| //===----------------------------------------------------------------------===// |
| // |
| // 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 |
| |
| // friend constexpr void iter_swap(const inner-iterator& x, const inner-iterator& y) |
| // noexcept(noexcept(ranges::iter_swap(x.i_.<current>, y.i_.<current>))) |
| // requires indirectly_swappable<iterator_t<Base>>; |
| |
| #include <ranges> |
| |
| #include <cassert> |
| #include <type_traits> |
| #include <utility> |
| #include "../types.h" |
| |
| namespace adl { |
| |
| template <bool IsNoexcept = false> |
| struct MaybeNoexceptIterator { |
| using value_type = int; |
| using difference_type = std::ptrdiff_t; |
| |
| value_type* ptr_ = nullptr; |
| int* iter_swap_invocations_ = nullptr; |
| |
| constexpr MaybeNoexceptIterator() = default; |
| constexpr explicit MaybeNoexceptIterator(int& iter_swaps) : iter_swap_invocations_(&iter_swaps) {} |
| |
| value_type& operator*() const { return *ptr_; } |
| |
| MaybeNoexceptIterator& operator++() { ++ptr_; return *this; } |
| MaybeNoexceptIterator operator++(int) { |
| MaybeNoexceptIterator prev = *this; |
| ++ptr_; |
| return prev; |
| } |
| |
| MaybeNoexceptIterator& operator--() { --ptr_; return *this; } |
| MaybeNoexceptIterator operator--(int) { |
| MaybeNoexceptIterator prev = *this; |
| --ptr_; |
| return prev; |
| } |
| |
| constexpr friend void iter_swap(MaybeNoexceptIterator a, MaybeNoexceptIterator) noexcept(IsNoexcept) { |
| if (a.iter_swap_invocations_) { |
| ++(*a.iter_swap_invocations_); |
| } |
| } |
| |
| friend bool operator==(const MaybeNoexceptIterator& lhs, const MaybeNoexceptIterator& rhs) { |
| return lhs.ptr_ == rhs.ptr_; |
| } |
| }; |
| |
| template <bool IsNoexcept = false> |
| struct View : std::ranges::view_base { |
| int* iter_swaps = nullptr; |
| |
| constexpr View() = default; |
| constexpr View(int& iter_swap_invocations) : iter_swaps(&iter_swap_invocations) { |
| } |
| |
| constexpr adl::MaybeNoexceptIterator<IsNoexcept> begin() { |
| return adl::MaybeNoexceptIterator<IsNoexcept>(*iter_swaps); |
| } |
| constexpr adl::MaybeNoexceptIterator<IsNoexcept> end() { |
| return adl::MaybeNoexceptIterator<IsNoexcept>(*iter_swaps); |
| } |
| }; |
| |
| } // namespace adl |
| |
| constexpr bool test() { |
| // Can use `iter_swap` with `inner-iterator`; `View` is a forward range. |
| { |
| // Non-const iterator. |
| { |
| SplitViewDiff v("abc def", " "); |
| auto segment = *v.begin(); |
| |
| auto i1 = segment.begin(); |
| auto i2 = i1++; |
| static_assert(std::is_void_v<decltype(iter_swap(i1, i2))>); |
| assert(*i1 == 'b'); |
| assert(*i2 == 'a'); |
| |
| iter_swap(i1, i2); |
| assert(*i1 == 'a'); |
| assert(*i2 == 'b'); |
| // Note that `iter_swap` swaps characters in the actual underlying range. |
| assert(*v.base().begin() == 'b'); |
| } |
| |
| // Const iterator. |
| { |
| SplitViewDiff v("abc def", " "); |
| auto segment = *v.begin(); |
| |
| auto i1 = segment.begin(); |
| const auto i2 = i1++; |
| static_assert(std::is_void_v<decltype(iter_swap(i1, i2))>); |
| static_assert(std::is_void_v<decltype(iter_swap(i2, i2))>); |
