libcxx/test/std/algorithms/alg.modifying.operations/alg.copy/ranges.copy_backward.pass.cpp

   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 // TODO: make `join_view` non-experimental once D2770 is implemented.
  13 // UNSUPPORTED: !c++experimental
  14 // UNSUPPORTED: GCC-ALWAYS_INLINE-FIXME
  15
  16 // template<bidirectional_iterator I1, sentinel_for<I1> S1, bidirectional_iterator I2>
  17 //   requires indirectly_copyable<I1, I2>
  18 //   constexpr ranges::copy_backward_result<I1, I2>
  19 //     ranges::copy_backward(I1 first, S1 last, I2 result);
  20 // template<bidirectional_range R, bidirectional_iterator I>
  21 //   requires indirectly_copyable<iterator_t<R>, I>
  22 //   constexpr ranges::copy_backward_result<borrowed_iterator_t<R>, I>
  23 //     ranges::copy_backward(R&& r, I result);
  24
  25 #include <algorithm>
  26 #include <array>
  27 #include <cassert>
  28 #include <deque>
  29 #include <ranges>
  30 #include <vector>
  31
  32 #include "almost_satisfies_types.h"
  33 #include "test_iterators.h"
  34
  35 template <class In, class Out = In, class Sent = sentinel_wrapper<In>>
  36 concept HasCopyBackwardIt = requires(In in, Sent sent, Out out) { std::ranges::copy_backward(in, sent, out); };
  37
  38 static_assert(HasCopyBackwardIt<int*>);
  39 static_assert(!HasCopyBackwardIt<InputIteratorNotDerivedFrom>);
  40 static_assert(!HasCopyBackwardIt<InputIteratorNotIndirectlyReadable>);
  41 static_assert(!HasCopyBackwardIt<InputIteratorNotInputOrOutputIterator>);
  42 static_assert(!HasCopyBackwardIt<int*, WeaklyIncrementableNotMovable>);
  43 struct NotIndirectlyCopyable {};
  44 static_assert(!HasCopyBackwardIt<int*, NotIndirectlyCopyable*>);
  45 static_assert(!HasCopyBackwardIt<int*, int*, SentinelForNotSemiregular>);
  46 static_assert(!HasCopyBackwardIt<int*, int*, SentinelForNotWeaklyEqualityComparableWith>);
  47
  48 template <class Range, class Out>
  49 concept HasCopyBackwardR = requires(Range range, Out out) { std::ranges::copy_backward(range, out); };
  50
  51 static_assert(HasCopyBackwardR<std::array<int, 10>, int*>);
  52 static_assert(!HasCopyBackwardR<InputRangeNotDerivedFrom, int*>);
  53 static_assert(!HasCopyBackwardR<InputRangeNotIndirectlyReadable, int*>);
  54 static_assert(!HasCopyBackwardR<InputRangeNotInputOrOutputIterator, int*>);
  55 static_assert(!HasCopyBackwardR<WeaklyIncrementableNotMovable, int*>);
  56 static_assert(!HasCopyBackwardR<UncheckedRange<NotIndirectlyCopyable*>, int*>);
  57 static_assert(!HasCopyBackwardR<InputRangeNotSentinelSemiregular, int*>);
  58 static_assert(!HasCopyBackwardR<InputRangeNotSentinelEqualityComparableWith, int*>);
  59
  60 static_assert(std::is_same_v<std::ranges::copy_result<int, long>, std::ranges::in_out_result<int, long>>);
  61
  62 template <class In, class Out, class Sent>
  63 constexpr void test_iterators() {
  64   { // simple test
  65     {
  66       std::array in {1, 2, 3, 4};
  67       std::array<int, 4> out;
  68       std::same_as<std::ranges::in_out_result<In, Out>> auto ret =
  69         std::ranges::copy_backward(In(in.data()), Sent(In(in.data() + in.size())), Out(out.data() + out.size()));
  70       assert(in == out);
  71       assert(base(ret.in) == in.data() + in.size());
  72       assert(base(ret.out) == out.data());
  73     }
  74     {
  75       std::array in {1, 2, 3, 4};
  76       std::array<int, 4> out;
  77       auto range = std::ranges::subrange(In(in.data()), Sent(In(in.data() + in.size())));
  78       std::same_as<std::ranges::in_out_result<In, Out>> auto ret =
  79           std::ranges::copy_backward(range, Out(out.data() + out.size()));
