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: libcpp-has-no-incomplete-ranges
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 <ranges>
27 
28 #include "almost_satisfies_types.h"
29 #include "MoveOnly.h"
30 #include "test_iterators.h"
31 
32 template <class In, class Out = In, class Sent = sentinel_wrapper<In>>
33 concept HasMoveBackwardIt = requires(In in, Sent sent, Out out) { std::ranges::move_backward(in, sent, out); };
34 
35 static_assert(HasMoveBackwardIt<int*>);
36 static_assert(!HasMoveBackwardIt<InputIteratorNotDerivedFrom>);
37 static_assert(!HasMoveBackwardIt<InputIteratorNotIndirectlyReadable>);
38 static_assert(!HasMoveBackwardIt<InputIteratorNotInputOrOutputIterator>);
39 static_assert(!HasMoveBackwardIt<int*, WeaklyIncrementableNotMovable>);
40 struct NotIndirectlyCopyable {};
41 static_assert(!HasMoveBackwardIt<int*, NotIndirectlyCopyable*>);
42 static_assert(!HasMoveBackwardIt<int*, int*, SentinelForNotSemiregular>);
43 static_assert(!HasMoveBackwardIt<int*, int*, SentinelForNotWeaklyEqualityComparableWith>);
44 
45 template <class Range, class Out>
46 concept HasMoveBackwardR = requires(Range range, Out out) { std::ranges::move_backward(range, out); };
47 
48 static_assert(HasMoveBackwardR<std::array<int, 10>, int*>);
49 static_assert(!HasMoveBackwardR<InputRangeNotDerivedFrom, int*>);
50 static_assert(!HasMoveBackwardR<InputRangeNotIndirectlyReadable, int*>);
51 static_assert(!HasMoveBackwardR<InputRangeNotInputOrOutputIterator, int*>);
52 static_assert(!HasMoveBackwardR<WeaklyIncrementableNotMovable, int*>);
53 static_assert(!HasMoveBackwardR<UncheckedRange<NotIndirectlyCopyable*>, int*>);
54 static_assert(!HasMoveBackwardR<InputRangeNotSentinelSemiregular, int*>);
55 static_assert(!HasMoveBackwardR<InputRangeNotSentinelEqualityComparableWith, int*>);
56 static_assert(!HasMoveBackwardR<UncheckedRange<int*>, WeaklyIncrementableNotMovable>);
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, int N>
test(std::array<int,N> in)61 constexpr void test(std::array<int, N> in) {
62   {
63     std::array<int, N> out;
64     std::same_as<std::ranges::in_out_result<In, Out>> decltype(auto) ret =
65       std::ranges::move_backward(In(in.data()), Sent(In(in.data() + in.size())), Out(out.data() + out.size()));
66     assert(in == out);
67     assert(base(ret.in) == in.data() + in.size());
68     assert(base(ret.out) == out.data());
69   }
70   {
71     std::array<int, N> out;
72     auto range = std::ranges::subrange(In(in.data()), Sent(In(in.data() + in.size())));
73     std::same_as<std::ranges::in_out_result<In, Out>> decltype(auto) ret =
74         std::ranges::move_backward(range, Out(out.data() + out.size()));
75     assert(in == out);
76     assert(base(ret.in) == in.data() + in.size());
77     assert(base(ret.out) == out.data());
78   }
79 }
80 
81 template <class In, class Out, class Sent = In>
test_iterators()82 constexpr void test_iterators() {
83   // simple test
84   test<In, Out, Sent, 4>({1, 2, 3, 4});
85   // check that an empty range works
86   test<In, Out, Sent, 0>({});
87 }
88 
89 template <class Out>
test_in_iterators()90 constexpr void test_in_iterators() {
91   test_iterators<bidirectional_iterator<int*>, Out, sentinel_wrapper<bidirectional_iterator<int*>>>();
92   test_iterators<bidirectional_iterator<int*>, Out>();
93   test_iterators<random_access_iterator<int*>, Out>();
94   test_iterators<contiguous_iterator<int*>, Out>();
95 }
96 
97 template <class Out>
test_proxy_in_iterators()98 constexpr void test_proxy_in_iterators() {
99   test_iterators<ProxyIterator<bidirectional_iterator<int*>>, Out, sentinel_wrapper<ProxyIterator<bidirectional_iterator<int*>>>>();
