/*
 *
 * @APPLE_LICENSE_HEADER_START@
 *
 * Copyright (c) 1999-2001 Apple Computer, Inc.  All Rights Reserved. The
 * contents of this file constitute Original Code as defined in and are
 * subject to the Apple Public Source License Version 1.2 (the 'License').
 * You may not use this file except in compliance with the License.  Please
 * obtain a copy of the License at http://www.apple.com/publicsource and
 * read it before using this file.
 *
 * This Original Code and all software distributed under the License are
 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY, FITNESS
 * FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.  Please
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 */
/*
	File:		OSHeap.h

	Contains:	Implements a heap
					

*/

#ifndef _OSHEAP_H_
#define _OSHEAP_H_

#define _OSHEAP_TESTING_ 0

#include "OSCond.h"

class OSHeapElem;

class OSHeap
{
	public:
	
		enum
		{
			kDefaultStartSize = 1024 //UInt32
		};
		
		OSHeap(UInt32 inStartSize = kDefaultStartSize);
		~OSHeap() { if (fHeap != NULL) delete fHeap; }
		
		//ACCESSORS
		UInt32		CurrentHeapSize() { return fFreeIndex - 1; }
		OSHeapElem*	PeekMin() { if (CurrentHeapSize() > 0) return fHeap[1]; return NULL; }
		
		//MODIFIERS
		
		//These are the two primary operations supported by the heap
		//abstract data type. both run in log(n) time.
		void			Insert(OSHeapElem*	inElem);
		OSHeapElem*		ExtractMin() { return Extract(1); }
		//removes specified element from the heap
		OSHeapElem*		Remove(OSHeapElem* elem);
		
#if _OSHEAP_TESTING_
		//returns true if it passed the test, false otherwise
		static Bool16		Test();
#endif
	
	private:
	
		OSHeapElem*		Extract(UInt32 index);
	
#if _OSHEAP_TESTING_
		//verifies that the heap is in fact a heap
		void			SanityCheck(UInt32 root);
#endif
	
		OSHeapElem**	fHeap;
		UInt32			fFreeIndex;
		UInt32			fArraySize;
};

class OSHeapElem
{
	public:
		OSHeapElem(void* enclosingObject = NULL)
			: fValue(0), fEnclosingObject(enclosingObject), fCurrentHeap(NULL) {}
		~OSHeapElem() {}
		
		//This data structure emphasizes performance over extensibility
		//If it were properly object-oriented, the compare routine would
		//be virtual. However, to avoid the use of v-functions in this data
		//structure, I am assuming that the objects are compared using a 64 bit number.
		//
		void	SetValue(SInt64 newValue) { fValue = newValue; }
		SInt64	GetValue()				{ return fValue; }
		void*	GetEnclosingObject() 	{ return fEnclosingObject; }
		Bool16	IsMemberOfAnyHeap()		{ return fCurrentHeap != NULL; }
		
	private:
	
		SInt64	fValue;
		void* fEnclosingObject;
		OSHeap*	fCurrentHeap;
		
		friend class OSHeap;
};
#endif //_OSHEAP_H_
