg1_type; 00135 return binder1st<_Operation>(__fn, _Arg1_type(__x)); 00136 } 00137 00138 /// One of the @link binders binder functors@endlink. 00139 template<typename _Operation> 00140 class binder2nd 00141 : public unary_function<typename _Operation::first_argument_type, 00142 typename _Operation::result_type> 00143 { 00144 protected: 00145 _Operation op; 00146 typename _Operation::second_argument_type value; 00147 00148 public: 00149 binder2nd(const _Operation& __x, 00150 const typename _Operation::second_argument_type& __y) 00151 : op(__x), value(__y) { } 00152 00153 typename _Operation::result_type 00154 operator()(const typename _Operation::first_argument_type& __x) const 00155 { return op(__x, value); } 00156 00157 // _GLIBCXX_RESOLVE_LIB_DEFECTS 00158 // 109. Missing binders for non-const sequence elements 00159 typename _Operation::result_type 00160 operator()(typename _Operation::first_argument_type& __x) const 00161 { return op(__x, value); } 00162 } _GLIBCXX_DEPRECATED; 00163 00164 /// One of the @link binders binder functors@endlink. 00165 template<typename _Operation, typename _Tp> 00166 inline binder2nd<_Operation> 00167 bind2nd(const _Operation& __fn, const _Tp& __x) 00168 { 00169 typedef typename _Operation::second_argument_type _Arg2_type; 00170 return binder2nd<_Operation>(__fn, _Arg2_type(__x)); 00171 } 00172 /** @} */ 00173 00174 _GLIBCXX_END_NAMESPACE_VERSION 00175 } // namespace 00176 00177 #endif /* _BACKWARD_BINDERS_H */