//===----------------------------------------------------------------------===//
//
// 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 InIter, class OutIter,
//          Callable<auto, const InIter::value_type&> Op>
//   requires OutputIterator<OutIter, Op::result_type> && CopyConstructible<Op>
// constexpr OutIter      // constexpr after C++17
//   transform(InIter first, InIter last, OutIter result, Op op);

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

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

TEST_CONSTEXPR int plusOne(int v) { return v + 1; }


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

    auto it = std::transform(std::begin(ia), std::end(ia), std::begin(ib), plusOne);

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


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

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

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

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

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

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

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

  return 0;
}