| //===----------------------------------------------------------------------===// |
| // |
| // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
| // See https://llvm.org/LICENSE.txt for license information. |
| // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
| // |
| //===----------------------------------------------------------------------===// |
| |
| // constexpr auto size() |
| // constexpr auto size() const |
| |
| // UNSUPPORTED: c++03, c++11, c++14, c++17, c++20 |
| |
| #include <cassert> |
| #include <cstddef> |
| #include <ranges> |
| |
| struct ConstSizedView : std::ranges::view_base { |
| bool* size_called; |
| int* begin() const; |
| int* end() const; |
| |
| constexpr std::size_t size() const { |
| *size_called = true; |
| return 3; |
| } |
| }; |
| |
| struct SizedView : std::ranges::view_base { |
| bool* size_called; |
| int* begin() const; |
| int* end() const; |
| |
| constexpr int size() { |
| *size_called = true; |
| return 5; |
| } |
| }; |
| |
| struct UnsizedView : std::ranges::view_base { |
| int* begin() const; |
| int* end() const; |
| }; |
| |
| template <class T> |
| concept HasSize = requires(T v) { v.size(); }; |
| |
| static_assert(HasSize<ConstSizedView>); |
| static_assert(HasSize<const ConstSizedView>); |
| static_assert(HasSize<SizedView>); |
| static_assert(!HasSize<const SizedView>); |
| static_assert(!HasSize<UnsizedView>); |
| static_assert(!HasSize<const UnsizedView>); |
| |
| constexpr bool test() { |
| { |
| bool size_called = false; |
| std::ranges::as_rvalue_view view(ConstSizedView{{}, &size_called}); |
| std::same_as<std::size_t> auto size = view.size(); |
| assert(size == 3); |
| assert(size_called); |
| } |
| |
| { |
| bool size_called = false; |
| std::ranges::as_rvalue_view view(SizedView{{}, &size_called}); |
| std::same_as<int> auto size = view.size(); |
| assert(size == 5); |
| assert(size_called); |
| } |
| |
| return true; |
| } |
| |
| int main(int, char**) { |
| test(); |
| static_assert(test()); |
| |
| return 0; |
| } |