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 10 11 // <iterator> 12 // template <class C> constexpr auto ssize(const C& c) 13 // -> common_type_t<ptrdiff_t, make_signed_t<decltype(c.size())>>; // C++20 14 // template <class T, ptrdiff_t> constexpr ptrdiff_t ssize(const T (&array)[N]) noexcept; // C++20 15 16 #include <iterator> 17 #include <cassert> 18 #include <vector> 19 #include <array> 20 #include <list> 21 #include <initializer_list> 22 #include <string_view> 23 24 #include "test_macros.h" 25 26 27 struct short_container { 28 uint16_t size() const { return 60000; } // not noexcept 29 }; 30 31 32 33 template<typename C> 34 void test_container(C& c) 35 { 36 // Can't say noexcept here because the container might not be 37 static_assert( std::is_signed_v<decltype(std::ssize(c))>, ""); 38 assert ( std::ssize(c) == static_cast<decltype(std::ssize(c))>(c.size())); 39 } 40 41 template<typename C> 42 void test_const_container(const C& c) 43 { 44 // Can't say noexcept here because the container might not be 45 static_assert( std::is_signed_v<decltype(std::ssize(c))>, ""); 46 assert ( std::ssize(c) == static_cast<decltype(std::ssize(c))>(c.size())); 47 } 48 49 template<typename T> 50 void test_const_container(const std::initializer_list<T>& c) 51 { 52 LIBCPP_ASSERT_NOEXCEPT(std::ssize(c)); // our std::ssize is conditionally noexcept 53 static_assert( std::is_signed_v<decltype(std::ssize(c))>, ""); 54 assert ( std::ssize(c) == static_cast<decltype(std::ssize(c))>(c.size())); 55 } 56 57 template<typename T> 58 void test_container(std::initializer_list<T>& c) 59 { 60 LIBCPP_ASSERT_NOEXCEPT(std::ssize(c)); // our std::ssize is conditionally noexcept 61 static_assert( std::is_signed_v<decltype(std::ssize(c))>, ""); 62 assert ( std::ssize(c) == static_cast<decltype(std::ssize(c))>(c.size())); 63 } 64 65 template<typename T, size_t Sz> 66 void test_const_array(const T (&array)[Sz]) 67 { 68 ASSERT_NOEXCEPT(std::ssize(array)); 69 static_assert( std::is_signed_v<decltype(std::ssize(array))>, ""); 70 assert ( std::ssize(array) == Sz ); 71 } 72 73 int main(int, char**) 74 { 75 std::vector<int> v; v.push_back(1); 76 std::list<int> l; l.push_back(2); 77 std::array<int, 1> a; a[0] = 3; 78 std::initializer_list<int> il = { 4 }; 79 test_container ( v ); 80 ASSERT_SAME_TYPE(ptrdiff_t, decltype(std::ssize(v))); 81 test_container ( l ); 82 ASSERT_SAME_TYPE(ptrdiff_t, decltype(std::ssize(l))); 83 test_container ( a ); 84 ASSERT_SAME_TYPE(ptrdiff_t, decltype(std::ssize(a))); 85 test_container ( il ); 86 ASSERT_SAME_TYPE(ptrdiff_t, decltype(std::ssize(il))); 87 88 test_const_container ( v ); 89 test_const_container ( l ); 90 test_const_container ( a ); 91 test_const_container ( il ); 92 93 std::string_view sv{"ABC"}; 94 test_container ( sv ); 95 ASSERT_SAME_TYPE(ptrdiff_t, decltype(std::ssize(sv))); 96 test_const_container ( sv ); 97 98 static constexpr int arrA [] { 1, 2, 3 }; 99 ASSERT_SAME_TYPE(ptrdiff_t, decltype(std::ssize(arrA))); 100 static_assert( std::is_signed_v<decltype(std::ssize(arrA))>, ""); 101 test_const_array ( arrA ); 102 103 // From P1227R2: 104 // Note that the code does not just return the std::make_signed variant of 105 // the container's size() method, because it's conceivable that a container 106 // might choose to represent its size as a uint16_t, supporting up to 107 // 65,535 elements, and it would be a disaster for std::ssize() to turn a 108 // size of 60,000 into a size of -5,536. 109 110 short_container sc; 111 // is the return type signed? Is it big enough to hold 60K? 112 // is the "signed version" of sc.size() too small? 113 static_assert( std::is_signed_v< decltype(std::ssize(sc))>, ""); 114 static_assert( std::numeric_limits< decltype(std::ssize(sc))>::max() > 60000, ""); 115 static_assert( std::numeric_limits<std::make_signed_t<decltype(std:: size(sc))>>::max() < 60000, ""); 116 assert (std::ssize(sc) == 60000); 117 LIBCPP_ASSERT_NOT_NOEXCEPT(std::ssize(sc)); 118 119 return 0; 120 } 121