1 /*
2 * Copyright © 2012 Google, Inc.
3 *
4 * This is part of HarfBuzz, a text shaping library.
5 *
6 * Permission is hereby granted, without written agreement and without
7 * license or royalty fees, to use, copy, modify, and distribute this
8 * software and its documentation for any purpose, provided that the
9 * above copyright notice and the following two paragraphs appear in
10 * all copies of this software.
11 *
12 * IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR
13 * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
14 * ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN
15 * IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
16 * DAMAGE.
17 *
18 * THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
19 * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
20 * FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS
21 * ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO
22 * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
23 *
24 * Google Author(s): Behdad Esfahbod
25 */
26
27 #ifndef HB_SET_PRIVATE_HH
28 #define HB_SET_PRIVATE_HH
29
30 #include "hb-private.hh"
31 #include "hb-object-private.hh"
32
33
34 /*
35 * The set digests here implement various "filters" that support
36 * "approximate member query". Conceptually these are like Bloom
37 * Filter and Quotient Filter, however, much smaller, faster, and
38 * designed to fit the requirements of our uses for glyph coverage
39 * queries.
40 *
41 * Our filters are highly accurate if the lookup covers fairly local
42 * set of glyphs, but fully flooded and ineffective if coverage is
43 * all over the place.
44 *
45 * The frozen-set can be used instead of a digest, to trade more
46 * memory for 100% accuracy, but in practice, that doesn't look like
47 * an attractive trade-off.
48 */
49
50 template <typename mask_t, unsigned int shift>
51 struct hb_set_digest_lowest_bits_t
52 {
53 ASSERT_POD ();
54
55 static const unsigned int mask_bytes = sizeof (mask_t);
56 static const unsigned int mask_bits = sizeof (mask_t) * 8;
57 static const unsigned int num_bits = 0
58 + (mask_bytes >= 1 ? 3 : 0)
59 + (mask_bytes >= 2 ? 1 : 0)
60 + (mask_bytes >= 4 ? 1 : 0)
61 + (mask_bytes >= 8 ? 1 : 0)
62 + (mask_bytes >= 16? 1 : 0)
63 + 0;
64
65 ASSERT_STATIC (shift < sizeof (hb_codepoint_t) * 8);
66 ASSERT_STATIC (shift + num_bits <= sizeof (hb_codepoint_t) * 8);
67
68 inline void init (void) {
69 mask = 0;
70 }
71
72 inline void add (hb_codepoint_t g) {
73 mask |= mask_for (g);
74 }
75
76 inline void add_range (hb_codepoint_t a, hb_codepoint_t b) {
77 if ((b >> shift) - (a >> shift) >= mask_bits - 1)
78 mask = (mask_t) -1;
79 else {
80 mask_t ma = mask_for (a);
81 mask_t mb = mask_for (b);
82 mask |= mb + (mb - ma) - (mb < ma);
83 }
84 }
85
86 inline bool may_have (hb_codepoint_t g) const {
87 return !!(mask & mask_for (g));
88 }
89
90 private:
91
92 static inline mask_t mask_for (hb_codepoint_t g) {
93 return ((mask_t) 1) << ((g >> shift) & (mask_bits - 1));
94 }
95 mask_t mask;
96 };
97
98 template <typename head_t, typename tail_t>
99 struct hb_set_digest_combiner_t
100 {
101 ASSERT_POD ();
102
103 inline void init (void) {
104 head.init ();
105 tail.init ();
106 }
107
108 inline void add (hb_codepoint_t g) {
109 head.add (g);
110 tail.add (g);
111 }
112
113 inline void add_range (hb_codepoint_t a, hb_codepoint_t b) {
114 head.add_range (a, b);
115 tail.add_range (a, b);
116 }
117
118 inline bool may_have (hb_codepoint_t g) const {
119 return head.may_have (g) && tail.may_have (g);
120 }
121
122 private:
123 head_t head;
124 tail_t tail;
125 };
126
127
128 /*
129 * hb_set_digest_t
130 *
131 * This is a combination of digests that performs "best".
132 * There is not much science to this: it's a result of intuition
133 * and testing.
