Kstars

src/priorityq-heap.h
1/*
2** Author: Eric Veach, July 1994.
3**
4*/
5
6#ifndef __priorityq_heap_h_
7#define __priorityq_heap_h_
8
9/* Use #define's so that another heap implementation can use this one */
10
11#define PQkey PQHeapKey
12#define PQhandle PQHeapHandle
13#define PriorityQ PriorityQHeap
14
15#define pqNewPriorityQ(leq) __gl_pqHeapNewPriorityQ(leq)
16#define pqDeletePriorityQ(pq) __gl_pqHeapDeletePriorityQ(pq)
17
18/* The basic operations are insertion of a new key (pqInsert),
19 * and examination/extraction of a key whose value is minimum
20 * (pqMinimum/pqExtractMin). Deletion is also allowed (pqDelete);
21 * for this purpose pqInsert returns a "handle" which is supplied
22 * as the argument.
23 *
24 * An initial heap may be created efficiently by calling pqInsert
25 * repeatedly, then calling pqInit. In any case pqInit must be called
26 * before any operations other than pqInsert are used.
27 *
28 * If the heap is empty, pqMinimum/pqExtractMin will return a NULL key.
29 * This may also be tested with pqIsEmpty.
30 */
31#define pqInit(pq) __gl_pqHeapInit(pq)
32#define pqInsert(pq, key) __gl_pqHeapInsert(pq, key)
33#define pqMinimum(pq) __gl_pqHeapMinimum(pq)
34#define pqExtractMin(pq) __gl_pqHeapExtractMin(pq)
35#define pqDelete(pq, handle) __gl_pqHeapDelete(pq, handle)
36#define pqIsEmpty(pq) __gl_pqHeapIsEmpty(pq)
37
38/* Since we support deletion the data structure is a little more
39 * complicated than an ordinary heap. "nodes" is the heap itself;
40 * active nodes are stored in the range 1..pq->size. When the
41 * heap exceeds its allocated size (pq->max), its size doubles.
42 * The children of node i are nodes 2i and 2i+1.
43 *
44 * Each node stores an index into an array "handles". Each handle
45 * stores a key, plus a pointer back to the node which currently
46 * represents that key (ie. nodes[handles[i].node].handle == i).
47 */
48
49typedef void *PQkey;
50typedef long PQhandle;
51typedef struct PriorityQ PriorityQ;
52
53typedef struct
54{
55 PQhandle handle;
56} PQnode;
57typedef struct
58{
59 PQkey key;
60 PQhandle node;
61} PQhandleElem;
62
63struct PriorityQ
64{
65 PQnode *nodes;
66 PQhandleElem *handles;
67 long size, max;
68 PQhandle freeList;
69 int initialized;
70 int (*leq)(PQkey key1, PQkey key2);
71};
72
73PriorityQ *pqNewPriorityQ(int (*leq)(PQkey key1, PQkey key2));
74void pqDeletePriorityQ(PriorityQ *pq);
75
76void pqInit(PriorityQ *pq);
77PQhandle pqInsert(PriorityQ *pq, PQkey key);
78PQkey pqExtractMin(PriorityQ *pq);
79void pqDelete(PriorityQ *pq, PQhandle handle);
80
81#define __gl_pqHeapMinimum(pq) ((pq)->handles[(pq)->nodes[1].handle].key)
82#define __gl_pqHeapIsEmpty(pq) ((pq)->size == 0)
83
84#endif
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