//===----------------------------------------------------------------------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is dual licensed under the MIT and the University of Illinois Open
// Source Licenses. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//

// <algorithm>

// template<InputIterator Iter1, InputIterator Iter2, CopyConstructible Compare>
//   requires Predicate<Compare, Iter1::value_type, Iter2::value_type>
//         && Predicate<Compare, Iter2::value_type, Iter1::value_type>
//   constexpr bool             // constexpr after C++17
//   lexicographical_compare(Iter1 first1, Iter1 last1,
//                           Iter2 first2, Iter2 last2, Compare comp);

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

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

#if TEST_STD_VER > 17
TEST_CONSTEXPR bool test_constexpr() {
    int ia[] = {1, 2, 3};
    int ib[] = {1, 3, 5, 2, 4, 6};

    std::greater<int> pred{};
    return !std::lexicographical_compare(std::begin(ia), std::end(ia), std::begin(ib), std::end(ib), pred)
        &&  std::lexicographical_compare(std::begin(ib), std::end(ib), std::begin(ia), std::end(ia), pred)
           ;
    }
#endif

template <class Iter1, class Iter2>
void
test()
{
    int ia[] = {1, 2, 3, 4};
    const unsigned sa = sizeof(ia)/sizeof(ia[0]);
    int ib[] = {1, 2, 3};
    typedef std::greater<int> C;
    C c;
    assert(!std::lexicographical_compare(Iter1(ia),   Iter1(ia+sa), Iter2(ib),   Iter2(ib+2),  c));
    assert( std::lexicographical_compare(Iter1(ib),   Iter1(ib+2),  Iter2(ia),   Iter2(ia+sa), c));
    assert(!std::lexicographical_compare(Iter1(ia),   Iter1(ia+sa), Iter2(ib),   Iter2(ib+3),  c));
    assert( std::lexicographical_compare(Iter1(ib),   Iter1(ib+3),  Iter2(ia),   Iter2(ia+sa), c));
    assert(!std::lexicographical_compare(Iter1(ia),   Iter1(ia+sa), Iter2(ib+1), Iter2(ib+3),  c));
    assert( std::lexicographical_compare(Iter1(ib+1), Iter1(ib+3),  Iter2(ia),   Iter2(ia+sa), c));
}

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

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

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

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

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

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