xref: /llvm-project/libcxx/test/std/strings/basic.string/string.cons/string_view_deduction.pass.cpp (revision f75f171b2050660a76d1458bf967a748770d54cc)
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 InputIterator>
13 //   basic_string(InputIterator begin, InputIterator end,
14 //   const Allocator& a = Allocator());
15 
16 // template<class charT,
17 //          class traits,
18 //          class Allocator = allocator<charT>
19 //          >
20 // basic_string(basic_string_view<charT, traits>, const Allocator& = Allocator())
21 //   -> basic_string<charT, traits, Allocator>;
22 //
23 //  The deduction guide shall not participate in overload resolution if Allocator
24 //  is a type that does not qualify as an allocator.
25 
26 #include <string>
27 #include <string_view>
28 #include <iterator>
29 #include <memory>
30 #include <type_traits>
31 #include <cassert>
32 #include <cstddef>
33 
34 #include "test_macros.h"
35 #include "test_allocator.h"
36 #include "min_allocator.h"
37 
38 bool test() {
39   {
40     std::string_view sv = "12345678901234";
41     std::basic_string s1(sv);
42     using S = decltype(s1); // what type did we get?
43     static_assert(std::is_same_v<S::value_type,                      char>,  "");
44     static_assert(std::is_same_v<S::traits_type,    std::char_traits<char>>, "");
45     static_assert(std::is_same_v<S::allocator_type,   std::allocator<char>>, "");
46     assert(s1.size() == sv.size());
47     assert(s1.compare(0, s1.size(), sv.data(), s1.size()) == 0);
48   }
49 
50   {
51     std::string_view sv = "12345678901234";
52     std::basic_string s1{sv, std::allocator<char>{}};
53     using S = decltype(s1); // what type did we get?
54     static_assert(std::is_same_v<S::value_type,                      char>,  "");
55     static_assert(std::is_same_v<S::traits_type,    std::char_traits<char>>, "");
56     static_assert(std::is_same_v<S::allocator_type,   std::allocator<char>>, "");
57     assert(s1.size() == sv.size());
58     assert(s1.compare(0, s1.size(), sv.data(), s1.size()) == 0);
59   }
60 #ifndef TEST_HAS_NO_WIDE_CHARACTERS
61   {
62     std::wstring_view sv = L"12345678901234";
63     std::basic_string s1{sv, test_allocator<wchar_t>{}};
64     using S = decltype(s1); // what type did we get?
65     static_assert(std::is_same_v<S::value_type,                      wchar_t>,  "");
66     static_assert(std::is_same_v<S::traits_type,    std::char_traits<wchar_t>>, "");
67     static_assert(std::is_same_v<S::allocator_type,   test_allocator<wchar_t>>, "");
68     assert(s1.size() == sv.size());
69     assert(s1.compare(0, s1.size(), sv.data(), s1.size()) == 0);
70   }
71 #endif
72 #if defined(__cpp_lib_char8_t) && __cpp_lib_char8_t >= 201811L
73   {
74     std::u8string_view sv = u8"12345678901234";
75     std::basic_string s1{sv, min_allocator<char8_t>{}};
76     using S = decltype(s1); // what type did we get?
77     static_assert(std::is_same_v<S::value_type,                      char8_t>,  "");
78     static_assert(std::is_same_v<S::traits_type,    std::char_traits<char8_t>>, "");
79     static_assert(std::is_same_v<S::allocator_type,    min_allocator<char8_t>>, "");
80     assert(s1.size() == sv.size());
81     assert(s1.compare(0, s1.size(), sv.data(), s1.size()) == 0);
82   }
83 #endif
84   {
85     std::u16string_view sv = u"12345678901234";
86     std::basic_string s1{sv, min_allocator<char16_t>{}};
87     using S = decltype(s1); // what type did we get?
88     static_assert(std::is_same_v<S::value_type,                      char16_t>,  "");
89     static_assert(std::is_same_v<S::traits_type,    std::char_traits<char16_t>>, "");
90     static_assert(std::is_same_v<S::allocator_type,    min_allocator<char16_t>>, "");
91     assert(s1.size() == sv.size());
92     assert(s1.compare(0, s1.size(), sv.data(), s1.size()) == 0);
93   }
94   {
95     std::u32string_view sv = U"12345678901234";
96     std::basic_string s1{sv, explicit_allocator<char32_t>{}};
97     using S = decltype(s1); // what type did we get?
98     static_assert(std::is_same_v<S::value_type,                        char32_t>,  "");
99     static_assert(std::is_same_v<S::traits_type,      std::char_traits<char32_t>>, "");
100     static_assert(std::is_same_v<S::allocator_type, explicit_allocator<char32_t>>, "");
101     assert(s1.size() == sv.size());
102     assert(s1.compare(0, s1.size(), sv.data(), s1.size()) == 0);
103   }
104 
105   return true;
106 }
107 
108 int main(int, char**)
109 {
110   test();
111 #if TEST_STD_VER > 17
112   // static_assert(test());
113 #endif
114 
115   return 0;
116 }
117