Line data Source code
1 : // Functor implementations -*- C++ -*-
2 :
3 : // Copyright (C) 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2009
4 : // Free Software Foundation, Inc.
5 : //
6 : // This file is part of the GNU ISO C++ Library. This library is free
7 : // software; you can redistribute it and/or modify it under the
8 : // terms of the GNU General Public License as published by the
9 : // Free Software Foundation; either version 3, or (at your option)
10 : // any later version.
11 :
12 : // This library is distributed in the hope that it will be useful,
13 : // but WITHOUT ANY WARRANTY; without even the implied warranty of
14 : // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 : // GNU General Public License for more details.
16 :
17 : // Under Section 7 of GPL version 3, you are granted additional
18 : // permissions described in the GCC Runtime Library Exception, version
19 : // 3.1, as published by the Free Software Foundation.
20 :
21 : // You should have received a copy of the GNU General Public License and
22 : // a copy of the GCC Runtime Library Exception along with this program;
23 : // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
24 : // <http://www.gnu.org/licenses/>.
25 :
26 : /*
27 : *
28 : * Copyright (c) 1994
29 : * Hewlett-Packard Company
30 : *
31 : * Permission to use, copy, modify, distribute and sell this software
32 : * and its documentation for any purpose is hereby granted without fee,
33 : * provided that the above copyright notice appear in all copies and
34 : * that both that copyright notice and this permission notice appear
35 : * in supporting documentation. Hewlett-Packard Company makes no
36 : * representations about the suitability of this software for any
37 : * purpose. It is provided "as is" without express or implied warranty.
38 : *
39 : *
40 : * Copyright (c) 1996-1998
41 : * Silicon Graphics Computer Systems, Inc.
42 : *
43 : * Permission to use, copy, modify, distribute and sell this software
44 : * and its documentation for any purpose is hereby granted without fee,
45 : * provided that the above copyright notice appear in all copies and
46 : * that both that copyright notice and this permission notice appear
47 : * in supporting documentation. Silicon Graphics makes no
48 : * representations about the suitability of this software for any
49 : * purpose. It is provided "as is" without express or implied warranty.
50 : */
51 :
52 : /** @file backward/binders.h
53 : * This is an internal header file, included by other library headers.
54 : * You should not attempt to use it directly.
55 : */
56 :
57 : #ifndef _BACKWARD_BINDERS_H
58 : #define _BACKWARD_BINDERS_H 1
59 :
60 : _GLIBCXX_BEGIN_NAMESPACE(std)
61 :
62 : // 20.3.6 binders
63 : /** @defgroup binders Binder Classes
64 : * @ingroup functors
65 : *
66 : * Binders turn functions/functors with two arguments into functors with
67 : * a single argument, storing an argument to be applied later. For
68 : * example, a variable @c B of type @c binder1st is constructed from a
69 : * functor @c f and an argument @c x. Later, B's @c operator() is called
70 : * with a single argument @c y. The return value is the value of @c f(x,y).
71 : * @c B can be "called" with various arguments (y1, y2, ...) and will in
72 : * turn call @c f(x,y1), @c f(x,y2), ...
73 : *
74 : * The function @c bind1st is provided to save some typing. It takes the
75 : * function and an argument as parameters, and returns an instance of
76 : * @c binder1st.
77 : *
78 : * The type @c binder2nd and its creator function @c bind2nd do the same
79 : * thing, but the stored argument is passed as the second parameter instead
80 : * of the first, e.g., @c bind2nd(std::minus<float>,1.3) will create a
81 : * functor whose @c operator() accepts a floating-point number, subtracts
82 : * 1.3 from it, and returns the result. (If @c bind1st had been used,
83 : * the functor would perform "1.3 - x" instead.
84 : *
85 : * Creator-wrapper functions like @c bind1st are intended to be used in
86 : * calling algorithms. Their return values will be temporary objects.
87 : * (The goal is to not require you to type names like
88 : * @c std::binder1st<std::plus<int>> for declaring a variable to hold the
89 : * return value from @c bind1st(std::plus<int>,5).
90 : *
91 : * These become more useful when combined with the composition functions.
92 : *
93 : * @{
94 : */
95 : /// One of the @link binders binder functors@endlink.
96 : template<typename _Operation>
97 : class binder1st
98 : : public unary_function<typename _Operation::second_argument_type,
99 : typename _Operation::result_type>
100 : {
101 : protected:
102 : _Operation op;
103 : typename _Operation::first_argument_type value;
104 :
105 : public:
106 0 : binder1st(const _Operation& __x,
107 : const typename _Operation::first_argument_type& __y)
108 0 : : op(__x), value(__y) { }
109 :
110 : typename _Operation::result_type
111 : operator()(const typename _Operation::second_argument_type& __x) const
112 : { return op(value, __x); }
113 :
114 : // _GLIBCXX_RESOLVE_LIB_DEFECTS
115 : // 109. Missing binders for non-const sequence elements
116 : typename _Operation::result_type
117 0 : operator()(typename _Operation::second_argument_type& __x) const
118 0 : { return op(value, __x); }
119 : } _GLIBCXX_DEPRECATED_ATTR;
120 :
121 : /// One of the @link binders binder functors@endlink.
122 : template<typename _Operation, typename _Tp>
123 : inline binder1st<_Operation>
124 0 : bind1st(const _Operation& __fn, const _Tp& __x)
125 : {
126 : typedef typename _Operation::first_argument_type _Arg1_type;
127 0 : return binder1st<_Operation>(__fn, _Arg1_type(__x));
128 : }
129 :
130 : /// One of the @link binders binder functors@endlink.
131 : template<typename _Operation>
132 : class binder2nd
133 : : public unary_function<typename _Operation::first_argument_type,
134 : typename _Operation::result_type>
135 : {
136 : protected:
137 : _Operation op;
138 : typename _Operation::second_argument_type value;
139 :
140 : public:
141 313696 : binder2nd(const _Operation& __x,
142 : const typename _Operation::second_argument_type& __y)
143 313696 : : op(__x), value(__y) { }
144 :
145 : typename _Operation::result_type
146 633 : operator()(const typename _Operation::first_argument_type& __x) const
147 633 : { return op(__x, value); }
148 :
149 : // _GLIBCXX_RESOLVE_LIB_DEFECTS
150 : // 109. Missing binders for non-const sequence elements
151 : typename _Operation::result_type
152 6587766 : operator()(typename _Operation::first_argument_type& __x) const
153 6587766 : { return op(__x, value); }
154 : } _GLIBCXX_DEPRECATED_ATTR;
155 :
156 : /// One of the @link binders binder functors@endlink.
157 : template<typename _Operation, typename _Tp>
158 : inline binder2nd<_Operation>
159 313696 : bind2nd(const _Operation& __fn, const _Tp& __x)
160 : {
161 : typedef typename _Operation::second_argument_type _Arg2_type;
162 313696 : return binder2nd<_Operation>(__fn, _Arg2_type(__x));
163 : }
164 : /** @} */
165 :
166 : _GLIBCXX_END_NAMESPACE
167 :
168 : #endif /* _BACKWARD_BINDERS_H */
|
