88 lines · cpp
1//===----------------------------------------------------------------------===//2//3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.4// See https://llvm.org/LICENSE.txt for license information.5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception6//7//===----------------------------------------------------------------------===//8 9// UNSUPPORTED: c++03, c++11, c++14, c++1710 11// constexpr sentinel(sentinel<!Const> s);12// requires Const && convertible_to<sentinel_t<V>, sentinel_t<Base>>;13 14#include <cassert>15#include <ranges>16 17#include "../types.h"18#include "test_range.h"19 20template <class T>21struct convertible_sentinel_wrapper {22 explicit convertible_sentinel_wrapper() = default;23 constexpr convertible_sentinel_wrapper(const T& it) : it_(it) {}24 25 template <class U>26 requires std::convertible_to<const U&, T>27 constexpr convertible_sentinel_wrapper(const convertible_sentinel_wrapper<U>& other) : it_(other.it_) {}28 29 constexpr friend bool operator==(convertible_sentinel_wrapper const& self, const T& other) {30 return self.it_ == other;31 }32 T it_;33};34 35struct ConstConvertibleView : BufferView<BufferView<int*>*> {36 using BufferView<BufferView<int*>*>::BufferView;37 38 using sentinel = convertible_sentinel_wrapper<BufferView<int*>*>;39 using const_sentinel = convertible_sentinel_wrapper<const BufferView<int*>*>;40 41 constexpr BufferView<int*>* begin() { return data_; }42 constexpr const BufferView<int*>* begin() const { return data_; }43 constexpr sentinel end() { return sentinel(data_ + size_); }44 constexpr const_sentinel end() const { return const_sentinel(data_ + size_); }45};46static_assert(!std::ranges::common_range<ConstConvertibleView>);47static_assert(std::convertible_to<std::ranges::sentinel_t<ConstConvertibleView>,48 std::ranges::sentinel_t<ConstConvertibleView const>>);49static_assert(!simple_view<ConstConvertibleView>);50 51constexpr bool test() {52 int buffer[4][4] = {{1, 2, 3, 4}, {5, 6, 7, 8}, {9, 10, 11, 12}, {13, 14, 15, 16}};53 {54 BufferView<int*> inners[] = {buffer[0], buffer[1], buffer[2]};55 ConstConvertibleView outer(inners);56 std::ranges::join_view jv(outer);57 auto sent1 = jv.end();58 std::ranges::sentinel_t<const decltype(jv)> sent2 = sent1;59 assert(std::as_const(jv).begin() != sent2);60 assert(std::ranges::next(std::as_const(jv).begin(), 12) == sent2);61 62 // We cannot create a non-const sentinel from a const sentinel.63 static_assert(!std::constructible_from<decltype(sent1), decltype(sent2)>);64 }65 66 {67 // cannot create a const sentinel from a non-const sentinel if the underlying68 // const sentinel cannot be created from the underlying non-const sentinel69 using Inner = BufferView<int*>;70 using ConstInconvertibleOuter =71 BufferView<forward_iterator<const Inner*>, sentinel_wrapper<forward_iterator<const Inner*>>,72 bidirectional_iterator<Inner*>, sentinel_wrapper<bidirectional_iterator<Inner*>>>;73 using JoinView = std::ranges::join_view<ConstInconvertibleOuter>;74 using sentinel_t = std::ranges::sentinel_t<JoinView>;75 using const_sentinel_t = std::ranges::sentinel_t<const JoinView>;76 static_assert(!std::constructible_from<sentinel_t, const_sentinel_t>);77 static_assert(!std::constructible_from<const_sentinel_t, sentinel_t>);78 }79 return true;80}81 82int main(int, char**) {83 test();84 static_assert(test());85 86 return 0;87}88