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 // class Allocator = allocator<typename iterator_traits<InputIterator>::value_type>> 14 // basic_string(InputIterator, InputIterator, Allocator = Allocator()) 15 // -> basic_string<typename iterator_traits<InputIterator>::value_type, 16 // char_traits<typename iterator_traits<InputIterator>::value_type>, 17 // Allocator>; 18 // 19 // The deduction guide shall not participate in overload resolution if InputIterator 20 // is a type that does not qualify as an input iterator, or if Allocator is a type 21 // that does not qualify as an allocator. 22 23 #include <cassert> 24 #include <cstddef> 25 #include <iterator> 26 #include <string> 27 #include <type_traits> 28 29 #include "test_macros.h" 30 #include "test_allocator.h" 31 #include "min_allocator.h" 32 33 class NotAnIterator {}; 34 using NotAnInputIterator = std::back_insert_iterator<std::basic_string<char16_t>>; 35 36 template <typename T> 37 struct NotAnAllocator { typedef T value_type; }; 38 39 template <class Iter, class Alloc, class = void> 40 struct CanDeduce : std::false_type { }; 41 42 template <class Iter, class Alloc> 43 struct CanDeduce<Iter, Alloc, decltype((void) 44 std::basic_string{std::declval<Iter>(), std::declval<Iter>(), std::declval<Alloc>()} 45 )> : std::true_type { }; 46 47 static_assert( CanDeduce<int*, std::allocator<int>>::value); 48 static_assert(!CanDeduce<NotAnIterator, std::allocator<char>>::value); 49 static_assert(!CanDeduce<NotAnInputIterator, std::allocator<char16_t>>::value); 50 static_assert(!CanDeduce<wchar_t const*, NotAnAllocator<wchar_t>>::value); 51 52 bool test() { 53 { 54 const char* s = "12345678901234"; 55 std::basic_string s1(s, s+10); // Can't use {} here 56 using S = decltype(s1); // what type did we get? 57 static_assert(std::is_same_v<S::value_type, char>, ""); 58 static_assert(std::is_same_v<S::traits_type, std::char_traits<char>>, ""); 59 static_assert(std::is_same_v<S::allocator_type, std::allocator<char>>, ""); 60 assert(s1.size() == 10); 61 assert(s1.compare(0, s1.size(), s, s1.size()) == 0); 62 } 63 { 64 const char* s = "12345678901234"; 65 std::basic_string s1{s, s+10, std::allocator<char>{}}; 66 using S = decltype(s1); // what type did we get? 67 static_assert(std::is_same_v<S::value_type, char>, ""); 68 static_assert(std::is_same_v<S::traits_type, std::char_traits<char>>, ""); 69 static_assert(std::is_same_v<S::allocator_type, std::allocator<char>>, ""); 70 assert(s1.size() == 10); 71 assert(s1.compare(0, s1.size(), s, s1.size()) == 0); 72 } 73 { 74 const wchar_t* s = L"12345678901234"; 75 std::basic_string s1{s, s+10, test_allocator<wchar_t>{}}; 76 using S = decltype(s1); // what type did we get? 77 static_assert(std::is_same_v<S::value_type, wchar_t>, ""); 78 static_assert(std::is_same_v<S::traits_type, std::char_traits<wchar_t>>, ""); 79 static_assert(std::is_same_v<S::allocator_type, test_allocator<wchar_t>>, ""); 80 assert(s1.size() == 10); 81 assert(s1.compare(0, s1.size(), s, s1.size()) == 0); 82 } 83 { 84 const char16_t* s = u"12345678901234"; 85 std::basic_string s1{s, s+10, min_allocator<char16_t>{}}; 86 using S = decltype(s1); // what type did we get? 87 static_assert(std::is_same_v<S::value_type, char16_t>, ""); 88 static_assert(std::is_same_v<S::traits_type, std::char_traits<char16_t>>, ""); 89 static_assert(std::is_same_v<S::allocator_type, min_allocator<char16_t>>, ""); 90 assert(s1.size() == 10); 91 assert(s1.compare(0, s1.size(), s, s1.size()) == 0); 92 } 93 { 94 const char32_t* s = U"12345678901234"; 95 std::basic_string s1{s, s+10, explicit_allocator<char32_t>{}}; 96 using S = decltype(s1); // what type did we get? 97 static_assert(std::is_same_v<S::value_type, char32_t>, ""); 98 static_assert(std::is_same_v<S::traits_type, std::char_traits<char32_t>>, ""); 99 static_assert(std::is_same_v<S::allocator_type, explicit_allocator<char32_t>>, ""); 100 assert(s1.size() == 10); 101 assert(s1.compare(0, s1.size(), s, s1.size()) == 0); 102 } 103 104 return true; 105 } 106 107 int main(int, char**) 108 { 109 test(); 110 #if TEST_STD_VER > 17 111 // static_assert(test()); 112 #endif 113 114 return 0; 115 } 116