065dc485bd
This patch implements https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2021/p2443r1.html (`views::chunk_by`). Reviewed By: #libc, var-const Differential Revision: https://reviews.llvm.org/D144767
100 lines
3.2 KiB
C++
100 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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// <ranges>
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// constexpr View base() const& requires copy_constructible<View>;
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// constexpr View base() &&;
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#include <ranges>
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#include <cassert>
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#include <concepts>
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#include <utility>
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struct Range : std::ranges::view_base {
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constexpr explicit Range(int* b, int* e) : begin_(b), end_(e) {}
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constexpr Range(Range const& other) : begin_(other.begin_), end_(other.end_), wasCopyInitialized(true) {}
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constexpr Range(Range&& other) : begin_(other.begin_), end_(other.end_), wasMoveInitialized(true) {}
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Range& operator=(Range const&) = default;
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Range& operator=(Range&&) = default;
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constexpr int* begin() const { return begin_; }
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constexpr int* end() const { return end_; }
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int* begin_;
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int* end_;
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bool wasCopyInitialized = false;
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bool wasMoveInitialized = false;
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};
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static_assert(std::ranges::view<Range>);
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static_assert(std::ranges::forward_range<Range>);
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struct Pred {
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bool operator()(int, int) const;
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};
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struct NonCopyableRange : std::ranges::view_base {
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explicit NonCopyableRange(int*, int*);
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NonCopyableRange(NonCopyableRange const&) = delete;
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NonCopyableRange(NonCopyableRange&&) = default;
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NonCopyableRange& operator=(NonCopyableRange const&) = default;
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NonCopyableRange& operator=(NonCopyableRange&&) = default;
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int* begin() const;
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int* end() const;
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};
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static_assert(!std::copy_constructible<NonCopyableRange>);
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template <typename T>
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concept CanCallBaseOn = requires(T t) { std::forward<T>(t).base(); };
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constexpr bool test() {
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int buff[] = {1, 2, 3, 4};
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// Check the const& overload
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{
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Range range(buff, buff + 4);
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std::ranges::chunk_by_view<Range, Pred> const view(range, Pred{});
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std::same_as<Range> decltype(auto) result = view.base();
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assert(result.wasCopyInitialized);
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assert(result.begin() == buff);
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assert(result.end() == buff + 4);
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}
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// Check the && overload
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{
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Range range(buff, buff + 4);
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std::ranges::chunk_by_view<Range, Pred> view(range, Pred{});
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std::same_as<Range> decltype(auto) result = std::move(view).base();
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assert(result.wasMoveInitialized);
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assert(result.begin() == buff);
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assert(result.end() == buff + 4);
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}
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// Ensure the const& overload is not considered when the base is not copy-constructible
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{
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static_assert(!CanCallBaseOn<std::ranges::chunk_by_view<NonCopyableRange, Pred> const&>);
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static_assert(!CanCallBaseOn<std::ranges::chunk_by_view<NonCopyableRange, Pred>&>);
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static_assert(!CanCallBaseOn<std::ranges::chunk_by_view<NonCopyableRange, Pred> const&&>);
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static_assert(CanCallBaseOn<std::ranges::chunk_by_view<NonCopyableRange, Pred>&&>);
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static_assert(CanCallBaseOn<std::ranges::chunk_by_view<NonCopyableRange, Pred>>);
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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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