100   test_iterators<ProxyIterator<bidirectional_iterator<int*>>, Out>();
101   test_iterators<ProxyIterator<random_access_iterator<int*>>, Out>();
102   test_iterators<ProxyIterator<contiguous_iterator<int*>>, Out>();
103 }
104 
105 struct IteratorWithMoveIter {
106   using value_type = int;
107   using difference_type = int;
108   explicit IteratorWithMoveIter() = default;
109   int* ptr;
IteratorWithMoveIterIteratorWithMoveIter110   constexpr IteratorWithMoveIter(int* ptr_) : ptr(ptr_) {}
111 
112   constexpr int& operator*() const; // iterator with iter_move should not be dereferenced
113 
operator ++IteratorWithMoveIter114   constexpr IteratorWithMoveIter& operator++() { ++ptr; return *this; }
operator ++IteratorWithMoveIter115   constexpr IteratorWithMoveIter operator++(int) { auto ret = *this; ++*this; return ret; }
116 
operator --IteratorWithMoveIter117   constexpr IteratorWithMoveIter& operator--() { --ptr; return *this; }
operator --IteratorWithMoveIter118   constexpr IteratorWithMoveIter operator--(int) { auto ret = *this; --*this; return ret; }
119 
iter_move(const IteratorWithMoveIter &)120   friend constexpr int iter_move(const IteratorWithMoveIter&) { return 42; }
121 
122   constexpr bool operator==(const IteratorWithMoveIter& other) const = default;
123 };
124 
test()125 constexpr bool test() {
126   test_in_iterators<bidirectional_iterator<int*>>();
127   test_in_iterators<random_access_iterator<int*>>();
128   test_in_iterators<contiguous_iterator<int*>>();
129 
130   test_proxy_in_iterators<ProxyIterator<bidirectional_iterator<int*>>>();
131   test_proxy_in_iterators<ProxyIterator<random_access_iterator<int*>>>();
132   test_proxy_in_iterators<ProxyIterator<contiguous_iterator<int*>>>();
133 
134   { // check that a move-only type works
135     {
136       MoveOnly a[] = {1, 2, 3};
137       MoveOnly b[3];
138       std::ranges::move_backward(a, std::end(b));
139       assert(b[0].get() == 1);
140       assert(b[1].get() == 2);
141       assert(b[2].get() == 3);
142     }
143     {
144       MoveOnly a[] = {1, 2, 3};
145       MoveOnly b[3];
146       std::ranges::move_backward(std::begin(a), std::end(a), std::end(b));
147       assert(b[0].get() == 1);
148       assert(b[1].get() == 2);
149       assert(b[2].get() == 3);
150     }
151   }
152 
153   { // check that a move-only type works for ProxyIterator
154     {
155       MoveOnly a[] = {1, 2, 3};
156       MoveOnly b[3];
157       ProxyRange proxyA{a};
158       ProxyRange proxyB{b};
159       std::ranges::move_backward(proxyA, std::ranges::next(proxyB.begin(), std::end(proxyB)));
160       assert(b[0].get() == 1);
161       assert(b[1].get() == 2);
162       assert(b[2].get() == 3);
163     }
164     {
165       MoveOnly a[] = {1, 2, 3};
166       MoveOnly b[3];
167       ProxyRange proxyA{a};
168       ProxyRange proxyB{b};
169       std::ranges::move_backward(std::begin(proxyA), std::end(proxyA),  std::ranges::next(proxyB.begin(), std::end(proxyB)));
170       assert(b[0].get() == 1);
171       assert(b[1].get() == 2);
172       assert(b[2].get() == 3);
173     }
174   }
175 
176   { // check that ranges::dangling is returned
177     std::array<int, 4> out;
178     std::same_as<std::ranges::in_out_result<std::ranges::dangling, int*>> auto ret =
179       std::ranges::move_backward(std::array {1, 2, 3, 4}, out.data() + out.size());
180     assert(ret.out == out.data());
181     assert((out == std::array{1, 2, 3, 4}));
182   }
183 
184   { // check that an iterator is returned with a borrowing range
185     std::array in {1, 2, 3, 4};
186     std::array<int, 4> out;
187     std::same_as<std::ranges::in_out_result<int*, int*>> auto ret =
