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1 : // Functor implementations -*- C++ -*-
2 :
3 : // Copyright (C) 2001-2019 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 :
63 : namespace 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 : } _GLIBCXX_DEPRECATED;
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 0 : binder2nd(const _Operation& __x,
153 : const typename _Operation::second_argument_type& __y)
154 : : op(__x), value(__y) { }
155 :
156 : typename _Operation::result_type
157 0 : operator()(const typename _Operation::first_argument_type& __x) const
158 0 : { 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 0 : operator()(typename _Operation::first_argument_type& __x) const
164 0 : { return op(__x, value); }
165 : } _GLIBCXX_DEPRECATED;
166 :
167 : /// One of the @link binders binder functors@endlink.
168 : template<typename _Operation, typename _Tp>
169 : inline binder2nd<_Operation>
170 0 : bind2nd(const _Operation& __fn, const _Tp& __x)
171 : {
172 : typedef typename _Operation::second_argument_type _Arg2_type;
173 0 : 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 */
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