Source/priorityq.h

/*
** SGI FREE SOFTWARE LICENSE B (Version 2.0, Sept. 18, 2008) 
** Copyright (C) [dates of first publication] Silicon Graphics, Inc.
** All Rights Reserved.
**
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** in the Software without restriction, including without limitation the rights
** to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
** of the Software, and to permit persons to whom the Software is furnished to do so,
** subject to the following conditions:
** 
** The above copyright notice including the dates of first publication and either this
** permission notice or a reference to http://oss.sgi.com/projects/FreeB/ shall be
** included in all copies or substantial portions of the Software. 
**
** THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
** INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
** PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL SILICON GRAPHICS, INC.
** BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
** TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE
** OR OTHER DEALINGS IN THE SOFTWARE.
** 
** Except as contained in this notice, the name of Silicon Graphics, Inc. shall not
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** this Software without prior written authorization from Silicon Graphics, Inc.
*/
/*
** Author: Eric Veach, July 1994.
*/

#ifndef PRIORITYQ_H
#define PRIORITYQ_H

/* The basic operations are insertion of a new key (pqInsert),
* and examination/extraction of a key whose value is minimum
* (pqMinimum/pqExtractMin).  Deletion is also allowed (pqDelete);
* for this purpose pqInsert returns a "handle" which is supplied
* as the argument.
*
* An initial heap may be created efficiently by calling pqInsert
* repeatedly, then calling pqInit.  In any case pqInit must be called
* before any operations other than pqInsert are used.
*
* If the heap is empty, pqMinimum/pqExtractMin will return a NULL key.
* This may also be tested with pqIsEmpty.
*/

/* Since we support deletion the data structure is a little more
* complicated than an ordinary heap.  "nodes" is the heap itself;
* active nodes are stored in the range 1..pq->size.  When the
* heap exceeds its allocated size (pq->max), its size doubles.
* The children of node i are nodes 2i and 2i+1.
*
* Each node stores an index into an array "handles".  Each handle
* stores a key, plus a pointer back to the node which currently
* represents that key (ie. nodes[handles[i].node].handle == i).
*/

typedef void *PQkey;
typedef int PQhandle;
typedef struct PriorityQHeap PriorityQHeap;

#define INV_HANDLE 0x0fffffff

typedef struct { PQhandle handle; } PQnode;
typedef struct { PQkey key; PQhandle node; } PQhandleElem;

struct PriorityQHeap {

	PQnode *nodes;
	PQhandleElem *handles;
	int size, max;
	PQhandle freeList;
	int initialized;

	int (*leq)(PQkey key1, PQkey key2);
};

typedef struct PriorityQ PriorityQ;

struct PriorityQ {
	PriorityQHeap *heap;

	PQkey *keys;
	PQkey **order;
	PQhandle size, max;
	int initialized;

	int (*leq)(PQkey key1, PQkey key2);
};

PriorityQ *pqNewPriorityQ( TESSalloc* alloc, int size, int (*leq)(PQkey key1, PQkey key2) );
void pqDeletePriorityQ( TESSalloc* alloc, PriorityQ *pq );

int pqInit( TESSalloc* alloc, PriorityQ *pq );
PQhandle pqInsert( TESSalloc* alloc, PriorityQ *pq, PQkey key );
PQkey pqExtractMin( PriorityQ *pq );
void pqDelete( PriorityQ *pq, PQhandle handle );

PQkey pqMinimum( PriorityQ *pq );
int pqIsEmpty( PriorityQ *pq );

#endif