//===----------------------------------------------------------------------===//
//
// 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<InputIterator InIter1, InputIterator InIter2, class OutIter,
//          Callable<auto, const InIter1::value_type&, const InIter2::value_type&> BinaryOp>
//   requires OutputIterator<OutIter, BinaryOp::result_type> && CopyConstructible<BinaryOp>
// constexpr OutIter      // constexpr after C++17
// transform(InIter1 first1, InIter1 last1, InIter2 first2, OutIter result, BinaryOp binary_op);

#include <algorithm>
#include <functional>
#include <cassert>

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

#if TEST_STD_VER > 17
TEST_CONSTEXPR bool test_constexpr() {
    const int ia[] = {1, 3, 6, 7};
    const int ib[] = {2, 4, 7, 8};
          int ic[] = {0, 0, 0, 0, 0}; // one bigger
    const int expected[] = {3, 7, 13, 15};

    auto it = std::transform(std::begin(ia), std::end(ia),
                             std::begin(ib), std::begin(ic), std::plus<int>());

    return it == (std::begin(ic) + std::size(ia))
        && *it == 0 // don't overwrite the last value in the output array
        && std::equal(std::begin(expected), std::end(expected), std::begin(ic), it)
        ;
    }
#endif


template<class InIter1, class InIter2, class OutIter>
void
test()
{
    int ia[] = {0, 1, 2, 3, 4};
    const unsigned sa = sizeof(ia)/sizeof(ia[0]);
    int ib[sa] = {1, 2, 3, 4, 5};
    OutIter r = std::transform(InIter1(ib), InIter1(ib+sa), InIter2(ia),
                               OutIter(ib), std::minus<int>());
    assert(base(r) == ib + sa);
    assert(ib[0] == 1);
    assert(ib[1] == 1);
    assert(ib[2] == 1);
    assert(ib[3] == 1);
    assert(ib[4] == 1);
}

int main(int, char**)
{
    test<cpp17_input_iterator<const int*>, cpp17_input_iterator<const int*>, cpp17_output_iterator<int*> >();
    test<cpp17_input_iterator<const int*>, cpp17_input_iterator<const int*>, cpp17_input_iterator<int*> >();
    test<cpp17_input_iterator<const int*>, cpp17_input_iterator<const int*>, forward_iterator<int*> >();
    test<cpp17_input_iterator<const int*>, cpp17_input_iterator<const int*>, bidirectional_iterator<int*> >();
    test<cpp17_input_iterator<const int*>, cpp17_input_iterator<const int*>, random_access_iterator<int*> >();
    test<cpp17_input_iterator<const int*>, cpp17_input_iterator<const int*>, int*>();

    test<cpp17_input_iterator<const int*>, forward_iterator<const int*>, cpp17_output_iterator<int*> >();
    test<cpp17_input_iterator<const int*>, forward_iterator<const int*>, cpp17_input_iterator<int*> >();
    test<cpp17_input_iterator<const int*>, forward_iterator<const int*>, forward_iterator<int*> >();
    test<cpp17_input_iterator<const int*>, forward_iterator<const int*>, bidirectional_iterator<int*> >();
    test<cpp17_input_iterator<const int*>, forward_iterator<const int*>, random_access_iterator<int*> >();
    test<cpp17_input_iterator<const int*>, forward_iterator<const int*>, int*>();

    test<cpp17_input_iterator<const int*>, bidirectional_iterator<const int*>, cpp17_output_iterator<int*> >();
    test<cpp17_input_iterator<const int*>, bidirectional_iterator<const int*>, cpp17_input_iterator<int*> >();
    test<cpp17_input_iterator<const int*>, bidirectional_iterator<const int*>, forward_iterator<int*> >();
    test<cpp17_input_iterator<const int*>, bidirectional_iterator<const int*>, bidirectional_iterator<int*> >();
    test<cpp17_input_iterator<const int*>, bidirectional_iterator<const int*>, random_access_iterator<int*> >();
    test<cpp17_input_iterator<const int*>, bidirectional_iterator<const int*>, int*>();

