1 /*
2 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
3 *
4 * This code is free software; you can redistribute it and/or modify it
5 * under the terms of the GNU General Public License version 2 only, as
6 * published by the Free Software Foundation. Oracle designates this
7 * particular file as subject to the "Classpath" exception as provided
8 * by Oracle in the LICENSE file that accompanied this code.
9 *
10 * This code is distributed in the hope that it will be useful, but WITHOUT
11 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
12 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
13 * version 2 for more details (a copy is included in the LICENSE file that
14 * accompanied this code).
15 *
16 * You should have received a copy of the GNU General Public License version
17 * 2 along with this work; if not, write to the Free Software Foundation,
18 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
19 *
20 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
21 * or visit www.oracle.com if you need additional information or have any
22 * questions.
23 */
24
25 // This file is available under and governed by the GNU General Public
26 // License version 2 only, as published by the Free Software Foundation.
27 // However, the following notice accompanied the original version of this
28 // file:
29 //
30 /*
31 * Copyright © 2012 Google, Inc.
32 *
33 * This is part of HarfBuzz, a text shaping library.
34 *
35 * Permission is hereby granted, without written agreement and without
36 * license or royalty fees, to use, copy, modify, and distribute this
37 * software and its documentation for any purpose, provided that the
38 * above copyright notice and the following two paragraphs appear in
39 * all copies of this software.
40 *
41 * IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR
42 * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
43 * ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN
44 * IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
45 * DAMAGE.
46 *
47 * THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
48 * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
49 * FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS
50 * ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO
51 * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
52 *
53 * Google Author(s): Behdad Esfahbod
54 */
55
56 #ifndef HB_SET_PRIVATE_HH
57 #define HB_SET_PRIVATE_HH
58
59 #include "hb-private.hh"
60 #include "hb-object-private.hh"
61
62
63 /*
64 * The set digests here implement various "filters" that support
65 * "approximate member query". Conceptually these are like Bloom
66 * Filter and Quotient Filter, however, much smaller, faster, and
67 * designed to fit the requirements of our uses for glyph coverage
68 * queries.
69 *
70 * Our filters are highly accurate if the lookup covers fairly local
71 * set of glyphs, but fully flooded and ineffective if coverage is
72 * all over the place.
73 *
74 * The frozen-set can be used instead of a digest, to trade more
75 * memory for 100% accuracy, but in practice, that doesn't look like
76 * an attractive trade-off.
77 */
78
79 template <typename mask_t, unsigned int shift>
80 struct hb_set_digest_lowest_bits_t
81 {
82 ASSERT_POD ();
83
84 static const unsigned int mask_bytes = sizeof (mask_t);
85 static const unsigned int mask_bits = sizeof (mask_t) * 8;
86 static const unsigned int num_bits = 0
87 + (mask_bytes >= 1 ? 3 : 0)
88 + (mask_bytes >= 2 ? 1 : 0)
89 + (mask_bytes >= 4 ? 1 : 0)
90 + (mask_bytes >= 8 ? 1 : 0)
91 + (mask_bytes >= 16? 1 : 0)
92 + 0;
93
94 ASSERT_STATIC (shift < sizeof (hb_codepoint_t) * 8);
95 ASSERT_STATIC (shift + num_bits <= sizeof (hb_codepoint_t) * 8);
96
97 inline void init (void) {
98 mask = 0;
99 }
100
101 inline void add (hb_codepoint_t g) {
102 mask |= mask_for (g);
103 }
104
105 inline void add_range (hb_codepoint_t a, hb_codepoint_t b) {
106 if ((b >> shift) - (a >> shift) >= mask_bits - 1)
107 mask = (mask_t) -1;
108 else {
109 mask_t ma = mask_for (a);
110 mask_t mb = mask_for (b);
111 mask |= mb + (mb - ma) - (mb < ma);
112 }
113 }
114
115 inline bool may_have (hb_codepoint_t g) const {
116 return !!(mask & mask_for (g));
117 }
118
119 private:
120
121 static inline mask_t mask_for (hb_codepoint_t g) {
122 return ((mask_t) 1) << ((g >> shift) & (mask_bits - 1));
123 }
124 mask_t mask;
125 };
126
127 template <typename head_t, typename tail_t>
128 struct hb_set_digest_combiner_t
129 {
130 ASSERT_POD ();
131
132 inline void init (void) {
133 head.init ();
134 tail.init ();
135 }
136
137 inline void add (hb_codepoint_t g) {
138 head.add (g);
139 tail.add (g);
140 }
141
142 inline void add_range (hb_codepoint_t a, hb_codepoint_t b) {
143 head.add_range (a, b);
144 tail.add_range (a, b);
145 }
146
147 inline bool may_have (hb_codepoint_t g) const {
148 return head.may_have (g) && tail.may_have (g);
149 }
150
151 private:
152 head_t head;
153 tail_t tail;
154 };
155
156
157 /*
158 * hb_set_digest_t
159 *
160 * This is a combination of digests that performs "best".
