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

// <forward_list>

// void unique();      // C++17 and before
// size_type unique(); // C++20 and after; constexpr since C++26

#include <forward_list>
#include <iterator>
#include <cassert>

#include "test_macros.h"
#include "min_allocator.h"

template <class L>
TEST_CONSTEXPR_CXX26 void do_unique(L& l, typename L::size_type expected) {
  typename L::size_type old_size = std::distance(l.begin(), l.end());
#if TEST_STD_VER > 17
  ASSERT_SAME_TYPE(decltype(l.unique()), typename L::size_type);
  assert(l.unique() == expected);
#else
  ASSERT_SAME_TYPE(decltype(l.unique()), void);
  l.unique();
#endif
  assert(old_size - std::distance(l.begin(), l.end()) == expected);
}

TEST_CONSTEXPR_CXX26 bool test() {
  {
    typedef int T;
    typedef std::forward_list<T> C;
    const T t1[] = {0, 5, 5, 0, 0, 0, 5};
    const T t2[] = {0, 5, 0, 5};
    C c1(std::begin(t1), std::end(t1));
    C c2(std::begin(t2), std::end(t2));
    do_unique(c1, 3);
    assert(c1 == c2);
  }
  {
    typedef int T;
    typedef std::forward_list<T> C;
    const T t1[] = {0, 0, 0, 0};
    const T t2[] = {0};
    C c1(std::begin(t1), std::end(t1));
    C c2(std::begin(t2), std::end(t2));
    do_unique(c1, 3);
    assert(c1 == c2);
  }
  {
    typedef int T;
    typedef std::forward_list<T> C;
    const T t1[] = {5, 5, 5};
    const T t2[] = {5};
    C c1(std::begin(t1), std::end(t1));
    C c2(std::begin(t2), std::end(t2));
    do_unique(c1, 2);
    assert(c1 == c2);
  }
  {
    typedef int T;
    typedef std::forward_list<T> C;
    C c1;
    C c2;
    do_unique(c1, 0);
    assert(c1 == c2);
  }
  {
    typedef int T;
    typedef std::forward_list<T> C;
    const T t1[] = {5, 5, 5, 0};
    const T t2[] = {5, 0};
    C c1(std::begin(t1), std::end(t1));
    C c2(std::begin(t2), std::end(t2));
    do_unique(c1, 2);
    assert(c1 == c2);
  }
#if TEST_STD_VER >= 11
  {
    typedef int T;
    typedef std::forward_list<T, min_allocator<T>> C;
    const T t1[] = {0, 5, 5, 0, 0, 0, 5};
    const T t2[] = {0, 5, 0, 5};
    C c1(std::begin(t1), std::end(t1));
    C c2(std::begin(t2), std::end(t2));
    do_unique(c1, 3);
    assert(c1 == c2);
  }
  {
    typedef int T;
    typedef std::forward_list<T, min_allocator<T>> C;
    const T t1[] = {0, 0, 0, 0};
    const T t2[] = {0};
    C c1(std::begin(t1), std::end(t1));
    C c2(std::begin(t2), std::end(t2));
    do_unique(c1, 3);
    assert(c1 == c2);
  }
  {
    typedef int T;
    typedef std::forward_list<T, min_allocator<T>> C;
    const T t1[] = {5, 5, 5};
    const T t2[] = {5};
    C c1(std::begin(t1), std::end(t1));
    C c2(std::begin(t2), std::end(t2));
    do_unique(c1, 2);
    assert(c1 == c2);
  }
  {
    typedef int T;
    typedef std::forward_list<T, min_allocator<T>> C;
    C c1;
    C c2;
    do_unique(c1, 0);
    assert(c1 == c2);
  }
  {
    typedef int T;
    typedef std::forward_list<T, min_allocator<T>> C;
    const T t1[] = {5, 5, 5, 0};
    const T t2[] = {5, 0};
    C c1(std::begin(t1), std::end(t1));
    C c2(std::begin(t2), std::end(t2));
    do_unique(c1, 2);
    assert(c1 == c2);
  }
#endif

  return true;
}

int main(int, char**) {
  assert(test());
#if TEST_STD_VER >= 26
  static_assert(test());
#endif

  return 0;
}
