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strbuf: replace quick sort with bubble sort

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No need to call the heavy artillery, when the original array
is sorted. Reduces complexity from n² log n to n log n, where
n is the number of items in the array, not very large, but
still.
This commit is contained in:
Zbigniew Jędrzejewski-Szmek 2013-03-30 22:12:56 -04:00
parent a9c307e5d2
commit 3c8bed4ee0
1 changed files with 31 additions and 10 deletions
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41
src/shared/strbuf.c
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@ -95,13 +95,36 @@ void strbuf_cleanup(struct strbuf *str) {
free(str);
}
static int strbuf_children_cmp(const void *v1, const void *v2) {
const struct strbuf_child_entry *n1 = v1;
const struct strbuf_child_entry *n2 = v2;
static int strbuf_children_cmp(const struct strbuf_child_entry *n1,
const struct strbuf_child_entry *n2) {
return n1->c - n2->c;
}
static void bubbleinsert(struct strbuf_node *node,
uint8_t c,
struct strbuf_node *node_child) {
struct strbuf_child_entry new = {
.c = c,
.child = node_child,
};
int left = 0, right = node->children_count;
while (right > left) {
int middle = (right + left) / 2 ;
if (strbuf_children_cmp(&node->children[middle], &new) <= 0)
left = middle + 1;
else
right = middle;
}
memmove(node->children + left + 1, node->children + left,
sizeof(struct strbuf_child_entry) * (node->children_count - left));
node->children[left] = new;
node->children_count ++;
}
/* add string, return the index/offset into the buffer */
ssize_t strbuf_add_string(struct strbuf *str, const char *s, size_t len) {
uint8_t c;
@ -137,8 +160,9 @@ ssize_t strbuf_add_string(struct strbuf *str, const char *s, size_t len) {
/* lookup child node */
c = s[len - 1 - depth];
search.c = c;
child = bsearch(&search, node->children, node->children_count, sizeof(struct strbuf_child_entry),
strbuf_children_cmp);
child = bsearch(&search, node->children, node->children_count,
sizeof(struct strbuf_child_entry),
(__compar_fn_t) strbuf_children_cmp);
if (!child)
break;
node = child->child;
@ -171,10 +195,7 @@ ssize_t strbuf_add_string(struct strbuf *str, const char *s, size_t len) {
str->nodes_count++;
node->children = child;
node->children[node->children_count].c = c;
node->children[node->children_count].child = node_child;
node->children_count++;
qsort(node->children, node->children_count, sizeof(struct strbuf_child_entry), strbuf_children_cmp);
bubbleinsert(node, c, node_child);
return off;
}