stl_iterator_base_funcs.h revision 97403 
1// Functions used by iterators -*- C++ -*-
2
3// Copyright (C) 2001, 2002 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 2, 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// You should have received a copy of the GNU General Public License along
17// with this library; see the file COPYING.  If not, write to the Free
18// Software Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307,
19// USA.
20
21// As a special exception, you may use this file as part of a free software
22// library without restriction.  Specifically, if other files instantiate
23// templates or use macros or inline functions from this file, or you compile
24// this file and link it with other files to produce an executable, this
25// file does not by itself cause the resulting executable to be covered by
26// the GNU General Public License.  This exception does not however
27// invalidate any other reasons why the executable file might be covered by
28// the GNU General Public License.
29
30/*
31 *
32 * Copyright (c) 1994
33 * Hewlett-Packard Company
34 *
35 * Permission to use, copy, modify, distribute and sell this software
36 * and its documentation for any purpose is hereby granted without fee,
37 * provided that the above copyright notice appear in all copies and
38 * that both that copyright notice and this permission notice appear
39 * in supporting documentation.  Hewlett-Packard Company makes no
40 * representations about the suitability of this software for any
41 * purpose.  It is provided "as is" without express or implied warranty.
42 *
43 *
44 * Copyright (c) 1996-1998
45 * Silicon Graphics Computer Systems, Inc.
46 *
47 * Permission to use, copy, modify, distribute and sell this software
48 * and its documentation for any purpose is hereby granted without fee,
49 * provided that the above copyright notice appear in all copies and
50 * that both that copyright notice and this permission notice appear
51 * in supporting documentation.  Silicon Graphics makes no
52 * representations about the suitability of this software for any
53 * purpose.  It is provided "as is" without express or implied warranty.
54 */
55
56/** @file stl_iterator_base_funcs.h
57 *  This is an internal header file, included by other library headers.
58 *  You should not attempt to use it directly.
59 *
60 *  This file contains all of the general iterator-related utility
61 *  functions, such as distance() and advance().
62 */
63
64#ifndef __GLIBCPP_INTERNAL_ITERATOR_BASE_FUNCS_H
65#define __GLIBCPP_INTERNAL_ITERATOR_BASE_FUNCS_H
66
67#pragma GCC system_header
68#include <bits/concept_check.h>
69
70// Since this entire file is within namespace std, there's no reason to
71// waste two spaces along the left column.  Thus the leading indentation is
72// slightly violated from here on.
73namespace std
74{
75template<typename _InputIterator>
76  inline typename iterator_traits<_InputIterator>::difference_type
77  __distance(_InputIterator __first, _InputIterator __last, input_iterator_tag)
78  {
79    // concept requirements
80    __glibcpp_function_requires(_InputIteratorConcept<_InputIterator>)
81
82    typename iterator_traits<_InputIterator>::difference_type __n = 0;
83    while (__first != __last) {
84      ++__first; ++__n;
85    }
86    return __n;
87  }
88
89template<typename _RandomAccessIterator>
90  inline typename iterator_traits<_RandomAccessIterator>::difference_type
91  __distance(_RandomAccessIterator __first, _RandomAccessIterator __last,
92             random_access_iterator_tag)
93  {
94    // concept requirements
95    __glibcpp_function_requires(_RandomAccessIteratorConcept<_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*/
111template<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 __distance(__first, __last, __iterator_category(__first));
117  }
118
119template<typename _InputIter, typename _Distance>
120  inline void
121  __advance(_InputIter& __i, _Distance __n, input_iterator_tag)
122  {
123    // concept requirements
124    __glibcpp_function_requires(_InputIteratorConcept<_InputIter>)
125    while (__n--) ++__i;
126  }
127
128template<typename _BidirectionalIterator, typename _Distance>
129  inline void
130  __advance(_BidirectionalIterator& __i, _Distance __n,
131            bidirectional_iterator_tag)
132  {
133    // concept requirements
134    __glibcpp_function_requires(_BidirectionalIteratorConcept<_BidirectionalIterator>)
135
136    if (__n > 0)
137      while (__n--) ++__i;
138    else
139      while (__n++) --__i;
140  }
141
142template<typename _RandomAccessIterator, typename _Distance>
143  inline void
144  __advance(_RandomAccessIterator& __i, _Distance __n,
145            random_access_iterator_tag)
146  {
147    // concept requirements
148    __glibcpp_function_requires(_RandomAccessIteratorConcept<_RandomAccessIterator>)
149    __i += __n;
150  }
151
152/**
153 *  @brief A generalization of pointer arithmetic.
154 *  @param  i  An input iterator.
155 *  @param  n  The "delta" by which to change @p i.
156 *  @return  Nothing.
157 *
158 *  This increments @p i by @p n.  For bidirectional and random access
159 *  iterators, @p n may be negative, in which case @p i is decremented.
160 *
161 *  For random access iterators, this uses their @c + and @c - operations
162 *  and are constant time.  For other %iterator classes they are linear time.
163*/
164template<typename _InputIterator, typename _Distance>
165  inline void
166  advance(_InputIterator& __i, _Distance __n)
167  {
168    // concept requirements -- taken care of in __advance
169    __advance(__i, __n, __iterator_category(__i));
170  }
171
172} // namespace std
173
174#endif /* __GLIBCPP_INTERNAL_ITERATOR_BASE_FUNCS_H */
175
176
177// Local Variables:
178// mode:C++
179// End:
180