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 // UNSUPPORTED: c++03, c++11, c++14, c++17
10 // UNSUPPORTED: GCC-ALWAYS_INLINE-FIXME
11 
12 // <algorithm>
13 
14 // template<bidirectional_iterator I1, sentinel_for<I1> S1, bidirectional_iterator I2>
15 //   requires indirectly_movable<I1, I2>
16 //   constexpr ranges::move_backward_result<I1, I2>
17 //     ranges::move_backward(I1 first, S1 last, I2 result);
18 // template<bidirectional_range R, bidirectional_iterator I>
19 //   requires indirectly_movable<iterator_t<R>, I>
20 //   constexpr ranges::move_backward_result<borrowed_iterator_t<R>, I>
21 //     ranges::move_backward(R&& r, I result);
22 
23 #include <algorithm>
24 #include <array>
25 #include <cassert>
26 #include <deque>
27 #include <iterator>
28 #include <ranges>
29 #include <vector>
30 
31 #include "almost_satisfies_types.h"
32 #include "MoveOnly.h"
33 #include "test_iterators.h"
34 
35 template <class In, class Out = In, class Sent = sentinel_wrapper<In>>
36 concept HasMoveBackwardIt = requires(In in, Sent sent, Out out) { std::ranges::move_backward(in, sent, out); };
37 
38 static_assert(HasMoveBackwardIt<int*>);
39 static_assert(!HasMoveBackwardIt<InputIteratorNotDerivedFrom>);
40 static_assert(!HasMoveBackwardIt<InputIteratorNotIndirectlyReadable>);
41 static_assert(!HasMoveBackwardIt<InputIteratorNotInputOrOutputIterator>);
42 static_assert(!HasMoveBackwardIt<int*, WeaklyIncrementableNotMovable>);
43 struct NotIndirectlyCopyable {};
44 static_assert(!HasMoveBackwardIt<int*, NotIndirectlyCopyable*>);
45 static_assert(!HasMoveBackwardIt<int*, int*, SentinelForNotSemiregular>);
46 static_assert(!HasMoveBackwardIt<int*, int*, SentinelForNotWeaklyEqualityComparableWith>);
47 
48 template <class Range, class Out>
49 concept HasMoveBackwardR = requires(Range range, Out out) { std::ranges::move_backward(range, out); };
50 
51 static_assert(HasMoveBackwardR<std::array<int, 10>, int*>);
52 static_assert(!HasMoveBackwardR<InputRangeNotDerivedFrom, int*>);
53 static_assert(!HasMoveBackwardR<InputRangeNotIndirectlyReadable, int*>);
54 static_assert(!HasMoveBackwardR<InputRangeNotInputOrOutputIterator, int*>);
55 static_assert(!HasMoveBackwardR<WeaklyIncrementableNotMovable, int*>);
56 static_assert(!HasMoveBackwardR<UncheckedRange<NotIndirectlyCopyable*>, int*>);
57 static_assert(!HasMoveBackwardR<InputRangeNotSentinelSemiregular, int*>);
58 static_assert(!HasMoveBackwardR<InputRangeNotSentinelEqualityComparableWith, int*>);
59 static_assert(!HasMoveBackwardR<UncheckedRange<int*>, WeaklyIncrementableNotMovable>);
60 
61 static_assert(std::is_same_v<std::ranges::copy_result<int, long>, std::ranges::in_out_result<int, long>>);
62 
63 template <class In, class Out, class Sent, int N>
64 constexpr void test(std::array<int, N> in) {
65   {
66     std::array<int, N> out;
67     std::same_as<std::ranges::in_out_result<In, Out>> decltype(auto) ret =
68       std::ranges::move_backward(In(in.data()), Sent(In(in.data() + in.size())), Out(out.data() + out.size()));
69     assert(in == out);
70     assert(base(ret.in) == in.data() + in.size());
71     assert(base(ret.out) == out.data());
72   }
73   {
74     std::array<int, N> 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>> decltype(auto) ret =
77         std::ranges::move_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 template <class In, class Out, class Sent = In>
85 constexpr void test_iterators() {
86   // simple test
87   test<In, Out, Sent, 4>({1, 2, 3, 4});
88   // check that an empty range works
89   test<In, Out, Sent, 0>({});
