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3party/libtess2/Source/priorityq.h

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+/*
+** SGI FREE SOFTWARE LICENSE B (Version 2.0, Sept. 18, 2008)
+** Copyright (C) [dates of first publication] Silicon Graphics, Inc.
+** All Rights Reserved.
+**
+** Permission is hereby granted, free of charge, to any person obtaining a copy
+** of this software and associated documentation files (the "Software"), to deal
+** 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
+** be used in advertising or otherwise to promote the sale, use or other dealings in
+** 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