  80       assert(in == out);
  81       assert(base(ret.in) == in.data() + in.size());
  82       assert(base(ret.out) == out.data());
  83     }
  84   }
  85
  86   { // check that an empty range works
  87     {
  88       std::array<int, 0> in;
  89       std::array<int, 0> out;
  90       auto ret =
  91           std::ranges::copy_backward(In(in.data()), Sent(In(in.data() + in.size())), Out(out.data() + out.size()));
  92       assert(base(ret.in) == in.data() + in.size());
  93       assert(base(ret.out) == out.data());
  94     }
  95     {
  96       std::array<int, 0> in;
  97       std::array<int, 0> out;
  98       auto range = std::ranges::subrange(In(in.data()), Sent(In(in.data() + in.size())));
  99       auto ret = std::ranges::copy_backward(range, Out(out.data()));
 100       assert(base(ret.in) == in.data() + in.size());
 101       assert(base(ret.out) == out.data());
 102     }
 103   }
 104 }
 105
 106 template <class InContainer, class OutContainer, class In, class Out, class Sent = In>
 107 constexpr void test_containers() {
 108   {
 109     InContainer in {1, 2, 3, 4};
 110     OutContainer out(4);
 111     std::same_as<std::ranges::in_out_result<In, Out>> auto ret =
 112       std::ranges::copy_backward(In(in.begin()), Sent(In(in.end())), Out(out.end()));
 113     assert(std::ranges::equal(in, out));
 114     assert(base(ret.in) == in.end());
 115     assert(base(ret.out) == out.begin());
 116   }
 117   {
 118     InContainer in {1, 2, 3, 4};
 119     OutContainer out(4);
 120     auto range = std::ranges::subrange(In(in.begin()), Sent(In(in.end())));
 121     std::same_as<std::ranges::in_out_result<In, Out>> auto ret = std::ranges::copy_backward(range, Out(out.end()));
 122     assert(std::ranges::equal(in, out));
 123     assert(base(ret.in) == in.end());
 124     assert(base(ret.out) == out.begin());
 125   }
 126 }
 127
 128 template <class Iter, class Sent>
 129 constexpr void test_join_view() {
 130   auto to_subranges = std::views::transform([](auto& vec) {
 131           return std::ranges::subrange(Iter(vec.begin()), Sent(Iter(vec.end())));
 132         });
 133
 134   { // segmented -> contiguous
 135     std::vector<std::vector<int>> vectors = {};
 136     auto range = vectors | to_subranges;
 137     std::vector<std::ranges::subrange<Iter, Sent>> subrange_vector(range.begin(), range.end());
 138     std::array<int, 0> arr;
 139
 140     std::ranges::copy_backward(subrange_vector | std::views::join, arr.end());
 141     assert(std::ranges::equal(arr, std::array<int, 0>{}));
 142   }
 143   { // segmented -> contiguous
 144     std::vector<std::vector<int>> vectors = {{1, 2, 3, 4}, {5, 6, 7, 8}, {9, 10}, {}};
 145     auto range = vectors | to_subranges;
 146     std::vector<std::ranges::subrange<Iter, Sent>> subrange_vector(range.begin(), range.end());
 147     std::array<int, 10> arr;
 148
 149     std::ranges::copy_backward(subrange_vector | std::views::join, arr.end());
 150     assert(std::ranges::equal(arr, std::array{1, 2, 3, 4, 5, 6, 7, 8, 9, 10}));
 151   }
 152   { // contiguous -> segmented
 153     std::vector<std::vector<int>> vectors = {{0, 0, 0, 0}, {0, 0}, {0, 0, 0, 0}, {}};
 154     auto range = vectors | to_subranges;
 155     std::vector<std::ranges::subrange<Iter, Sent>> subrange_vector(range.begin(), range.end());
 156     std::array arr = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10};
 157
 158     std::ranges::copy_backward(arr, (subrange_vector | std::views::join).end());
 159     assert(std::ranges::equal(subrange_vector | std::views::join, std::array{1, 2, 3, 4, 5, 6, 7, 8, 9, 10}));
 160   }
 161   { // segmented -> segmented
