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// <string>
10
11// const_reference operator[](size_type pos) const; // constexpr since C++20
12// reference operator[](size_type pos); // constexpr since C++20
13
14#include <string>
15#include <cassert>
16
17#include "test_macros.h"
18#include "min_allocator.h"
19
20template <class S>
21TEST_CONSTEXPR_CXX20 void test_string() {
22 S s("0123456789");
23 const S& cs = s;
24 ASSERT_SAME_TYPE(decltype(s[0]), typename S::reference);
25 ASSERT_SAME_TYPE(decltype(cs[0]), typename S::const_reference);
26 LIBCPP_ASSERT_NOEXCEPT(s[0]);
27 LIBCPP_ASSERT_NOEXCEPT(cs[0]);
28 for (typename S::size_type i = 0; i < cs.size(); ++i) {
29 assert(s[i] == static_cast<char>('0' + i));
30 assert(cs[i] == s[i]);
31 }
32 assert(cs[cs.size()] == '\0');
33 const S s2 = S();
34 assert(s2[0] == '\0');
35}
36
37// Same, but for the string that doesn't fit into SSO.
38template <class S>
39TEST_CONSTEXPR_CXX20 void test_string_long() {
40 S s("0123456789012345678901234567890123456789");
41 const S& cs = s;
42 ASSERT_SAME_TYPE(decltype(s[0]), typename S::reference);
43 ASSERT_SAME_TYPE(decltype(cs[0]), typename S::const_reference);
44 LIBCPP_ASSERT_NOEXCEPT(s[0]);
45 LIBCPP_ASSERT_NOEXCEPT(cs[0]);
46 for (typename S::size_type i = 0; i < cs.size(); ++i) {
47 assert(s[i] == static_cast<char>('0' + (i % 10)));
48 assert(cs[i] == s[i]);
49 }
50 assert(s[33] == static_cast<char>('0' + (33 % 10)));
51 assert(cs[34] == s[34]);
52 assert(cs[cs.size()] == '\0');
53 const S s2 = S();
54 assert(s2[0] == '\0');
55}
56
57TEST_CONSTEXPR_CXX20 bool test() {
58 test_string<std::string>();
59#if TEST_STD_VER >= 11
60 test_string<std::basic_string<char, std::char_traits<char>, min_allocator<char>>>();
61 test_string_long<std::basic_string<char, std::char_traits<char>, min_allocator<char>>>();
62#endif
63
64 return true;
65}
66
67int main(int, char**) {
68 test();
69#if TEST_STD_VER > 17
70 static_assert(test());
71#endif
72
73 return 0;
74}
75

source code of libcxx/test/std/strings/basic.string/string.access/index.pass.cpp