90 }
91 
92 template <class InContainer, class OutContainer, class In, class Out, class Sent = In>
93 constexpr void test_containers() {
94   {
95     InContainer in {1, 2, 3, 4};
96     OutContainer out(4);
97     std::same_as<std::ranges::in_out_result<In, Out>> auto ret =
98       std::ranges::move_backward(In(in.begin()), Sent(In(in.end())), Out(out.end()));
99     assert(std::ranges::equal(in, out));
100     assert(base(ret.in) == in.end());
101     assert(base(ret.out) == out.begin());
102   }
103   {
104     InContainer in {1, 2, 3, 4};
105     OutContainer out(4);
106     auto range = std::ranges::subrange(In(in.begin()), Sent(In(in.end())));
107     std::same_as<std::ranges::in_out_result<In, Out>> auto ret = std::ranges::move_backward(range, Out(out.end()));
108     assert(std::ranges::equal(in, out));
109     assert(base(ret.in) == in.end());
110     assert(base(ret.out) == out.begin());
111   }
112 }
113 
114 template <template <class> class InIter, template <class> class OutIter>
115 constexpr void test_sentinels() {
116   test_iterators<InIter<int*>, OutIter<int*>, InIter<int*>>();
117   test_iterators<InIter<int*>, OutIter<int*>, sentinel_wrapper<InIter<int*>>>();
118   test_iterators<InIter<int*>, OutIter<int*>, sized_sentinel<InIter<int*>>>();
119 
120   if (!std::is_constant_evaluated()) {
121     if constexpr (!std::is_same_v<InIter<int*>, contiguous_iterator<int*>> &&
122                   !std::is_same_v<OutIter<int*>, contiguous_iterator<int*>> &&
123                   !std::is_same_v<InIter<int*>, ContiguousProxyIterator<int*>> &&
124                   !std::is_same_v<OutIter<int*>, ContiguousProxyIterator<int*>>) {
125       test_containers<std::deque<int>,
126                       std::deque<int>,
127                       InIter<std::deque<int>::iterator>,
128                       OutIter<std::deque<int>::iterator>>();
129       test_containers<std::deque<int>,
130                       std::vector<int>,
131                       InIter<std::deque<int>::iterator>,
132                       OutIter<std::vector<int>::iterator>>();
133       test_containers<std::vector<int>,
134                       std::deque<int>,
135                       InIter<std::vector<int>::iterator>,
136                       OutIter<std::deque<int>::iterator>>();
137       test_containers<std::vector<int>,
138                       std::vector<int>,
139                       InIter<std::vector<int>::iterator>,
140                       OutIter<std::vector<int>::iterator>>();
141     }
142   }
143 }
144 
145 template <template <class> class Out>
146 constexpr void test_in_iterators() {
147   test_sentinels<bidirectional_iterator, Out>();
148   test_sentinels<random_access_iterator, Out>();
149   test_sentinels<contiguous_iterator, Out>();
150   test_sentinels<std::type_identity_t, Out>();
151 }
152 
153 template <template <class> class Out>
154 constexpr void test_proxy_in_iterators() {
155   test_sentinels<BidirectionalProxyIterator, Out>();
156   test_sentinels<RandomAccessProxyIterator, Out>();
157   test_sentinels<ContiguousProxyIterator, Out>();
158   test_sentinels<ProxyIterator, Out>();
159 }
160 
161 struct IteratorWithMoveIter {
162   using value_type = int;
163   using difference_type = int;
164   explicit IteratorWithMoveIter() = default;
165   int* ptr;
166   constexpr IteratorWithMoveIter(int* ptr_) : ptr(ptr_) {}
167 
168   constexpr int& operator*() const; // iterator with iter_move should not be dereferenced
169 
170   constexpr IteratorWithMoveIter& operator++() { ++ptr; return *this; }
