priorityq.h

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 * SGI FREE SOFTWARE LICENSE B (Version 2.0, Sept. 18, 2008)
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 * shall be included in all copies or substantial portions of the Software.
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/*
** Author: Eric Veach, July 1994.
**
*/

#ifndef __priorityq_sort_h_
#define __priorityq_sort_h_

#include "priorityq-heap.h"

#undef PQkey
#undef PQhandle
#undef PriorityQ
#undef pqNewPriorityQ
#undef pqDeletePriorityQ
#undef pqInit
#undef pqInsert
#undef pqMinimum
#undef pqExtractMin
#undef pqDelete
#undef pqIsEmpty

/* Use #define's so that another heap implementation can use this one */

#define PQkey        PQSortKey
#define PQhandle     PQSortHandle
#define PriorityQ    PriorityQSort

#define pqNewPriorityQ(leq)   __gl_pqSortNewPriorityQ(leq)
#define pqDeletePriorityQ(pq) __gl_pqSortDeletePriorityQ(pq)

/* 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.
 */
#define pqInit(pq)      __gl_pqSortInit(pq)
#define pqInsert(pq,key)   __gl_pqSortInsert(pq,key)
#define pqMinimum(pq)      __gl_pqSortMinimum(pq)
#define pqExtractMin(pq)   __gl_pqSortExtractMin(pq)
#define pqDelete(pq,handle)   __gl_pqSortDelete(pq,handle)
#define pqIsEmpty(pq)      __gl_pqSortIsEmpty(pq)


/* 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 PQHeapKey PQkey;
typedef PQHeapHandle PQhandle;
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( int (*leq)(PQkey key1, PQkey key2) );
void     pqDeletePriorityQ( PriorityQ *pq );

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

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

#endif