summaryrefslogtreecommitdiff
path: root/src/libwapcaplet.c
blob: 0d761683898047fce9ff5b63fa071389195faf9f (plain)
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
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
/* libwapcaplet.c
 *
 * String internment and management tools.
 *
 * Copyright 2009 The NetSurf Browser Project.
 *		  Daniel Silverstone <dsilvers@netsurf-browser.org>
 */

#include <stdlib.h>
#include <string.h>
#include <assert.h>

#include "libwapcaplet/libwapcaplet.h"

#ifndef UNUSED
#define UNUSED(x) ((x) = (x))
#endif

typedef uint32_t lwc_refcounter;

static inline lwc_hash
lwc_calculate_hash(const char *str, size_t len)
{
	lwc_hash z = 0x811c9dc5;
	

	while (len > 0) {
		z *= 0x01000193;
		z ^= *str++;
                len--;
	}

	return z;
}

struct lwc_string_s {
        lwc_string **	prevptr;
        lwc_string *	next;
        size_t		len;
        lwc_hash	hash;
        lwc_refcounter	refcnt;
        lwc_string *	insensitive;
};

#define STR_OF(str) ((char *)(str + 1))
#define CSTR_OF(str) ((const char *)(str + 1))

#define NR_BUCKETS_DEFAULT	(4091)

typedef struct lwc_context_s {
        lwc_string **		buckets;
        lwc_hash		bucketcount;
} lwc_context;

static lwc_context *ctx = NULL;

#define LWC_ALLOC(s) malloc(s)
#define LWC_FREE(p) free(p)

typedef lwc_hash (*lwc_hasher)(const char *, size_t);
typedef int (*lwc_strncmp)(const char *, const char *, size_t);
typedef void (*lwc_memcpy)(char *, const char *, size_t);

static lwc_error
_lwc_initialise(void)
{
        assert(alloc);
        
        if (ctx != NULL)
                return lwc_error_ok;
        
        ctx = LWC_ALLOC(sizeof(lwc_context));
        
        if (ctx == NULL)
                return lwc_error_oom;
        
        memset(ctx, 0, sizeof(lwc_context));
        
        ctx->bucketcount = NR_BUCKETS_DEFAULT;
        ctx->buckets = LWC_ALLOC(sizeof(lwc_string *) * ctx->bucketcount);
        
        if (ctx->buckets == NULL) {
                LWC_FREE(ctx);
                return lwc_error_oom;
        }
        
        memset(ctx->buckets, 0, sizeof(lwc_string *) * ctx->bucketcount);
        
        return lwc_error_ok;
}

static lwc_error
__lwc_intern(const char *s, size_t slen,
             lwc_string **ret,
             lwc_hasher hasher,
             lwc_strncmp compare,
             lwc_memcpy copy)
{
        lwc_hash h;
        lwc_hash bucket;
        lwc_string *str;
        lwc_error eret;
        
        assert((s != NULL) || (slen == 0));
        assert(ret);
        
        if (ctx == NULL) {
                eret = _lwc_initialise();
                if (eret != lwc_error_ok)
                        return eret;
        }
        
        h = hasher(s, slen);
        bucket = h % ctx->bucketcount;
        str = ctx->buckets[bucket];
        
        while (str != NULL) {
                if ((str->hash == h) && (str->len == slen)) {
                        if (compare(CSTR_OF(str), s, slen) == 0) {
                                str->refcnt++;
                                *ret = str;
                                return lwc_error_ok;
                        }
                }
                str = str->next;
        }
        
        /* Add one for the additional NUL. */
        *ret = str = LWC_ALLOC(sizeof(lwc_string) + slen + 1);
        
        if (str == NULL)
                return lwc_error_oom;
        
        str->prevptr = &(ctx->buckets[bucket]);
        str->next = ctx->buckets[bucket];
        if (str->next != NULL)
                str->next->prevptr = &(str->next);
        ctx->buckets[bucket] = str;

        str->len = slen;
        str->hash = h;
        str->refcnt = 1;
        str->insensitive = NULL;
        
        copy(STR_OF(str), s, slen);

