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-exception
6 //
7 //===----------------------------------------------------------------------===//
8
9 // <algorithm>
10
11 // UNSUPPORTED: c++03, c++11, c++14, c++17
12 // UNSUPPORTED: GCC-ALWAYS_INLINE-FIXME
13
14 // template<bidirectional_iterator I1, sentinel_for<I1> S1, bidirectional_iterator I2>
15 // requires indirectly_copyable<I1, I2>
16 // constexpr ranges::copy_backward_result<I1, I2>
17 // ranges::copy_backward(I1 first, S1 last, I2 result);
18 // template<bidirectional_range R, bidirectional_iterator I>
19 // requires indirectly_copyable<iterator_t<R>, I>
20 // constexpr ranges::copy_backward_result<borrowed_iterator_t<R>, I>
21 // ranges::copy_backward(R&& r, I result);
22
23 #include <algorithm>
24 #include <array>
25 #include <cassert>
26 #include <deque>
27 #include <ranges>
28 #include <vector>
29
30 #include "almost_satisfies_types.h"
31 #include "test_iterators.h"
32
33 template <class In, class Out = In, class Sent = sentinel_wrapper<In>>
34 concept HasCopyBackwardIt = requires(In in, Sent sent, Out out) { std::ranges::copy_backward(in, sent, out); };
35
36 static_assert(HasCopyBackwardIt<int*>);
37 static_assert(!HasCopyBackwardIt<InputIteratorNotDerivedFrom>);
38 static_assert(!HasCopyBackwardIt<InputIteratorNotIndirectlyReadable>);
39 static_assert(!HasCopyBackwardIt<InputIteratorNotInputOrOutputIterator>);
40 static_assert(!HasCopyBackwardIt<int*, WeaklyIncrementableNotMovable>);
41 struct NotIndirectlyCopyable {};
42 static_assert(!HasCopyBackwardIt<int*, NotIndirectlyCopyable*>);
43 static_assert(!HasCopyBackwardIt<int*, int*, SentinelForNotSemiregular>);
44 static_assert(!HasCopyBackwardIt<int*, int*, SentinelForNotWeaklyEqualityComparableWith>);
45
46 template <class Range, class Out>
47 concept HasCopyBackwardR = requires(Range range, Out out) { std::ranges::copy_backward(range, out); };
48
49 static_assert(HasCopyBackwardR<std::array<int, 10>, int*>);
50 static_assert(!HasCopyBackwardR<InputRangeNotDerivedFrom, int*>);
51 static_assert(!HasCopyBackwardR<InputRangeNotIndirectlyReadable, int*>);
52 static_assert(!HasCopyBackwardR<InputRangeNotInputOrOutputIterator, int*>);
53 static_assert(!HasCopyBackwardR<WeaklyIncrementableNotMovable, int*>);
54 static_assert(!HasCopyBackwardR<UncheckedRange<NotIndirectlyCopyable*>, int*>);
55 static_assert(!HasCopyBackwardR<InputRangeNotSentinelSemiregular, int*>);
56 static_assert(!HasCopyBackwardR<InputRangeNotSentinelEqualityComparableWith, int*>);
57
58 static_assert(std::is_same_v<std::ranges::copy_result<int, long>, std::ranges::in_out_result<int, long>>);
59
60 template <class In, class Out, class Sent>
test_iterators()61 constexpr void test_iterators() {
62 { // simple test
63 {
64 std::array in {1, 2, 3, 4};
65 std::array<int, 4> out;
66 std::same_as<std::ranges::in_out_result<In, Out>> auto ret =
67 std::ranges::copy_backward(In(in.data()), Sent(In(in.data() + in.size())), Out(out.data() + out.size()));
68 assert(in == out);
69 assert(base(ret.in) == in.data() + in.size());
70 assert(base(ret.out) == out.data());
71 }
72 {
73 std::array in {1, 2, 3, 4};
74 std::array<int, 4> out;
75 auto range = std::ranges::subrange(In(in.data()), Sent(In(in.data() + in.size())));
