Merge branch 'rs/help-unknown-ref-does-not-return'
[git/git.git] / prio-queue.c
CommitLineData
b4b594a3 1#include "cache.h"
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2#include "prio-queue.h"
3
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4static inline int compare(struct prio_queue *queue, int i, int j)
5{
e8f91e3d 6 int cmp = queue->compare(queue->array[i].data, queue->array[j].data,
6d63baa4 7 queue->cb_data);
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8 if (!cmp)
9 cmp = queue->array[i].ctr - queue->array[j].ctr;
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10 return cmp;
11}
12
13static inline void swap(struct prio_queue *queue, int i, int j)
14{
35d803bc 15 SWAP(queue->array[i], queue->array[j]);
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16}
17
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18void prio_queue_reverse(struct prio_queue *queue)
19{
20 int i, j;
21
22 if (queue->compare != NULL)
033abf97 23 BUG("prio_queue_reverse() on non-LIFO queue");
1f9e18b7 24 for (i = 0; i < (j = (queue->nr - 1) - i); i++)
6d63baa4 25 swap(queue, i, j);
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26}
27
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28void clear_prio_queue(struct prio_queue *queue)
29{
88ce3ef6 30 FREE_AND_NULL(queue->array);
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31 queue->nr = 0;
32 queue->alloc = 0;
e8f91e3d 33 queue->insertion_ctr = 0;
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34}
35
36void prio_queue_put(struct prio_queue *queue, void *thing)
37{
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38 int ix, parent;
39
40 /* Append at the end */
41 ALLOC_GROW(queue->array, queue->nr + 1, queue->alloc);
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42 queue->array[queue->nr].ctr = queue->insertion_ctr++;
43 queue->array[queue->nr].data = thing;
44 queue->nr++;
6d63baa4 45 if (!queue->compare)
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46 return; /* LIFO */
47
48 /* Bubble up the new one */
49 for (ix = queue->nr - 1; ix; ix = parent) {
50 parent = (ix - 1) / 2;
6d63baa4 51 if (compare(queue, parent, ix) <= 0)
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52 break;
53
6d63baa4 54 swap(queue, parent, ix);
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55 }
56}
57
58void *prio_queue_get(struct prio_queue *queue)
59{
6d63baa4 60 void *result;
b4b594a3 61 int ix, child;
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62
63 if (!queue->nr)
64 return NULL;
6d63baa4 65 if (!queue->compare)
e8f91e3d 66 return queue->array[--queue->nr].data; /* LIFO */
b4b594a3 67
e8f91e3d 68 result = queue->array[0].data;
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69 if (!--queue->nr)
70 return result;
71
72 queue->array[0] = queue->array[queue->nr];
73
74 /* Push down the one at the root */
75 for (ix = 0; ix * 2 + 1 < queue->nr; ix = child) {
76 child = ix * 2 + 1; /* left */
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77 if (child + 1 < queue->nr &&
78 compare(queue, child, child + 1) >= 0)
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79 child++; /* use right child */
80
6d63baa4 81 if (compare(queue, ix, child) <= 0)
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82 break;
83
6d63baa4 84 swap(queue, child, ix);
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85 }
86 return result;
87}
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88
89void *prio_queue_peek(struct prio_queue *queue)
90{
91 if (!queue->nr)
92 return NULL;
93 if (!queue->compare)
94 return queue->array[queue->nr - 1].data;
95 return queue->array[0].data;
96}