161 * There is not much science to this: it's a result of intuition
162 * and testing.
163 */
164 typedef hb_set_digest_combiner_t
165 <
166 hb_set_digest_lowest_bits_t<unsigned long, 4>,
167 hb_set_digest_combiner_t
168 <
169 hb_set_digest_lowest_bits_t<unsigned long, 0>,
170 hb_set_digest_lowest_bits_t<unsigned long, 9>
171 >
172 > hb_set_digest_t;
173
174
175
176 /*
177 * hb_set_t
178 */
179
180
181 /* TODO Make this faster and memmory efficient. */
182
183 struct hb_set_t
184 {
185 friend struct hb_frozen_set_t;
186
187 hb_object_header_t header;
188 ASSERT_POD ();
189 bool in_error;
190
191 inline void init (void) {
192 hb_object_init (this);
193 clear ();
194 }
195 inline void fini (void) {
196 }
197 inline void clear (void) {
198 if (unlikely (hb_object_is_inert (this)))
199 return;
200 in_error = false;
201 memset (elts, 0, sizeof elts);
202 }
203 inline bool is_empty (void) const {
204 for (unsigned int i = 0; i < ARRAY_LENGTH (elts); i++)
205 if (elts[i])
206 return false;
207 return true;
208 }
209 inline void add (hb_codepoint_t g)
210 {
211 if (unlikely (in_error)) return;
212 if (unlikely (g == INVALID)) return;
213 if (unlikely (g > MAX_G)) return;
214 elt (g) |= mask (g);
215 }
216 inline void add_range (hb_codepoint_t a, hb_codepoint_t b)
217 {
218 if (unlikely (in_error)) return;
219 /* TODO Speedup */
220 for (unsigned int i = a; i < b + 1; i++)
221 add (i);
222 }
223 inline void del (hb_codepoint_t g)
224 {
225 if (unlikely (in_error)) return;
226 if (unlikely (g > MAX_G)) return;
227 elt (g) &= ~mask (g);
228 }
229 inline void del_range (hb_codepoint_t a, hb_codepoint_t b)
230 {
231 if (unlikely (in_error)) return;
232 /* TODO Speedup */
233 for (unsigned int i = a; i < b + 1; i++)
234 del (i);
235 }
236 inline bool has (hb_codepoint_t g) const
237 {
238 if (unlikely (g > MAX_G)) return false;
239 return !!(elt (g) & mask (g));
240 }
241 inline bool intersects (hb_codepoint_t first,
242 hb_codepoint_t last) const
243 {
244 if (unlikely (first > MAX_G)) return false;
245 if (unlikely (last > MAX_G)) last = MAX_G;
246 unsigned int end = last + 1;
247 for (hb_codepoint_t i = first; i < end; i++)
248 if (has (i))
249 return true;
250 return false;
251 }
252 inline bool is_equal (const hb_set_t *other) const
253 {
254 for (unsigned int i = 0; i < ELTS; i++)
255 if (elts[i] != other->elts[i])
256 return false;
257 return true;
258 }
259 inline void set (const hb_set_t *other)
260 {
261 if (unlikely (in_error)) return;
262 for (unsigned int i = 0; i < ELTS; i++)
263 elts[i] = other->elts[i];
264 }
265 inline void union_ (const hb_set_t *other)
266 {
267 if (unlikely (in_error)) return;
268 for (unsigned int i = 0; i < ELTS; i++)
269 elts[i] |= other->elts[i];
270 }
271 inline void intersect (const hb_set_t *other)
272 {
273 if (unlikely (in_error)) return;
274 for (unsigned int i = 0; i < ELTS; i++)
275 elts[i] &= other->elts[i];
276 }
277 inline void subtract (const hb_set_t *other)
278 {
279 if (unlikely (in_error)) return;
280 for (unsigned int i = 0; i < ELTS; i++)
281 elts[i] &= ~other->elts[i];
282 }
283 inline void symmetric_difference (const hb_set_t *other)
284 {
285 if (unlikely (in_error)) return;
286 for (unsigned int i = 0; i < ELTS; i++)
287 elts[i] ^= other->elts[i];
288 }
289 inline void invert (void)
290 {
291 if (unlikely (in_error)) return;
292 for (unsigned int i = 0; i < ELTS; i++)
293 elts[i] = ~elts[i];
294 }
295 inline bool next (hb_codepoint_t *codepoint) const
296 {