188         std::ranges::move_backward(std::views::all(in), out.data() + out.size());
189     assert(ret.in == in.data() + in.size());
190     assert(ret.out == out.data());
191     assert(in == out);
192   }
193 
194   { // check that every element is moved exactly once
195     struct MoveOnce {
196       bool moved = false;
197       constexpr MoveOnce() = default;
198       constexpr MoveOnce(const MoveOnce& other) = delete;
199       constexpr MoveOnce& operator=(const MoveOnce& other) {
200         assert(!other.moved);
201         moved = true;
202         return *this;
203       }
204     };
205     {
206       std::array<MoveOnce, 4> in {};
207       std::array<MoveOnce, 4> out {};
208       auto ret = std::ranges::move_backward(in.begin(), in.end(), out.end());
209       assert(ret.in == in.end());
210       assert(ret.out == out.begin());
211       assert(std::all_of(out.begin(), out.end(), [](const auto& e) { return e.moved; }));
212     }
213     {
214       std::array<MoveOnce, 4> in {};
215       std::array<MoveOnce, 4> out {};
216       auto ret = std::ranges::move_backward(in, out.end());
217       assert(ret.in == in.end());
218       assert(ret.out == out.begin());
219       assert(std::all_of(out.begin(), out.end(), [](const auto& e) { return e.moved; }));
220     }
221   }
222 
223   { // check that the range is moved backwards
224     struct OnlyBackwardsMovable {
225       OnlyBackwardsMovable* next = nullptr;
226       bool canMove = false;
227       OnlyBackwardsMovable() = default;
228       constexpr OnlyBackwardsMovable& operator=(const OnlyBackwardsMovable&) {
229         assert(canMove);
230         if (next != nullptr)
231           next->canMove = true;
232         return *this;
233       }
234     };
235     {
236       std::array<OnlyBackwardsMovable, 3> in {};
237       std::array<OnlyBackwardsMovable, 3> out {};
238       out[1].next = &out[0];
239       out[2].next = &out[1];
240       out[2].canMove = true;
241       auto ret = std::ranges::move_backward(in, out.end());
242       assert(ret.in == in.end());
243       assert(ret.out == out.begin());
244       assert(out[0].canMove);
245       assert(out[1].canMove);
246       assert(out[2].canMove);
247     }
248     {
249       std::array<OnlyBackwardsMovable, 3> in {};
250       std::array<OnlyBackwardsMovable, 3> out {};
251       out[1].next = &out[0];
252       out[2].next = &out[1];
253       out[2].canMove = true;
254       auto ret = std::ranges::move_backward(in.begin(), in.end(), out.end());
255       assert(ret.in == in.end());
256       assert(ret.out == out.begin());
257       assert(out[0].canMove);
258       assert(out[1].canMove);
259       assert(out[2].canMove);
260     }
261   }
262 
263   { // check that iter_move is used properly
264     {
265       int a[] = {1, 2, 3, 4};
266       std::array<int, 4> b;
267       auto ret = std::ranges::move_backward(IteratorWithMoveIter(a), IteratorWithMoveIter(a + 4), b.data() + b.size());
268       assert(ret.in == a + 4);
269       assert(ret.out == b.data());
270       assert((b == std::array {42, 42, 42, 42}));
271     }
272     {
273       int a[] = {1, 2, 3, 4};
274       std::array<int, 4> b;
275       auto range = std::ranges::subrange(IteratorWithMoveIter(a), IteratorWithMoveIter(a + 4));
276       auto ret = std::ranges::move_backward(range, b.data() + b.size());
277       assert(ret.in == a + 4);
278       assert(ret.out == b.data());
279       assert((b == std::array {42, 42, 42, 42}));
280     }
281   }
282 
283   return true;
284 }
285 
main(int,char **)286 int main(int, char**) {
287   test();
288   static_assert(test());
289 
290   return 0;
291 }
292