| //===----------------------------------------------------------------------===// |
| // |
| // 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 |
| // |
| //===----------------------------------------------------------------------===// |
| |
| // UNSUPPORTED: c++03, c++11, c++14, c++17, c++20 |
| |
| // constexpr auto begin() requires (!(simple-view<Views> && ...)); |
| // constexpr auto begin() const requires (range<const Views> && ...); |
| |
| #include <ranges> |
| |
| #include <cassert> |
| #include <concepts> |
| #include <tuple> |
| #include <utility> |
| |
| #include "types.h" |
| |
| template <class T> |
| concept HasConstBegin = requires(const T& ct) { ct.begin(); }; |
| |
| template <class T> |
| concept HasBegin = requires(T& t) { t.begin(); }; |
| |
| template <class T> |
| concept HasConstAndNonConstBegin = |
| HasConstBegin<T> && |
| requires(T& t, const T& ct) { requires !std::same_as<decltype(t.begin()), decltype(ct.begin())>; }; |
| |
| template <class T> |
| concept HasOnlyNonConstBegin = HasBegin<T> && ! |
| HasConstBegin<T>; |
| |
| template <class T> |
| concept HasOnlyConstBegin = HasConstBegin<T> && ! |
| HasConstAndNonConstBegin<T>; |
| |
| struct NoConstBeginView : std::ranges::view_base { |
| int* begin(); |
| int* end(); |
| }; |
| |
| constexpr bool test() { |
| int buffer[8] = {1, 2, 3, 4, 5, 6, 7, 8}; |
| { |
| // all underlying iterators should be at the begin position |
| std::ranges::zip_view v(SizedRandomAccessView{buffer}, std::views::iota(0), std::ranges::single_view(2.)); |
| std::same_as<std::tuple<int&, int, double&>> decltype(auto) val = *v.begin(); |
| assert(val == std::make_tuple(1, 0, 2.0)); |
| assert(&(std::get<0>(val)) == &buffer[0]); |
| } |
| |
| { |
| // with empty range |
| std::ranges::zip_view v(SizedRandomAccessView{buffer}, std::ranges::empty_view<int>()); |
| assert(v.begin() == v.end()); |
| } |
| |
| { |
| // underlying ranges all model simple-view |
| std::ranges::zip_view v(SimpleCommon{buffer}, SimpleCommon{buffer}); |
| static_assert(std::is_same_v<decltype(v.begin()), decltype(std::as_const(v).begin())>); |
| assert(v.begin() == std::as_const(v).begin()); |
| auto [x, y] = *std::as_const(v).begin(); |
| assert(&x == &buffer[0]); |
| assert(&y == &buffer[0]); |
| |
| using View = decltype(v); |
| static_assert(HasOnlyConstBegin<View>); |
| static_assert(!HasOnlyNonConstBegin<View>); |
| static_assert(!HasConstAndNonConstBegin<View>); |
| } |
| |
| { |
| // not all underlying ranges model simple-view |
| std::ranges::zip_view v(SimpleCommon{buffer}, NonSimpleNonCommon{buffer}); |
| static_assert(!std::is_same_v<decltype(v.begin()), decltype(std::as_const(v).begin())>); |
| assert(v.begin() == std::as_const(v).begin()); |
| auto [x, y] = *std::as_const(v).begin(); |
| assert(&x == &buffer[0]); |
| assert(&y == &buffer[0]); |
| |
| using View = decltype(v); |
| static_assert(!HasOnlyConstBegin<View>); |
| static_assert(!HasOnlyNonConstBegin<View>); |
| static_assert(HasConstAndNonConstBegin<View>); |
| } |
| |
| { |
| // underlying const R is not a range |
| using View = std::ranges::zip_view<SimpleCommon, NoConstBeginView>; |
| static_assert(!HasOnlyConstBegin<View>); |
| static_assert(HasOnlyNonConstBegin<View>); |
| static_assert(!HasConstAndNonConstBegin<View>); |
| } |
| return true; |
| } |
| |
| int main(int, char**) { |
| test(); |
| static_assert(test()); |
| |
| return 0; |
| } |