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 // template<bidirectional_iterator I1, sentinel_for<I1> S1, bidirectional_iterator I2>
14 //   requires indirectly_movable<I1, I2>
15 //   constexpr ranges::move_backward_result<I1, I2>
16 //     ranges::move_backward(I1 first, S1 last, I2 result);
17 // template<bidirectional_range R, bidirectional_iterator I>
18 //   requires indirectly_movable<iterator_t<R>, I>
19 //   constexpr ranges::move_backward_result<borrowed_iterator_t<R>, I>
20 //     ranges::move_backward(R&& r, I result);
21 
22 #include <algorithm>
23 #include <array>
24 #include <cassert>
25 #include <deque>
26 #include <ranges>
27 #include <vector>
28 
29 #include "almost_satisfies_types.h"
30 #include "MoveOnly.h"
31 #include "test_iterators.h"
32 
33 template <class In, class Out = In, class Sent = sentinel_wrapper<In>>
34 concept HasMoveBackwardIt = requires(In in, Sent sent, Out out) { std::ranges::move_backward(in, sent, out); };
35 
36 static_assert(HasMoveBackwardIt<int*>);
37 static_assert(!HasMoveBackwardIt<InputIteratorNotDerivedFrom>);
38 static_assert(!HasMoveBackwardIt<InputIteratorNotIndirectlyReadable>);
39 static_assert(!HasMoveBackwardIt<InputIteratorNotInputOrOutputIterator>);
40 static_assert(!HasMoveBackwardIt<int*, WeaklyIncrementableNotMovable>);
41 struct NotIndirectlyCopyable {};
42 static_assert(!HasMoveBackwardIt<int*, NotIndirectlyCopyable*>);
43 static_assert(!HasMoveBackwardIt<int*, int*, SentinelForNotSemiregular>);
44 static_assert(!HasMoveBackwardIt<int*, int*, SentinelForNotWeaklyEqualityComparableWith>);
45 
46 template <class Range, class Out>
47 concept HasMoveBackwardR = requires(Range range, Out out) { std::ranges::move_backward(range, out); };
48 
49 static_assert(HasMoveBackwardR<std::array<int, 10>, int*>);
50 static_assert(!HasMoveBackwardR<InputRangeNotDerivedFrom, int*>);
51 static_assert(!HasMoveBackwardR<InputRangeNotIndirectlyReadable, int*>);
52 static_assert(!HasMoveBackwardR<InputRangeNotInputOrOutputIterator, int*>);
53 static_assert(!HasMoveBackwardR<WeaklyIncrementableNotMovable, int*>);
54 static_assert(!HasMoveBackwardR<UncheckedRange<NotIndirectlyCopyable*>, int*>);
55 static_assert(!HasMoveBackwardR<InputRangeNotSentinelSemiregular, int*>);
56 static_assert(!HasMoveBackwardR<InputRangeNotSentinelEqualityComparableWith, int*>);
57 static_assert(!HasMoveBackwardR<UncheckedRange<int*>, WeaklyIncrementableNotMovable>);
58 
59 static_assert(std::is_same_v<std::ranges::copy_result<int, long>, std::ranges::in_out_result<int, long>>);
60 
61 template <class In, class Out, class Sent, int N>
62 constexpr void test(std::array<int, N> in) {
63   {
64     std::array<int, N> out;
65     std::same_as<std::ranges::in_out_result<In, Out>> decltype(auto) ret =
66       std::ranges::move_backward(In(in.data()), Sent(In(in.data() + in.size())), Out(out.data() + out.size()));
67     assert(in == out);
68     assert(base(ret.in) == in.data() + in.size());
69     assert(base(ret.out) == out.data());
70   }
71   {
72     std::array<int, N> out;
73     auto range = std::ranges::subrange(In(in.data()), Sent(In(in.data() + in.size())));
74     std::same_as<std::ranges::in_out_result<In, Out>> decltype(auto) ret =
75         std::ranges::move_backward(range, Out(out.data() + out.size()));
76     assert(in == out);
77     assert(base(ret.in) == in.data() + in.size());
78     assert(base(ret.out) == out.data());
79   }
80 }
81 
82 template <class In, class Out, class Sent = In>
83 constexpr void test_iterators() {
84   // simple test
85   test<In, Out, Sent, 4>({1, 2, 3, 4});
86   // check that an empty range works
87   test<In, Out, Sent, 0>({});
88 }
89 
90 template <class InContainer, class OutContainer, class In, class Out, class Sent = In>
91 constexpr void test_containers() {
92   {
93     InContainer in {1, 2, 3, 4};
94     OutContainer out(4);
95     std::same_as<std::ranges::in_out_result<In, Out>> auto ret =
96       std::ranges::move_backward(In(in.begin()), Sent(In(in.end())), Out(out.end()));
97     assert(std::ranges::equal(in, out));
98     assert(base(ret.in) == in.end());
99     assert(base(ret.out) == out.begin());
100   }
101   {
102     InContainer in {1, 2, 3, 4};
103     OutContainer out(4);
104     auto range = std::ranges::subrange(In(in.begin()), Sent(In(in.end())));
105     std::same_as<std::ranges::in_out_result<In, Out>> auto ret = std::ranges::move_backward(range, Out(out.end()));
106     assert(std::ranges::equal(in, out));
107     assert(base(ret.in) == in.end());
108     assert(base(ret.out) == out.begin());
109   }
110 }
