libstdc++-v3/include/backward/binders.h

   1 // Functor implementations -*- C++ -*-
   2
   3 // Copyright (C) 2001-2018 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       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     } _GLIBCXX_DEPRECATED;
 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 */