125 lines · cpp
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-exception6//7//===----------------------------------------------------------------------===//8 9// UNSUPPORTED: c++03, c++11, c++14, c++1710 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++2014// template <class T, ptrdiff_t> constexpr ptrdiff_t ssize(const T (&array)[N]) noexcept; // C++2015 16#include <array>17#include <cassert>18#include <cstdint>19#include <initializer_list>20#include <iterator>21#include <limits>22#include <list>23#include <string_view>24#include <type_traits>25#include <vector>26 27#include "test_macros.h"28 29// Ignore warning about std::numeric_limits comparisons being tautological.30TEST_GCC_DIAGNOSTIC_IGNORED("-Wtype-limits")31 32struct short_container {33 std::uint16_t size() const { return 60000; } // not noexcept34};35 36template<typename C>37void test_container(C& c)38{39// Can't say noexcept here because the container might not be40 static_assert( std::is_signed_v<decltype(std::ssize(c))>, "");41 assert ( std::ssize(c) == static_cast<decltype(std::ssize(c))>(c.size()));42}43 44template<typename C>45void test_const_container(const C& c)46{47// Can't say noexcept here because the container might not be48 static_assert( std::is_signed_v<decltype(std::ssize(c))>, "");49 assert ( std::ssize(c) == static_cast<decltype(std::ssize(c))>(c.size()));50}51 52template<typename T>53void test_const_container(const std::initializer_list<T>& c)54{55 LIBCPP_ASSERT_NOEXCEPT(std::ssize(c)); // our std::ssize is conditionally noexcept56 static_assert( std::is_signed_v<decltype(std::ssize(c))>, "");57 assert ( std::ssize(c) == static_cast<decltype(std::ssize(c))>(c.size()));58}59 60template<typename T>61void test_container(std::initializer_list<T>& c)62{63 LIBCPP_ASSERT_NOEXCEPT(std::ssize(c)); // our std::ssize is conditionally noexcept64 static_assert( std::is_signed_v<decltype(std::ssize(c))>, "");65 assert ( std::ssize(c) == static_cast<decltype(std::ssize(c))>(c.size()));66}67 68template<typename T, std::size_t Sz>69void test_const_array(const T (&array)[Sz])70{71 ASSERT_NOEXCEPT(std::ssize(array));72 static_assert( std::is_signed_v<decltype(std::ssize(array))>, "");73 assert ( std::ssize(array) == Sz );74}75 76int main(int, char**)77{78 std::vector<int> v; v.push_back(1);79 std::list<int> l; l.push_back(2);80 std::array<int, 1> a; a[0] = 3;81 std::initializer_list<int> il = { 4 };82 using SSize = std::common_type_t<std::ptrdiff_t, std::make_signed_t<std::size_t>>;83 test_container ( v );84 ASSERT_SAME_TYPE(SSize, decltype(std::ssize(v)));85 test_container ( l );86 ASSERT_SAME_TYPE(SSize, decltype(std::ssize(l)));87 test_container ( a );88 ASSERT_SAME_TYPE(SSize, decltype(std::ssize(a)));89 test_container ( il );90 ASSERT_SAME_TYPE(SSize, decltype(std::ssize(il)));91 92 test_const_container ( v );93 test_const_container ( l );94 test_const_container ( a );95 test_const_container ( il );96 97 std::string_view sv{"ABC"};98 test_container ( sv );99 ASSERT_SAME_TYPE(SSize, decltype(std::ssize(sv)));100 test_const_container ( sv );101 102 static constexpr int arrA [] { 1, 2, 3 };103 ASSERT_SAME_TYPE(std::ptrdiff_t, decltype(std::ssize(arrA)));104 static_assert( std::is_signed_v<decltype(std::ssize(arrA))>, "");105 test_const_array ( arrA );106 107// From P1227R2:108// Note that the code does not just return the std::make_signed variant of109// the container's size() method, because it's conceivable that a container110// might choose to represent its size as a uint16_t, supporting up to111// 65,535 elements, and it would be a disaster for std::ssize() to turn a112// size of 60,000 into a size of -5,536.113 114 short_container sc;115// is the return type signed? Is it big enough to hold 60K?116// is the "signed version" of sc.size() too small?117 static_assert( std::is_signed_v< decltype(std::ssize(sc))>, "");118 static_assert( std::numeric_limits< decltype(std::ssize(sc))>::max() > 60000, "");119 static_assert( std::numeric_limits<std::make_signed_t<decltype(std:: size(sc))>>::max() < 60000, "");120 assert (std::ssize(sc) == 60000);121 LIBCPP_ASSERT_NOT_NOEXCEPT(std::ssize(sc));122 123 return 0;124}125