File indexing completed on 2024-04-21 14:46:24

 /*
 ** Author: Eric Veach, July 1994.
 **
 */
 
 #ifndef __priorityq_heap_h_
 #define __priorityq_heap_h_
 
 /* Use #define's so that another heap implementation can use this one */
 
 #define PQkey     PQHeapKey
 #define PQhandle  PQHeapHandle
 #define PriorityQ PriorityQHeap
 
 #define pqNewPriorityQ(leq)   __gl_pqHeapNewPriorityQ(leq)
 #define pqDeletePriorityQ(pq) __gl_pqHeapDeletePriorityQ(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_pqHeapInit(pq)
 #define pqInsert(pq, key)    __gl_pqHeapInsert(pq, key)
 #define pqMinimum(pq)        __gl_pqHeapMinimum(pq)
 #define pqExtractMin(pq)     __gl_pqHeapExtractMin(pq)
 #define pqDelete(pq, handle) __gl_pqHeapDelete(pq, handle)
 #define pqIsEmpty(pq)        __gl_pqHeapIsEmpty(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 void *PQkey;
 typedef long PQhandle;
 typedef struct PriorityQ PriorityQ;
 
 typedef struct
 {
     PQhandle handle;
 } PQnode;
 typedef struct
 {
     PQkey key;
     PQhandle node;
 } PQhandleElem;
 
 struct PriorityQ
 {
     PQnode *nodes;
     PQhandleElem *handles;
     long size, max;
     PQhandle freeList;
     int initialized;
     int (*leq)(PQkey key1, PQkey key2);
 };
 
 PriorityQ *pqNewPriorityQ(int (*leq)(PQkey key1, PQkey key2));
 void pqDeletePriorityQ(PriorityQ *pq);
 
 void pqInit(PriorityQ *pq);
 PQhandle pqInsert(PriorityQ *pq, PQkey key);
 PQkey pqExtractMin(PriorityQ *pq);
 void pqDelete(PriorityQ *pq, PQhandle handle);
 
 #define __gl_pqHeapMinimum(pq) ((pq)->handles[(pq)->nodes[1].handle].key)
 #define __gl_pqHeapIsEmpty(pq) ((pq)->size == 0)
 
 #endif