ahash.h

A Set of Simple C++ Hash Templates

#ifndef THE_HASH_THAT_WAS_DESIGNED_BY_ME_H__20061020
#define THE_HASH_THAT_WAS_DESIGNED_BY_ME_H__20061020

#include "ahashp.h"

/**
	\brief Hash table
	
	A more complicated hash table that that simplifies the use of it's child class, but make T a little more complex.\n
	To setup this class:\n
	1. You derive your hash class from this class.\n
	2. T must also have comparison operator.\n
	3. Follow the requirements for _HashP\<T, KEY_TYPE\>.\n
	4. You must create the definition for the static member m_NULL. Somewhere in your class's CPP file put \code template <> T _Hash<T>::m_NULL = T(); \endcode Replacing T with the actual name of your class. M_NULL will be returned by Get() to indicate a NULL value. One such way to do this is give a bool member to T, say m_bNULL, then assign \code m_NULL.m_bNULL = true; \endcode
*/

template <typename T, typename KEY_TYPE = const char *>
class _Hash : public _HashP<T, KEY_TYPE> {
protected:
	_Hash(int nBucketSize = 0);

public:
	/**
	 *  \brief A const version of Get(KEY_TYPE)
	 */
	const T &Get(KEY_TYPE ref) const {
		const T *pElement = Find(ref);
		return (pElement == NULL ? m_NULL : *pElement);
	}
	/**
	 *  \brief Get an element from the table
	 * @param ref The reference used to find the element
	 * @return A reference to the element sought, or m_NULL if not found.
	 */
	T &Get(KEY_TYPE ref);

public:
	//!The null value indicating an empty set
	/**It is necessary that this be defined in your program. Then the child class or the instance owner will be able to use his own criteria to identify a NULL value*/
	static T m_NULL;
};

/**
 * \brief Basic constructor
 * @param nBucketSize The initial size of the bucket array
 */
template <typename T, typename KEY_TYPE>
_Hash<T, KEY_TYPE>::_Hash(int nBucketSize) : _HashP<T, KEY_TYPE>(nBucketSize) {
}

template <typename T, typename KEY_TYPE>
T &_Hash<T, KEY_TYPE>::Get(KEY_TYPE ref) {
	T *p = _HashP<T, KEY_TYPE>::Get(ref);
	if (p == NULL) return m_NULL;

	return *p;
}

#endif