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