| assert(*i1 == 'b'); |
| assert(*i2 == 'a'); |
| |
| iter_swap(i1, i2); |
| assert(*i1 == 'a'); |
| assert(*i2 == 'b'); |
| assert(*v.base().begin() == 'b'); |
| } |
| } |
| |
| // Can use `iter_swap` with `inner-iterator`; `View` is an input range. |
| { |
| |
| // Non-const iterator. |
| { |
| // Iterators belong to the same view. |
| { |
| SplitViewInput v("abc def", ' '); |
| auto segment = *v.begin(); |
| |
| auto i1 = segment.begin(); |
| auto i2 = i1; |
| ++i1; |
| static_assert(std::is_void_v<decltype(iter_swap(i1, i2))>); |
| assert(*i1 == 'b'); |
| // For an input view, all inner iterators are essentially thin proxies to the same underlying iterator. |
| assert(*i2 == 'b'); |
| |
| iter_swap(i1, i2); |
| assert(*i1 == 'b'); |
| assert(*i2 == 'b'); |
| } |
| |
| // Iterators belong to different views. |
| { |
| SplitViewInput v1("abc def", ' '); |
| auto val1 = *v1.begin(); |
| SplitViewInput v2 = v1; |
| auto val2 = *v2.begin(); |
| |
| auto i1 = val1.begin(); |
| auto i2 = val2.begin(); |
| ++i1; |
| assert(*i1 == 'b'); |
| assert(*i2 == 'a'); |
| |
| iter_swap(i1, i2); |
| assert(*i1 == 'a'); |
| assert(*i2 == 'b'); |
| } |
| } |
| |
| // Const iterator. |
| { |
| SplitViewInput v("abc def", ' '); |
| auto segment = *v.begin(); |
| |
| const auto i1 = segment.begin(); |
| const auto i2 = i1; |
| static_assert(std::is_void_v<decltype(iter_swap(i1, i2))>); |
| assert(*i1 == 'a'); |
| assert(*i2 == 'a'); |
| |
| iter_swap(i1, i2); |
| assert(*i1 == 'a'); |
| assert(*i2 == 'a'); |
| } |
| } |
| |
| // Ensure the `iter_swap` customization point is being used. |
| { |
| int iter_swap_invocations = 0; |
| adl::View<> input(iter_swap_invocations); |
| std::ranges::lazy_split_view<adl::View<>, adl::View<>> v(input, adl::View<>()); |
| |
| auto segment = *v.begin(); |
| auto i = segment.begin(); |
| iter_swap(i, i); |
| assert(iter_swap_invocations == 1); |
| } |
| |
| // Check the `noexcept` specification. |
| { |
| { |
| using ThrowingSplitView = std::ranges::lazy_split_view<adl::View<false>, adl::View<false>>; |
| using ThrowingValueType = std::ranges::iterator_t<ThrowingSplitView>::value_type; |
| using ThrowingIter = std::ranges::iterator_t<ThrowingValueType>; |
| ASSERT_NOT_NOEXCEPT(std::ranges::iter_swap( |
| std::declval<adl::MaybeNoexceptIterator<false>>(), |
| std::declval<adl::MaybeNoexceptIterator<false>>())); |
| ASSERT_NOT_NOEXCEPT(iter_swap(std::declval<ThrowingIter>(), std::declval<ThrowingIter>())); |
| } |
| |
| { |
| using NoexceptSplitView = std::ranges::lazy_split_view<adl::View<true>, adl::View<true>>; |
| using NoexceptValueType = std::ranges::iterator_t<NoexceptSplitView>::value_type; |
| using NoexceptIter = std::ranges::iterator_t<NoexceptValueType>; |
| ASSERT_NOEXCEPT(std::ranges::iter_swap( |
| std::declval<adl::MaybeNoexceptIterator<true>>(), |
| std::declval<adl::MaybeNoexceptIterator<true>>())); |
| ASSERT_NOEXCEPT(iter_swap(std::declval<NoexceptIter>(), std::declval<NoexceptIter>())); |
| } |
| } |
| |
| return true; |
| } |
| |
| int main(int, char**) { |
| test(); |
| static_assert(test()); |
| |
| return 0; |
| } |