162 lines
3 KiB
C
162 lines
3 KiB
C
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// Notes
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// Make sure extension is stripped if it needs to be
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// Template class must have
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// 1. A GetName() accessor - a null terminated string case insensitive
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// 2. A Destroy() function - normally "delete this"
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// 3. SetNext(T *) and T *GetNext() functions
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#define HASH_SIZE 1024
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template <class T, int TSize = HASH_SIZE, int (*TCompare)(const char *, const char *) = strcmp>
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class CHash
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{
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private:
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T *mHashTable[TSize];
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T *mNext;
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int mCount;
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T *mPrevious; // Internal work variable
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long mHash; // Internal work variable
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// Creates the hash value and sets the mHash member
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void CreateHash(const char *key)
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{
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int i = 0;
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char letter;
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mHash = 0;
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letter = *key++;
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while (letter)
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{
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mHash += (long)(letter) * (i + 119);
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i++;
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letter = *key++;
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}
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mHash &= TSize - 1;
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}
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public:
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// Constructor
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CHash(void)
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{
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memset(mHashTable, NULL, sizeof(mHashTable));
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mNext = NULL;
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mCount = 0;
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mPrevious = NULL;
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mHash = 0;
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}
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// Destructor
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~CHash(void)
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{
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#ifdef _DEBUG
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// Com_OPrintf("Shutting down %s hash table .....", typeid(T).name());
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#endif
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clear();
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#ifdef _DEBUG
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Com_OPrintf(" done\n");
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#endif
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}
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// Returns the total number of entries in the hash table
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int count(void) const { return(mCount); }
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// Inserts an item into the hash table
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void insert(T *item)
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{
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CreateHash(item->GetName());
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item->SetNext(mHashTable[mHash]);
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mHashTable[mHash] = item;
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mCount++;
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}
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// Finds an item in the hash table (sets the mPrevious member)
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T *find(const char *key)
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{
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CreateHash(key);
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T *item = mHashTable[mHash];
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mPrevious = NULL;
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while(item)
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{
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mNext = item->GetNext();
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if(!TCompare(item->GetName(), key))
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{
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return(item);
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}
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mPrevious = item;
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item = mNext;
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}
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return(NULL);
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}
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// Remove item from the hash table referenced by key
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bool remove(const char *key)
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{
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T *item = find(key);
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if(item)
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{
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T *next = item->GetNext();
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if(mPrevious)
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{
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mPrevious->SetNext(next);
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}
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else
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{
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mHashTable[mHash] = next;
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}
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item->Destroy();
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mCount--;
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return(true);
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}
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return(false);
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}
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// Remove item from hash referenced by item
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bool remove(T *item)
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{
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return(remove(item->GetName()));
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}
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// Returns the first valid entry
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T *head(void)
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{
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mHash = -1;
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mNext = NULL;
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return(next());
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}
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// Returns the next entry in the hash table
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T *next(void)
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{
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T *item;
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assert(mHash < TSize);
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if(mNext)
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{
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item = mNext;
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mNext = item->GetNext();
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return(item);
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}
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mHash++;
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for( ; mHash < TSize; mHash++)
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{
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item = mHashTable[mHash];
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if(item)
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{
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mNext = item->GetNext();
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return(item);
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}
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}
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return(NULL);
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}
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// Destroy all entries in the hash table
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void clear(void)
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{
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T *item = head();
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while(item)
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{
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remove(item);
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item = next();
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}
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}
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// Override the [] operator
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T *operator[](const char *key) { return(find(key)); }
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};
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// end
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