1//===----------------------------------------------------------------------===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8
9// <iterator>
10
11// All of these became constexpr in C++17
12//
13// template <InputIterator Iter, class Distance>
14// constexpr void advance(Iter& i, Distance n);
15//
16// template <BidirectionalIterator Iter, class Distance>
17// constexpr void advance(Iter& i, Distance n);
18//
19// template <RandomAccessIterator Iter, class Distance>
20// constexpr void advance(Iter& i, Distance n);
21
22
23// TODO: test_iterators.h includes <ranges>, and <ranges> includes <chrono> and <atomic>.
24// Lots of implementation headers under <__chrono/> and <atomic> has signed to unsigned conversion,
25// which will trigger the -Wsign-conversion warning.
26// Once those headers are fixed, enable the -Wsign-conversion for this test by removing
27// <TODO:Remove brackets> below
28
29// Make sure we catch forced conversions to the difference_type if they happen.
30// ADDITIONAL_COMPILE_FLAGS<TODO:Remove brackets>(gcc-style-warnings): -Wsign-conversion
31
32#include <iterator>
33#include <cassert>
34#include <cstddef>
35#include <type_traits>
36
37#include "test_macros.h"
38#include "test_iterators.h"
39
40template <class Distance, class It>
41TEST_CONSTEXPR_CXX17
42void check_advance(It it, Distance n, It result)
43{
44 static_assert(std::is_same<decltype(std::advance(it, n)), void>::value, "");
45 std::advance(it, n);
46 assert(it == result);
47}
48
49TEST_CONSTEXPR_CXX17 bool tests()
50{
51 const char* s = "1234567890";
52
53 // Check with iterator_traits::difference_type
54 {
55 typedef std::iterator_traits<const char*>::difference_type Distance;
56 check_advance<Distance>(cpp17_input_iterator<const char*>(s), 10, cpp17_input_iterator<const char*>(s+10));
57 check_advance<Distance>(forward_iterator<const char*>(s), 10, forward_iterator<const char*>(s+10));
58 check_advance<Distance>(bidirectional_iterator<const char*>(s+5), 5, bidirectional_iterator<const char*>(s+10));
59 check_advance<Distance>(bidirectional_iterator<const char*>(s+5), -5, bidirectional_iterator<const char*>(s));
60 check_advance<Distance>(random_access_iterator<const char*>(s+5), 5, random_access_iterator<const char*>(s+10));
61 check_advance<Distance>(random_access_iterator<const char*>(s+5), -5, random_access_iterator<const char*>(s));
62 check_advance<Distance>(s+5, 5, s+10);
63 check_advance<Distance>(s+5, -5, s);
64 }
65
66 // Also check with other distance types
67 {
68 typedef int Distance;
69 check_advance<Distance>(cpp17_input_iterator<const char*>(s), 10, cpp17_input_iterator<const char*>(s+10));
70 check_advance<Distance>(forward_iterator<const char*>(s), 10, forward_iterator<const char*>(s+10));
71 check_advance<Distance>(bidirectional_iterator<const char*>(s), 10, bidirectional_iterator<const char*>(s+10));
72 check_advance<Distance>(random_access_iterator<const char*>(s), 10, random_access_iterator<const char*>(s+10));
73 }
74
75 // Check with unsigned distance types to catch signedness-change issues
76 {
77 typedef std::size_t Distance;
78 check_advance<Distance>(cpp17_input_iterator<const char*>(s), 10u, cpp17_input_iterator<const char*>(s+10));
79 check_advance<Distance>(forward_iterator<const char*>(s), 10u, forward_iterator<const char*>(s+10));
80 check_advance<Distance>(bidirectional_iterator<const char*>(s), 10u, bidirectional_iterator<const char*>(s+10));
81 check_advance<Distance>(random_access_iterator<const char*>(s), 10u, random_access_iterator<const char*>(s+10));
82 }
83
84 return true;
85}
86
87int main(int, char**)
88{
89 tests();
90#if TEST_STD_VER >= 17
91 static_assert(tests(), "");
92#endif
93 return 0;
94}
95

source code of libcxx/test/std/iterators/iterator.primitives/iterator.operations/advance.pass.cpp