00001 // Functor implementations -*- C++ -*- 00002 00003 // Copyright (C) 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2009, 2010 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 * You should not attempt to use it directly. 00055 */ 00056 00057 #ifndef _BACKWARD_BINDERS_H 00058 #define _BACKWARD_BINDERS_H 1 00059 00060 _GLIBCXX_BEGIN_NAMESPACE(std) 00061 00062 // 20.3.6 binders 00063 /** @defgroup binders Binder Classes 00064 * @ingroup functors 00065 * 00066 * Binders turn functions/functors with two arguments into functors 00067 * with a single argument, storing an argument to be applied later. 00068 * For example, a variable @c B of type @c binder1st is constructed 00069 * from a functor @c f and an argument @c x. Later, B's @c 00070 * operator() is called with a single argument @c y. The return 00071 * value is the value of @c f(x,y). @c B can be @a called with 00072 * various arguments (y1, y2, ...) and will in turn call @c 00073 * f(x,y1), @c f(x,y2), ... 00074 * 00075 * The function @c bind1st is provided to save some typing. It takes the 00076 * function and an argument as parameters, and returns an instance of 00077 * @c binder1st. 00078 * 00079 * The type @c binder2nd and its creator function @c bind2nd do the same 00080 * thing, but the stored argument is passed as the second parameter instead 00081 * of the first, e.g., @c bind2nd(std::minus<float>,1.3) will create a 00082 * functor whose @c operator() accepts a floating-point number, subtracts 00083 * 1.3 from it, and returns the result. (If @c bind1st had been used, 00084 * the functor would perform <em>1.3 - x</em> instead. 00085 * 00086 * Creator-wrapper functions like @c bind1st are intended to be used in 00087 * calling algorithms. Their return values will be temporary objects. 00088 * (The goal is to not require you to type names like 00089 * @c std::binder1st<std::plus<int>> for declaring a variable to hold the 00090 * return value from @c bind1st(std::plus<int>,5). 00091 * 00092 * These become more useful when combined with the composition functions. 00093 * 00094 * @{ 00095 */ 00096 /// One of the @link binders binder functors@endlink. 00097 template<typename _Operation> 00098 class binder1st 00099 : public unary_function<typename _Operation::second_argument_type, 00100 typename _Operation::result_type> 00101 { 00102 protected: 00103 _Operation op; 00104 typename _Operation::first_argument_type value; 00105 00106 public: 00107 binder1st(const _Operation& __x, 00108 const typename _Operation::first_argument_type& __y) 00109 : op(__x), value(__y) { } 00110 00111 typename _Operation::result_type 00112 operator()(const typename _Operation::second_argument_type& __x) const 00113 { return op(value, __x); } 00114 00115 // _GLIBCXX_RESOLVE_LIB_DEFECTS 00116 // 109. Missing binders for non-const sequence elements 00117 typename _Operation::result_type 00118 operator()(typename _Operation::second_argument_type& __x) const 00119 { return op(value, __x); } 00120 } _GLIBCXX_DEPRECATED_ATTR; 00121 00122 /// One of the @link binders binder functors@endlink. 00123 template<typename _Operation, typename _Tp> 00124 inline binder1st<_Operation> 00125 bind1st(const _Operation& __fn, const _Tp& __x) 00126 { 00127 typedef typename _Operation::first_argument_type _Arg1_type; 00128 return binder1st<_Operation>(__fn, _Arg1_type(__x)); 00129 } 00130 00131 /// One of the @link binders binder functors@endlink. 00132 template<typename _Operation> 00133 class binder2nd 00134 : public unary_function<typename _Operation::first_argument_type, 00135 typename _Operation::result_type> 00136 { 00137 protected: 00138 _Operation op; 00139 typename _Operation::second_argument_type value; 00140 00141 public: 00142 binder2nd(const _Operation& __x, 00143 const typename _Operation::second_argument_type& __y) 00144 : op(__x), value(__y) { } 00145 00146 typename _Operation::result_type 00147 operator()(const typename _Operation::first_argument_type& __x) const 00148 { return op(__x, value); } 00149 00150 // _GLIBCXX_RESOLVE_LIB_DEFECTS 00151 // 109. Missing binders for non-const sequence elements 00152 typename _Operation::result_type 00153 operator()(typename _Operation::first_argument_type& __x) const 00154 { return op(__x, value); } 00155 } _GLIBCXX_DEPRECATED_ATTR; 00156 00157 /// One of the @link binders binder functors@endlink. 00158 template<typename _Operation, typename _Tp> 00159 inline binder2nd<_Operation> 00160 bind2nd(const _Operation& __fn, const _Tp& __x) 00161 { 00162 typedef typename _Operation::second_argument_type _Arg2_type; 00163 return binder2nd<_Operation>(__fn, _Arg2_type(__x)); 00164 } 00165 /** @} */ 00166 00167 _GLIBCXX_END_NAMESPACE 00168 00169 #endif /* _BACKWARD_BINDERS_H */