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/** @author Jia Pan */

#ifndef COAL_BROADPHASE_SPARSEHASHTABLE_H
#define COAL_BROADPHASE_SPARSEHASHTABLE_H

#include <set>
#include <vector>
#include <list>
#include <unordered_map>

namespace coal {

namespace detail {

template <typename U, typename V>
class unordered_map_hash_table : public std::unordered_map<U, V> {
  typedef std::unordered_map<U, V> Base;

 public:
  unordered_map_hash_table() : Base() {};
};

/// @brief A hash table implemented using unordered_map
template <typename Key, typename Data, typename HashFnc,
          template <typename, typename> class TableT = unordered_map_hash_table>
class SparseHashTable {
 protected:
  HashFnc h_;
  typedef std::list<Data> Bin;
  typedef TableT<size_t, Bin> Table;

  Table table_;

 public:
  SparseHashTable(const HashFnc& h);

  /// @brief Init the hash table. The bucket size is dynamically decided.
  void init(size_t);

  /// @brief insert one key-value pair into the hash table
  void insert(Key key, Data value);

  /// @brief find the elements whose key is the same as the query
  std::vector<Data> query(Key key) const;

  /// @brief remove one key-value pair from the hash table
  void remove(Key key, Data value);

  /// @brief clear the hash table
  void clear();
};

}  // namespace detail
}  // namespace coal

#include "coal/broadphase/detail/sparse_hash_table-inl.h"

#endif
