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 <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 noexcept
34};
35
36template<typename C>
37void test_container(C& c)
38{
39// Can't say noexcept here because the container might not be
40 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 be
48 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 noexcept
56 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 noexcept
64 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(x: 1);
79 std::list<int> l; l.push_back(x: 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 ( c&: v );
84 ASSERT_SAME_TYPE(SSize, decltype(std::ssize(v)));
85 test_container ( c&: l );
86 ASSERT_SAME_TYPE(SSize, decltype(std::ssize(l)));
87 test_container ( c&: a );
88 ASSERT_SAME_TYPE(SSize, decltype(std::ssize(a)));
89 test_container ( c&: il );
90 ASSERT_SAME_TYPE(SSize, decltype(std::ssize(il)));
91
92 test_const_container ( c: v );
93 test_const_container ( c: l );
94 test_const_container ( c: a );
95 test_const_container ( c: il );
96
97 std::string_view sv{"ABC"};
98 test_container ( c&: sv );
99 ASSERT_SAME_TYPE(SSize, decltype(std::ssize(sv)));
100 test_const_container ( c: 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 ( array: arrA );
106
107// From P1227R2:
108// Note that the code does not just return the std::make_signed variant of
109// the container's size() method, because it's conceivable that a container
110// might choose to represent its size as a uint16_t, supporting up to
111// 65,535 elements, and it would be a disaster for std::ssize() to turn a
112// 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(cont: sc))>, "");
118 static_assert( std::numeric_limits< decltype(std::ssize(cont: sc))>::max() > 60000, "");
119 static_assert( std::numeric_limits<std::make_signed_t<decltype(std:: size(cont: sc))>>::max() < 60000, "");
120 assert (std::ssize(sc) == 60000);
121 LIBCPP_ASSERT_NOT_NOEXCEPT(std::ssize(sc));
122
123 return 0;
124}
125

source code of libcxx/test/std/iterators/iterator.container/ssize.pass.cpp