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 // UNSUPPORTED: c++03, c++11, c++14, c++17, c++20
10
11 // <string>
12
13 // template<class Operation>
14 // void resize_and_overwrite(size_type n, Operation op)
15
16 #include <algorithm>
17 #include <cassert>
18 #include <string>
19
20 #include "make_string.h"
21 #include "test_macros.h"
22
23 template <class S>
test_appending(size_t k,size_t N,size_t new_capacity)24 constexpr void test_appending(size_t k, size_t N, size_t new_capacity) {
25 assert(N > k);
26 assert(new_capacity >= N);
27 auto s = S(k, 'a');
28 s.resize_and_overwrite(new_capacity, [&](auto* p, auto n) {
29 assert(n == new_capacity);
30 LIBCPP_ASSERT(s.size() == new_capacity);
31 LIBCPP_ASSERT(s.begin().base() == p);
32 assert(std::all_of(p, p + k, [](const auto ch) { return ch == 'a'; }));
33 std::fill(p + k, p + n, 'b');
34 p[n] = 'c'; // will be overwritten
35 return N;
36 });
37 const S expected = S(k, 'a') + S(N - k, 'b');
38 assert(s == expected);
39 assert(s.c_str()[N] == '\0');
40 }
41
42 template <class S>
test_truncating(size_t o,size_t N)43 constexpr void test_truncating(size_t o, size_t N) {
44 assert(N < o);
45 auto s = S(o, 'a');
46 s.resize_and_overwrite(N, [&](auto* p, auto n) {
47 assert(n == N);
48 LIBCPP_ASSERT(s.size() == n);
49 LIBCPP_ASSERT(s.begin().base() == p);
50 assert(std::all_of(p, p + n, [](auto ch) { return ch == 'a'; }));
51 p[n - 1] = 'b';
52 p[n] = 'c'; // will be overwritten
53 return n;
54 });
55 const S expected = S(N - 1, 'a') + S(1, 'b');
56 assert(s == expected);
57 assert(s.c_str()[N] == '\0');
58 }
59
60 template <class CharT>
test()61 constexpr bool test() {
62 using S = std::basic_string<CharT>;
63 test_appending<S>(10, 15, 15);
64 test_appending<S>(10, 15, 20);
65 test_appending<S>(10, 40, 40);
66 test_appending<S>(10, 40, 50);
67 test_appending<S>(30, 35, 35);
68 test_appending<S>(30, 35, 45);
69 test_appending<S>(10, 15, 30);
70 test_truncating<S>(15, 10);
71 test_truncating<S>(40, 35);
72 test_truncating<S>(40, 10);
73
74 return true;
75 }
76
test_value_categories()77 void test_value_categories() {
78 std::string s;
79 s.resize_and_overwrite(10, [](char*&&, size_t&&) { return 0; });
80 s.resize_and_overwrite(10, [](char* const&, const size_t&) { return 0; });
81 struct RefQualified {
82 int operator()(char*, size_t) && { return 0; }
83 };
84 s.resize_and_overwrite(10, RefQualified{});
85 }
86
main(int,char **)87 int main(int, char**) {
88 test<char>();
89 test<char8_t>();
90 test<char16_t>();
91 test<char32_t>();
92
93 static_assert(test<char>());
94 static_assert(test<char8_t>());
95 static_assert(test<char16_t>());
96 static_assert(test<char32_t>());
97
98 #ifndef TEST_HAS_NO_WIDE_CHARACTERS
99 test<wchar_t>();
100 static_assert(test<wchar_t>());
101 #endif
102 return 0;
103 }
104