111 
112 template <template <class> class InIter, template <class> class OutIter>
113 constexpr void test_sentinels() {
114   test_iterators<InIter<int*>, OutIter<int*>, InIter<int*>>();
115   test_iterators<InIter<int*>, OutIter<int*>, sentinel_wrapper<InIter<int*>>>();
116   test_iterators<InIter<int*>, OutIter<int*>, sized_sentinel<InIter<int*>>>();
117 
118   if (!std::is_constant_evaluated()) {
119     if constexpr (!std::is_same_v<InIter<int*>, contiguous_iterator<int*>> &&
120                   !std::is_same_v<OutIter<int*>, contiguous_iterator<int*>> &&
121                   !std::is_same_v<InIter<int*>, ContiguousProxyIterator<int*>> &&
122                   !std::is_same_v<OutIter<int*>, ContiguousProxyIterator<int*>>) {
123       test_containers<std::deque<int>,
124                       std::deque<int>,
125                       InIter<std::deque<int>::iterator>,
126                       OutIter<std::deque<int>::iterator>>();
127       test_containers<std::deque<int>,
128                       std::vector<int>,
129                       InIter<std::deque<int>::iterator>,
130                       OutIter<std::vector<int>::iterator>>();
131       test_containers<std::vector<int>,
132                       std::deque<int>,
133                       InIter<std::vector<int>::iterator>,
134                       OutIter<std::deque<int>::iterator>>();
135       test_containers<std::vector<int>,
136                       std::vector<int>,
137                       InIter<std::vector<int>::iterator>,
138                       OutIter<std::vector<int>::iterator>>();
139     }
140   }
141 }
142 
143 template <template <class> class Out>
144 constexpr void test_in_iterators() {
145   test_sentinels<bidirectional_iterator, Out>();
146   test_sentinels<random_access_iterator, Out>();
147   test_sentinels<contiguous_iterator, Out>();
148   test_sentinels<std::type_identity_t, Out>();
149 }
150 
151 template <template <class> class Out>
152 constexpr void test_proxy_in_iterators() {
153   test_sentinels<BidirectionalProxyIterator, Out>();
154   test_sentinels<RandomAccessProxyIterator, Out>();
155   test_sentinels<ContiguousProxyIterator, Out>();
156   test_sentinels<ProxyIterator, Out>();
157 }
158 
159 struct IteratorWithMoveIter {
160   using value_type = int;
161   using difference_type = int;
162   explicit IteratorWithMoveIter() = default;
163   int* ptr;
164   constexpr IteratorWithMoveIter(int* ptr_) : ptr(ptr_) {}
165 
166   constexpr int& operator*() const; // iterator with iter_move should not be dereferenced
167 
168   constexpr IteratorWithMoveIter& operator++() { ++ptr; return *this; }
169   constexpr IteratorWithMoveIter operator++(int) { auto ret = *this; ++*this; return ret; }
170 
171   constexpr IteratorWithMoveIter& operator--() { --ptr; return *this; }
172   constexpr IteratorWithMoveIter operator--(int) { auto ret = *this; --*this; return ret; }
173 
174   friend constexpr int iter_move(const IteratorWithMoveIter&) { return 42; }
175 
176   constexpr bool operator==(const IteratorWithMoveIter& other) const = default;
177 };
178 
179 constexpr bool test() {
180   test_in_iterators<bidirectional_iterator>();
181   test_in_iterators<random_access_iterator>();
182   test_in_iterators<contiguous_iterator>();
183   test_in_iterators<std::type_identity_t>();
184 
185   test_proxy_in_iterators<BidirectionalProxyIterator>();
186   test_proxy_in_iterators<RandomAccessProxyIterator>();
187   test_proxy_in_iterators<ContiguousProxyIterator>();
188   test_proxy_in_iterators<ProxyIterator>();
189 
190   { // check that a move-only type works
191     {
192       MoveOnly a[] = {1, 2, 3};
193       MoveOnly b[3];
194       std::ranges::move_backward(a, std::end(b));
195       assert(b[0].get() == 1);
196       assert(b[1].get() == 2);
197       assert(b[2].get() == 3);
198     }
199     {
200       MoveOnly a[] = {1, 2, 3};
201       MoveOnly b[3];
202       std::ranges::move_backward(std::begin(a), std::end(a), std::end(b));
203       assert(b[0].get() == 1);
204       assert(b[1].get() == 2);
205       assert(b[2].get() == 3);
206     }
207   }
208 
209   { // check that a move-only type works for ProxyIterator
210     {
211       MoveOnly a[] = {1, 2, 3};
212       MoveOnly b[3];
213       ProxyRange proxyA{a};
214       ProxyRange proxyB{b};
215       std::ranges::move_backward(proxyA, std::ranges::next(proxyB.begin(), std::end(proxyB)));
216       assert(b[0].get() == 1);
217       assert(b[1].get() == 2);
218       assert(b[2].get() == 3);
219     }
220     {
221       MoveOnly a[] = {1, 2, 3};
