156 lines
4.1 KiB
C++
156 lines
4.1 KiB
C++
/**
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* @file llsimplehash.h
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*
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* $LicenseInfo:firstyear=2003&license=viewerlgpl$
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* Second Life Viewer Source Code
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* Copyright (C) 2010, Linden Research, Inc.
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation;
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* version 2.1 of the License only.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*
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* Linden Research, Inc., 945 Battery Street, San Francisco, CA 94111 USA
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* $/LicenseInfo$
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*/
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#ifndef LL_LLSIMPLEHASH_H
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#define LL_LLSIMPLEHASH_H
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#include "llstl.h"
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template <typename HASH_KEY_TYPE>
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class LLSimpleHashEntry
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{
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protected:
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HASH_KEY_TYPE mHashKey;
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LLSimpleHashEntry<HASH_KEY_TYPE>* mNextEntry;
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public:
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LLSimpleHashEntry(HASH_KEY_TYPE key) :
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mHashKey(key),
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mNextEntry(0)
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{
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}
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virtual ~LLSimpleHashEntry()
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{
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}
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HASH_KEY_TYPE getHashKey() const
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{
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return mHashKey;
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}
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LLSimpleHashEntry<HASH_KEY_TYPE>* getNextEntry() const
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{
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return mNextEntry;
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}
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void setNextEntry(LLSimpleHashEntry<HASH_KEY_TYPE>* next)
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{
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mNextEntry = next;
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}
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};
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template <typename HASH_KEY_TYPE, int TABLE_SIZE>
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class LL_COMMON_API LLSimpleHash
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{
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public:
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LLSimpleHash()
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{
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llassert(TABLE_SIZE);
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llassert((TABLE_SIZE ^ (TABLE_SIZE-1)) == (TABLE_SIZE | (TABLE_SIZE-1))); // power of 2
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memset(mEntryTable, 0, sizeof(mEntryTable));
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}
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virtual ~LLSimpleHash()
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{
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}
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virtual int getIndex(HASH_KEY_TYPE key)
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{
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return key & (TABLE_SIZE-1);
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}
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bool insert(LLSimpleHashEntry<HASH_KEY_TYPE>* entry)
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{
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llassert(entry->getNextEntry() == 0);
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int index = getIndex(entry->getHashKey());
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entry->setNextEntry(mEntryTable[index]);
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mEntryTable[index] = entry;
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return true;
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}
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LLSimpleHashEntry<HASH_KEY_TYPE>* find(HASH_KEY_TYPE key)
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{
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int index = getIndex(key);
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LLSimpleHashEntry<HASH_KEY_TYPE>* res = mEntryTable[index];
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while(res && (res->getHashKey() != key))
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{
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res = res->getNextEntry();
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}
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return res;
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}
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bool erase(LLSimpleHashEntry<HASH_KEY_TYPE>* entry)
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{
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return erase(entry->getHashKey());
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}
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bool erase(HASH_KEY_TYPE key)
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{
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int index = getIndex(key);
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LLSimpleHashEntry<HASH_KEY_TYPE>* prev = 0;
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LLSimpleHashEntry<HASH_KEY_TYPE>* res = mEntryTable[index];
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while(res && (res->getHashKey() != key))
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{
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prev = res;
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res = res->getNextEntry();
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}
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if (res)
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{
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LLSimpleHashEntry<HASH_KEY_TYPE>* next = res->getNextEntry();
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if (prev)
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{
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prev->setNextEntry(next);
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}
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else
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{
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mEntryTable[index] = next;
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}
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return true;
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}
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else
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{
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return false;
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}
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}
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// Removes and returns an arbitrary ("first") element from the table
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// Used for deleting the entire table.
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LLSimpleHashEntry<HASH_KEY_TYPE>* pop_element()
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{
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for (int i=0; i<TABLE_SIZE; i++)
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{
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LLSimpleHashEntry<HASH_KEY_TYPE>* entry = mEntryTable[i];
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if (entry)
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{
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mEntryTable[i] = entry->getNextEntry();
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return entry;
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}
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}
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return 0;
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}
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// debugging
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LLSimpleHashEntry<HASH_KEY_TYPE>* get_element_at_index(S32 index) const
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{
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return mEntryTable[index];
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}
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private:
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LLSimpleHashEntry<HASH_KEY_TYPE>* mEntryTable[TABLE_SIZE];
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};
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#endif // LL_LLSIMPLEHASH_H
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