use SWAP macro
[git/git.git] / prio-queue.c
1 #include "cache.h"
2 #include "prio-queue.h"
3
4 static inline int compare(struct prio_queue *queue, int i, int j)
5 {
6 int cmp = queue->compare(queue->array[i].data, queue->array[j].data,
7 queue->cb_data);
8 if (!cmp)
9 cmp = queue->array[i].ctr - queue->array[j].ctr;
10 return cmp;
11 }
12
13 static inline void swap(struct prio_queue *queue, int i, int j)
14 {
15 SWAP(queue->array[i], queue->array[j]);
16 }
17
18 void prio_queue_reverse(struct prio_queue *queue)
19 {
20 int i, j;
21
22 if (queue->compare != NULL)
23 die("BUG: prio_queue_reverse() on non-LIFO queue");
24 for (i = 0; i <= (j = (queue->nr - 1) - i); i++)
25 swap(queue, i, j);
26 }
27
28 void clear_prio_queue(struct prio_queue *queue)
29 {
30 free(queue->array);
31 queue->nr = 0;
32 queue->alloc = 0;
33 queue->array = NULL;
34 queue->insertion_ctr = 0;
35 }
36
37 void prio_queue_put(struct prio_queue *queue, void *thing)
38 {
39 int ix, parent;
40
41 /* Append at the end */
42 ALLOC_GROW(queue->array, queue->nr + 1, queue->alloc);
43 queue->array[queue->nr].ctr = queue->insertion_ctr++;
44 queue->array[queue->nr].data = thing;
45 queue->nr++;
46 if (!queue->compare)
47 return; /* LIFO */
48
49 /* Bubble up the new one */
50 for (ix = queue->nr - 1; ix; ix = parent) {
51 parent = (ix - 1) / 2;
52 if (compare(queue, parent, ix) <= 0)
53 break;
54
55 swap(queue, parent, ix);
56 }
57 }
58
59 void *prio_queue_get(struct prio_queue *queue)
60 {
61 void *result;
62 int ix, child;
63
64 if (!queue->nr)
65 return NULL;
66 if (!queue->compare)
67 return queue->array[--queue->nr].data; /* LIFO */
68
69 result = queue->array[0].data;
70 if (!--queue->nr)
71 return result;
72
73 queue->array[0] = queue->array[queue->nr];
74
75 /* Push down the one at the root */
76 for (ix = 0; ix * 2 + 1 < queue->nr; ix = child) {
77 child = ix * 2 + 1; /* left */
78 if (child + 1 < queue->nr &&
79 compare(queue, child, child + 1) >= 0)
80 child++; /* use right child */
81
82 if (compare(queue, ix, child) <= 0)
83 break;
84
85 swap(queue, child, ix);
86 }
87 return result;
88 }