forked from barnowl/barnowl
-
Notifications
You must be signed in to change notification settings - Fork 15
/
obarray.c
67 lines (61 loc) · 1.58 KB
/
obarray.c
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
#include <stdlib.h>
#include <string.h>
#include "owl.h"
/*
* At the moment, the obarray is represented as a sorted list of
* strings. I judge this a reasonable tradeoff between simplicity and
* reasonable efficient lookup (insertion should be comparatively
* rare)
*/
/* Helper method: Lookup a key in the obarray. If the key exists,
* return its index, and the interned value in *val. Otherwise, return
* the index it should be inserted at.
*/
static int owl_obarray_lookup(const owl_obarray *oa, const char *key, const char **val)
{
int first, last, mid;
const char * str;
int cmp;
mid = 0;
first = 0;
last = owl_list_get_size(&(oa->strings)) - 1;
while(first <= last) {
mid = first + (last - first)/2;
str = owl_list_get_element(&(oa->strings), mid);
cmp = strcmp(key, str);
if(cmp == 0) {
*val = str;
return mid;
} else if(cmp < 0) {
first = mid + 1;
} else {
last = mid - 1;
}
}
*val = NULL;
return mid;
}
/* Returns NULL if the string doesn't exist in the obarray */
const char * owl_obarray_find(const owl_obarray *oa, const char * string)
{
const char *v;
owl_obarray_lookup(oa, string, &v);
return v;
}
/* Inserts the string into the obarray if it doesn't exist */
const char * owl_obarray_insert(owl_obarray *oa, const char * string)
{
const char *v;
int i;
i = owl_obarray_lookup(oa, string, &v);
if(!v) {
char *v2 = owl_strdup(string);
owl_list_insert_element(&(oa->strings), i, v2);
return v2;
}
return v;
}
void owl_obarray_init(owl_obarray *oa)
{
owl_list_create(&(oa->strings));
}