2f28e1db53
Implement `ranges::stride_view` in libc++. This PR was migrated from Phabricator (https://reviews.llvm.org/D156924). Closes #105198 Co-authored-by: Louis Dionne <ldionne.2@gmail.com> Co-authored-by: A. Jiang <de34@live.cn>
108 lines
3.2 KiB
C++
108 lines
3.2 KiB
C++
//===----------------------------------------------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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// UNSUPPORTED: c++03, c++11, c++14, c++17, c++20
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// constexpr V base() const& requires copy_constructible<V>;
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// constexpr V base() &&;
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#include <cassert>
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#include <concepts>
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#include <ranges>
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#include <utility>
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#include "test_iterators.h"
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#include "types.h"
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template <typename T>
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constexpr bool has_lvalue_qualified_base(T&& t) {
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// Thanks to forwarding references, t's type is
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// preserved from the caller. No matter the type of
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// the argument, when it is used here, t is an l value
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// (after all, it has a name). Therefore, this code
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// will test whether the l value const-ref-qualified
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// version of base is callable.
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return requires { t.base(); };
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}
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using CopyableInputView = CopyableView<cpp17_input_iterator<int*>>;
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using MoveOnlyInputView = MoveOnlyView<cpp17_input_iterator<int*>>;
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constexpr bool test() {
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int buff[] = {1, 2, 3, 4, 5, 6, 7, 8};
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constexpr int N = 8;
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// l-value ref qualified
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// const &
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{
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const std::ranges::stride_view<CopyableInputView> view(
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CopyableInputView(cpp17_input_iterator<int*>(buff), cpp17_input_iterator<int*>(buff + N)), 1);
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static_assert(has_lvalue_qualified_base(view));
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std::same_as<CopyableInputView> decltype(auto) s = view.base();
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assert(*s.begin() == *buff);
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}
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// &
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{
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std::ranges::stride_view<CopyableInputView> view(
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CopyableInputView(cpp17_input_iterator<int*>(buff), cpp17_input_iterator<int*>(buff + N)), 1);
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std::same_as<CopyableInputView> decltype(auto) s = view.base();
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assert(*s.begin() == *buff);
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static_assert(has_lvalue_qualified_base(view));
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}
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// r-value ref qualified
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// &&
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{
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std::ranges::stride_view<CopyableInputView> view(
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CopyableInputView(cpp17_input_iterator<int*>(buff), cpp17_input_iterator<int*>(buff + N)), 1);
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static_assert(has_lvalue_qualified_base(view));
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std::same_as<CopyableInputView> decltype(auto) s = std::move(view).base();
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assert(*s.begin() == *buff);
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}
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// const &&
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{
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const std::ranges::stride_view<CopyableInputView> view(
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CopyableInputView(cpp17_input_iterator<int*>(buff), cpp17_input_iterator<int*>(buff + N)), 1);
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static_assert(has_lvalue_qualified_base(view));
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std::same_as<CopyableInputView> decltype(auto) s = std::move(view).base();
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assert(*s.begin() == *buff);
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}
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// &&
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{
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std::ranges::stride_view<MoveOnlyInputView> view(
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MoveOnlyInputView(cpp17_input_iterator<int*>(buff), cpp17_input_iterator<int*>(buff + N)), 1);
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// Because the base of the stride view is move only,
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// the const & version is not applicable and, therefore,
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// there is no l-value qualified base method.
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static_assert(!has_lvalue_qualified_base(view));
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std::same_as<MoveOnlyInputView> decltype(auto) s = std::move(view).base();
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assert(*s.begin() == *buff);
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}
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return true;
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}
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int main(int, char**) {
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test();
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static_assert(test());
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return 0;
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}
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