    test<cpp17_input_iterator<const int*>, random_access_iterator<const int*>, cpp17_output_iterator<int*> >();
    test<cpp17_input_iterator<const int*>, random_access_iterator<const int*>, cpp17_input_iterator<int*> >();
    test<cpp17_input_iterator<const int*>, random_access_iterator<const int*>, forward_iterator<int*> >();
    test<cpp17_input_iterator<const int*>, random_access_iterator<const int*>, bidirectional_iterator<int*> >();
    test<cpp17_input_iterator<const int*>, random_access_iterator<const int*>, random_access_iterator<int*> >();
    test<cpp17_input_iterator<const int*>, random_access_iterator<const int*>, int*>();

    test<cpp17_input_iterator<const int*>, const int*, cpp17_output_iterator<int*> >();
    test<cpp17_input_iterator<const int*>, const int*, cpp17_input_iterator<int*> >();
    test<cpp17_input_iterator<const int*>, const int*, forward_iterator<int*> >();
    test<cpp17_input_iterator<const int*>, const int*, bidirectional_iterator<int*> >();
    test<cpp17_input_iterator<const int*>, const int*, random_access_iterator<int*> >();
    test<cpp17_input_iterator<const int*>, const int*, int*>();

    test<forward_iterator<const int*>, cpp17_input_iterator<const int*>, cpp17_output_iterator<int*> >();
    test<forward_iterator<const int*>, cpp17_input_iterator<const int*>, cpp17_input_iterator<int*> >();
    test<forward_iterator<const int*>, cpp17_input_iterator<const int*>, forward_iterator<int*> >();
    test<forward_iterator<const int*>, cpp17_input_iterator<const int*>, bidirectional_iterator<int*> >();
    test<forward_iterator<const int*>, cpp17_input_iterator<const int*>, random_access_iterator<int*> >();
    test<forward_iterator<const int*>, cpp17_input_iterator<const int*>, int*>();

    test<forward_iterator<const int*>, forward_iterator<const int*>, cpp17_output_iterator<int*> >();
    test<forward_iterator<const int*>, forward_iterator<const int*>, cpp17_input_iterator<int*> >();
    test<forward_iterator<const int*>, forward_iterator<const int*>, forward_iterator<int*> >();
    test<forward_iterator<const int*>, forward_iterator<const int*>, bidirectional_iterator<int*> >();
    test<forward_iterator<const int*>, forward_iterator<const int*>, random_access_iterator<int*> >();
    test<forward_iterator<const int*>, forward_iterator<const int*>, int*>();

    test<forward_iterator<const int*>, bidirectional_iterator<const int*>, cpp17_output_iterator<int*> >();
    test<forward_iterator<const int*>, bidirectional_iterator<const int*>, cpp17_input_iterator<int*> >();
    test<forward_iterator<const int*>, bidirectional_iterator<const int*>, forward_iterator<int*> >();
    test<forward_iterator<const int*>, bidirectional_iterator<const int*>, bidirectional_iterator<int*> >();
    test<forward_iterator<const int*>, bidirectional_iterator<const int*>, random_access_iterator<int*> >();
    test<forward_iterator<const int*>, bidirectional_iterator<const int*>, int*>();

    test<forward_iterator<const int*>, random_access_iterator<const int*>, cpp17_output_iterator<int*> >();
    test<forward_iterator<const int*>, random_access_iterator<const int*>, cpp17_input_iterator<int*> >();
    test<forward_iterator<const int*>, random_access_iterator<const int*>, forward_iterator<int*> >();
    test<forward_iterator<const int*>, random_access_iterator<const int*>, bidirectional_iterator<int*> >();
    test<forward_iterator<const int*>, random_access_iterator<const int*>, random_access_iterator<int*> >();
    test<forward_iterator<const int*>, random_access_iterator<const int*>, int*>();

    test<forward_iterator<const int*>, const int*, cpp17_output_iterator<int*> >();
    test<forward_iterator<const int*>, const int*, cpp17_input_iterator<int*> >();
    test<forward_iterator<const int*>, const int*, forward_iterator<int*> >();
    test<forward_iterator<const int*>, const int*, bidirectional_iterator<int*> >();
    test<forward_iterator<const int*>, const int*, random_access_iterator<int*> >();
    test<forward_iterator<const int*>, const int*, int*>();