76 std::same_as<std::ranges::in_out_result<In, Out>> auto ret =
77 std::ranges::copy_backward(range, Out(out.data() + out.size()));
78 assert(in == out);
79 assert(base(ret.in) == in.data() + in.size());
80 assert(base(ret.out) == out.data());
81 }
82 }
83
84 { // check that an empty range works
85 {
86 std::array<int, 0> in;
87 std::array<int, 0> out;
88 auto ret =
89 std::ranges::copy_backward(In(in.data()), Sent(In(in.data() + in.size())), Out(out.data() + out.size()));
90 assert(base(ret.in) == in.data() + in.size());
91 assert(base(ret.out) == out.data());
92 }
93 {
94 std::array<int, 0> in;
95 std::array<int, 0> out;
96 auto range = std::ranges::subrange(In(in.data()), Sent(In(in.data() + in.size())));
97 auto ret = std::ranges::copy_backward(range, Out(out.data()));
98 assert(base(ret.in) == in.data() + in.size());
99 assert(base(ret.out) == out.data());
100 }
101 }
102 }
103
104 template <class InContainer, class OutContainer, class In, class Out, class Sent = In>
test_containers()105 constexpr void test_containers() {
106 {
107 InContainer in {1, 2, 3, 4};
108 OutContainer out(4);
109 std::same_as<std::ranges::in_out_result<In, Out>> auto ret =
110 std::ranges::copy_backward(In(in.begin()), Sent(In(in.end())), Out(out.end()));
111 assert(std::ranges::equal(in, out));
112 assert(base(ret.in) == in.end());
113 assert(base(ret.out) == out.begin());
114 }
115 {
116 InContainer in {1, 2, 3, 4};
117 OutContainer out(4);
118 auto range = std::ranges::subrange(In(in.begin()), Sent(In(in.end())));
119 std::same_as<std::ranges::in_out_result<In, Out>> auto ret = std::ranges::copy_backward(range, Out(out.end()));
120 assert(std::ranges::equal(in, out));
121 assert(base(ret.in) == in.end());
122 assert(base(ret.out) == out.begin());
123 }
124 }
125
126 template <class Iter, class Sent>
test_join_view()127 constexpr void test_join_view() {
128 auto to_subranges = std::views::transform([](auto& vec) {
129 return std::ranges::subrange(Iter(vec.begin()), Sent(Iter(vec.end())));
130 });
131
132 { // segmented -> contiguous
133 std::vector<std::vector<int>> vectors = {};
134 auto range = vectors | to_subranges;
135 std::vector<std::ranges::subrange<Iter, Sent>> subrange_vector(range.begin(), range.end());
136 std::array<int, 0> arr;
137
138 std::ranges::copy_backward(subrange_vector | std::views::join, arr.end());
139 assert(std::ranges::equal(arr, std::array<int, 0>{}));
140 }
141 { // segmented -> contiguous
142 std::vector<std::vector<int>> vectors = {{1, 2, 3, 4}, {5, 6, 7, 8}, {9, 10}, {}};
143 auto range = vectors | to_subranges;
144 std::vector<std::ranges::subrange<Iter, Sent>> subrange_vector(range.begin(), range.end());
145 std::array<int, 10> arr;
146
147 std::ranges::copy_backward(subrange_vector | std::views::join, arr.end());
148 assert(std::ranges::equal(arr, std::array{1, 2, 3, 4, 5, 6, 7, 8, 9, 10}));
149 }
150 { // contiguous -> segmented
151 std::vector<std::vector<int>> vectors = {{0, 0, 0, 0}, {0, 0}, {0, 0, 0, 0}, {}};
152 auto range = vectors | to_subranges;
153 std::vector<std::ranges::subrange<Iter, Sent>> subrange_vector(range.begin(), range.end());
154 std::array arr = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10};
155
156 std::ranges::copy_backward(arr, (subrange_vector | std::views::join).end());
