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