134 */
135 typedef hb_set_digest_combiner_t
136 <
137 hb_set_digest_lowest_bits_t<unsigned long, 4>,
138 hb_set_digest_combiner_t
139 <
140 hb_set_digest_lowest_bits_t<unsigned long, 0>,
141 hb_set_digest_lowest_bits_t<unsigned long, 9>
142 >
143 > hb_set_digest_t;
144
145
146
147 /*
148 * hb_set_t
149 */
150
151
152 /* TODO Make this faster and memmory efficient. */
153
154 struct hb_set_t
155 {
156 friend struct hb_frozen_set_t;
157
158 hb_object_header_t header;
159 ASSERT_POD ();
160 bool in_error;
161
162 inline void init (void) {
163 hb_object_init (this);
164 clear ();
165 }
166 inline void fini (void) {
167 }
168 inline void clear (void) {
169 if (unlikely (hb_object_is_inert (this)))
170 return;
171 in_error = false;
172 memset (elts, 0, sizeof elts);
173 }
174 inline bool is_empty (void) const {
175 for (unsigned int i = 0; i < ARRAY_LENGTH (elts); i++)
176 if (elts[i])
177 return false;
178 return true;
179 }
180 inline void add (hb_codepoint_t g)
181 {
182 if (unlikely (in_error)) return;
183 if (unlikely (g == INVALID)) return;
184 if (unlikely (g > MAX_G)) return;
185 elt (g) |= mask (g);
186 }
187 inline void add_range (hb_codepoint_t a, hb_codepoint_t b)
188 {
189 if (unlikely (in_error)) return;
190 /* TODO Speedup */
191 for (unsigned int i = a; i < b + 1; i++)
192 add (i);
193 }
194 inline void del (hb_codepoint_t g)
195 {
196 if (unlikely (in_error)) return;
197 if (unlikely (g > MAX_G)) return;
198 elt (g) &= ~mask (g);
199 }
200 inline void del_range (hb_codepoint_t a, hb_codepoint_t b)
201 {
202 if (unlikely (in_error)) return;
203 /* TODO Speedup */
204 for (unsigned int i = a; i < b + 1; i++)
205 del (i);
206 }
207 inline bool has (hb_codepoint_t g) const
208 {
209 if (unlikely (g > MAX_G)) return false;
210 return !!(elt (g) & mask (g));
211 }
212 inline bool intersects (hb_codepoint_t first,
213 hb_codepoint_t last) const
214 {
215 if (unlikely (first > MAX_G)) return false;
216 if (unlikely (last > MAX_G)) last = MAX_G;
217 unsigned int end = last + 1;
218 for (hb_codepoint_t i = first; i < end; i++)
219 if (has (i))
220 return true;
221 return false;
222 }
223 inline bool is_equal (const hb_set_t *other) const
224 {
225 for (unsigned int i = 0; i < ELTS; i++)
226 if (elts[i] != other->elts[i])
227 return false;
228 return true;
229 }
230 inline void set (const hb_set_t *other)
231 {
232 if (unlikely (in_error)) return;
233 for (unsigned int i = 0; i < ELTS; i++)
234 elts[i] = other->elts[i];
235 }
236 inline void union_ (const hb_set_t *other)
237 {
238 if (unlikely (in_error)) return;
239 for (unsigned int i = 0; i < ELTS; i++)
240 elts[i] |= other->elts[i];
241 }
242 inline void intersect (const hb_set_t *other)
243 {
244 if (unlikely (in_error)) return;
245 for (unsigned int i = 0; i < ELTS; i++)
246 elts[i] &= other->elts[i];
247 }
248 inline void subtract (const hb_set_t *other)
249 {
250 if (unlikely (in_error)) return;
251 for (unsigned int i = 0; i < ELTS; i++)
252 elts[i] &= ~other->elts[i];
253 }
254 inline void symmetric_difference (const hb_set_t *other)
255 {
256 if (unlikely (in_error)) return;
257 for (unsigned int i = 0; i < ELTS; i++)
258 elts[i] ^= other->elts[i];
259 }
260 inline void invert (void)
261 {
262 if (unlikely (in_error)) return;
263 for (unsigned int i = 0; i < ELTS; i++)
264 elts[i] = ~elts[i];
265 }
266 inline bool next (hb_codepoint_t *codepoint) const
267 {
268 if (unlikely (*codepoint == INVALID)) {
