stl_iterator_base_funcs.h

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00001 // Functions used by iterators -*- C++ -*-
00002 
00003 // Copyright (C) 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010
00004 // Free Software Foundation, Inc.
00005 //
00006 // This file is part of the GNU ISO C++ Library.  This library is free
00007 // software; you can redistribute it and/or modify it under the
00008 // terms of the GNU General Public License as published by the
00009 // Free Software Foundation; either version 3, or (at your option)
00010 // any later version.
00011 
00012 // This library is distributed in the hope that it will be useful,
00013 // but WITHOUT ANY WARRANTY; without even the implied warranty of
00014 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
00015 // GNU General Public License for more details.
00016 
00017 // Under Section 7 of GPL version 3, you are granted additional
00018 // permissions described in the GCC Runtime Library Exception, version
00019 // 3.1, as published by the Free Software Foundation.
00020 
00021 // You should have received a copy of the GNU General Public License and
00022 // a copy of the GCC Runtime Library Exception along with this program;
00023 // see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
00024 // <http://www.gnu.org/licenses/>.
00025 
00026 /*
00027  *
00028  * Copyright (c) 1994
00029  * Hewlett-Packard Company
00030  *
00031  * Permission to use, copy, modify, distribute and sell this software
00032  * and its documentation for any purpose is hereby granted without fee,
00033  * provided that the above copyright notice appear in all copies and
00034  * that both that copyright notice and this permission notice appear
00035  * in supporting documentation.  Hewlett-Packard Company makes no
00036  * representations about the suitability of this software for any
00037  * purpose.  It is provided "as is" without express or implied warranty.
00038  *
00039  *
00040  * Copyright (c) 1996-1998
00041  * Silicon Graphics Computer Systems, Inc.
00042  *
00043  * Permission to use, copy, modify, distribute and sell this software
00044  * and its documentation for any purpose is hereby granted without fee,
00045  * provided that the above copyright notice appear in all copies and
00046  * that both that copyright notice and this permission notice appear
00047  * in supporting documentation.  Silicon Graphics makes no
00048  * representations about the suitability of this software for any
00049  * purpose.  It is provided "as is" without express or implied warranty.
00050  */
00051 
00052 /** @file stl_iterator_base_funcs.h
00053  *  This is an internal header file, included by other library headers.
00054  *  You should not attempt to use it directly.
00055  *
00056  *  This file contains all of the general iterator-related utility
00057  *  functions, such as distance() and advance().
00058  */
00059 
00060 #ifndef _STL_ITERATOR_BASE_FUNCS_H
00061 #define _STL_ITERATOR_BASE_FUNCS_H 1
00062 
00063 #pragma GCC system_header
00064 
00065 #include <bits/concept_check.h>
00066 
00067 _GLIBCXX_BEGIN_NAMESPACE(std)
00068 
00069   template<typename _InputIterator>
00070     inline typename iterator_traits<_InputIterator>::difference_type
00071     __distance(_InputIterator __first, _InputIterator __last,
00072                input_iterator_tag)
00073     {
00074       // concept requirements
00075       __glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)
00076 
00077       typename iterator_traits<_InputIterator>::difference_type __n = 0;
00078       while (__first != __last)
00079     {
00080       ++__first;
00081       ++__n;
00082     }
00083       return __n;
00084     }
00085 
00086   template<typename _RandomAccessIterator>
00087     inline typename iterator_traits<_RandomAccessIterator>::difference_type
00088     __distance(_RandomAccessIterator __first, _RandomAccessIterator __last,
00089                random_access_iterator_tag)
00090     {
00091       // concept requirements
00092       __glibcxx_function_requires(_RandomAccessIteratorConcept<
00093                   _RandomAccessIterator>)
00094       return __last - __first;
00095     }
00096 
00097   /**
00098    *  @brief A generalization of pointer arithmetic.
00099    *  @param  first  An input iterator.
00100    *  @param  last  An input iterator.
00101    *  @return  The distance between them.
00102    *
00103    *  Returns @c n such that first + n == last.  This requires that @p last
00104    *  must be reachable from @p first.  Note that @c n may be negative.