157 assert(std::ranges::equal(subrange_vector | std::views::join, std::array{1, 2, 3, 4, 5, 6, 7, 8, 9, 10}));
158 }
159 { // segmented -> segmented
160 std::vector<std::vector<int>> vectors = {{1, 2, 3, 4}, {5, 6, 7, 8}, {9, 10}, {}};
161 auto range1 = vectors | to_subranges;
162 std::vector<std::ranges::subrange<Iter, Sent>> subrange_vector(range1.begin(), range1.end());
163 std::vector<std::vector<int>> to_vectors = {{0, 0, 0, 0}, {0, 0, 0, 0}, {}, {0, 0}};
164 auto range2 = to_vectors | to_subranges;
165 std::vector<std::ranges::subrange<Iter, Sent>> to_subrange_vector(range2.begin(), range2.end());
166
167 std::ranges::copy_backward(subrange_vector | std::views::join, (to_subrange_vector | std::views::join).end());
168 assert(std::ranges::equal(to_subrange_vector | std::views::join, std::array{1, 2, 3, 4, 5, 6, 7, 8, 9, 10}));
169 }
170 }
171
172 template <class>
173 constexpr bool is_proxy_iterator = false;
174
175 template <class Iter>
176 constexpr bool is_proxy_iterator<ProxyIterator<Iter>> = true;
177
178 template <template <class> class InIter, template <class> class OutIter>
test_sentinels()179 constexpr void test_sentinels() {
180 test_iterators<InIter<int*>, OutIter<int*>, InIter<int*>>();
181 test_iterators<InIter<int*>, OutIter<int*>, sentinel_wrapper<InIter<int*>>>();
182 test_iterators<InIter<int*>, OutIter<int*>, sized_sentinel<InIter<int*>>>();
183
184 if constexpr (!std::is_same_v<InIter<int*>, contiguous_iterator<int*>> &&
185 !std::is_same_v<OutIter<int*>, contiguous_iterator<int*>> &&
186 !std::is_same_v<InIter<int*>, ContiguousProxyIterator<int*>> &&
187 !std::is_same_v<OutIter<int*>, ContiguousProxyIterator<int*>>) {
188 if (!std::is_constant_evaluated()) {
189 test_containers<std::deque<int>,
190 std::deque<int>,
191 InIter<std::deque<int>::iterator>,
192 OutIter<std::deque<int>::iterator>>();
193 test_containers<std::deque<int>,
194 std::vector<int>,
195 InIter<std::deque<int>::iterator>,
196 OutIter<std::vector<int>::iterator>>();
197 test_containers<std::vector<int>,
198 std::deque<int>,
199 InIter<std::vector<int>::iterator>,
200 OutIter<std::deque<int>::iterator>>();
201 test_containers<std::vector<int>,
202 std::vector<int>,
203 InIter<std::vector<int>::iterator>,
204 OutIter<std::vector<int>::iterator>>();
205 }
206 if constexpr (!is_proxy_iterator<InIter<int*>>)
207 test_join_view<InIter<std::vector<int>::iterator>, InIter<std::vector<int>::iterator>>();
208 }
209 }
210
211 template <template <class> class Out>
test_in_iterators()212 constexpr void test_in_iterators() {
213 test_sentinels<bidirectional_iterator, Out>();
214 test_sentinels<random_access_iterator, Out>();
215 test_sentinels<contiguous_iterator, Out>();
216 test_sentinels<std::type_identity_t, Out>();
217 }
218
219 template <template <class> class Out>
test_proxy_in_iterators()220 constexpr void test_proxy_in_iterators() {
221 test_sentinels<BidirectionalProxyIterator, Out>();
222 test_sentinels<RandomAccessProxyIterator, Out>();
223 test_sentinels<ContiguousProxyIterator, Out>();
224 test_sentinels<ProxyIterator, Out>();
225 }
226
test()227 constexpr bool test() {
228 test_in_iterators<bidirectional_iterator>();
229 test_in_iterators<random_access_iterator>();
230 test_in_iterators<contiguous_iterator>();
