// Copyright 2021 Christian Mazakas.
// Distributed under the Boost Software License, Version 1.0. (See accompanying
// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)

// clang-format off
#include "../helpers/prefix.hpp"
#include <boost/unordered_set.hpp>
#include <boost/unordered_map.hpp>
#include "../helpers/postfix.hpp"
// clang-format on

#include "../helpers/test.hpp"

#include <boost/container_hash/hash.hpp>

struct key
{
  int x_;
  static int count_;

  key(int x) : x_(x) { ++count_; }
  key(key const& k) : x_(k.x_) { ++count_; }

  key& operator=(key const& k)
  {
    x_ = k.x_;
    ++count_;
    return *this;
  }
};

int key::count_;

struct transparent_hasher
{
  typedef void is_transparent;

  std::size_t operator()(key const& k) const
  {
    return boost::hash<int>()(k.x_);
  }

  std::size_t operator()(int const k) const { return boost::hash<int>()(k); }
};

struct transparent_key_equal
{
  typedef void is_transparent;

  static bool was_called_;

  bool operator()(key const& k1, key const& k2) const { return k1.x_ == k2.x_; }
  bool operator()(int const x, key const& k1) const
  {
    was_called_ = true;
    return k1.x_ == x;
  }
};

bool transparent_key_equal::was_called_;

UNORDERED_AUTO_TEST (unordered_map_transparent_count) {
  key::count_ = 0;
  transparent_key_equal::was_called_ = false;

  boost::unordered_map<key, int, transparent_hasher, transparent_key_equal> map;

  // initial `key(0)` expression increases the count
  // then copying into the `unordered_map` increments the count again thus we
  // have 2
  //
  map[key(0)] = 1337;
  BOOST_TEST(key::count_ == 2);

  // now the number of `key` objects created should be a constant and never
  // touched again
  //
  std::size_t count = 0;
  count = map.count(0);

  BOOST_TEST(count == 1);
  BOOST_TEST(key::count_ == 2);
  BOOST_TEST(map.key_eq().was_called_);

  count = map.count(1);

  BOOST_TEST(count == 0);
  BOOST_TEST(key::count_ == 2);

  count = map.count(key(0));
  BOOST_TEST(count == 1);
  BOOST_TEST(key::count_ > 2);
}

RUN_TESTS()