    test<bidirectional_iterator<const int*>, cpp17_input_iterator<const int*>, cpp17_output_iterator<int*> >();
    test<bidirectional_iterator<const int*>, cpp17_input_iterator<const int*>, cpp17_input_iterator<int*> >();
    test<bidirectional_iterator<const int*>, cpp17_input_iterator<const int*>, forward_iterator<int*> >();
    test<bidirectional_iterator<const int*>, cpp17_input_iterator<const int*>, bidirectional_iterator<int*> >();
    test<bidirectional_iterator<const int*>, cpp17_input_iterator<const int*>, random_access_iterator<int*> >();
    test<bidirectional_iterator<const int*>, cpp17_input_iterator<const int*>, int*>();

    test<bidirectional_iterator<const int*>, forward_iterator<const int*>, cpp17_output_iterator<int*> >();
    test<bidirectional_iterator<const int*>, forward_iterator<const int*>, cpp17_input_iterator<int*> >();
    test<bidirectional_iterator<const int*>, forward_iterator<const int*>, forward_iterator<int*> >();
    test<bidirectional_iterator<const int*>, forward_iterator<const int*>, bidirectional_iterator<int*> >();
    test<bidirectional_iterator<const int*>, forward_iterator<const int*>, random_access_iterator<int*> >();
    test<bidirectional_iterator<const int*>, forward_iterator<const int*>, int*>();

    test<bidirectional_iterator<const int*>, bidirectional_iterator<const int*>, cpp17_output_iterator<int*> >();
    test<bidirectional_iterator<const int*>, bidirectional_iterator<const int*>, cpp17_input_iterator<int*> >();
    test<bidirectional_iterator<const int*>, bidirectional_iterator<const int*>, forward_iterator<int*> >();
    test<bidirectional_iterator<const int*>, bidirectional_iterator<const int*>, bidirectional_iterator<int*> >();
    test<bidirectional_iterator<const int*>, bidirectional_iterator<const int*>, random_access_iterator<int*> >();
    test<bidirectional_iterator<const int*>, bidirectional_iterator<const int*>, int*>();

    test<bidirectional_iterator<const int*>, random_access_iterator<const int*>, cpp17_output_iterator<int*> >();
    test<bidirectional_iterator<const int*>, random_access_iterator<const int*>, cpp17_input_iterator<int*> >();
    test<bidirectional_iterator<const int*>, random_access_iterator<const int*>, forward_iterator<int*> >();
    test<bidirectional_iterator<const int*>, random_access_iterator<const int*>, bidirectional_iterator<int*> >();
    test<bidirectional_iterator<const int*>, random_access_iterator<const int*>, random_access_iterator<int*> >();
    test<bidirectional_iterator<const int*>, random_access_iterator<const int*>, int*>();

    test<bidirectional_iterator<const int*>, const int*, cpp17_output_iterator<int*> >();
    test<bidirectional_iterator<const int*>, const int*, cpp17_input_iterator<int*> >();
    test<bidirectional_iterator<const int*>, const int*, forward_iterator<int*> >();
    test<bidirectional_iterator<const int*>, const int*, bidirectional_iterator<int*> >();
    test<bidirectional_iterator<const int*>, const int*, random_access_iterator<int*> >();
    test<bidirectional_iterator<const int*>, const int*, int*>();

    test<random_access_iterator<const int*>, cpp17_input_iterator<const int*>, cpp17_output_iterator<int*> >();
    test<random_access_iterator<const int*>, cpp17_input_iterator<const int*>, cpp17_input_iterator<int*> >();
    test<random_access_iterator<const int*>, cpp17_input_iterator<const int*>, forward_iterator<int*> >();
    test<random_access_iterator<const int*>, cpp17_input_iterator<const int*>, bidirectional_iterator<int*> >();
    test<random_access_iterator<const int*>, cpp17_input_iterator<const int*>, random_access_iterator<int*> >();
    test<random_access_iterator<const int*>, cpp17_input_iterator<const int*>, int*>();

    test<random_access_iterator<const int*>, forward_iterator<const int*>, cpp17_output_iterator<int*> >();
    test<random_access_iterator<const int*>, forward_iterator<const int*>, cpp17_input_iterator<int*> >();
    test<random_access_iterator<const int*>, forward_iterator<const int*>, forward_iterator<int*> >();
    test<random_access_iterator<const int*>, forward_iterator<const int*>, bidirectional_iterator<int*> >();
    test<random_access_iterator<const int*>, forward_iterator<const int*>, random_access_iterator<int*> >();
    test<random_access_iterator<const int*>, forward_iterator<const int*>, int*>();

