hashmap.h

Data Abstraction & Problem Solving with C++源码

// *************************************************
// Header file HashMap.h 
// The HashMap is derived from the STL vector and map 
// *************************************************
#include <vector>
#include <map>
using namespace std;

template <class Key, class T, class Hash>
class HashMap : private vector<map<Key, T> > 
{
   public:
		
	HashMap(const int maxBuckets);
	// Constructor 
	// Precondition: The HashMap is empty.
	// Postcondition: The HashMap is initialized to hold
	// maxBuckets. The Hash template parameter is assigned to
	// the hash variable.
		
	T& operator[](Key& key);
	// Overloads the subscript operator for the HashMap class
	// Precondition: The HashMap contains a hash for type T.  
	// Postcondition: The value of a hashed key is returned.

	map<Key, T>::const_iterator findItem(const Key& key);
	// Hashes the key to find the vector index.
	// Finds the map element using the key as the index.
	// Precondition: The HashMap contains a hash for type T.
	// Postcondition: An iterator to the (key, item) pair is
	// returned.
	// If the item is not in the map, the iterator points to
	// the end of the map.

	void insert (const Key& key, const T& item);
	// Hashes the key to find the vector index.
	// Inserts the (key, item) pair into the map at that index.
	// Precondition: The HashMap contains a hash for the
	// type T.
	// Postcondition: The (key, item) pair is inserted
	// at the hashed index.
		
	int erase(const Key& k);
	// Removes the item with the Key k in the hash table.
	// Precondition: The HashMap contains a hash for the
	// type T.
	// Postcondition: The (key, item) pair at the hashed index
	// is removed.
	// The number of items removed is returned (either 0 or 1).  
			
	Hash hash;   // the hash function object
};  // end HashMap

#include "HashMap.cpp"
// End of header file