231 test_in_iterators<std::type_identity_t>();
232
233 test_proxy_in_iterators<BidirectionalProxyIterator>();
234 test_proxy_in_iterators<RandomAccessProxyIterator>();
235 test_proxy_in_iterators<ContiguousProxyIterator>();
236
237 { // check that ranges::dangling is returned
238 std::array<int, 4> out;
239 std::same_as<std::ranges::in_out_result<std::ranges::dangling, int*>> auto ret =
240 std::ranges::copy_backward(std::array {1, 2, 3, 4}, out.data() + out.size());
241 assert(ret.out == out.data());
242 assert((out == std::array{1, 2, 3, 4}));
243 }
244
245 { // check that an iterator is returned with a borrowing range
246 std::array in {1, 2, 3, 4};
247 std::array<int, 4> out;
248 std::same_as<std::ranges::in_out_result<std::array<int, 4>::iterator, int*>> auto ret =
249 std::ranges::copy_backward(std::views::all(in), out.data() + out.size());
250 assert(ret.in == in.end());
251 assert(ret.out == out.data());
252 assert(in == out);
253 }
254
255 { // check that every element is copied exactly once
256 struct CopyOnce {
257 bool copied = false;
258 constexpr CopyOnce() = default;
259 constexpr CopyOnce(const CopyOnce& other) = delete;
260 constexpr CopyOnce& operator=(const CopyOnce& other) {
261 assert(!other.copied);
262 copied = true;
263 return *this;
264 }
265 };
266 {
267 std::array<CopyOnce, 4> in {};
268 std::array<CopyOnce, 4> out {};
269 auto ret = std::ranges::copy_backward(in.begin(), in.end(), out.end());
270 assert(ret.in == in.end());
271 assert(ret.out == out.begin());
272 assert(std::all_of(out.begin(), out.end(), [](const auto& e) { return e.copied; }));
273 }
274 {
275 std::array<CopyOnce, 4> in {};
276 std::array<CopyOnce, 4> out {};
277 auto ret = std::ranges::copy_backward(in, out.end());
278 assert(ret.in == in.end());
279 assert(ret.out == out.begin());
280 assert(std::all_of(out.begin(), out.end(), [](const auto& e) { return e.copied; }));
281 }
282 }
283
284 { // check that the range is copied backwards
285 struct OnlyBackwardsCopyable {
286 OnlyBackwardsCopyable* next = nullptr;
287 bool canCopy = false;
288 OnlyBackwardsCopyable() = default;
289 constexpr OnlyBackwardsCopyable& operator=(const OnlyBackwardsCopyable&) {
290 assert(canCopy);
291 if (next != nullptr)
292 next->canCopy = true;
293 return *this;
294 }
295 };
296 {
297 std::array<OnlyBackwardsCopyable, 3> in {};
298 std::array<OnlyBackwardsCopyable, 3> out {};
299 out[1].next = &out[0];
300 out[2].next = &out[1];
301 out[2].canCopy = true;
302 auto ret = std::ranges::copy_backward(in, out.end());
303 assert(ret.in == in.end());
304 assert(ret.out == out.begin());
305 assert(out[0].canCopy);
306 assert(out[1].canCopy);
307 assert(out[2].canCopy);
308 }
309 {
310 std::array<OnlyBackwardsCopyable, 3> in {};
311 std::array<OnlyBackwardsCopyable, 3> out {};
312 out[1].next = &out[0];
313 out[2].next = &out[1];
314 out[2].canCopy = true;
315 auto ret = std::ranges::copy_backward(in.begin(), in.end(), out.end());
316 assert(ret.in == in.end());
317 assert(ret.out == out.begin());
318 assert(out[0].canCopy);
319 assert(out[1].canCopy);
320 assert(out[2].canCopy);
321 }
322 }
323
324 return true;
325 }
326
main(int,char **)327 int main(int, char**) {
328 test();
329 static_assert(test());
330
331 return 0;
332 }
333