    test<random_access_iterator<const int*>, bidirectional_iterator<const int*>, cpp17_output_iterator<int*> >();
    test<random_access_iterator<const int*>, bidirectional_iterator<const int*>, cpp17_input_iterator<int*> >();
    test<random_access_iterator<const int*>, bidirectional_iterator<const int*>, forward_iterator<int*> >();
    test<random_access_iterator<const int*>, bidirectional_iterator<const int*>, bidirectional_iterator<int*> >();
    test<random_access_iterator<const int*>, bidirectional_iterator<const int*>, random_access_iterator<int*> >();
    test<random_access_iterator<const int*>, bidirectional_iterator<const int*>, int*>();

    test<random_access_iterator<const int*>, random_access_iterator<const int*>, cpp17_output_iterator<int*> >();
    test<random_access_iterator<const int*>, random_access_iterator<const int*>, cpp17_input_iterator<int*> >();
    test<random_access_iterator<const int*>, random_access_iterator<const int*>, forward_iterator<int*> >();
    test<random_access_iterator<const int*>, random_access_iterator<const int*>, bidirectional_iterator<int*> >();
    test<random_access_iterator<const int*>, random_access_iterator<const int*>, random_access_iterator<int*> >();
    test<random_access_iterator<const int*>, random_access_iterator<const int*>, int*>();

    test<random_access_iterator<const int*>, const int*, cpp17_output_iterator<int*> >();
    test<random_access_iterator<const int*>, const int*, cpp17_input_iterator<int*> >();
    test<random_access_iterator<const int*>, const int*, forward_iterator<int*> >();
    test<random_access_iterator<const int*>, const int*, bidirectional_iterator<int*> >();
    test<random_access_iterator<const int*>, const int*, random_access_iterator<int*> >();
    test<random_access_iterator<const int*>, const int*, int*>();

    test<const int*, cpp17_input_iterator<const int*>, cpp17_output_iterator<int*> >();
    test<const int*, cpp17_input_iterator<const int*>, cpp17_input_iterator<int*> >();
    test<const int*, cpp17_input_iterator<const int*>, forward_iterator<int*> >();
    test<const int*, cpp17_input_iterator<const int*>, bidirectional_iterator<int*> >();
    test<const int*, cpp17_input_iterator<const int*>, random_access_iterator<int*> >();
    test<const int*, cpp17_input_iterator<const int*>, int*>();

    test<const int*, forward_iterator<const int*>, cpp17_output_iterator<int*> >();
    test<const int*, forward_iterator<const int*>, cpp17_input_iterator<int*> >();
    test<const int*, forward_iterator<const int*>, forward_iterator<int*> >();
    test<const int*, forward_iterator<const int*>, bidirectional_iterator<int*> >();
    test<const int*, forward_iterator<const int*>, random_access_iterator<int*> >();
    test<const int*, forward_iterator<const int*>, int*>();

    test<const int*, bidirectional_iterator<const int*>, cpp17_output_iterator<int*> >();
    test<const int*, bidirectional_iterator<const int*>, cpp17_input_iterator<int*> >();
    test<const int*, bidirectional_iterator<const int*>, forward_iterator<int*> >();
    test<const int*, bidirectional_iterator<const int*>, bidirectional_iterator<int*> >();
    test<const int*, bidirectional_iterator<const int*>, random_access_iterator<int*> >();
    test<const int*, bidirectional_iterator<const int*>, int*>();

    test<const int*, random_access_iterator<const int*>, cpp17_output_iterator<int*> >();
    test<const int*, random_access_iterator<const int*>, cpp17_input_iterator<int*> >();
    test<const int*, random_access_iterator<const int*>, forward_iterator<int*> >();
    test<const int*, random_access_iterator<const int*>, bidirectional_iterator<int*> >();
    test<const int*, random_access_iterator<const int*>, random_access_iterator<int*> >();
    test<const int*, random_access_iterator<const int*>, int*>();

    test<const int*, const int*, cpp17_output_iterator<int*> >();
    test<const int*, const int*, cpp17_input_iterator<int*> >();
    test<const int*, const int*, forward_iterator<int*> >();
    test<const int*, const int*, bidirectional_iterator<int*> >();
    test<const int*, const int*, random_access_iterator<int*> >();
    test<const int*, const int*, int*>();

#if TEST_STD_VER > 17
    static_assert(test_constexpr());
#endif

  return 0;
}
