1// Functor implementations -*- C++ -*-
2
3// Copyright (C) 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2009, 2010, 2011
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 *  Do not attempt to use it directly. @headername{functional}
55 */
56
57#ifndef _BACKWARD_BINDERS_H
58#define _BACKWARD_BINDERS_H 1
59
60namespace std _GLIBCXX_VISIBILITY(default)
61{
62_GLIBCXX_BEGIN_NAMESPACE_VERSION
63
64  // 20.3.6 binders
65  /** @defgroup binders Binder Classes
66   * @ingroup functors
67   *
68   *  Binders turn functions/functors with two arguments into functors
69   *  with a single argument, storing an argument to be applied later.
70   *  For example, a variable @c B of type @c binder1st is constructed
71   *  from a functor @c f and an argument @c x. Later, B's @c
72   *  operator() is called with a single argument @c y. The return
73   *  value is the value of @c f(x,y). @c B can be @a called with
74   *  various arguments (y1, y2, ...) and will in turn call @c
75   *  f(x,y1), @c f(x,y2), ...
76   *
77   *  The function @c bind1st is provided to save some typing. It takes the
78   *  function and an argument as parameters, and returns an instance of
79   *  @c binder1st.
80   *
81   *  The type @c binder2nd and its creator function @c bind2nd do the same
82   *  thing, but the stored argument is passed as the second parameter instead
83   *  of the first, e.g., @c bind2nd(std::minus<float>(),1.3) will create a
84   *  functor whose @c operator() accepts a floating-point number, subtracts
85   *  1.3 from it, and returns the result. (If @c bind1st had been used,
86   *  the functor would perform <em>1.3 - x</em> instead.
87   *
88   *  Creator-wrapper functions like @c bind1st are intended to be used in
89   *  calling algorithms. Their return values will be temporary objects.
90   *  (The goal is to not require you to type names like
91   *  @c std::binder1st<std::plus<int>> for declaring a variable to hold the
92   *  return value from @c bind1st(std::plus<int>(),5).
93   *
94   *  These become more useful when combined with the composition functions.
95   *
96   *  These functions are deprecated in C++11 and can be replaced by
97   *  @c std::bind (or @c std::tr1::bind) which is more powerful and flexible,
98   *  supporting functions with any number of arguments.  Uses of @c bind1st
99   *  can be replaced by @c std::bind(f, x, std::placeholders::_1) and
100   *  @c bind2nd by @c std::bind(f, std::placeholders::_1, x).
101   *  @{
102   */
103  /// One of the @link binders binder functors@endlink.
104  template<typename _Operation>
105    class binder1st
106    : public unary_function<typename _Operation::second_argument_type,
107			    typename _Operation::result_type>
108    {
109    protected:
110      _Operation op;
111      typename _Operation::first_argument_type value;
112
113    public:
114      binder1st(const _Operation& __x,
115		const typename _Operation::first_argument_type& __y)
116      : op(__x), value(__y) { }
117
118      typename _Operation::result_type
119      operator()(const typename _Operation::second_argument_type& __x) const
120      { return op(value, __x); }
121
122      // _GLIBCXX_RESOLVE_LIB_DEFECTS
123      // 109.  Missing binders for non-const sequence elements
124      typename _Operation::result_type
125      operator()(typename _Operation::second_argument_type& __x) const
126      { return op(value, __x); }
127    } _GLIBCXX_DEPRECATED;
128
129  /// One of the @link binders binder functors@endlink.
130  template<typename _Operation, typename _Tp>
131    inline binder1st<_Operation>
132    bind1st(const _Operation& __fn, const _Tp& __x)
133    {
134      typedef typename _Operation::first_argument_type _Arg1_type;
135      return binder1st<_Operation>(__fn, _Arg1_type(__x));
136    }
137
138  /// One of the @link binders binder functors@endlink.
139  template<typename _Operation>
140    class binder2nd
141    : public unary_function<typename _Operation::first_argument_type,
142			    typename _Operation::result_type>
143    {
144    protected:
145      _Operation op;
146      typename _Operation::second_argument_type value;
147
148    public:
149      binder2nd(const _Operation& __x,
150		const typename _Operation::second_argument_type& __y)
151      : op(__x), value(__y) { }
152
153      typename _Operation::result_type
154      operator()(const typename _Operation::first_argument_type& __x) const
155      { return op(__x, value); }
156
157      // _GLIBCXX_RESOLVE_LIB_DEFECTS
158      // 109.  Missing binders for non-const sequence elements
159      typename _Operation::result_type
160      operator()(typename _Operation::first_argument_type& __x) const
161      { return op(__x, value); }
162    } _GLIBCXX_DEPRECATED;
163
164  /// One of the @link binders binder functors@endlink.
165  template<typename _Operation, typename _Tp>
166    inline binder2nd<_Operation>
167    bind2nd(const _Operation& __fn, const _Tp& __x)
168    {
169      typedef typename _Operation::second_argument_type _Arg2_type;
170      return binder2nd<_Operation>(__fn, _Arg2_type(__x));
171    }
172  /** @}  */
173
174_GLIBCXX_END_NAMESPACE_VERSION
175} // namespace
176
177#endif /* _BACKWARD_BINDERS_H */
178