297 if (unlikely (*codepoint == INVALID)) {
298 hb_codepoint_t i = get_min ();
299 if (i != INVALID) {
300 *codepoint = i;
301 return true;
302 } else {
303 *codepoint = INVALID;
304 return false;
305 }
306 }
307 for (hb_codepoint_t i = *codepoint + 1; i < MAX_G + 1; i++)
308 if (has (i)) {
309 *codepoint = i;
310 return true;
311 }
312 *codepoint = INVALID;
313 return false;
314 }
315 inline bool next_range (hb_codepoint_t *first, hb_codepoint_t *last) const
316 {
317 hb_codepoint_t i;
318
319 i = *last;
320 if (!next (&i))
321 {
322 *last = *first = INVALID;
323 return false;
324 }
325
326 *last = *first = i;
327 while (next (&i) && i == *last + 1)
328 (*last)++;
329
330 return true;
331 }
332
333 inline unsigned int get_population (void) const
334 {
335 unsigned int count = 0;
336 for (unsigned int i = 0; i < ELTS; i++)
337 count += _hb_popcount32 (elts[i]);
338 return count;
339 }
340 inline hb_codepoint_t get_min (void) const
341 {
342 for (unsigned int i = 0; i < ELTS; i++)
343 if (elts[i])
344 for (unsigned int j = 0; j < BITS; j++)
345 if (elts[i] & (1 << j))
346 return i * BITS + j;
347 return INVALID;
348 }
349 inline hb_codepoint_t get_max (void) const
350 {
351 for (unsigned int i = ELTS; i; i--)
352 if (elts[i - 1])
353 for (unsigned int j = BITS; j; j--)
354 if (elts[i - 1] & (1 << (j - 1)))
355 return (i - 1) * BITS + (j - 1);
356 return INVALID;
357 }
358
359 typedef uint32_t elt_t;
360 static const unsigned int MAX_G = 65536 - 1; /* XXX Fix this... */
361 static const unsigned int SHIFT = 5;
362 static const unsigned int BITS = (1 << SHIFT);
363 static const unsigned int MASK = BITS - 1;
364 static const unsigned int ELTS = (MAX_G + 1 + (BITS - 1)) / BITS;
365 static const hb_codepoint_t INVALID = HB_SET_VALUE_INVALID;
366
367 elt_t &elt (hb_codepoint_t g) { return elts[g >> SHIFT]; }
368 elt_t const &elt (hb_codepoint_t g) const { return elts[g >> SHIFT]; }
369 elt_t mask (hb_codepoint_t g) const { return elt_t (1) << (g & MASK); }
370
371 elt_t elts[ELTS]; /* XXX 8kb */
372
373 ASSERT_STATIC (sizeof (elt_t) * 8 == BITS);
374 ASSERT_STATIC (sizeof (elt_t) * 8 * ELTS > MAX_G);
375 };
376
377 struct hb_frozen_set_t
378 {
379 static const unsigned int SHIFT = hb_set_t::SHIFT;
380 static const unsigned int BITS = hb_set_t::BITS;
381 static const unsigned int MASK = hb_set_t::MASK;
382 typedef hb_set_t::elt_t elt_t;
383
384 inline void init (const hb_set_t &set)
385 {
386 start = count = 0;
387 elts = NULL;
388
389 unsigned int max = set.get_max ();
390 if (max == set.INVALID)
391 return;
392 unsigned int min = set.get_min ();
393 const elt_t &min_elt = set.elt (min);
394
395 start = min & ~MASK;
396 count = max - start + 1;
397 unsigned int num_elts = (count + BITS - 1) / BITS;
398 unsigned int elts_size = num_elts * sizeof (elt_t);
399 elts = (elt_t *) malloc (elts_size);
400 if (unlikely (!elts))
401 {
402 start = count = 0;
403 return;
404 }
405 memcpy (elts, &min_elt, elts_size);
406 }
407
408 inline void fini (void)
409 {
410 if (elts)
411 free (elts);
412 }
413
414 inline bool has (hb_codepoint_t g) const
415 {
416 /* hb_codepoint_t is unsigned. */
417 g -= start;
418 if (unlikely (g > count)) return false;
419 return !!(elt (g) & mask (g));
420 }
421
422 elt_t const &elt (hb_codepoint_t g) const { return elts[g >> SHIFT]; }
423 elt_t mask (hb_codepoint_t g) const { return elt_t (1) << (g & MASK); }
424
425 private:
426 hb_codepoint_t start, count;
427 elt_t *elts;
428 };
429
430
431 #endif /* HB_SET_PRIVATE_HH */