www.pudn.com > MP3CORD.rar > hashtable.h

/*____________________________________________________________________________ 
	 
	FreeAmp - The Free MP3 Player 
 
	Portions Copyright (C) 1998-1999 EMusic.com 
 
	This program is free software; you can redistribute it and/or modify 
	it under the terms of the GNU General Public License as published by 
	the Free Software Foundation; either version 2 of the License, or 
	(at your option) any later version. 
 
	This program is distributed in the hope that it will be useful, 
	but WITHOUT ANY WARRANTY; without even the implied warranty of 
	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the 
	GNU General Public License for more details. 
 
	You should have received a copy of the GNU General Public License 
	along with this program; if not, write to the Free Software 
	Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. 
	 
	$Id: hashtable.h,v 1.5 1999/10/19 07:12:45 elrod Exp $ 
____________________________________________________________________________*/ 
 
#ifndef INCLUDED_HASHTABLE_H_ 
#define INCLUDED_HASHTABLE_H_ 
 
#define KEYLENGTH 64 
 
#include  
 
using namespace std; 
 
#include "config.h" 
 
template class HashElem { 
 public: 
    ~HashElem() { delete val; } 
    HashElem *next; 
    char key[KEYLENGTH]; 
    T val; 
}; 
 
 
template class HashTable  { 
 public: 
    HashTable(int32 slots = 10); 
    ~HashTable(); 
     
    T Value(const char *key); 
    void Insert(const char *key, T val); 
    void Remove(const char *key); 
 private: 
    HashElem **hashSlots; 
    int32 numSlots; 
     
    int32 hashkey(const char *); 
}; 
 
template HashTable::HashTable(int32 slots) { 
    if (slots < 5) slots = 5; 
    hashSlots = new HashElem*[slots]; 
    memset(hashSlots,'\0',slots*sizeof(HashElem *)); 
    numSlots = slots; 
} 
 
 
template HashTable::~HashTable() { 
    if (hashSlots) { 
	HashElem *phe; 
	for (int i=0;i *next = phe->next; 
		delete phe; 
		phe = next; 
	    } 
	} 
	delete hashSlots; 
	hashSlots = NULL; 
    } 
} 
 
template T HashTable::Value(const char *key) { 
    int32 num = hashkey(key); 
//    cout << "Keynum: " << num << endl; 
    if (num >= 0) { 
	HashElem *pElem = hashSlots[num]; 
	while (pElem) { 
	    if (!strncmp(key,pElem->key,KEYLENGTH-1)) { 
		return pElem->val; 
	    } 
	    pElem = pElem->next; 
	} 
	return NULL; 
    } else { 
	return NULL; 
    } 
} 
 
 
template void HashTable::Insert(const char *key, T val) { 
    int32 num = hashkey(key); 
//    cout << "Keynum: " << num << endl; 
    if (num >= 0) { 
	if (hashSlots[num]) { 
	    HashElem *pIns = hashSlots[num]; 
	    while (pIns->next) { 
		pIns = pIns->next; 
	    } 
	    pIns->next = new HashElem(); 
	    pIns->next->next = NULL; 
	    pIns->next->val = val; 
	    strncpy(pIns->next->key,key,KEYLENGTH-1); 
	} else { 
	    hashSlots[num] = new HashElem(); 
	    hashSlots[num]->next = NULL; 
	    strncpy(hashSlots[num]->key,key,KEYLENGTH-1); 
	    hashSlots[num]->val = val; 
	} 
    } 
} 
 
 
template void HashTable::Remove(const char *key) { 
    int32 num = hashkey(key); 
    if (num >= 0) { 
	HashElem *pElem = hashSlots[num]; 
	HashElem *pPrev = NULL; 
	while (pElem) { 
	    if (!strncmp(pElem->key,key,KEYLENGTH-1)) { 
		if (pPrev) { 
		    pPrev->next = pElem->next; 
		} else { 
		    hashSlots[num] = pElem->next; 
		} 
		delete pElem; 
		return; 
	    } 
	    pPrev = pElem; 
	    pElem = pElem->next; 
	} 
    } 
} 
 
 
template int32 HashTable::hashkey(const char *key) { 
    if (key) { 
	int ind = 0; 
	int32 total = 0; 
	while (key[ind]) { 
	    total += (int32)(key[ind]); 
	    ind++; 
	} 
	return total % numSlots; 
    } 
    return -1; 
} 
 
 
#endif // _HASHTABLE_H_