1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
|
//===----------------------------------------------------------------------===//
//
// 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
// constexpr auto begin();
// constexpr auto begin() const
// requires forward_range<const V> &&
// is_reference_v<range_reference_t<const V>> &&
// input_range<range_reference_t<const V>>;
#include <algorithm>
#include <cassert>
#include <ranges>
#include <string_view>
#include "types.h"
struct NonSimpleParentView : std::ranges::view_base {
ChildView* begin() { return nullptr; }
const ChildView* begin() const;
const ChildView* end() const;
};
struct SimpleParentView : std::ranges::view_base {
const ChildView* begin() const;
const ChildView* end() const;
};
struct ConstNotRange : std::ranges::view_base {
const ChildView* begin();
const ChildView* end();
};
static_assert(std::ranges::range<ConstNotRange>);
static_assert(!std::ranges::range<const ConstNotRange>);
template <class T>
concept HasConstBegin = requires(const T& t) { t.begin(); };
constexpr bool test() {
int buffer[4][4] = {{1111, 2222, 3333, 4444}, {555, 666, 777, 888}, {99, 1010, 1111, 1212}, {13, 14, 15, 16}};
{
ChildView children[4] = {ChildView(buffer[0]), ChildView(buffer[1]), ChildView(buffer[2]), ChildView(buffer[3])};
auto jv = std::ranges::join_view(ParentView{children});
assert(*jv.begin() == 1111);
}
{
CopyableChild children[4] = {CopyableChild(buffer[0], 4), CopyableChild(buffer[1], 0), CopyableChild(buffer[2], 1),
CopyableChild(buffer[3], 0)};
auto jv = std::ranges::join_view(ParentView{children});
assert(*jv.begin() == 1111);
}
// Parent is empty.
{
CopyableChild children[4] = {CopyableChild(buffer[0]), CopyableChild(buffer[1]), CopyableChild(buffer[2]),
CopyableChild(buffer[3])};
std::ranges::join_view jv(ParentView(children, 0));
assert(jv.begin() == jv.end());
}
// Parent size is one.
{
CopyableChild children[1] = {CopyableChild(buffer[0])};
std::ranges::join_view jv(ParentView(children, 1));
assert(*jv.begin() == 1111);
}
// Parent and child size is one.
{
CopyableChild children[1] = {CopyableChild(buffer[0], 1)};
std::ranges::join_view jv(ParentView(children, 1));
assert(*jv.begin() == 1111);
}
// Parent size is one child is empty
{
CopyableChild children[1] = {CopyableChild(buffer[0], 0)};
std::ranges::join_view jv(ParentView(children, 1));
assert(jv.begin() == jv.end());
}
// Has all empty children.
{
CopyableChild children[4] = {CopyableChild(buffer[0], 0), CopyableChild(buffer[1], 0), CopyableChild(buffer[2], 0),
CopyableChild(buffer[3], 0)};
auto jv = std::ranges::join_view(ParentView{children});
assert(jv.begin() == jv.end());
}
// First child is empty, others are not.
{
CopyableChild children[4] = {CopyableChild(buffer[0], 4), CopyableChild(buffer[1], 0), CopyableChild(buffer[2], 0),
CopyableChild(buffer[3], 0)};
auto jv = std::ranges::join_view(ParentView{children});
assert(*jv.begin() == 1111);
}
// Last child is empty, others are not.
{
CopyableChild children[4] = {CopyableChild(buffer[0], 4), CopyableChild(buffer[1], 4), CopyableChild(buffer[2], 4),
CopyableChild(buffer[3], 0)};
auto jv = std::ranges::join_view(ParentView{children});
assert(*jv.begin() == 1111);
}
{
std::ranges::join_view jv(buffer);
assert(*jv.begin() == 1111);
}
{
const std::ranges::join_view jv(buffer);
assert(*jv.begin() == 1111);
static_assert(HasConstBegin<decltype(jv)>);
}
// !forward_range<const V>
{
std::ranges::join_view jv{ConstNotRange{}};
static_assert(!HasConstBegin<decltype(jv)>);
}
// !is_reference_v<range_reference_t<const V>>
{
auto innerRValueRange = std::views::iota(0, 5) | std::views::transform([](int) { return ChildView{}; });
static_assert(!std::is_reference_v<std::ranges::range_reference_t<const decltype(innerRValueRange)>>);
std::ranges::join_view jv{innerRValueRange};
static_assert(!HasConstBegin<decltype(jv)>);
}
// !simple-view<V>
{
std::ranges::join_view<NonSimpleParentView> jv;
static_assert(!std::same_as<decltype(jv.begin()), decltype(std::as_const(jv).begin())>);
}
// simple-view<V> && is_reference_v<range_reference_t<V>>;
{
std::ranges::join_view<SimpleParentView> jv;
static_assert(std::same_as<decltype(jv.begin()), decltype(std::as_const(jv).begin())>);
}
// Check stashing iterators (LWG3698: regex_iterator and join_view don't work together very well)
{
std::ranges::join_view<StashingRange> jv;
assert(std::ranges::equal(std::views::counted(jv.begin(), 10), std::string_view{"aababcabcd"}));
}
// LWG3700: The `const begin` of the `join_view` family does not require `InnerRng` to be a range
{
std::ranges::join_view<ConstNonJoinableRange> jv;
static_assert(!HasConstBegin<decltype(jv)>);
}
// Check example from LWG3700
{
auto r = std::views::iota(0, 5) | std::views::split(1);
auto s = std::views::single(r);
auto j = s | std::views::join;
auto f = j.front();
assert(std::ranges::equal(f, std::views::single(0)));
}
return true;
}
int main(int, char**) {
test();
static_assert(test());
return 0;
}
|