222       MoveOnly b[3];
223       ProxyRange proxyA{a};
224       ProxyRange proxyB{b};
225       std::ranges::move_backward(std::begin(proxyA), std::end(proxyA),  std::ranges::next(proxyB.begin(), std::end(proxyB)));
226       assert(b[0].get() == 1);
227       assert(b[1].get() == 2);
228       assert(b[2].get() == 3);
229     }
230   }
231 
232   { // check that ranges::dangling is returned
233     std::array<int, 4> out;
234     std::same_as<std::ranges::in_out_result<std::ranges::dangling, int*>> auto ret =
235       std::ranges::move_backward(std::array {1, 2, 3, 4}, out.data() + out.size());
236     assert(ret.out == out.data());
237     assert((out == std::array{1, 2, 3, 4}));
238   }
239 
240   { // check that an iterator is returned with a borrowing range
241     std::array in {1, 2, 3, 4};
242     std::array<int, 4> out;
243     std::same_as<std::ranges::in_out_result<int*, int*>> auto ret =
244         std::ranges::move_backward(std::views::all(in), out.data() + out.size());
245     assert(ret.in == in.data() + in.size());
246     assert(ret.out == out.data());
247     assert(in == out);
248   }
249 
250   { // check that every element is moved exactly once
251     struct MoveOnce {
252       bool moved = false;
253       constexpr MoveOnce() = default;
254       constexpr MoveOnce(const MoveOnce& other) = delete;
255       constexpr MoveOnce& operator=(const MoveOnce& other) {
256         assert(!other.moved);
257         moved = true;
258         return *this;
259       }
260     };
261     {
262       std::array<MoveOnce, 4> in {};
263       std::array<MoveOnce, 4> out {};
264       auto ret = std::ranges::move_backward(in.begin(), in.end(), out.end());
265       assert(ret.in == in.end());
266       assert(ret.out == out.begin());
267       assert(std::all_of(out.begin(), out.end(), [](const auto& e) { return e.moved; }));
268     }
269     {
270       std::array<MoveOnce, 4> in {};
271       std::array<MoveOnce, 4> out {};
272       auto ret = std::ranges::move_backward(in, out.end());
273       assert(ret.in == in.end());
274       assert(ret.out == out.begin());
275       assert(std::all_of(out.begin(), out.end(), [](const auto& e) { return e.moved; }));
276     }
277   }
278 
279   { // check that the range is moved backwards
280     struct OnlyBackwardsMovable {
281       OnlyBackwardsMovable* next = nullptr;
282       bool canMove = false;
283       OnlyBackwardsMovable() = default;
284       constexpr OnlyBackwardsMovable& operator=(const OnlyBackwardsMovable&) {
285         assert(canMove);
286         if (next != nullptr)
287           next->canMove = true;
288         return *this;
289       }
290     };
291     {
292       std::array<OnlyBackwardsMovable, 3> in {};
293       std::array<OnlyBackwardsMovable, 3> out {};
294       out[1].next = &out[0];
295       out[2].next = &out[1];
296       out[2].canMove = true;
297       auto ret = std::ranges::move_backward(in, out.end());
298       assert(ret.in == in.end());
299       assert(ret.out == out.begin());
300       assert(out[0].canMove);
301       assert(out[1].canMove);
302       assert(out[2].canMove);
303     }
304     {
305       std::array<OnlyBackwardsMovable, 3> in {};
306       std::array<OnlyBackwardsMovable, 3> out {};
307       out[1].next = &out[0];
308       out[2].next = &out[1];
309       out[2].canMove = true;
310       auto ret = std::ranges::move_backward(in.begin(), in.end(), out.end());
311       assert(ret.in == in.end());
312       assert(ret.out == out.begin());
313       assert(out[0].canMove);
314       assert(out[1].canMove);
315       assert(out[2].canMove);
316     }
317   }
318 
319   { // check that iter_move is used properly
320     {
321       int a[] = {1, 2, 3, 4};
322       std::array<int, 4> b;
323       auto ret = std::ranges::move_backward(IteratorWithMoveIter(a), IteratorWithMoveIter(a + 4), b.data() + b.size());
324       assert(ret.in == a + 4);
325       assert(ret.out == b.data());
326       assert((b == std::array {42, 42, 42, 42}));
327     }
328     {
329       int a[] = {1, 2, 3, 4};
330       std::array<int, 4> b;
331       auto range = std::ranges::subrange(IteratorWithMoveIter(a), IteratorWithMoveIter(a + 4));
332       auto ret = std::ranges::move_backward(range, b.data() + b.size());
333       assert(ret.in == a + 4);
334       assert(ret.out == b.data());
335       assert((b == std::array {42, 42, 42, 42}));
336     }
337   }
338 
339   return true;
340 }
341 
342 int main(int, char**) {
343   test();
344   static_assert(test());
345 
346   return 0;
347 }
348