//===----------------------------------------------------------------------===//
//
// 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
//
//===----------------------------------------------------------------------===//

// <numeric>
// UNSUPPORTED: c++03, c++11, c++14
// UNSUPPORTED: clang-8
// UNSUPPORTED: gcc-9

// Became constexpr in C++20
// template <class InputIterator1, class InputIterator2, class T>
//   T transform_reduce(InputIterator1 first1, InputIterator1 last1,
//                      InputIterator2 first2, T init);


#include <numeric>
#include <cassert>
#include <iterator>

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

template <class Iter1, class Iter2, class T>
TEST_CONSTEXPR_CXX20 void
test(Iter1 first1, Iter1 last1, Iter2 first2, T init, T x)
{
    static_assert( std::is_same_v<T,
            decltype(std::transform_reduce(first1, last1, first2, init))> );
    assert(std::transform_reduce(first1, last1, first2, init) == x);
}

template <class SIter, class UIter>
TEST_CONSTEXPR_CXX20 void
test()
{
    int ia[]          = {1, 2, 3, 4, 5, 6};
    unsigned int ua[] = {2, 4, 6, 8, 10,12};
    unsigned sa = sizeof(ia) / sizeof(ia[0]);
    assert(sa == sizeof(ua) / sizeof(ua[0]));       // just to be sure

    test(SIter(ia), SIter(ia),    UIter(ua), 0,   0);
    test(UIter(ua), UIter(ua),    SIter(ia), 1,   1);
    test(SIter(ia), SIter(ia+1),  UIter(ua), 0,   2);
    test(UIter(ua), UIter(ua+1),  SIter(ia), 2,   4);
    test(SIter(ia), SIter(ia+2),  UIter(ua), 0,  10);
    test(UIter(ua), UIter(ua+2),  SIter(ia), 3,  13);
    test(SIter(ia), SIter(ia+sa), UIter(ua), 0, 182);
    test(UIter(ua), UIter(ua+sa), SIter(ia), 4, 186);
}

template <typename T, typename Init>
TEST_CONSTEXPR_CXX20 void
test_return_type()
{
    T *p = nullptr;
    static_assert( std::is_same_v<Init,
                       decltype(std::transform_reduce(p, p, p, Init{}))> );
}

TEST_CONSTEXPR_CXX20 void
test_move_only_types()
{
    MoveOnly ia[] = {{1}, {2}, {3}};
    MoveOnly ib[] = {{1}, {2}, {3}};
    assert(14 ==
        std::transform_reduce(std::begin(ia), std::end(ia), std::begin(ib), MoveOnly{0}).get());
}

TEST_CONSTEXPR_CXX20 bool
test()
{
    test_return_type<char, int>();
    test_return_type<int, int>();
    test_return_type<int, unsigned long>();
    test_return_type<float, int>();
    test_return_type<short, float>();
    test_return_type<double, char>();
    test_return_type<char, double>();

//  All the iterator categories
    test<input_iterator        <const int*>, input_iterator        <const unsigned int*> >();
    test<input_iterator        <const int*>, forward_iterator      <const unsigned int*> >();
    test<input_iterator        <const int*>, bidirectional_iterator<const unsigned int*> >();
    test<input_iterator        <const int*>, random_access_iterator<const unsigned int*> >();

    test<forward_iterator      <const int*>, input_iterator        <const unsigned int*> >();
    test<forward_iterator      <const int*>, forward_iterator      <const unsigned int*> >();
    test<forward_iterator      <const int*>, bidirectional_iterator<const unsigned int*> >();
    test<forward_iterator      <const int*>, random_access_iterator<const unsigned int*> >();

    test<bidirectional_iterator<const int*>, input_iterator        <const unsigned int*> >();
    test<bidirectional_iterator<const int*>, forward_iterator      <const unsigned int*> >();
    test<bidirectional_iterator<const int*>, bidirectional_iterator<const unsigned int*> >();
    test<bidirectional_iterator<const int*>, random_access_iterator<const unsigned int*> >();

    test<random_access_iterator<const int*>, input_iterator        <const unsigned int*> >();
    test<random_access_iterator<const int*>, forward_iterator      <const unsigned int*> >();
    test<random_access_iterator<const int*>, bidirectional_iterator<const unsigned int*> >();
    test<random_access_iterator<const int*>, random_access_iterator<const unsigned int*> >();

//  just plain pointers (const vs. non-const, too)
    test<const int*, const unsigned int *>();
    test<const int*,       unsigned int *>();
    test<      int*, const unsigned int *>();
    test<      int*,       unsigned int *>();

    test_move_only_types();

    return true;
}

int main(int, char**)
{
    test();
#if TEST_STD_VER > 17
    static_assert(test());
#endif
    return 0;
}