llvm-project/libcxx/test/std/algorithms/alg.modifying.operations/alg.rotate/rotate_copy.pass.cpp

//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//

// <algorithm>

// template<ForwardIterator InIter, OutputIterator<auto, InIter::reference> OutIter>
//   constexpr OutIter          // constexpr since C++20
//   rotate_copy(InIter first, InIter middle, InIter last, OutIter result);

#include <algorithm>
#include <cassert>

#include "test_macros.h"
#include "test_iterators.h"
#include "type_algorithms.h"

struct TestIter {
  template <class InIter>
  TEST_CONSTEXPR_CXX20 void operator()() const {
    types::for_each(
        types::concatenate_t<types::forward_iterator_list<int*>, types::type_list<cpp17_output_iterator<int*> > >(),
        TestImpl<InIter>());
  }

  template <class InIter>
  struct TestImpl {
    template <class OutIter>
    TEST_CONSTEXPR_CXX20 void operator()() const {
      int ia[]          = {0, 1, 2, 3};
      const unsigned sa = sizeof(ia) / sizeof(ia[0]);
      int ib[sa]        = {0};

      OutIter r = std::rotate_copy(InIter(ia), InIter(ia), InIter(ia), OutIter(ib));
      assert(base(r) == ib);

      r = std::rotate_copy(InIter(ia), InIter(ia), InIter(ia + 1), OutIter(ib));
      assert(base(r) == ib + 1);
      assert(ib[0] == 0);

      r = std::rotate_copy(InIter(ia), InIter(ia + 1), InIter(ia + 1), OutIter(ib));
      assert(base(r) == ib + 1);
      assert(ib[0] == 0);

      r = std::rotate_copy(InIter(ia), InIter(ia), InIter(ia + 2), OutIter(ib));
      assert(base(r) == ib + 2);
      assert(ib[0] == 0);
      assert(ib[1] == 1);

      r = std::rotate_copy(InIter(ia), InIter(ia + 1), InIter(ia + 2), OutIter(ib));
      assert(base(r) == ib + 2);
      assert(ib[0] == 1);
      assert(ib[1] == 0);

      r = std::rotate_copy(InIter(ia), InIter(ia + 2), InIter(ia + 2), OutIter(ib));
      assert(base(r) == ib + 2);
      assert(ib[0] == 0);
      assert(ib[1] == 1);

      r = std::rotate_copy(InIter(ia), InIter(ia), InIter(ia + 3), OutIter(ib));
      assert(base(r) == ib + 3);
      assert(ib[0] == 0);
      assert(ib[1] == 1);
      assert(ib[2] == 2);

      r = std::rotate_copy(InIter(ia), InIter(ia + 1), InIter(ia + 3), OutIter(ib));
      assert(base(r) == ib + 3);
      assert(ib[0] == 1);
      assert(ib[1] == 2);
      assert(ib[2] == 0);

      r = std::rotate_copy(InIter(ia), InIter(ia + 2), InIter(ia + 3), OutIter(ib));
      assert(base(r) == ib + 3);
      assert(ib[0] == 2);
      assert(ib[1] == 0);
      assert(ib[2] == 1);

      r = std::rotate_copy(InIter(ia), InIter(ia + 3), InIter(ia + 3), OutIter(ib));
      assert(base(r) == ib + 3);
      assert(ib[0] == 0);
      assert(ib[1] == 1);
      assert(ib[2] == 2);

      r = std::rotate_copy(InIter(ia), InIter(ia), InIter(ia + 4), OutIter(ib));
      assert(base(r) == ib + 4);
      assert(ib[0] == 0);
      assert(ib[1] == 1);
      assert(ib[2] == 2);
      assert(ib[3] == 3);

      r = std::rotate_copy(InIter(ia), InIter(ia + 1), InIter(ia + 4), OutIter(ib));
      assert(base(r) == ib + 4);
      assert(ib[0] == 1);
      assert(ib[1] == 2);
      assert(ib[2] == 3);
      assert(ib[3] == 0);

      r = std::rotate_copy(InIter(ia), InIter(ia + 2), InIter(ia + 4), OutIter(ib));
      assert(base(r) == ib + 4);
      assert(ib[0] == 2);
      assert(ib[1] == 3);
      assert(ib[2] == 0);
      assert(ib[3] == 1);

      r = std::rotate_copy(InIter(ia), InIter(ia + 3), InIter(ia + 4), OutIter(ib));
      assert(base(r) == ib + 4);
      assert(ib[0] == 3);
      assert(ib[1] == 0);
      assert(ib[2] == 1);
      assert(ib[3] == 2);

      r = std::rotate_copy(InIter(ia), InIter(ia + 4), InIter(ia + 4), OutIter(ib));
      assert(base(r) == ib + 4);
      assert(ib[0] == 0);
      assert(ib[1] == 1);
      assert(ib[2] == 2);
      assert(ib[3] == 3);

      {
        int ints[]        = {1, 3, 5, 2, 5, 6};
        int const n_ints  = sizeof(ints) / sizeof(int);
        int zeros[n_ints] = {0};

        const std::size_t N = 2;
        const auto middle   = std::begin(ints) + N;
        auto it             = std::rotate_copy(std::begin(ints), middle, std::end(ints), std::begin(zeros));
        assert(std::distance(std::begin(zeros), it) == n_ints);
        assert(std::equal(std::begin(ints), middle, std::begin(zeros) + n_ints - N));
        assert(std::equal(middle, std::end(ints), std::begin(zeros)));
      }
    }
  };
};

TEST_CONSTEXPR_CXX20 bool test() {
  types::for_each(types::bidirectional_iterator_list<const int*>(), TestIter());
  return true;
}

int main(int, char**) {
  test();

#if TEST_STD_VER >= 20
  static_assert(test());
#endif
  return 0;
}