//===----------------------------------------------------------------------===//
//
// 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 Iter1, ForwardIterator Iter2,
//          Predicate<auto, Iter1::value_type, Iter2::value_type> Pred>
//   requires CopyConstructible<Pred>
//   constexpr Iter1  // constexpr after C++17
//   find_end(Iter1 first1, Iter1 last1, Iter2 first2, Iter2 last2, Pred pred);

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

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

struct count_equal
{
    static unsigned count;
    template <class T>
    TEST_CONSTEXPR_CXX14 bool operator()(const T& x, const T& y)
        {++count; return x == y;}
};

#if TEST_STD_VER > 17
constexpr bool test_constexpr() {
    int ia[] = {0, 1, 2};
    int ib[] = {4, 5, 6};
    int ic[] = {0, 1, 2, 3, 4, 5, 0, 1, 2, 3, 4, 0, 1, 2, 3, 0, 1, 2, 0, 1, 0};
    typedef forward_iterator<int*>       FI;
    typedef bidirectional_iterator<int*> BI;
    typedef random_access_iterator<int*> RI;
    std::equal_to<int> eq{};
    return    (std::find_end(FI(std::begin(ic)), FI(std::end(ic)), FI(std::begin(ia)), FI(std::end(ia)), eq) == FI(ic+15))
           && (std::find_end(FI(std::begin(ic)), FI(std::end(ic)), FI(std::begin(ib)), FI(std::end(ib)), eq) == FI(std::end(ic)))
           && (std::find_end(BI(std::begin(ic)), BI(std::end(ic)), BI(std::begin(ia)), BI(std::end(ia)), eq) == BI(ic+15))
           && (std::find_end(BI(std::begin(ic)), BI(std::end(ic)), BI(std::begin(ib)), BI(std::end(ib)), eq) == BI(std::end(ic)))
           && (std::find_end(RI(std::begin(ic)), RI(std::end(ic)), RI(std::begin(ia)), RI(std::end(ia)), eq) == RI(ic+15))
           && (std::find_end(RI(std::begin(ic)), RI(std::end(ic)), RI(std::begin(ib)), RI(std::end(ib)), eq) == RI(std::end(ic)))
           ;
    }
#endif

unsigned count_equal::count = 0;

template <class Iter1, class Iter2>
void
test()
{
    int ia[] = {0, 1, 2, 3, 4, 5, 0, 1, 2, 3, 4, 0, 1, 2, 3, 0, 1, 2, 0, 1, 0};
    const unsigned sa = sizeof(ia)/sizeof(ia[0]);
    int b[] = {0};
    count_equal::count = 0;
    assert(std::find_end(Iter1(ia), Iter1(ia+sa), Iter2(b), Iter2(b+1), count_equal()) == Iter1(ia+sa-1));
    assert(count_equal::count <= 1*(sa-1+1));
    int c[] = {0, 1};
    count_equal::count = 0;
    assert(std::find_end(Iter1(ia), Iter1(ia+sa), Iter2(c), Iter2(c+2), count_equal()) == Iter1(ia+18));
    assert(count_equal::count <= 2*(sa-2+1));
    int d[] = {0, 1, 2};
    count_equal::count = 0;
    assert(std::find_end(Iter1(ia), Iter1(ia+sa), Iter2(d), Iter2(d+3), count_equal()) == Iter1(ia+15));
    assert(count_equal::count <= 3*(sa-3+1));
    int e[] = {0, 1, 2, 3};
    count_equal::count = 0;
    assert(std::find_end(Iter1(ia), Iter1(ia+sa), Iter2(e), Iter2(e+4), count_equal()) == Iter1(ia+11));
    assert(count_equal::count <= 4*(sa-4+1));
    int f[] = {0, 1, 2, 3, 4};
    count_equal::count = 0;
    assert(std::find_end(Iter1(ia), Iter1(ia+sa), Iter2(f), Iter2(f+5), count_equal()) == Iter1(ia+6));
    assert(count_equal::count <= 5*(sa-5+1));
    int g[] = {0, 1, 2, 3, 4, 5};
    count_equal::count = 0;
    assert(std::find_end(Iter1(ia), Iter1(ia+sa), Iter2(g), Iter2(g+6), count_equal()) == Iter1(ia));
    assert(count_equal::count <= 6*(sa-6+1));
    int h[] = {0, 1, 2, 3, 4, 5, 6};
    count_equal::count = 0;
    assert(std::find_end(Iter1(ia), Iter1(ia+sa), Iter2(h), Iter2(h+7), count_equal()) == Iter1(ia+sa));
    assert(count_equal::count <= 7*(sa-7+1));
    count_equal::count = 0;
    assert(std::find_end(Iter1(ia), Iter1(ia+sa), Iter2(b), Iter2(b), count_equal()) == Iter1(ia+sa));
    assert(count_equal::count <= 0);
    count_equal::count = 0;
    assert(std::find_end(Iter1(ia), Iter1(ia), Iter2(b), Iter2(b+1), count_equal()) == Iter1(ia));
    assert(count_equal::count <= 0);
}

int main(int, char**)
{
    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<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<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*> >();

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

  return 0;
}