src/pqueue.h

   1 /*
   2  * Copyright (C) 2009-2012 the libgit2 contributors
   3  *
   4  * This file is part of libgit2, distributed under the GNU GPL v2 with
   5  * a Linking Exception. For full terms see the included COPYING file.
   6  */
   7
   8 #ifndef INCLUDE_pqueue_h__
   9 #define INCLUDE_pqueue_h__
  10
  11 /** callback functions to get/set/compare the priority of an element */
  12 typedef int (*git_pqueue_cmp)(void *a, void *b);
  13
  14 /** the priority queue handle */
  15 typedef struct {
  16         size_t size, avail, step;
  17         git_pqueue_cmp cmppri;
  18         void **d;
  19 } git_pqueue;
  20
  21
  22 /**
  23  * initialize the queue
  24  *
  25  * @param n the initial estimate of the number of queue items for which memory
  26  *                      should be preallocated
  27  * @param cmppri the callback function to compare two nodes of the queue
  28  *
  29  * @Return the handle or NULL for insufficent memory
  30  */
  31 int git_pqueue_init(git_pqueue *q, size_t n, git_pqueue_cmp cmppri);
  32
  33
  34 /**
  35  * free all memory used by the queue
  36  * @param q the queue
  37  */
  38 void git_pqueue_free(git_pqueue *q);
  39
  40 /**
  41  * clear all the elements in the queue
  42  * @param q the queue
  43  */
  44 void git_pqueue_clear(git_pqueue *q);
  45
  46 /**
  47  * return the size of the queue.
  48  * @param q the queue
  49  */
  50 size_t git_pqueue_size(git_pqueue *q);
  51
  52
  53 /**
  54  * insert an item into the queue.
  55  * @param q the queue
  56  * @param d the item
  57  * @return 0 on success
  58  */
  59 int git_pqueue_insert(git_pqueue *q, void *d);
  60
  61
  62 /**
  63  * pop the highest-ranking item from the queue.
  64  * @param p the queue
  65  * @param d where to copy the entry to
  66  * @return NULL on error, otherwise the entry
  67  */
  68 void *git_pqueue_pop(git_pqueue *q);
  69
  70
  71 /**
  72  * access highest-ranking item without removing it.
  73  * @param q the queue
  74  * @param d the entry
  75  * @return NULL on error, otherwise the entry
  76  */
  77 void *git_pqueue_peek(git_pqueue *q);
  78
  79 #endif /* PQUEUE_H */
  80 /** @} */
  81