Start preparing for 1.8.4.2
[alt-git.git] / prio-queue.h
blob9c3cd1f875ce553c2c10645c9b7df6b4287306f8
1 #ifndef PRIO_QUEUE_H
2 #define PRIO_QUEUE_H
4 /*
5 * A priority queue implementation, primarily for keeping track of
6 * commits in the 'date-order' so that we process them from new to old
7 * as they are discovered, but can be used to hold any pointer to
8 * struct. The caller is responsible for supplying a function to
9 * compare two "things".
11 * Alternatively, this data structure can also be used as a LIFO stack
12 * by specifying NULL as the comparison function.
16 * Compare two "things", one and two; the third parameter is cb_data
17 * in the prio_queue structure. The result is returned as a sign of
18 * the return value, being the same as the sign of the result of
19 * subtracting "two" from "one" (i.e. negative if "one" sorts earlier
20 * than "two").
22 typedef int (*prio_queue_compare_fn)(const void *one, const void *two, void *cb_data);
24 struct prio_queue {
25 prio_queue_compare_fn compare;
26 void *cb_data;
27 int alloc, nr;
28 void **array;
32 * Add the "thing" to the queue.
34 extern void prio_queue_put(struct prio_queue *, void *thing);
37 * Extract the "thing" that compares the smallest out of the queue,
38 * or NULL. If compare function is NULL, the queue acts as a LIFO
39 * stack.
41 extern void *prio_queue_get(struct prio_queue *);
43 extern void clear_prio_queue(struct prio_queue *);
45 /* Reverse the LIFO elements */
46 extern void prio_queue_reverse(struct prio_queue *);
48 #endif /* PRIO_QUEUE_H */