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 
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>
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>
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 <template <class> class InIter, template <class> class OutIter>
127 constexpr void test_sentinels() {
128   test_iterators<InIter<int*>, OutIter<int*>, InIter<int*>>();
129   test_iterators<InIter<int*>, OutIter<int*>, sentinel_wrapper<InIter<int*>>>();
130   test_iterators<InIter<int*>, OutIter<int*>, sized_sentinel<InIter<int*>>>();
131 
132   if (!std::is_constant_evaluated()) {
133     if constexpr (!std::is_same_v<InIter<int*>, contiguous_iterator<int*>> &&
134                   !std::is_same_v<OutIter<int*>, contiguous_iterator<int*>> &&
135                   !std::is_same_v<InIter<int*>, ContiguousProxyIterator<int*>> &&
136                   !std::is_same_v<OutIter<int*>, ContiguousProxyIterator<int*>>) {
137       test_containers<std::deque<int>,
138                       std::deque<int>,
139                       InIter<std::deque<int>::iterator>,
140                       OutIter<std::deque<int>::iterator>>();
141       test_containers<std::deque<int>,
142                       std::vector<int>,
143                       InIter<std::deque<int>::iterator>,
144                       OutIter<std::vector<int>::iterator>>();
145       test_containers<std::vector<int>,
146                       std::deque<int>,
147                       InIter<std::vector<int>::iterator>,
148                       OutIter<std::deque<int>::iterator>>();
149       test_containers<std::vector<int>,
150                       std::vector<int>,
151                       InIter<std::vector<int>::iterator>,
152                       OutIter<std::vector<int>::iterator>>();
153     }
154   }
155 }
156 
157 template <template <class> class Out>
158 constexpr void test_in_iterators() {
159   test_sentinels<bidirectional_iterator, Out>();
160   test_sentinels<random_access_iterator, Out>();
161   test_sentinels<contiguous_iterator, Out>();
162   test_sentinels<std::type_identity_t, Out>();
163 }
164 
165 template <template <class> class Out>
166 constexpr void test_proxy_in_iterators() {
167   test_sentinels<BidirectionalProxyIterator, Out>();
168   test_sentinels<RandomAccessProxyIterator, Out>();
169   test_sentinels<ContiguousProxyIterator, Out>();
170   test_sentinels<ProxyIterator, Out>();
171 }
172 
173 constexpr bool test() {
174   test_in_iterators<bidirectional_iterator>();
175   test_in_iterators<random_access_iterator>();
176   test_in_iterators<contiguous_iterator>();
177   test_in_iterators<std::type_identity_t>();
178 
179   test_proxy_in_iterators<BidirectionalProxyIterator>();
180   test_proxy_in_iterators<RandomAccessProxyIterator>();
181   test_proxy_in_iterators<ContiguousProxyIterator>();
182 
183   { // check that ranges::dangling is returned
184     std::array<int, 4> out;
185     std::same_as<std::ranges::in_out_result<std::ranges::dangling, int*>> auto ret =
186       std::ranges::copy_backward(std::array {1, 2, 3, 4}, out.data() + out.size());
187     assert(ret.out == out.data());
188     assert((out == std::array{1, 2, 3, 4}));
189   }
190 
191   { // check that an iterator is returned with a borrowing range
192     std::array in {1, 2, 3, 4};
193     std::array<int, 4> out;
194     std::same_as<std::ranges::in_out_result<int*, int*>> auto ret =
195         std::ranges::copy_backward(std::views::all(in), out.data() + out.size());
196     assert(ret.in == in.data() + in.size());
197     assert(ret.out == out.data());
198     assert(in == out);
199   }
200 
201   { // check that every element is copied exactly once
202     struct CopyOnce {
203       bool copied = false;
204       constexpr CopyOnce() = default;
205       constexpr CopyOnce(const CopyOnce& other) = delete;
206       constexpr CopyOnce& operator=(const CopyOnce& other) {
207         assert(!other.copied);
208         copied = true;
209         return *this;
210       }
211     };
212     {
213       std::array<CopyOnce, 4> in {};
214       std::array<CopyOnce, 4> out {};
215       auto ret = std::ranges::copy_backward(in.begin(), in.end(), out.end());
216       assert(ret.in == in.end());
217       assert(ret.out == out.begin());
218       assert(std::all_of(out.begin(), out.end(), [](const auto& e) { return e.copied; }));
219     }
220     {
221       std::array<CopyOnce, 4> in {};
222       std::array<CopyOnce, 4> out {};
223       auto ret = std::ranges::copy_backward(in, out.end());
224       assert(ret.in == in.end());
225       assert(ret.out == out.begin());
226       assert(std::all_of(out.begin(), out.end(), [](const auto& e) { return e.copied; }));
227     }
228   }
229 
230   { // check that the range is copied backwards
231     struct OnlyBackwardsCopyable {
232       OnlyBackwardsCopyable* next = nullptr;
233       bool canCopy = false;
234       OnlyBackwardsCopyable() = default;
235       constexpr OnlyBackwardsCopyable& operator=(const OnlyBackwardsCopyable&) {
236         assert(canCopy);
237         if (next != nullptr)
238           next->canCopy = true;
239         return *this;
240       }
241     };
242     {
243       std::array<OnlyBackwardsCopyable, 3> in {};
244       std::array<OnlyBackwardsCopyable, 3> out {};
245       out[1].next = &out[0];
246       out[2].next = &out[1];
247       out[2].canCopy = true;
248       auto ret = std::ranges::copy_backward(in, out.end());
249       assert(ret.in == in.end());
250       assert(ret.out == out.begin());
251       assert(out[0].canCopy);
252       assert(out[1].canCopy);
253       assert(out[2].canCopy);
254     }
255     {
256       std::array<OnlyBackwardsCopyable, 3> in {};
257       std::array<OnlyBackwardsCopyable, 3> out {};
258       out[1].next = &out[0];
259       out[2].next = &out[1];
260       out[2].canCopy = true;
261       auto ret = std::ranges::copy_backward(in.begin(), in.end(), out.end());
262       assert(ret.in == in.end());
263       assert(ret.out == out.begin());
264       assert(out[0].canCopy);
265       assert(out[1].canCopy);
266       assert(out[2].canCopy);
267     }
268   }
269 
270   return true;
271 }
272 
273 int main(int, char**) {
274   test();
275   static_assert(test());
276 
277   return 0;
278 }
279