        /* Guarantee NUL termination */
        STR_OF(str)[slen] = '\0';
        
        return lwc_error_ok;
}

lwc_error
lwc_intern_string(const char *s, size_t slen,
                  lwc_string **ret)
{
        return __lwc_intern(s, slen, ret,
                            lwc_calculate_hash,
                            strncmp, (lwc_memcpy)memcpy);
}

lwc_error
lwc_intern_substring(lwc_string *str,
                     size_t ssoffset, size_t sslen,
                     lwc_string **ret)
{
        assert(str);
        assert(ret);
        
        if (ssoffset >= str->len)
                return lwc_error_range;
        if ((ssoffset + sslen) > str->len)
                return lwc_error_range;
        
        return lwc_intern_string(CSTR_OF(str) + ssoffset, sslen, ret);
}

lwc_string *
lwc_string_ref(lwc_string *str)
{
        assert(str);
        
        str->refcnt++;
        
        return str;
}

void
lwc_string_unref(lwc_string *str)
{
        assert(str);
        
        if (--(str->refcnt) > 1)
                return;
        
        if ((str->refcnt == 1) && (str->insensitive != str))
                return;
        
        *(str->prevptr) = str->next;
        
        if (str->next != NULL)
                str->next->prevptr = str->prevptr;

        if (str->insensitive != NULL && str->refcnt == 0)
                lwc_string_unref(str->insensitive);

#ifndef NDEBUG
        memset(str, 0xA5, sizeof(*str) + str->len);
#endif
        
        LWC_FREE(str);
}

/**** Shonky caseless bits ****/

static inline char
dolower(const char c)
{
        if (c >= 'A' && c <= 'Z')
                return c + 'a' - 'A';
        return c;
}

static inline lwc_hash
lwc_calculate_lcase_hash(const char *str, size_t len)
{
	lwc_hash z = 0x811c9dc5;
	

	while (len > 0) {
		z *= 0x01000193;
		z ^= dolower(*str++);
                len--;
	}

	return z;
}

static int
lwc_lcase_strncmp(const char *s1, const char *s2, size_t n)
{
        while (n--) {
                if (*s1++ != dolower(*s2++))
                        /** @todo Test this somehow? */
                        return 1;
        }
        return 0;
}

static void
lwc_lcase_memcpy(char *target, const char *source, size_t n)
{
        while (n--) {
                *target++ = dolower(*source++);
        }
}

static lwc_error
lwc_intern_caseless_string(lwc_string *str)
{
        assert(str);
        assert(str->insensitive == NULL);
        
        return __lwc_intern(CSTR_OF(str),
                            str->len, &(str->insensitive),
                            lwc_calculate_lcase_hash,
                            lwc_lcase_strncmp,
                            lwc_lcase_memcpy);
}

lwc_error
lwc_string_caseless_isequal(lwc_string *str1,
                            lwc_string *str2,
                            bool *ret)
{
        lwc_error err;
        assert(str1);
        assert(str2);
        
        if (str1->insensitive == NULL) {
                err = lwc_intern_caseless_string(str1);
                if (err != lwc_error_ok)
                        return err;
        }
        if (str2->insensitive == NULL) {
                err = lwc_intern_caseless_string(str2);
                if (err != lwc_error_ok)
                        return err;
        }
        
        *ret = (str1->insensitive == str2->insensitive);
        return lwc_error_ok;
}

/**** Simple accessors ****/

const char *
lwc_string_data(lwc_string *str)
{
        assert(str);
        
        return CSTR_OF(str);
}

size_t
lwc_string_length(lwc_string *str)
{
        assert(str);
        
        return str->len;
}

uint32_t
lwc_string_hash_value(lwc_string *str)
{
	assert(str);

	return str->hash;
}

/**** Iteration ****/

void
lwc_iterate_strings(lwc_iteration_callback_fn cb, void *pw)
{
        lwc_hash n;
        lwc_string *str;
        
        for (n = 0; n < ctx->bucketcount; ++n) {
                for (str = ctx->buckets[n]; str != NULL; str = str->next)
                        cb(str, pw);
        }
}