181 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 auto begin();12// constexpr auto begin() const13// requires forward_range<const V> &&14// is_reference_v<range_reference_t<const V>> &&15// input_range<range_reference_t<const V>>;16 17#include <algorithm>18#include <cassert>19#include <ranges>20#include <string_view>21 22#include "types.h"23 24struct NonSimpleParentView : std::ranges::view_base {25 ChildView* begin() { return nullptr; }26 const ChildView* begin() const;27 const ChildView* end() const;28};29 30struct SimpleParentView : std::ranges::view_base {31 const ChildView* begin() const;32 const ChildView* end() const;33};34 35struct ConstNotRange : std::ranges::view_base {36 const ChildView* begin();37 const ChildView* end();38};39static_assert(std::ranges::range<ConstNotRange>);40static_assert(!std::ranges::range<const ConstNotRange>);41 42template <class T>43concept HasConstBegin = requires(const T& t) { t.begin(); };44 45constexpr bool test() {46 int buffer[4][4] = {{1111, 2222, 3333, 4444}, {555, 666, 777, 888}, {99, 1010, 1111, 1212}, {13, 14, 15, 16}};47 48 {49 ChildView children[4] = {ChildView(buffer[0]), ChildView(buffer[1]), ChildView(buffer[2]), ChildView(buffer[3])};50 auto jv = std::ranges::join_view(ParentView{children});51 assert(*jv.begin() == 1111);52 }53 54 {55 CopyableChild children[4] = {CopyableChild(buffer[0], 4), CopyableChild(buffer[1], 0), CopyableChild(buffer[2], 1),56 CopyableChild(buffer[3], 0)};57 auto jv = std::ranges::join_view(ParentView{children});58 assert(*jv.begin() == 1111);59 }60 61 // Parent is empty.62 {63 CopyableChild children[4] = {CopyableChild(buffer[0]), CopyableChild(buffer[1]), CopyableChild(buffer[2]),64 CopyableChild(buffer[3])};65 std::ranges::join_view jv(ParentView(children, 0));66 assert(jv.begin() == jv.end());67 }68 69 // Parent size is one.70 {71 CopyableChild children[1] = {CopyableChild(buffer[0])};72 std::ranges::join_view jv(ParentView(children, 1));73 assert(*jv.begin() == 1111);74 }75 76 // Parent and child size is one.77 {78 CopyableChild children[1] = {CopyableChild(buffer[0], 1)};79 std::ranges::join_view jv(ParentView(children, 1));80 assert(*jv.begin() == 1111);81 }82 83 // Parent size is one child is empty84 {85 CopyableChild children[1] = {CopyableChild(buffer[0], 0)};86 std::ranges::join_view jv(ParentView(children, 1));87 assert(jv.begin() == jv.end());88 }89 90 // Has all empty children.91 {92 CopyableChild children[4] = {CopyableChild(buffer[0], 0), CopyableChild(buffer[1], 0), CopyableChild(buffer[2], 0),93 CopyableChild(buffer[3], 0)};94 auto jv = std::ranges::join_view(ParentView{children});95 assert(jv.begin() == jv.end());96 }97 98 // First child is empty, others are not.99 {100 CopyableChild children[4] = {CopyableChild(buffer[0], 4), CopyableChild(buffer[1], 0), CopyableChild(buffer[2], 0),101 CopyableChild(buffer[3], 0)};102 auto jv = std::ranges::join_view(ParentView{children});103 assert(*jv.begin() == 1111);104 }105 106 // Last child is empty, others are not.107 {108 CopyableChild children[4] = {CopyableChild(buffer[0], 4), CopyableChild(buffer[1], 4), CopyableChild(buffer[2], 4),109 CopyableChild(buffer[3], 0)};110 auto jv = std::ranges::join_view(ParentView{children});111 assert(*jv.begin() == 1111);112 }113 114 {115 std::ranges::join_view jv(buffer);116 assert(*jv.begin() == 1111);117 }118 119 {120 const std::ranges::join_view jv(buffer);121 assert(*jv.begin() == 1111);122 static_assert(HasConstBegin<decltype(jv)>);123 }124 125 // !forward_range<const V>126 {127 std::ranges::join_view jv{ConstNotRange{}};128 static_assert(!HasConstBegin<decltype(jv)>);129 }130 131 // !is_reference_v<range_reference_t<const V>>132 {133 auto innerRValueRange = std::views::iota(0, 5) | std::views::transform([](int) { return ChildView{}; });134 static_assert(!std::is_reference_v<std::ranges::range_reference_t<const decltype(innerRValueRange)>>);135 std::ranges::join_view jv{innerRValueRange};136 static_assert(!HasConstBegin<decltype(jv)>);137 }138 139 // !simple-view<V>140 {141 std::ranges::join_view<NonSimpleParentView> jv;142 static_assert(!std::same_as<decltype(jv.begin()), decltype(std::as_const(jv).begin())>);143 }144 145 // simple-view<V> && is_reference_v<range_reference_t<V>>;146 {147 std::ranges::join_view<SimpleParentView> jv;148 static_assert(std::same_as<decltype(jv.begin()), decltype(std::as_const(jv).begin())>);149 }150 151 // Check stashing iterators (LWG3698: regex_iterator and join_view don't work together very well)152 {153 std::ranges::join_view<StashingRange> jv;154 assert(std::ranges::equal(std::views::counted(jv.begin(), 10), std::string_view{"aababcabcd"}));155 }156 157 // LWG3700: The `const begin` of the `join_view` family does not require `InnerRng` to be a range158 {159 std::ranges::join_view<ConstNonJoinableRange> jv;160 static_assert(!HasConstBegin<decltype(jv)>);161 }162 163 // Check example from LWG3700164 {165 auto r = std::views::iota(0, 5) | std::views::split(1);166 auto s = std::views::single(r);167 auto j = s | std::views::join;168 auto f = j.front();169 assert(std::ranges::equal(f, std::views::single(0)));170 }171 172 return true;173}174 175int main(int, char**) {176 test();177 static_assert(test());178 179 return 0;180}181