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
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
|
/* This code is based on ccan/strset.c. */
#include <ccan/strmap/strmap.h>
#include <ccan/short_types/short_types.h>
#include <ccan/str/str.h>
#include <ccan/ilog/ilog.h>
#include <assert.h>
#include <stdlib.h>
#include <errno.h>
struct node {
/* These point to strings or nodes. */
struct strmap child[2];
/* The byte number where first bit differs. */
size_t byte_num;
/* The bit where these children differ. */
u8 bit_num;
};
/* Closest member to this in a non-empty map. */
static struct strmap *closest(struct strmap *n, const char *member)
{
size_t len = strlen(member);
const u8 *bytes = (const u8 *)member;
/* Anything with NULL value is a node. */
while (!n->v) {
u8 direction = 0;
if (n->u.n->byte_num < len) {
u8 c = bytes[n->u.n->byte_num];
direction = (c >> n->u.n->bit_num) & 1;
}
n = &n->u.n->child[direction];
}
return n;
}
void *strmap_get_(const struct strmap *map, const char *member)
{
struct strmap *n;
/* Not empty map? */
if (map->u.n) {
n = closest((struct strmap *)map, member);
if (streq(member, n->u.s))
return n->v;
}
errno = ENOENT;
return NULL;
}
bool strmap_add_(struct strmap *map, const char *member, const void *value)
{
size_t len = strlen(member);
const u8 *bytes = (const u8 *)member;
struct strmap *n;
struct node *newn;
size_t byte_num;
u8 bit_num, new_dir;
assert(value);
/* Empty map? */
if (!map->u.n) {
map->u.s = member;
map->v = (void *)value;
return true;
}
/* Find closest existing member. */
n = closest(map, member);
/* Find where they differ. */
for (byte_num = 0; n->u.s[byte_num] == member[byte_num]; byte_num++) {
if (member[byte_num] == '\0') {
/* All identical! */
errno = EEXIST;
return false;
}
}
/* Find which bit differs (if we had ilog8, we'd use it) */
bit_num = ilog32_nz((u8)n->u.s[byte_num] ^ bytes[byte_num]) - 1;
assert(bit_num < CHAR_BIT);
/* Which direction do we go at this bit? */
new_dir = ((bytes[byte_num]) >> bit_num) & 1;
/* Allocate new node. */
newn = malloc(sizeof(*newn));
if (!newn) {
errno = ENOMEM;
return false;
}
newn->byte_num = byte_num;
newn->bit_num = bit_num;
newn->child[new_dir].v = (void *)value;
newn->child[new_dir].u.s = member;
/* Find where to insert: not closest, but first which differs! */
n = map;
while (!n->v) {
u8 direction = 0;
if (n->u.n->byte_num > byte_num)
break;
/* Subtle: bit numbers are "backwards" for comparison */
if (n->u.n->byte_num == byte_num && n->u.n->bit_num < bit_num)
break;
if (n->u.n->byte_num < len) {
u8 c = bytes[n->u.n->byte_num];
direction = (c >> n->u.n->bit_num) & 1;
}
n = &n->u.n->child[direction];
}
newn->child[!new_dir] = *n;
n->u.n = newn;
n->v = NULL;
return true;
}
char *strmap_del_(struct strmap *map, const char *member, void **valuep)
{
size_t len = strlen(member);
const u8 *bytes = (const u8 *)member;
struct strmap *parent = NULL, *n;
const char *ret = NULL;
u8 direction = 0; /* prevent bogus gcc warning. */
/* Empty map? */
if (!map->u.n) {
errno = ENOENT;
return NULL;
}
/* Find closest, but keep track of parent. */
n = map;
/* Anything with NULL value is a node. */
while (!n->v) {
u8 c = 0;
parent = n;
if (n->u.n->byte_num < len) {
c = bytes[n->u.n->byte_num];
direction = (c >> n->u.n->bit_num) & 1;
} else
direction = 0;
n = &n->u.n->child[direction];
}
/* Did we find it? */
if (!streq(member, n->u.s)) {
errno = ENOENT;
return NULL;
}
ret = n->u.s;
if (valuep)
*valuep = n->v;
if (!parent) {
/* We deleted last node. */
map->u.n = NULL;
} else {
struct node *old = parent->u.n;
/* Raise other node to parent. */
*parent = old->child[!direction];
free(old);
}
return (char *)ret;
}
static bool iterate(struct strmap n,
bool (*handle)(const char *, void *, void *),
const void *data)
{
if (n.v)
return handle(n.u.s, n.v, (void *)data);
return iterate(n.u.n->child[0], handle, data)
&& iterate(n.u.n->child[1], handle, data);
}
void strmap_iterate_(const struct strmap *map,
bool (*handle)(const char *, void *, void *),
const void *data)
{
/* Empty map? */
if (!map->u.n)
return;
iterate(*map, handle, data);
}
const struct strmap *strmap_prefix_(const struct strmap *map,
const char *prefix)
{
const struct strmap *n, *top;
size_t len = strlen(prefix);
const u8 *bytes = (const u8 *)prefix;
/* Empty map -> return empty map. */
if (!map->u.n)
return map;
top = n = map;
/* We walk to find the top, but keep going to check prefix matches. */
while (!n->v) {
u8 c = 0, direction;
if (n->u.n->byte_num < len)
c = bytes[n->u.n->byte_num];
direction = (c >> n->u.n->bit_num) & 1;
n = &n->u.n->child[direction];
if (c)
top = n;
}
if (!strstarts(n->u.s, prefix)) {
/* Convenient return for prefixes which do not appear in map. */
static const struct strmap empty_map;
return &empty_map;
}
return top;
}
static void clear(struct strmap n)
{
if (!n.v) {
clear(n.u.n->child[0]);
clear(n.u.n->child[1]);
free(n.u.n);
}
}
void strmap_clear_(struct strmap *map)
{
if (map->u.n)
clear(*map);
map->u.n = NULL;
}
|