 162     std::vector<std::vector<int>> vectors = {{1, 2, 3, 4}, {5, 6, 7, 8}, {9, 10}, {}};
 163     auto range1 = vectors | to_subranges;
 164     std::vector<std::ranges::subrange<Iter, Sent>> subrange_vector(range1.begin(), range1.end());
 165     std::vector<std::vector<int>> to_vectors = {{0, 0, 0, 0}, {0, 0, 0, 0}, {}, {0, 0}};
 166     auto range2 = to_vectors | to_subranges;
 167     std::vector<std::ranges::subrange<Iter, Sent>> to_subrange_vector(range2.begin(), range2.end());
 168
 169     std::ranges::copy_backward(subrange_vector | std::views::join, (to_subrange_vector | std::views::join).end());
 170     assert(std::ranges::equal(to_subrange_vector | std::views::join, std::array{1, 2, 3, 4, 5, 6, 7, 8, 9, 10}));
 171   }
 172 }
 173
 174 template <class>
 175 constexpr bool is_proxy_iterator = false;
 176
 177 template <class Iter>
 178 constexpr bool is_proxy_iterator<ProxyIterator<Iter>> = true;
 179
 180 template <template <class> class InIter, template <class> class OutIter>
 181 constexpr void test_sentinels() {
 182   test_iterators<InIter<int*>, OutIter<int*>, InIter<int*>>();
 183   test_iterators<InIter<int*>, OutIter<int*>, sentinel_wrapper<InIter<int*>>>();
 184   test_iterators<InIter<int*>, OutIter<int*>, sized_sentinel<InIter<int*>>>();
 185
 186   if constexpr (!std::is_same_v<InIter<int*>, contiguous_iterator<int*>> &&
 187                 !std::is_same_v<OutIter<int*>, contiguous_iterator<int*>> &&
 188                 !std::is_same_v<InIter<int*>, ContiguousProxyIterator<int*>> &&
 189                 !std::is_same_v<OutIter<int*>, ContiguousProxyIterator<int*>>) {
 190     if (!std::is_constant_evaluated()) {
 191       test_containers<std::deque<int>,
 192                       std::deque<int>,
 193                       InIter<std::deque<int>::iterator>,
 194                       OutIter<std::deque<int>::iterator>>();
 195       test_containers<std::deque<int>,
 196                       std::vector<int>,
 197                       InIter<std::deque<int>::iterator>,
 198                       OutIter<std::vector<int>::iterator>>();
 199       test_containers<std::vector<int>,
 200                       std::deque<int>,
 201                       InIter<std::vector<int>::iterator>,
 202                       OutIter<std::deque<int>::iterator>>();
 203       test_containers<std::vector<int>,
 204                       std::vector<int>,
 205                       InIter<std::vector<int>::iterator>,
 206                       OutIter<std::vector<int>::iterator>>();
 207     }
 208     if constexpr (!is_proxy_iterator<InIter<int*>>)
 209       test_join_view<InIter<std::vector<int>::iterator>, InIter<std::vector<int>::iterator>>();
 210   }
 211 }
 212
 213 template <template <class> class Out>
 214 constexpr void test_in_iterators() {
 215   test_sentinels<bidirectional_iterator, Out>();
 216   test_sentinels<random_access_iterator, Out>();
 217   test_sentinels<contiguous_iterator, Out>();
 218   test_sentinels<std::type_identity_t, Out>();
 219 }
 220
 221 template <template <class> class Out>
 222 constexpr void test_proxy_in_iterators() {
 223   test_sentinels<BidirectionalProxyIterator, Out>();
 224   test_sentinels<RandomAccessProxyIterator, Out>();
 225   test_sentinels<ContiguousProxyIterator, Out>();
 226   test_sentinels<ProxyIterator, Out>();
 227 }
 228
 229 constexpr bool test() {
 230   test_in_iterators<bidirectional_iterator>();
 231   test_in_iterators<random_access_iterator>();
 232   test_in_iterators<contiguous_iterator>();
 233   test_in_iterators<std::type_identity_t>();
 234
 235   test_proxy_in_iterators<BidirectionalProxyIterator>();
