//===----------------------------------------------------------------------===//
//
// 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>

// template <class Compare> void sort(Compare comp);

#include <forward_list>
#include <iterator>
#include <algorithm>
#include <vector>
#include <functional>
#include <random>
#include <cassert>

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

std::mt19937 randomness;

struct Payload {
  int val;
  int side;
  Payload(int v) : val(v), side(0) {}
  Payload(int v, int s) : val(v), side(s) {}
  bool operator<(const Payload& rhs) const { return val < rhs.val; }
};

bool greater(const Payload& lhs, const Payload& rhs) { return lhs.val > rhs.val; }

void test_stable(int N) {
  typedef Payload T;
  typedef std::forward_list<T> C;
  typedef std::vector<T> V;
  V v;
  for (int i = 0; i < N; ++i)
    v.push_back(Payload(i / 2));
  std::shuffle(v.begin(), v.end(), randomness);
  for (int i = 0; i < N; ++i)
    v[i].side = i;

  C c(v.begin(), v.end());
  c.sort(greater);
  assert(std::distance(c.begin(), c.end()) == N);

  //  Are we sorted?
  typename C::const_iterator j = c.begin();
  for (int i = 0; i < N; ++i, ++j)
    assert(j->val == (N - 1 - i) / 2);

  //  Are we stable?
  for (C::const_iterator it = c.begin(); it != c.end(); ++it) {
    C::const_iterator next = std::next(it);
    if (next != c.end() && it->val == next->val)
      assert(it->side < next->side);
  }
}

template <class C>
void test(int N) {
  typedef typename C::value_type T;
  typedef std::vector<T> V;
  V v;
  for (int i = 0; i < N; ++i)
    v.push_back(i);
  std::shuffle(v.begin(), v.end(), randomness);
  C c(v.begin(), v.end());
  c.sort(std::greater<T>());
  assert(std::distance(c.begin(), c.end()) == N);
  typename C::const_iterator j = c.begin();
  for (int i = 0; i < N; ++i, ++j)
    assert(*j == N - 1 - i);
}

int main(int, char**) {
  for (int i = 0; i < 40; ++i)
    test<std::forward_list<int> >(i);
#if TEST_STD_VER >= 11
  for (int i = 0; i < 40; ++i)
    test<std::forward_list<int, min_allocator<int>> >(i);
#endif

  for (int i = 0; i < 40; ++i)
    test_stable(i);

  return 0;
}
