1// Functor implementations -*- C++ -*-
2
3// Copyright (C) 2001-2021 Free Software Foundation, Inc.
4//
5// This file is part of the GNU ISO C++ Library. This library is free
6// software; you can redistribute it and/or modify it under the
7// terms of the GNU General Public License as published by the
8// Free Software Foundation; either version 3, or (at your option)
9// any later version.
10
11// This library is distributed in the hope that it will be useful,
12// but WITHOUT ANY WARRANTY; without even the implied warranty of
13// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14// GNU General Public License for more details.
15
16// Under Section 7 of GPL version 3, you are granted additional
17// permissions described in the GCC Runtime Library Exception, version
18// 3.1, as published by the Free Software Foundation.
19
20// You should have received a copy of the GNU General Public License and
21// a copy of the GCC Runtime Library Exception along with this program;
22// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
23// <http://www.gnu.org/licenses/>.
24
25/*
26 *
27 * Copyright (c) 1994
28 * Hewlett-Packard Company
29 *
30 * Permission to use, copy, modify, distribute and sell this software
31 * and its documentation for any purpose is hereby granted without fee,
32 * provided that the above copyright notice appear in all copies and
33 * that both that copyright notice and this permission notice appear
34 * in supporting documentation. Hewlett-Packard Company makes no
35 * representations about the suitability of this software for any
36 * purpose. It is provided "as is" without express or implied warranty.
37 *
38 *
39 * Copyright (c) 1996-1998
40 * Silicon Graphics Computer Systems, Inc.
41 *
42 * Permission to use, copy, modify, distribute and sell this software
43 * and its documentation for any purpose is hereby granted without fee,
44 * provided that the above copyright notice appear in all copies and
45 * that both that copyright notice and this permission notice appear
46 * in supporting documentation. Silicon Graphics makes no
47 * representations about the suitability of this software for any
48 * purpose. It is provided "as is" without express or implied warranty.
49 */
50
51/** @file backward/binders.h
52 * This is an internal header file, included by other library headers.
53 * Do not attempt to use it directly. @headername{functional}
54 */
55
56#ifndef _BACKWARD_BINDERS_H
57#define _BACKWARD_BINDERS_H 1
58
59// Suppress deprecated warning for this file.
60#pragma GCC diagnostic push
61#pragma GCC diagnostic ignored "-Wdeprecated-declarations"
62
63namespace std _GLIBCXX_VISIBILITY(default)
64{
65_GLIBCXX_BEGIN_NAMESPACE_VERSION
66
67 // 20.3.6 binders
68 /** @defgroup binders Binder Classes
69 * @ingroup functors
70 *
71 * Binders turn functions/functors with two arguments into functors
72 * with a single argument, storing an argument to be applied later.
73 * For example, a variable @c B of type @c binder1st is constructed
74 * from a functor @c f and an argument @c x. Later, B's @c
75 * operator() is called with a single argument @c y. The return
76 * value is the value of @c f(x,y). @c B can be @a called with
77 * various arguments (y1, y2, ...) and will in turn call @c
78 * f(x,y1), @c f(x,y2), ...
79 *
80 * The function @c bind1st is provided to save some typing. It takes the
81 * function and an argument as parameters, and returns an instance of
82 * @c binder1st.
83 *
84 * The type @c binder2nd and its creator function @c bind2nd do the same
85 * thing, but the stored argument is passed as the second parameter instead
86 * of the first, e.g., @c bind2nd(std::minus<float>(),1.3) will create a
87 * functor whose @c operator() accepts a floating-point number, subtracts
88 * 1.3 from it, and returns the result. (If @c bind1st had been used,
89 * the functor would perform <em>1.3 - x</em> instead.
90 *
91 * Creator-wrapper functions like @c bind1st are intended to be used in
92 * calling algorithms. Their return values will be temporary objects.
93 * (The goal is to not require you to type names like
94 * @c std::binder1st<std::plus<int>> for declaring a variable to hold the
95 * return value from @c bind1st(std::plus<int>(),5).
96 *
97 * These become more useful when combined with the composition functions.
98 *
99 * These functions are deprecated in C++11 and can be replaced by
100 * @c std::bind (or @c std::tr1::bind) which is more powerful and flexible,
101 * supporting functions with any number of arguments. Uses of @c bind1st
102 * can be replaced by @c std::bind(f, x, std::placeholders::_1) and
103 * @c bind2nd by @c std::bind(f, std::placeholders::_1, x).
104 * @{
105 */
106 /// One of the @link binders binder functors@endlink.
107 template<typename _Operation>
108 class binder1st
109 : public unary_function<typename _Operation::second_argument_type,
110 typename _Operation::result_type>
111 {
112 protected:
113 _Operation op;
114 typename _Operation::first_argument_type value;
115
116 public:
117 binder1st(const _Operation& __x,
118 const typename _Operation::first_argument_type& __y)
119 : op(__x), value(__y) { }
120
121 typename _Operation::result_type
122 operator()(const typename _Operation::second_argument_type& __x) const
123 { return op(value, __x); }
124
125 // _GLIBCXX_RESOLVE_LIB_DEFECTS
126 // 109. Missing binders for non-const sequence elements
127 typename _Operation::result_type
128 operator()(typename _Operation::second_argument_type& __x) const
129 { return op(value, __x); }
130 } _GLIBCXX11_DEPRECATED_SUGGEST("std::bind");
131
132 /// One of the @link binders binder functors@endlink.
133 template<typename _Operation, typename _Tp>
134 inline binder1st<_Operation>
135 bind1st(const _Operation& __fn, const _Tp& __x)
136 {
137 typedef typename _Operation::first_argument_type _Arg1_type;
138 return binder1st<_Operation>(__fn, _Arg1_type(__x));
139 }
140
141 /// One of the @link binders binder functors@endlink.
142 template<typename _Operation>
143 class binder2nd
144 : public unary_function<typename _Operation::first_argument_type,
145 typename _Operation::result_type>
146 {
147 protected:
148 _Operation op;
149 typename _Operation::second_argument_type value;
150
151 public:
152 binder2nd(const _Operation& __x,
153 const typename _Operation::second_argument_type& __y)
154 : op(__x), value(__y) { }
155
156 typename _Operation::result_type
157 operator()(const typename _Operation::first_argument_type& __x) const
158 { return op(__x, value); }
159
160 // _GLIBCXX_RESOLVE_LIB_DEFECTS
161 // 109. Missing binders for non-const sequence elements
162 typename _Operation::result_type
163 operator()(typename _Operation::first_argument_type& __x) const
164 { return op(__x, value); }
165 } _GLIBCXX11_DEPRECATED_SUGGEST("std::bind");
166
167 /// One of the @link binders binder functors@endlink.
168 template<typename _Operation, typename _Tp>
169 inline binder2nd<_Operation>
170 bind2nd(const _Operation& __fn, const _Tp& __x)
171 {
172 typedef typename _Operation::second_argument_type _Arg2_type;
173 return binder2nd<_Operation>(__fn, _Arg2_type(__x));
174 }
175 /** @} */
176
177_GLIBCXX_END_NAMESPACE_VERSION
178} // namespace
179
180#pragma GCC diagnostic pop
181
182#endif /* _BACKWARD_BINDERS_H */
183