//    Copyright 2022 Jij Inc.

//    Licensed under the Apache License, Version 2.0 (the "License");
//    you may not use this file except in compliance with the License.
//    You may obtain a copy of the License at

//        http://www.apache.org/licenses/LICENSE-2.0

//    Unless required by applicable law or agreed to in writing, software
//    distributed under the License is distributed on an "AS IS" BASIS,
//    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
//    See the License for the specific language governing permissions and
//    limitations under the License.

#pragma once

#include <cstddef>
#include <unordered_map>
#include <utility>

#include "openjij/graph/graph.hpp"

namespace openjij {
namespace utility {

/**
 * @brief hash class for std::pair
 */
struct PairHash {

  /**
   * @brief generate hash for std::pair
   *
   * @param p std::pair variable
   *
   * @return generated hash
   */
  template <class T1, class T2>
  inline size_t operator()(const std::pair<T1, T2> &p) const {
    size_t lhs = std::hash<T1>()(p.first);
    size_t rhs = std::hash<T2>()(p.second);
    return lhs ^ (rhs + 0x9e3779b9 + (lhs << 6) + (lhs >> 2));
  }
};
} // namespace utility
} // namespace openjij
