1// Copyright (C) 2017 Michel Morin.
2//
3// Distributed under the Boost Software License, Version 1.0.
4// (See accompanying file LICENSE_1_0.txt or copy at
5// http://www.boost.org/LICENSE_1_0.txt)
6
7#ifndef BOOST_ITERATOR_ADVANCE_HPP
8#define BOOST_ITERATOR_ADVANCE_HPP
9
10#include <boost/config.hpp>
11#include <boost/detail/workaround.hpp>
12#include <boost/iterator/iterator_categories.hpp>
13
14namespace boost {
15namespace iterators {
16
17 namespace detail {
18 template <typename InputIterator, typename Distance>
19 inline BOOST_CXX14_CONSTEXPR void
20 advance_impl(
21 InputIterator& it
22 , Distance n
23 , incrementable_traversal_tag
24 )
25 {
26 while (n > 0) {
27 ++it;
28 --n;
29 }
30 }
31
32#if BOOST_WORKAROUND(BOOST_GCC_VERSION, >= 40600)
33// type-limits warning issued below when n is an unsigned integral
34#pragma GCC diagnostic push
35#pragma GCC diagnostic ignored "-Wtype-limits"
36#endif
37
38 template <typename BidirectionalIterator, typename Distance>
39 inline BOOST_CXX14_CONSTEXPR void
40 advance_impl(
41 BidirectionalIterator& it
42 , Distance n
43 , bidirectional_traversal_tag
44 )
45 {
46 if (n >= 0) {
47 while (n > 0) {
48 ++it;
49 --n;
50 }
51 }
52 else {
53 while (n < 0) {
54 --it;
55 ++n;
56 }
57 }
58 }
59
60#if BOOST_WORKAROUND(BOOST_GCC_VERSION, >= 40600)
61#pragma GCC diagnostic pop
62#endif
63
64 template <typename RandomAccessIterator, typename Distance>
65 inline BOOST_CXX14_CONSTEXPR void
66 advance_impl(
67 RandomAccessIterator& it
68 , Distance n
69 , random_access_traversal_tag
70 )
71 {
72 it += n;
73 }
74 }
75
76 namespace advance_adl_barrier {
77 template <typename InputIterator, typename Distance>
78 inline BOOST_CXX14_CONSTEXPR void
79 advance(InputIterator& it, Distance n)
80 {
81 detail::advance_impl(
82 it, n, typename iterator_traversal<InputIterator>::type()
83 );
84 }
85 }
86
87 using namespace advance_adl_barrier;
88
89} // namespace iterators
90
91using namespace iterators::advance_adl_barrier;
92
93} // namespace boost
94
95#endif
96

source code of boost/libs/iterator/include/boost/iterator/advance.hpp