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// constexpr auto size()
12// requires sized_range<V>
13// constexpr auto size() const
14// requires sized_range<const V>
15
16#include <ranges>
17
18#include "test_macros.h"
19#include "types.h"
20
21template<class T>
22concept SizeInvocable = requires(std::ranges::drop_view<T> t) { t.size(); };
23
24constexpr bool test() {
25 // sized_range<V>
26 std::ranges::drop_view dropView1(MoveOnlyView(), 4);
27 assert(dropView1.size() == 4);
28
29 // sized_range<V>
30 std::ranges::drop_view dropView2(MoveOnlyView(), 0);
31 assert(dropView2.size() == 8);
32
33 // sized_range<const V>
34 const std::ranges::drop_view dropView3(MoveOnlyView(), 8);
35 assert(dropView3.size() == 0);
36
37 // sized_range<const V>
38 const std::ranges::drop_view dropView4(MoveOnlyView(), 10);
39 assert(dropView4.size() == 0);
40
41 // Because ForwardView is not a sized_range.
42 static_assert(!SizeInvocable<ForwardView>);
43
44 return true;
45}
46
47int main(int, char**) {
48 test();
49 static_assert(test());
50
51 return 0;
52}
53

source code of libcxx/test/std/ranges/range.adaptors/range.drop/size.pass.cpp