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 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
  65 #include <bits/concept_check.h>
  66
  67 _GLIBCXX_BEGIN_NAMESPACE(std)
  68
  69   template<typename _InputIterator>
  70     inline typename iterator_traits<_InputIterator>::difference_type
  71     __distance(_InputIterator __first, _InputIterator __last,
  72                input_iterator_tag)
  73     {
  74       // concept requirements
  75       __glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)
  76
  77       typename iterator_traits<_InputIterator>::difference_type __n = 0;
  78       while (__first != __last)
  79         {
  80           ++__first;
  81           ++__n;
  82         }
  83       return __n;
  84     }
  85
  86   template<typename _RandomAccessIterator>
  87     inline typename iterator_traits<_RandomAccessIterator>::difference_type
  88     __distance(_RandomAccessIterator __first, _RandomAccessIterator __last,
  89                random_access_iterator_tag)
  90     {
  91       // concept requirements
  92       __glibcxx_function_requires(_RandomAccessIteratorConcept<
  93                                   _RandomAccessIterator>)
  94       return __last - __first;
  95     }
  96
  97   /**
  98    *  @brief A generalization of pointer arithmetic.
  99    *  @param  first  An input iterator.
 100    *  @param  last  An input iterator.
 101    *  @return  The distance between them.
 102    *
 103    *  Returns @c n such that first + n == last.  This requires that @p last
 104    *  must be reachable from @p first.  Note that @c n may be negative.
 105    *
 106    *  For random access iterators, this uses their @c + and @c - operations
 107    *  and are constant time.  For other %iterator classes they are linear time.
 108   */
 109   template<typename _InputIterator>
 110     inline typename iterator_traits<_InputIterator>::difference_type
 111     distance(_InputIterator __first, _InputIterator __last)
 112     {
 113       // concept requirements -- taken care of in __distance
 114       return std::__distance(__first, __last,
 115                              std::__iterator_category(__first));
 116     }
 117
 118   template<typename _InputIterator, typename _Distance>
 119     inline void
 120     __advance(_InputIterator& __i, _Distance __n, input_iterator_tag)
 121     {
 122       // concept requirements
 123       __glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)
 124       while (__n--)
 125         ++__i;
 126     }
 127
 128   template<typename _BidirectionalIterator, typename _Distance>
 129     inline void
 130     __advance(_BidirectionalIterator& __i, _Distance __n,
 131               bidirectional_iterator_tag)
 132     {
 133       // concept requirements
 134       __glibcxx_function_requires(_BidirectionalIteratorConcept<
 135                                   _BidirectionalIterator>)
 136       if (__n > 0)
 137         while (__n--)
 138           ++__i;
 139       else
 140         while (__n++)
 141           --__i;
 142     }
 143
 144   template<typename _RandomAccessIterator, typename _Distance>
 145     inline void
 146     __advance(_RandomAccessIterator& __i, _Distance __n,
 147               random_access_iterator_tag)
 148     {
 149       // concept requirements
 150       __glibcxx_function_requires(_RandomAccessIteratorConcept<
 151                                   _RandomAccessIterator>)
 152       __i += __n;
 153     }
 154
 155   /**
 156    *  @brief A generalization of pointer arithmetic.
 157    *  @param  i  An input iterator.
 158    *  @param  n  The @a delta by which to change @p i.
 159    *  @return  Nothing.
 160    *
 161    *  This increments @p i by @p n.  For bidirectional and random access
 162    *  iterators, @p n may be negative, in which case @p i is decremented.
 163    *
 164    *  For random access iterators, this uses their @c + and @c - operations
 165    *  and are constant time.  For other %iterator classes they are linear time.
 166   */
 167   template<typename _InputIterator, typename _Distance>
 168     inline void
 169     advance(_InputIterator& __i, _Distance __n)
 170     {
 171       // concept requirements -- taken care of in __advance
 172       typename iterator_traits<_InputIterator>::difference_type __d = __n;
 173       std::__advance(__i, __d, std::__iterator_category(__i));
 174     }
 175
 176 _GLIBCXX_END_NAMESPACE
 177
 178 #ifdef __GXX_EXPERIMENTAL_CXX0X__
 179
 180 #include <ext/type_traits.h> // For __enable_if and __is_iterator
 181
 182 _GLIBCXX_BEGIN_NAMESPACE(std)
 183
 184   template<typename _ForwardIterator>
 185     inline typename
 186     __gnu_cxx::__enable_if<__is_iterator<_ForwardIterator>::__value,
 187                            _ForwardIterator>::__type
 188     next(_ForwardIterator __x, typename
 189          iterator_traits<_ForwardIterator>::difference_type __n = 1)
 190     {
 191       std::advance(__x, __n);
 192       return __x;
 193     }
 194
 195   template<typename _BidirectionalIterator>
 196     inline typename
 197     __gnu_cxx::__enable_if<__is_iterator<_BidirectionalIterator>::__value,
 198                            _BidirectionalIterator>::__type
 199     prev(_BidirectionalIterator __x, typename
 200          iterator_traits<_BidirectionalIterator>::difference_type __n = 1)
 201     {
 202       std::advance(__x, -__n);
 203       return __x;
 204     }
 205
 206 _GLIBCXX_END_NAMESPACE
 207
 208 #endif // __GXX_EXPERIMENTAL_CXX0X__
 209
 210 #endif /* _STL_ITERATOR_BASE_FUNCS_H */