171   constexpr IteratorWithMoveIter operator++(int) { auto ret = *this; ++*this; return ret; }
172 
173   constexpr IteratorWithMoveIter& operator--() { --ptr; return *this; }
174   constexpr IteratorWithMoveIter operator--(int) { auto ret = *this; --*this; return ret; }
175 
176   friend constexpr int iter_move(const IteratorWithMoveIter&) { return 42; }
177 
178   constexpr bool operator==(const IteratorWithMoveIter& other) const = default;
179 };
180 
181 constexpr bool test() {
182   test_in_iterators<bidirectional_iterator>();
183   test_in_iterators<random_access_iterator>();
184   test_in_iterators<contiguous_iterator>();
185   test_in_iterators<std::type_identity_t>();
186 
187   test_proxy_in_iterators<BidirectionalProxyIterator>();
188   test_proxy_in_iterators<RandomAccessProxyIterator>();
189   test_proxy_in_iterators<ContiguousProxyIterator>();
190   test_proxy_in_iterators<ProxyIterator>();
191 
192   { // check that a move-only type works
193     // When non-trivial
194     {
195       MoveOnly a[] = {1, 2, 3};
196       MoveOnly b[3];
197       std::ranges::move_backward(a, std::end(b));
198       assert(b[0].get() == 1);
199       assert(b[1].get() == 2);
200       assert(b[2].get() == 3);
201     }
202     {
203       MoveOnly a[] = {1, 2, 3};
204       MoveOnly b[3];
205       std::ranges::move_backward(std::begin(a), std::end(a), std::end(b));
206       assert(b[0].get() == 1);
207       assert(b[1].get() == 2);
208       assert(b[2].get() == 3);
209     }
210 
211     // When trivial
212     {
213       TrivialMoveOnly a[] = {1, 2, 3};
214       TrivialMoveOnly b[3];
215       std::ranges::move_backward(a, std::end(b));
216       assert(b[0].get() == 1);
217       assert(b[1].get() == 2);
218       assert(b[2].get() == 3);
219     }
220     {
221       TrivialMoveOnly a[] = {1, 2, 3};
222       TrivialMoveOnly b[3];
223       std::ranges::move_backward(std::begin(a), std::end(a), std::end(b));
224       assert(b[0].get() == 1);
225       assert(b[1].get() == 2);
226       assert(b[2].get() == 3);
227     }
228   }
229 
230   { // check that a move-only type works for ProxyIterator
231     {
232       MoveOnly a[] = {1, 2, 3};
233       MoveOnly b[3];
234       ProxyRange proxyA{a};
235       ProxyRange proxyB{b};
236       std::ranges::move_backward(proxyA, std::ranges::next(proxyB.begin(), std::end(proxyB)));
237       assert(b[0].get() == 1);
238       assert(b[1].get() == 2);
239       assert(b[2].get() == 3);
240     }
241     {
242       MoveOnly a[] = {1, 2, 3};
243       MoveOnly b[3];
244       ProxyRange proxyA{a};
245       ProxyRange proxyB{b};
246       std::ranges::move_backward(std::begin(proxyA), std::end(proxyA),  std::ranges::next(proxyB.begin(), std::end(proxyB)));
247       assert(b[0].get() == 1);
248       assert(b[1].get() == 2);
249       assert(b[2].get() == 3);
250     }
251   }
252 
253   { // check that ranges::dangling is returned
254     std::array<int, 4> out;
255     std::same_as<std::ranges::in_out_result<std::ranges::dangling, int*>> auto ret =
256       std::ranges::move_backward(std::array {1, 2, 3, 4}, out.data() + out.size());
257     assert(ret.out == out.data());
258     assert((out == std::array{1, 2, 3, 4}));
259   }
260 
261   { // check that an iterator is returned with a borrowing range
262     std::array in {1, 2, 3, 4};
263     std::array<int, 4> out;
264     std::same_as<std::ranges::in_out_result<int*, int*>> auto ret =
265         std::ranges::move_backward(std::views::all(in), out.data() + out.size());
