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 
15 // template<bidirectional_iterator I1, sentinel_for<I1> S1, bidirectional_iterator I2>
16 //   requires indirectly_copyable<I1, I2>
17 //   constexpr ranges::copy_backward_result<I1, I2>
18 //     ranges::copy_backward(I1 first, S1 last, I2 result);
19 // template<bidirectional_range R, bidirectional_iterator I>
20 //   requires indirectly_copyable<iterator_t<R>, I>
21 //   constexpr ranges::copy_backward_result<borrowed_iterator_t<R>, I>
22 //     ranges::copy_backward(R&& r, I result);
23 
24 #include <algorithm>
25 #include <array>
26 #include <cassert>
27 #include <ranges>
28 
29 #include "almost_satisfies_types.h"
30 #include "test_iterators.h"
31 
32 template <class In, class Out = In, class Sent = sentinel_wrapper<In>>
33 concept HasCopyBackwardIt = requires(In in, Sent sent, Out out) { std::ranges::copy_backward(in, sent, out); };
34 
35 static_assert(HasCopyBackwardIt<int*>);
36 static_assert(!HasCopyBackwardIt<InputIteratorNotDerivedFrom>);
37 static_assert(!HasCopyBackwardIt<InputIteratorNotIndirectlyReadable>);
38 static_assert(!HasCopyBackwardIt<InputIteratorNotInputOrOutputIterator>);
39 static_assert(!HasCopyBackwardIt<int*, WeaklyIncrementableNotMovable>);
40 struct NotIndirectlyCopyable {};
41 static_assert(!HasCopyBackwardIt<int*, NotIndirectlyCopyable*>);
42 static_assert(!HasCopyBackwardIt<int*, int*, SentinelForNotSemiregular>);
43 static_assert(!HasCopyBackwardIt<int*, int*, SentinelForNotWeaklyEqualityComparableWith>);
44 
45 template <class Range, class Out>
46 concept HasCopyBackwardR = requires(Range range, Out out) { std::ranges::copy_backward(range, out); };
47 
48 static_assert(HasCopyBackwardR<std::array<int, 10>, int*>);
49 static_assert(!HasCopyBackwardR<InputRangeNotDerivedFrom, int*>);
50 static_assert(!HasCopyBackwardR<InputRangeNotIndirectlyReadable, int*>);
51 static_assert(!HasCopyBackwardR<InputRangeNotInputOrOutputIterator, int*>);
52 static_assert(!HasCopyBackwardR<WeaklyIncrementableNotMovable, int*>);
53 static_assert(!HasCopyBackwardR<UncheckedRange<NotIndirectlyCopyable*>, int*>);
54 static_assert(!HasCopyBackwardR<InputRangeNotSentinelSemiregular, int*>);
55 static_assert(!HasCopyBackwardR<InputRangeNotSentinelEqualityComparableWith, int*>);
56 
57 static_assert(std::is_same_v<std::ranges::copy_result<int, long>, std::ranges::in_out_result<int, long>>);
58 
59 template <class In, class Out, class Sent>
60 constexpr void test_iterators() {
61   { // simple test
62     {
63       std::array in {1, 2, 3, 4};
64       std::array<int, 4> out;
65       std::same_as<std::ranges::in_out_result<In, Out>> auto ret =
66         std::ranges::copy_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 in {1, 2, 3, 4};
73       std::array<int, 4> out;
74       auto range = std::ranges::subrange(In(in.data()), Sent(In(in.data() + in.size())));
75       std::same_as<std::ranges::in_out_result<In, Out>> auto ret =
76           std::ranges::copy_backward(range, Out(out.data() + out.size()));
77       assert(in == out);
78       assert(base(ret.in) == in.data() + in.size());
79       assert(base(ret.out) == out.data());
80     }
81   }
82 
83   { // check that an empty range works
84     {
85       std::array<int, 0> in;
86       std::array<int, 0> out;
87       auto ret =
88           std::ranges::copy_backward(In(in.data()), Sent(In(in.data() + in.size())), Out(out.data() + out.size()));
89       assert(base(ret.in) == in.data() + in.size());
90       assert(base(ret.out) == out.data());
91     }
92     {
93       std::array<int, 0> in;
94       std::array<int, 0> out;
95       auto range = std::ranges::subrange(In(in.data()), Sent(In(in.data() + in.size())));
96       auto ret = std::ranges::copy_backward(range, Out(out.data()));
97       assert(base(ret.in) == in.data() + in.size());
98       assert(base(ret.out) == out.data());
99     }
100   }
101 }
102 
103 template <class InIter, class OutIter>
104 constexpr void test_sentinels() {
105   test_iterators<InIter, OutIter, InIter>();
106   test_iterators<InIter, OutIter, sentinel_wrapper<InIter>>();
107   test_iterators<InIter, OutIter, sized_sentinel<InIter>>();
108 }
109 
110 template <class Out>
111 constexpr void test_in_iterators() {
112   test_sentinels<bidirectional_iterator<int*>, Out>();
