Imported existing code

indra/llcommon/llsimplehash.h

@@ -0,0 +1,161 @@
+/** 
+ * @file llsimplehash.h
+ *
+ * $LicenseInfo:firstyear=2003&license=viewergpl$
+ * 
+ * Copyright (c) 2003-2009, Linden Research, Inc.
+ * 
+ * Second Life Viewer Source Code
+ * The source code in this file ("Source Code") is provided by Linden Lab
+ * to you under the terms of the GNU General Public License, version 2.0
+ * ("GPL"), unless you have obtained a separate licensing agreement
+ * ("Other License"), formally executed by you and Linden Lab.  Terms of
+ * the GPL can be found in doc/GPL-license.txt in this distribution, or
+ * online at http://secondlifegrid.net/programs/open_source/licensing/gplv2
+ * 
+ * There are special exceptions to the terms and conditions of the GPL as
+ * it is applied to this Source Code. View the full text of the exception
+ * in the file doc/FLOSS-exception.txt in this software distribution, or
+ * online at
+ * http://secondlifegrid.net/programs/open_source/licensing/flossexception
+ * 
+ * By copying, modifying or distributing this software, you acknowledge
+ * that you have read and understood your obligations described above,
+ * and agree to abide by those obligations.
+ * 
+ * ALL LINDEN LAB SOURCE CODE IS PROVIDED "AS IS." LINDEN LAB MAKES NO
+ * WARRANTIES, EXPRESS, IMPLIED OR OTHERWISE, REGARDING ITS ACCURACY,
+ * COMPLETENESS OR PERFORMANCE.
+ * $/LicenseInfo$
+ */
+
+#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