266     assert(ret.in == in.data() + in.size());
267     assert(ret.out == out.data());
268     assert(in == out);
269   }
270 
271   { // check that every element is moved exactly once
272     struct MoveOnce {
273       bool moved = false;
274       constexpr MoveOnce() = default;
275       constexpr MoveOnce(const MoveOnce& other) = delete;
276       constexpr MoveOnce& operator=(const MoveOnce& other) {
277         assert(!other.moved);
278         moved = true;
279         return *this;
280       }
281     };
282     {
283       std::array<MoveOnce, 4> in {};
284       std::array<MoveOnce, 4> out {};
285       auto ret = std::ranges::move_backward(in.begin(), in.end(), out.end());
286       assert(ret.in == in.end());
287       assert(ret.out == out.begin());
288       assert(std::all_of(out.begin(), out.end(), [](const auto& e) { return e.moved; }));
289     }
290     {
291       std::array<MoveOnce, 4> in {};
292       std::array<MoveOnce, 4> out {};
293       auto ret = std::ranges::move_backward(in, out.end());
294       assert(ret.in == in.end());
295       assert(ret.out == out.begin());
296       assert(std::all_of(out.begin(), out.end(), [](const auto& e) { return e.moved; }));
297     }
298   }
299 
300   { // check that the range is moved backwards
301     struct OnlyBackwardsMovable {
302       OnlyBackwardsMovable* next = nullptr;
303       bool canMove = false;
304       OnlyBackwardsMovable() = default;
305       constexpr OnlyBackwardsMovable& operator=(const OnlyBackwardsMovable&) {
306         assert(canMove);
307         if (next != nullptr)
308           next->canMove = true;
309         return *this;
310       }
311     };
312     {
313       std::array<OnlyBackwardsMovable, 3> in {};
314       std::array<OnlyBackwardsMovable, 3> out {};
315       out[1].next = &out[0];
316       out[2].next = &out[1];
317       out[2].canMove = true;
318       auto ret = std::ranges::move_backward(in, out.end());
319       assert(ret.in == in.end());
320       assert(ret.out == out.begin());
321       assert(out[0].canMove);
322       assert(out[1].canMove);
323       assert(out[2].canMove);
324     }
325     {
326       std::array<OnlyBackwardsMovable, 3> in {};
327       std::array<OnlyBackwardsMovable, 3> out {};
328       out[1].next = &out[0];
329       out[2].next = &out[1];
330       out[2].canMove = true;
331       auto ret = std::ranges::move_backward(in.begin(), in.end(), out.end());
332       assert(ret.in == in.end());
333       assert(ret.out == out.begin());
334       assert(out[0].canMove);
335       assert(out[1].canMove);
336       assert(out[2].canMove);
337     }
338   }
339 
340   { // check that iter_move is used properly
341     {
342       int a[] = {1, 2, 3, 4};
343       std::array<int, 4> b;
344       auto ret = std::ranges::move_backward(IteratorWithMoveIter(a), IteratorWithMoveIter(a + 4), b.data() + b.size());
345       assert(ret.in == a + 4);
346       assert(ret.out == b.data());
347       assert((b == std::array {42, 42, 42, 42}));
348     }
349     {
350       int a[] = {1, 2, 3, 4};
351       std::array<int, 4> b;
352       auto range = std::ranges::subrange(IteratorWithMoveIter(a), IteratorWithMoveIter(a + 4));
353       auto ret = std::ranges::move_backward(range, b.data() + b.size());
354       assert(ret.in == a + 4);
355       assert(ret.out == b.data());
356       assert((b == std::array {42, 42, 42, 42}));
357     }
358   }
359 
360   return true;
361 }
362 
363 int main(int, char**) {
364   test();
365   static_assert(test());
366 
367   return 0;
368 }
369