// CMSC 341 - Fall 2019 - Project 5
// hash.h

// Templated, hash table implementation.  Each buckets is a heap.  A
// bucket contains objects with the same key values stored as a
// max-heap based on priority.  Collisions are resolved by linear
// probing.

// To work with Heap and HashTable, the template class T must provide
// the following:
//  (a) Default constructor
//  (b) priority function (unsigned priority())
//  (c) key function (string key())
//  (d) overloaded insertion operator

#ifndef _HASH_H
#define _HASH_H

#include <string>
#include "heap.h"

using std::string;

// Hash function typedef.  The hash function must return an 'unsigned
// int' value.  Reduction mod N is the responsiblity of the caller,
// not the hash function.
typedef unsigned (*hash_fn)(string);

class Grader;

template <class T>
class HashTable {

  friend Grader;
  
 public:
  // Constructor.  Requires table size and hash function.
  HashTable(unsigned size, hash_fn hash);

  // Destructor, copy, and assignment
  ~HashTable();
  HashTable(const HashTable<T>& ht);
  const HashTable<T>& operator=(const HashTable<T>& ht);

  // In-line functions
  
  // Table size; set by constructor
  unsigned tableSize() const { return _N; }
  // Number of entries in the table
  unsigned numEntries() const { return _n; }
  // Load factor
  float lambda() const { return ((float) _n) / _N; }

  // Main hash table functions
  
  // insert returns 'true' if successful; 'false' otherwise
  bool insert(const T& object);
  // getNext retrieves **and removes** the highest priority order of
  // type indicated by key.  It returns 'true' if successful; 'false'
  // otherwise.
  bool getNext(string key, T& obj);

  // Dump the entire hash table
  void dump() const;
  
 private:
  unsigned _N;       // hash table size
  unsigned _n;       // current number of entries
  hash_fn _hash;     // hash function
  Heap<T> *_table;   // array of heaps

  // ***********************************************
  // Private helper function declarations go here! *
  // ***********************************************
  
};

// *****************************************
// Templated function definitions go here! *
// *****************************************

#endif