113   test_sentinels<random_access_iterator<int*>, Out>();
114   test_sentinels<contiguous_iterator<int*>, Out>();
115 }
116 
117 template <class Out>
118 constexpr void test_proxy_in_iterators() {
119   test_sentinels<ProxyIterator<bidirectional_iterator<int*>>, Out>();
120   test_sentinels<ProxyIterator<random_access_iterator<int*>>, Out>();
121   test_sentinels<ProxyIterator<contiguous_iterator<int*>>, Out>();
122 }
123 
124 constexpr bool test() {
125   test_in_iterators<bidirectional_iterator<int*>>();
126   test_in_iterators<random_access_iterator<int*>>();
127   test_in_iterators<contiguous_iterator<int*>>();
128 
129   test_proxy_in_iterators<ProxyIterator<bidirectional_iterator<int*>>>();
130   test_proxy_in_iterators<ProxyIterator<random_access_iterator<int*>>>();
131   test_proxy_in_iterators<ProxyIterator<contiguous_iterator<int*>>>();
132 
133   { // check that ranges::dangling is returned
134     std::array<int, 4> out;
135     std::same_as<std::ranges::in_out_result<std::ranges::dangling, int*>> auto ret =
136       std::ranges::copy_backward(std::array {1, 2, 3, 4}, out.data() + out.size());
137     assert(ret.out == out.data());
138     assert((out == std::array{1, 2, 3, 4}));
139   }
140 
141   { // check that an iterator is returned with a borrowing range
142     std::array in {1, 2, 3, 4};
143     std::array<int, 4> out;
144     std::same_as<std::ranges::in_out_result<int*, int*>> auto ret =
145         std::ranges::copy_backward(std::views::all(in), out.data() + out.size());
146     assert(ret.in == in.data() + in.size());
147     assert(ret.out == out.data());
148     assert(in == out);
149   }
150 
151   { // check that every element is copied exactly once
152     struct CopyOnce {
153       bool copied = false;
154       constexpr CopyOnce() = default;
155       constexpr CopyOnce(const CopyOnce& other) = delete;
156       constexpr CopyOnce& operator=(const CopyOnce& other) {
157         assert(!other.copied);
158         copied = true;
159         return *this;
160       }
161     };
162     {
163       std::array<CopyOnce, 4> in {};
164       std::array<CopyOnce, 4> out {};
165       auto ret = std::ranges::copy_backward(in.begin(), in.end(), out.end());
166       assert(ret.in == in.end());
167       assert(ret.out == out.begin());
168       assert(std::all_of(out.begin(), out.end(), [](const auto& e) { return e.copied; }));
169     }
170     {
171       std::array<CopyOnce, 4> in {};
172       std::array<CopyOnce, 4> out {};
173       auto ret = std::ranges::copy_backward(in, out.end());
174       assert(ret.in == in.end());
175       assert(ret.out == out.begin());
176       assert(std::all_of(out.begin(), out.end(), [](const auto& e) { return e.copied; }));
177     }
178   }
179 
180   { // check that the range is copied backwards
181     struct OnlyBackwardsCopyable {
182       OnlyBackwardsCopyable* next = nullptr;
183       bool canCopy = false;
184       OnlyBackwardsCopyable() = default;
185       constexpr OnlyBackwardsCopyable& operator=(const OnlyBackwardsCopyable&) {
186         assert(canCopy);
187         if (next != nullptr)
188           next->canCopy = true;
189         return *this;
190       }
191     };
192     {
193       std::array<OnlyBackwardsCopyable, 3> in {};
194       std::array<OnlyBackwardsCopyable, 3> out {};
195       out[1].next = &out[0];
196       out[2].next = &out[1];
197       out[2].canCopy = true;
198       auto ret = std::ranges::copy_backward(in, out.end());
199       assert(ret.in == in.end());
200       assert(ret.out == out.begin());
201       assert(out[0].canCopy);
202       assert(out[1].canCopy);
203       assert(out[2].canCopy);
204     }
205     {
206       std::array<OnlyBackwardsCopyable, 3> in {};
207       std::array<OnlyBackwardsCopyable, 3> out {};
208       out[1].next = &out[0];
209       out[2].next = &out[1];
210       out[2].canCopy = true;
211       auto ret = std::ranges::copy_backward(in.begin(), in.end(), out.end());
212       assert(ret.in == in.end());
213       assert(ret.out == out.begin());
214       assert(out[0].canCopy);
215       assert(out[1].canCopy);
216       assert(out[2].canCopy);
217     }
218   }
219 
220   return true;
221 }
222 
223 int main(int, char**) {
224   test();
225   static_assert(test());
226 
227   return 0;
228 }
229