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src/libtess2/priorityq.h

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00001 /*
00002 ** SGI FREE SOFTWARE LICENSE B (Version 2.0, Sept. 18, 2008) 
00003 ** Copyright (C) [dates of first publication] Silicon Graphics, Inc.
00004 ** All Rights Reserved.
00005 **
00006 ** Permission is hereby granted, free of charge, to any person obtaining a copy
00007 ** of this software and associated documentation files (the "Software"), to deal
00008 ** in the Software without restriction, including without limitation the rights
00009 ** to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
00010 ** of the Software, and to permit persons to whom the Software is furnished to do so,
00011 ** subject to the following conditions:
00012 ** 
00013 ** The above copyright notice including the dates of first publication and either this
00014 ** permission notice or a reference to http://oss.sgi.com/projects/FreeB/ shall be
00015 ** included in all copies or substantial portions of the Software. 
00016 **
00017 ** THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
00018 ** INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
00019 ** PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL SILICON GRAPHICS, INC.
00020 ** BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
00021 ** TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE
00022 ** OR OTHER DEALINGS IN THE SOFTWARE.
00023 ** 
00024 ** Except as contained in this notice, the name of Silicon Graphics, Inc. shall not
00025 ** be used in advertising or otherwise to promote the sale, use or other dealings in
00026 ** this Software without prior written authorization from Silicon Graphics, Inc.
00027 */
00028 /*
00029 ** Author: Eric Veach, July 1994.
00030 */
00031 
00032 #ifndef PRIORITYQ_H
00033 #define PRIORITYQ_H
00034 
00035 /* The basic operations are insertion of a new key (pqInsert),
00036 * and examination/extraction of a key whose value is minimum
00037 * (pqMinimum/pqExtractMin).  Deletion is also allowed (pqDelete);
00038 * for this purpose pqInsert returns a "handle" which is supplied
00039 * as the argument.
00040 *
00041 * An initial heap may be created efficiently by calling pqInsert
00042 * repeatedly, then calling pqInit.  In any case pqInit must be called
00043 * before any operations other than pqInsert are used.
00044 *
00045 * If the heap is empty, pqMinimum/pqExtractMin will return a NULL key.
00046 * This may also be tested with pqIsEmpty.
00047 */
00048 
00049 /* Since we support deletion the data structure is a little more
00050 * complicated than an ordinary heap.  "nodes" is the heap itself;
00051 * active nodes are stored in the range 1..pq->size.  When the
00052 * heap exceeds its allocated size (pq->max), its size doubles.
00053 * The children of node i are nodes 2i and 2i+1.
00054 *
00055 * Each node stores an index into an array "handles".  Each handle
00056 * stores a key, plus a pointer back to the node which currently
00057 * represents that key (ie. nodes[handles[i].node].handle == i).
00058 */
00059 
00060 typedef void *PQkey;
00061 typedef int PQhandle;
00062 typedef struct PriorityQHeap PriorityQHeap;
00063 
00064 #define INV_HANDLE 0x0fffffff
00065 
00066 typedef struct { PQhandle handle; } PQnode;
00067 typedef struct { PQkey key; PQhandle node; } PQhandleElem;
00068 
00069 struct PriorityQHeap {
00070 
00071     PQnode *nodes;
00072     PQhandleElem *handles;
00073     int size, max;
00074     PQhandle freeList;
00075     int initialized;
00076 
00077     int (*leq)(PQkey key1, PQkey key2);
00078 };
00079 
00080 typedef struct PriorityQ PriorityQ;
00081 
00082 struct PriorityQ {
00083     PriorityQHeap *heap;
00084 
00085     PQkey *keys;
00086     PQkey **order;
00087     PQhandle size, max;
00088     int initialized;
00089 
00090     int (*leq)(PQkey key1, PQkey key2);
00091 };
00092 
00093 PriorityQ *pqNewPriorityQ( TESSalloc* alloc, int size, int (*leq)(PQkey key1, PQkey key2) );
00094 void pqDeletePriorityQ( TESSalloc* alloc, PriorityQ *pq );
00095 
00096 int pqInit( TESSalloc* alloc, PriorityQ *pq );
00097 PQhandle pqInsert( TESSalloc* alloc, PriorityQ *pq, PQkey key );
00098 PQkey pqExtractMin( PriorityQ *pq );
00099 void pqDelete( PriorityQ *pq, PQhandle handle );
00100 
00101 PQkey pqMinimum( PriorityQ *pq );
00102 int pqIsEmpty( PriorityQ *pq );
00103 
00104 #endif