1 // -*- C++ -*-
2 //===----------------------------------------------------------------------===//
3 //
4 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
5 // See https://llvm.org/LICENSE.txt for license information.
6 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
7 //
8 //===----------------------------------------------------------------------===//
9
10 #ifndef _LIBCPP___CXX03___ITERATOR_ADVANCE_H
11 #define _LIBCPP___CXX03___ITERATOR_ADVANCE_H
12
13 #include <__cxx03/__assert>
14 #include <__cxx03/__config>
15 #include <__cxx03/__iterator/iterator_traits.h>
16 #include <__cxx03/__type_traits/enable_if.h>
17 #include <__cxx03/__type_traits/is_integral.h>
18 #include <__cxx03/__utility/convert_to_integral.h>
19 #include <__cxx03/__utility/declval.h>
20 #include <__cxx03/__utility/move.h>
21 #include <__cxx03/__utility/unreachable.h>
22 #include <__cxx03/limits>
23
24 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
25 # pragma GCC system_header
26 #endif
27
28 _LIBCPP_PUSH_MACROS
29 #include <__cxx03/__undef_macros>
30
31 _LIBCPP_BEGIN_NAMESPACE_STD
32
33 template <class _InputIter>
34 _LIBCPP_HIDE_FROM_ABI void
__advance(_InputIter & __i,typename iterator_traits<_InputIter>::difference_type __n,input_iterator_tag)35 __advance(_InputIter& __i, typename iterator_traits<_InputIter>::difference_type __n, input_iterator_tag) {
36 for (; __n > 0; --__n)
37 ++__i;
38 }
39
40 template <class _BiDirIter>
41 _LIBCPP_HIDE_FROM_ABI void
__advance(_BiDirIter & __i,typename iterator_traits<_BiDirIter>::difference_type __n,bidirectional_iterator_tag)42 __advance(_BiDirIter& __i, typename iterator_traits<_BiDirIter>::difference_type __n, bidirectional_iterator_tag) {
43 if (__n >= 0)
44 for (; __n > 0; --__n)
45 ++__i;
46 else
47 for (; __n < 0; ++__n)
48 --__i;
49 }
50
51 template <class _RandIter>
52 _LIBCPP_HIDE_FROM_ABI void
__advance(_RandIter & __i,typename iterator_traits<_RandIter>::difference_type __n,random_access_iterator_tag)53 __advance(_RandIter& __i, typename iterator_traits<_RandIter>::difference_type __n, random_access_iterator_tag) {
54 __i += __n;
55 }
56
57 template < class _InputIter,
58 class _Distance,
59 class _IntegralDistance = decltype(std::__convert_to_integral(std::declval<_Distance>())),
60 __enable_if_t<is_integral<_IntegralDistance>::value, int> = 0>
advance(_InputIter & __i,_Distance __orig_n)61 _LIBCPP_HIDE_FROM_ABI void advance(_InputIter& __i, _Distance __orig_n) {
62 typedef typename iterator_traits<_InputIter>::difference_type _Difference;
63 _Difference __n = static_cast<_Difference>(std::__convert_to_integral(__orig_n));
64 // Calling `advance` with a negative value on a non-bidirectional iterator is a no-op in the current implementation.
65 _LIBCPP_ASSERT_PEDANTIC(__n >= 0 || __has_bidirectional_iterator_category<_InputIter>::value,
66 "Attempt to advance(it, n) with negative n on a non-bidirectional iterator");
67 std::__advance(__i, __n, typename iterator_traits<_InputIter>::iterator_category());
68 }
69
70 _LIBCPP_END_NAMESPACE_STD
71
72 _LIBCPP_POP_MACROS
73
74 #endif // _LIBCPP___CXX03___ITERATOR_ADVANCE_H
75