00105    *
00106    *  For random access iterators, this uses their @c + and @c - operations
00107    *  and are constant time.  For other %iterator classes they are linear time.
00108   */
00109   template<typename _InputIterator>
00110     inline typename iterator_traits<_InputIterator>::difference_type
00111     distance(_InputIterator __first, _InputIterator __last)
00112     {
00113       // concept requirements -- taken care of in __distance
00114       return std::__distance(__first, __last,
00115                  std::__iterator_category(__first));
00116     }
00117 
00118   template<typename _InputIterator, typename _Distance>
00119     inline void
00120     __advance(_InputIterator& __i, _Distance __n, input_iterator_tag)
00121     {
00122       // concept requirements
00123       __glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)
00124       while (__n--)
00125     ++__i;
00126     }
00127 
00128   template<typename _BidirectionalIterator, typename _Distance>
00129     inline void
00130     __advance(_BidirectionalIterator& __i, _Distance __n,
00131           bidirectional_iterator_tag)
00132     {
00133       // concept requirements
00134       __glibcxx_function_requires(_BidirectionalIteratorConcept<
00135                   _BidirectionalIterator>)
00136       if (__n > 0)
00137         while (__n--)
00138       ++__i;
00139       else
00140         while (__n++)
00141       --__i;
00142     }
00143 
00144   template<typename _RandomAccessIterator, typename _Distance>
00145     inline void
00146     __advance(_RandomAccessIterator& __i, _Distance __n,
00147               random_access_iterator_tag)
00148     {
00149       // concept requirements
00150       __glibcxx_function_requires(_RandomAccessIteratorConcept<
00151                   _RandomAccessIterator>)
00152       __i += __n;
00153     }
00154 
00155   /**
00156    *  @brief A generalization of pointer arithmetic.
00157    *  @param  i  An input iterator.
00158    *  @param  n  The @a delta by which to change @p i.
00159    *  @return  Nothing.
00160    *
00161    *  This increments @p i by @p n.  For bidirectional and random access
00162    *  iterators, @p n may be negative, in which case @p i is decremented.
00163    *
00164    *  For random access iterators, this uses their @c + and @c - operations
00165    *  and are constant time.  For other %iterator classes they are linear time.
00166   */
00167   template<typename _InputIterator, typename _Distance>
00168     inline void
00169     advance(_InputIterator& __i, _Distance __n)
00170     {
00171       // concept requirements -- taken care of in __advance
00172       typename iterator_traits<_InputIterator>::difference_type __d = __n;
00173       std::__advance(__i, __d, std::__iterator_category(__i));
00174     }
00175 
00176 _GLIBCXX_END_NAMESPACE
00177 
00178 #ifdef __GXX_EXPERIMENTAL_CXX0X__
00179 
00180 #include <ext/type_traits.h> // For __enable_if and __is_iterator
00181 
00182 _GLIBCXX_BEGIN_NAMESPACE(std)
00183 
00184   template<typename _ForwardIterator>
00185     inline typename
00186     __gnu_cxx::__enable_if<__is_iterator<_ForwardIterator>::__value,
00187                _ForwardIterator>::__type
00188     next(_ForwardIterator __x, typename
00189      iterator_traits<_ForwardIterator>::difference_type __n = 1)
00190     {
00191       std::advance(__x, __n);
00192       return __x;
00193     }
00194 
00195   template<typename _BidirectionalIterator>
00196     inline typename
00197     __gnu_cxx::__enable_if<__is_iterator<_BidirectionalIterator>::__value,
00198                _BidirectionalIterator>::__type
00199     prev(_BidirectionalIterator __x, typename
00200      iterator_traits<_BidirectionalIterator>::difference_type __n = 1) 
00201     {
00202       std::advance(__x, -__n);
00203       return __x;
00204     }
00205 
00206 _GLIBCXX_END_NAMESPACE
00207 
00208 #endif // __GXX_EXPERIMENTAL_CXX0X__
00209 
00210 #endif /* _STL_ITERATOR_BASE_FUNCS_H */