libstdc++-v3/include/bits/stl_iterator_base_funcs.h

   1 // Functions used by iterators -*- C++ -*-
   2
   3 // Copyright (C) 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010
   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 bits/stl_iterator_base_funcs.h
  53  *  This is an internal header file, included by other library headers.
  54  *  Do not attempt to use it directly. @headername{iterator}
  55  *
  56  *  This file contains all of the general iterator-related utility
  57  *  functions, such as distance() and advance().
  58  */
  59
  60 #ifndef _STL_ITERATOR_BASE_FUNCS_H
  61 #define _STL_ITERATOR_BASE_FUNCS_H 1
  62
  63 #pragma GCC system_header
  64
  65 #include <bits/concept_check.h>
  66
  67 namespace std _GLIBCXX_VISIBILITY(default)
  68 {
  69 _GLIBCXX_BEGIN_NAMESPACE_VERSION
  70
  71   template<typename _InputIterator>
  72     inline typename iterator_traits<_InputIterator>::difference_type
  73     __distance(_InputIterator __first, _InputIterator __last,
  74                input_iterator_tag)
  75     {
  76       // concept requirements
  77       __glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)
  78
  79       typename iterator_traits<_InputIterator>::difference_type __n = 0;
  80       while (__first != __last)
  81         {
  82           ++__first;
  83           ++__n;
  84         }
  85       return __n;
  86     }
  87
  88   template<typename _RandomAccessIterator>
  89     inline typename iterator_traits<_RandomAccessIterator>::difference_type
  90     __distance(_RandomAccessIterator __first, _RandomAccessIterator __last,
  91                random_access_iterator_tag)
  92     {
  93       // concept requirements
  94       __glibcxx_function_requires(_RandomAccessIteratorConcept<
  95                                   _RandomAccessIterator>)
  96       return __last - __first;
  97     }
  98
  99   /**
 100    *  @brief A generalization of pointer arithmetic.
 101    *  @param  first  An input iterator.
 102    *  @param  last  An input iterator.
 103    *  @return  The distance between them.
 104    *
 105    *  Returns @c n such that first + n == last.  This requires that @p last
 106    *  must be reachable from @p first.  Note that @c n may be negative.
 107    *
 108    *  For random access iterators, this uses their @c + and @c - operations
 109    *  and are constant time.  For other %iterator classes they are linear time.
 110   */
 111   template<typename _InputIterator>
 112     inline typename iterator_traits<_InputIterator>::difference_type
 113     distance(_InputIterator __first, _InputIterator __last)
 114     {
 115       // concept requirements -- taken care of in __distance
 116       return std::__distance(__first, __last,
 117                              std::__iterator_category(__first));
 118     }
 119
 120   template<typename _InputIterator, typename _Distance>
 121     inline void
 122     __advance(_InputIterator& __i, _Distance __n, input_iterator_tag)
 123     {
 124       // concept requirements
 125       __glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)
 126       while (__n--)
 127         ++__i;
 128     }
 129
 130   template<typename _BidirectionalIterator, typename _Distance>
 131     inline void
 132     __advance(_BidirectionalIterator& __i, _Distance __n,
 133               bidirectional_iterator_tag)
 134     {
 135       // concept requirements
 136       __glibcxx_function_requires(_BidirectionalIteratorConcept<
 137                                   _BidirectionalIterator>)
 138       if (__n > 0)
 139         while (__n--)
 140           ++__i;
 141       else
 142         while (__n++)
 143           --__i;
 144     }
 145
 146   template<typename _RandomAccessIterator, typename _Distance>
 147     inline void
 148     __advance(_RandomAccessIterator& __i, _Distance __n,
 149               random_access_iterator_tag)
 150     {
 151       // concept requirements
 152       __glibcxx_function_requires(_RandomAccessIteratorConcept<
 153                                   _RandomAccessIterator>)
 154       __i += __n;
 155     }
 156
 157   /**
 158    *  @brief A generalization of pointer arithmetic.
 159    *  @param  i  An input iterator.
 160    *  @param  n  The @a delta by which to change @p i.
 161    *  @return  Nothing.
 162    *
 163    *  This increments @p i by @p n.  For bidirectional and random access
 164    *  iterators, @p n may be negative, in which case @p i is decremented.
 165    *
 166    *  For random access iterators, this uses their @c + and @c - operations
 167    *  and are constant time.  For other %iterator classes they are linear time.
 168   */
 169   template<typename _InputIterator, typename _Distance>
 170     inline void
 171     advance(_InputIterator& __i, _Distance __n)
 172     {
 173       // concept requirements -- taken care of in __advance
 174       typename iterator_traits<_InputIterator>::difference_type __d = __n;
 175       std::__advance(__i, __d, std::__iterator_category(__i));
 176     }
 177
 178 #ifdef __GXX_EXPERIMENTAL_CXX0X__
 179
 180   template<typename _ForwardIterator>
 181     inline _ForwardIterator
 182     next(_ForwardIterator __x, typename
 183          iterator_traits<_ForwardIterator>::difference_type __n = 1)
 184     {
 185       std::advance(__x, __n);
 186       return __x;
 187     }
 188
 189   template<typename _BidirectionalIterator>
 190     inline _BidirectionalIterator
 191     prev(_BidirectionalIterator __x, typename
 192          iterator_traits<_BidirectionalIterator>::difference_type __n = 1)
 193     {
 194       std::advance(__x, -__n);
 195       return __x;
 196     }
 197
 198 #endif // __GXX_EXPERIMENTAL_CXX0X__
 199
 200 _GLIBCXX_END_NAMESPACE_VERSION
 201 } // namespace
 202
 203 #endif /* _STL_ITERATOR_BASE_FUNCS_H */