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// UNSUPPORTED: c++03, c++11, c++14
11
12// template<class charT,
13// class traits,
14// class Allocator = allocator<charT>
15// >
16// basic_string(basic_string_view<charT, traits>, const Allocator& = Allocator())
17// -> basic_string<charT, traits, Allocator>;
18//
19// The deduction guide shall not participate in overload resolution if Allocator
20// is a type that does not qualify as an allocator.
21
22#include <string>
23#include <string_view>
24#include <iterator>
25#include <memory>
26#include <type_traits>
27#include <cassert>
28#include <cstddef>
29
30#include "test_macros.h"
31#include "test_allocator.h"
32#include "min_allocator.h"
33
34template <class StringView, class Allocator, class = void>
35struct CanDeduce : std::false_type {};
36
37template <class StringView, class Allocator>
38struct CanDeduce<StringView,
39 Allocator,
40 decltype((void)std::basic_string{std::declval<StringView>(), std::declval<Allocator>()})>
41 : std::true_type {};
42
43struct NotAnAllocator {};
44static_assert(CanDeduce<std::string_view, std::allocator<char>>::value);
45static_assert(!CanDeduce<std::string_view, NotAnAllocator>::value);
46
47TEST_CONSTEXPR_CXX20 bool test() {
48 {
49 std::string_view sv = "12345678901234";
50 std::basic_string s1(sv);
51 using S = decltype(s1); // what type did we get?
52 static_assert(std::is_same_v<S::value_type, char>, "");
53 static_assert(std::is_same_v<S::traits_type, std::char_traits<char>>, "");
54 static_assert(std::is_same_v<S::allocator_type, std::allocator<char>>, "");
55 assert(s1.size() == sv.size());
56 assert(s1.compare(0, s1.size(), sv.data(), s1.size()) == 0);
57 }
58
59 {
60 std::string_view sv = "12345678901234";
61 std::basic_string s1{sv, std::allocator<char>{}};
62 using S = decltype(s1); // what type did we get?
63 static_assert(std::is_same_v<S::value_type, char>, "");
64 static_assert(std::is_same_v<S::traits_type, std::char_traits<char>>, "");
65 static_assert(std::is_same_v<S::allocator_type, std::allocator<char>>, "");
66 assert(s1.size() == sv.size());
67 assert(s1.compare(0, s1.size(), sv.data(), s1.size()) == 0);
68 }
69#ifndef TEST_HAS_NO_WIDE_CHARACTERS
70 {
71 std::wstring_view sv = L"12345678901234";
72 std::basic_string s1{sv, test_allocator<wchar_t>{}};
73 using S = decltype(s1); // what type did we get?
74 static_assert(std::is_same_v<S::value_type, wchar_t>, "");
75 static_assert(std::is_same_v<S::traits_type, std::char_traits<wchar_t>>, "");
76 static_assert(std::is_same_v<S::allocator_type, test_allocator<wchar_t>>, "");
77 assert(s1.size() == sv.size());
78 assert(s1.compare(0, s1.size(), sv.data(), s1.size()) == 0);
79 }
80#endif
81#ifndef TEST_HAS_NO_CHAR8_T
82 {
83 std::u8string_view sv = u8"12345678901234";
84 std::basic_string s1{sv, min_allocator<char8_t>{}};
85 using S = decltype(s1); // what type did we get?
86 static_assert(std::is_same_v<S::value_type, char8_t>, "");
87 static_assert(std::is_same_v<S::traits_type, std::char_traits<char8_t>>, "");
88 static_assert(std::is_same_v<S::allocator_type, min_allocator<char8_t>>, "");
89 assert(s1.size() == sv.size());
90 assert(s1.compare(0, s1.size(), sv.data(), s1.size()) == 0);
91 }
92#endif
93 {
94 std::u16string_view sv = u"12345678901234";
95 std::basic_string s1{sv, min_allocator<char16_t>{}};
96 using S = decltype(s1); // what type did we get?
97 static_assert(std::is_same_v<S::value_type, char16_t>, "");
98 static_assert(std::is_same_v<S::traits_type, std::char_traits<char16_t>>, "");
99 static_assert(std::is_same_v<S::allocator_type, min_allocator<char16_t>>, "");
100 assert(s1.size() == sv.size());
101 assert(s1.compare(0, s1.size(), sv.data(), s1.size()) == 0);
102 }
103 {
104 std::u32string_view sv = U"12345678901234";
105 std::basic_string s1{sv, explicit_allocator<char32_t>{}};
106 using S = decltype(s1); // what type did we get?
107 static_assert(std::is_same_v<S::value_type, char32_t>, "");
108 static_assert(std::is_same_v<S::traits_type, std::char_traits<char32_t>>, "");
109 static_assert(std::is_same_v<S::allocator_type, explicit_allocator<char32_t>>, "");
110 assert(s1.size() == sv.size());
111 assert(s1.compare(0, s1.size(), sv.data(), s1.size()) == 0);
112 }
113
114 return true;
115}
116
117int main(int, char**) {
118 test();
119#if TEST_STD_VER > 17
120 static_assert(test());
121#endif
122
123 return 0;
124}
125

source code of libcxx/test/std/strings/basic.string/string.cons/string_view_deduction.pass.cpp