269 hb_codepoint_t i = get_min ();
270 if (i != INVALID) {
271 *codepoint = i;
272 return true;
273 } else {
274 *codepoint = INVALID;
275 return false;
276 }
277 }
278 for (hb_codepoint_t i = *codepoint + 1; i < MAX_G + 1; i++)
279 if (has (i)) {
280 *codepoint = i;
281 return true;
282 }
283 *codepoint = INVALID;
284 return false;
285 }
286 inline bool next_range (hb_codepoint_t *first, hb_codepoint_t *last) const
287 {
288 hb_codepoint_t i;
289
290 i = *last;
291 if (!next (&i))
292 {
293 *last = *first = INVALID;
294 return false;
295 }
296
297 *last = *first = i;
298 while (next (&i) && i == *last + 1)
299 (*last)++;
300
301 return true;
302 }
303
304 inline unsigned int get_population (void) const
305 {
306 unsigned int count = 0;
307 for (unsigned int i = 0; i < ELTS; i++)
308 count += _hb_popcount32 (elts[i]);
309 return count;
310 }
311 inline hb_codepoint_t get_min (void) const
312 {
313 for (unsigned int i = 0; i < ELTS; i++)
314 if (elts[i])
315 for (unsigned int j = 0; j < BITS; j++)
316 if (elts[i] & (1 << j))
317 return i * BITS + j;
318 return INVALID;
319 }
320 inline hb_codepoint_t get_max (void) const
321 {
322 for (unsigned int i = ELTS; i; i--)
323 if (elts[i - 1])
324 for (unsigned int j = BITS; j; j--)
325 if (elts[i - 1] & (1 << (j - 1)))
326 return (i - 1) * BITS + (j - 1);
327 return INVALID;
328 }
329
330 typedef uint32_t elt_t;
331 static const unsigned int MAX_G = 65536 - 1; /* XXX Fix this... */
332 static const unsigned int SHIFT = 5;
333 static const unsigned int BITS = (1 << SHIFT);
334 static const unsigned int MASK = BITS - 1;
335 static const unsigned int ELTS = (MAX_G + 1 + (BITS - 1)) / BITS;
336 static const hb_codepoint_t INVALID = HB_SET_VALUE_INVALID;
337
338 elt_t &elt (hb_codepoint_t g) { return elts[g >> SHIFT]; }
339 elt_t const &elt (hb_codepoint_t g) const { return elts[g >> SHIFT]; }
340 elt_t mask (hb_codepoint_t g) const { return elt_t (1) << (g & MASK); }
341
342 elt_t elts[ELTS]; /* XXX 8kb */
343
344 ASSERT_STATIC (sizeof (elt_t) * 8 == BITS);
345 ASSERT_STATIC (sizeof (elt_t) * 8 * ELTS > MAX_G);
346 };
347
348 struct hb_frozen_set_t
349 {
350 static const unsigned int SHIFT = hb_set_t::SHIFT;
351 static const unsigned int BITS = hb_set_t::BITS;
352 static const unsigned int MASK = hb_set_t::MASK;
353 typedef hb_set_t::elt_t elt_t;
354
355 inline void init (const hb_set_t &set)
356 {
357 start = count = 0;
358 elts = NULL;
359
360 unsigned int max = set.get_max ();
361 if (max == set.INVALID)
362 return;
363 unsigned int min = set.get_min ();
364 const elt_t &min_elt = set.elt (min);
365
366 start = min & ~MASK;
367 count = max - start + 1;
368 unsigned int num_elts = (count + BITS - 1) / BITS;
369 unsigned int elts_size = num_elts * sizeof (elt_t);
370 elts = (elt_t *) malloc (elts_size);
371 if (unlikely (!elts))
372 {
373 start = count = 0;
374 return;
375 }
376 memcpy (elts, &min_elt, elts_size);
377 }
378
379 inline void fini (void)
380 {
381 if (elts)
382 free (elts);
383 }
384
385 inline bool has (hb_codepoint_t g) const
386 {
387 /* hb_codepoint_t is unsigned. */
388 g -= start;
389 if (unlikely (g > count)) return false;
390 return !!(elt (g) & mask (g));
391 }
392
393 elt_t const &elt (hb_codepoint_t g) const { return elts[g >> SHIFT]; }
394 elt_t mask (hb_codepoint_t g) const { return elt_t (1) << (g & MASK); }
395
396 private:
397 hb_codepoint_t start, count;
398 elt_t *elts;
399 };
400
401
402 #endif /* HB_SET_PRIVATE_HH */