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/**
* @file llsimplehash.h
*
* Copyright (c) 2003-$CurrentYear$, Linden Research, Inc.
* $License$
*/
#ifndef LL_LLSIMPLEHASH_H
#define LL_LLSIMPLEHASH_H
#include "llstl.h"
template <typename HASH_KEY_TYPE>
class LLSimpleHashEntry
{
protected:
HASH_KEY_TYPE mHashKey;
LLSimpleHashEntry<HASH_KEY_TYPE>* mNextEntry;
public:
LLSimpleHashEntry(HASH_KEY_TYPE key) :
mHashKey(key),
mNextEntry(0)
{
}
virtual ~LLSimpleHashEntry()
{
}
HASH_KEY_TYPE getHashKey() const
{
return mHashKey;
}
LLSimpleHashEntry<HASH_KEY_TYPE>* getNextEntry() const
{
return mNextEntry;
}
void setNextEntry(LLSimpleHashEntry<HASH_KEY_TYPE>* next)
{
mNextEntry = next;
}
};
template <typename HASH_KEY_TYPE, int TABLE_SIZE>
class LLSimpleHash
{
public:
LLSimpleHash()
{
llassert(TABLE_SIZE);
llassert((TABLE_SIZE ^ (TABLE_SIZE-1)) == (TABLE_SIZE | (TABLE_SIZE-1))); // power of 2
memset(mEntryTable, 0, sizeof(mEntryTable));
}
virtual ~LLSimpleHash()
{
}
virtual int getIndex(HASH_KEY_TYPE key)
{
return key & (TABLE_SIZE-1);
}
bool insert(LLSimpleHashEntry<HASH_KEY_TYPE>* entry)
{
llassert(entry->getNextEntry() == 0);
int index = getIndex(entry->getHashKey());
entry->setNextEntry(mEntryTable[index]);
mEntryTable[index] = entry;
return true;
}
LLSimpleHashEntry<HASH_KEY_TYPE>* find(HASH_KEY_TYPE key)
{
int index = getIndex(key);
LLSimpleHashEntry<HASH_KEY_TYPE>* res = mEntryTable[index];
while(res && (res->getHashKey() != key))
{
res = res->getNextEntry();
}
return res;
}
bool erase(LLSimpleHashEntry<HASH_KEY_TYPE>* entry)
{
return erase(entry->getHashKey());
}
bool erase(HASH_KEY_TYPE key)
{
int index = getIndex(key);
LLSimpleHashEntry<HASH_KEY_TYPE>* prev = 0;
LLSimpleHashEntry<HASH_KEY_TYPE>* res = mEntryTable[index];
while(res && (res->getHashKey() != key))
{
prev = res;
res = res->getNextEntry();
}
if (res)
{
LLSimpleHashEntry<HASH_KEY_TYPE>* next = res->getNextEntry();
if (prev)
{
prev->setNextEntry(next);
}
else
{
mEntryTable[index] = next;
}
return true;
}
else
{
return false;
}
}
// Removes and returns an arbitrary ("first") element from the table
// Used for deleting the entire table.
LLSimpleHashEntry<HASH_KEY_TYPE>* pop_element()
{
for (int i=0; i<TABLE_SIZE; i++)
{
LLSimpleHashEntry<HASH_KEY_TYPE>* entry = mEntryTable[i];
if (entry)
{
mEntryTable[i] = entry->getNextEntry();
return entry;
}
}
return 0;
}
// debugging
LLSimpleHashEntry<HASH_KEY_TYPE>* get_element_at_index(S32 index) const
{
return mEntryTable[index];
}
private:
LLSimpleHashEntry<HASH_KEY_TYPE>* mEntryTable[TABLE_SIZE];
};
#endif // LL_LLSIMPLEHASH_H
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