 236   test_proxy_in_iterators<RandomAccessProxyIterator>();
 237   test_proxy_in_iterators<ContiguousProxyIterator>();
 238
 239   { // check that ranges::dangling is returned
 240     std::array<int, 4> out;
 241     std::same_as<std::ranges::in_out_result<std::ranges::dangling, int*>> auto ret =
 242       std::ranges::copy_backward(std::array {1, 2, 3, 4}, out.data() + out.size());
 243     assert(ret.out == out.data());
 244     assert((out == std::array{1, 2, 3, 4}));
 245   }
 246
 247   { // check that an iterator is returned with a borrowing range
 248     std::array in {1, 2, 3, 4};
 249     std::array<int, 4> out;
 250     std::same_as<std::ranges::in_out_result<int*, int*>> auto ret =
 251         std::ranges::copy_backward(std::views::all(in), out.data() + out.size());
 252     assert(ret.in == in.data() + in.size());
 253     assert(ret.out == out.data());
 254     assert(in == out);
 255   }
 256
 257   { // check that every element is copied exactly once
 258     struct CopyOnce {
 259       bool copied = false;
 260       constexpr CopyOnce() = default;
 261       constexpr CopyOnce(const CopyOnce& other) = delete;
 262       constexpr CopyOnce& operator=(const CopyOnce& other) {
 263         assert(!other.copied);
 264         copied = true;
 265         return *this;
 266       }
 267     };
 268     {
 269       std::array<CopyOnce, 4> in {};
 270       std::array<CopyOnce, 4> out {};
 271       auto ret = std::ranges::copy_backward(in.begin(), in.end(), out.end());
 272       assert(ret.in == in.end());
 273       assert(ret.out == out.begin());
 274       assert(std::all_of(out.begin(), out.end(), [](const auto& e) { return e.copied; }));
 275     }
 276     {
 277       std::array<CopyOnce, 4> in {};
 278       std::array<CopyOnce, 4> out {};
 279       auto ret = std::ranges::copy_backward(in, out.end());
 280       assert(ret.in == in.end());
 281       assert(ret.out == out.begin());
 282       assert(std::all_of(out.begin(), out.end(), [](const auto& e) { return e.copied; }));
 283     }
 284   }
 285
 286   { // check that the range is copied backwards
 287     struct OnlyBackwardsCopyable {
 288       OnlyBackwardsCopyable* next = nullptr;
 289       bool canCopy = false;
 290       OnlyBackwardsCopyable() = default;
 291       constexpr OnlyBackwardsCopyable& operator=(const OnlyBackwardsCopyable&) {
 292         assert(canCopy);
 293         if (next != nullptr)
 294           next->canCopy = true;
 295         return *this;
 296       }
 297     };
 298     {
 299       std::array<OnlyBackwardsCopyable, 3> in {};
 300       std::array<OnlyBackwardsCopyable, 3> out {};
 301       out[1].next = &out[0];
 302       out[2].next = &out[1];
 303       out[2].canCopy = true;
 304       auto ret = std::ranges::copy_backward(in, out.end());
 305       assert(ret.in == in.end());
 306       assert(ret.out == out.begin());
 307       assert(out[0].canCopy);
 308       assert(out[1].canCopy);
 309       assert(out[2].canCopy);
 310     }
 311     {
 312       std::array<OnlyBackwardsCopyable, 3> in {};
 313       std::array<OnlyBackwardsCopyable, 3> out {};
 314       out[1].next = &out[0];
 315       out[2].next = &out[1];
 316       out[2].canCopy = true;
 317       auto ret = std::ranges::copy_backward(in.begin(), in.end(), out.end());
 318       assert(ret.in == in.end());
 319       assert(ret.out == out.begin());
 320       assert(out[0].canCopy);
 321       assert(out[1].canCopy);
 322       assert(out[2].canCopy);
 323     }
 324   }
 325
 326   return true;
 327 }
 328
 329 int main(int, char**) {
 330   test();
 331   static_assert(test());
 332
 333   return 0;
 334 }