third_party/harfbuzz-ng/src/hb-set-private.hh

   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-set.h"
  32 #include "hb-object-private.hh"
  33
  34
  35 /*
  36  * The set digests here implement various "filters" that support
  37  * "approximate member query".  Conceptually these are like Bloom
  38  * Filter and Quotient Filter, however, much smaller, faster, and
  39  * designed to fit the requirements of our uses for glyph coverage
  40  * queries.  As a result, our filters have much higher.
  41  */
  42
  43 template <typename mask_t, unsigned int shift>
  44 struct hb_set_digest_lowest_bits_t
  45 {
  46   ASSERT_POD ();
  47
  48   static const unsigned int mask_bytes = sizeof (mask_t);
  49   static const unsigned int mask_bits = sizeof (mask_t) * 8;
  50   static const unsigned int num_bits = 0
  51                                      + (mask_bytes >= 1 ? 3 : 0)
  52                                      + (mask_bytes >= 2 ? 1 : 0)
  53                                      + (mask_bytes >= 4 ? 1 : 0)
  54                                      + (mask_bytes >= 8 ? 1 : 0)
  55                                      + (mask_bytes >= 16? 1 : 0)
  56                                      + 0;
  57
  58   ASSERT_STATIC (shift < sizeof (hb_codepoint_t) * 8);
  59   ASSERT_STATIC (shift + num_bits <= sizeof (hb_codepoint_t) * 8);
  60
  61   inline void init (void) {
  62     mask = 0;
  63   }
  64
  65   inline void add (hb_codepoint_t g) {
  66     mask |= mask_for (g);
  67   }
  68
  69   inline void add_range (hb_codepoint_t a, hb_codepoint_t b) {
  70     if ((b >> shift) - (a >> shift) >= mask_bits - 1)
  71       mask = (mask_t) -1;
  72     else {
  73       mask_t ma = mask_for (a);
  74       mask_t mb = mask_for (b);
  75       mask |= mb + (mb - ma) - (mb < ma);
  76     }
  77   }
  78
  79   inline bool may_have (hb_codepoint_t g) const {
  80     return !!(mask & mask_for (g));
  81   }
  82
  83   private:
  84
  85   static inline mask_t mask_for (hb_codepoint_t g) {
  86     return ((mask_t) 1) << ((g >> shift) & (mask_bits - 1));
  87   }
  88   mask_t mask;
  89 };
  90
  91 template <typename head_t, typename tail_t>
  92 struct hb_set_digest_combiner_t
  93 {
  94   ASSERT_POD ();
  95
  96   inline void init (void) {
  97     head.init ();
  98     tail.init ();
  99   }
 100
 101   inline void add (hb_codepoint_t g) {
 102     head.add (g);
 103     tail.add (g);
 104   }
 105
 106   inline void add_range (hb_codepoint_t a, hb_codepoint_t b) {
 107     head.add_range (a, b);
 108     tail.add_range (a, b);
 109   }
 110
 111   inline bool may_have (hb_codepoint_t g) const {
 112     return head.may_have (g) && tail.may_have (g);
 113   }
 114
 115   private:
 116   head_t head;
 117   tail_t tail;
 118 };
 119
 120
 121 /*
 122  * hb_set_digest_t
 123  *
 124  * This is a combination of digests that performs "best".
 125  * There is not much science to this: it's a result of intuition
 126  * and testing.
 127  */
 128 typedef hb_set_digest_combiner_t
 129 <
 130   hb_set_digest_lowest_bits_t<unsigned long, 4>,
 131   hb_set_digest_combiner_t
 132   <
 133     hb_set_digest_lowest_bits_t<unsigned long, 0>,
 134     hb_set_digest_lowest_bits_t<unsigned long, 9>
 135   >
 136 > hb_set_digest_t;
 137
 138
 139
 140 /*
 141  * hb_set_t
 142  */
 143
 144
 145 /* TODO Make this faster and memmory efficient. */
 146
 147 struct hb_set_t
 148 {
 149   hb_object_header_t header;
 150   ASSERT_POD ();
 151   bool in_error;
 152
 153   inline void init (void) {
 154     header.init ();
 155     clear ();
 156   }
 157   inline void fini (void) {
 158   }
 159   inline void clear (void) {
 160     if (unlikely (hb_object_is_inert (this)))
 161       return;
 162     in_error = false;
 163     memset (elts, 0, sizeof elts);
 164   }
 165   inline bool is_empty (void) const {
 166     for (unsigned int i = 0; i < ARRAY_LENGTH (elts); i++)
 167       if (elts[i])
 168         return false;
 169     return true;
 170   }
 171   inline void add (hb_codepoint_t g)
 172   {
 173     if (unlikely (in_error)) return;
 174     if (unlikely (g == INVALID)) return;
 175     if (unlikely (g > MAX_G)) return;
 176     elt (g) |= mask (g);
 177   }
 178   inline void add_range (hb_codepoint_t a, hb_codepoint_t b)
 179   {
 180     if (unlikely (in_error)) return;
 181     /* TODO Speedup */
 182     for (unsigned int i = a; i < b + 1; i++)
 183       add (i);
 184   }
 185   inline void del (hb_codepoint_t g)
 186   {
 187     if (unlikely (in_error)) return;
 188     if (unlikely (g > MAX_G)) return;
 189     elt (g) &= ~mask (g);
 190   }
 191   inline void del_range (hb_codepoint_t a, hb_codepoint_t b)
 192   {
 193     if (unlikely (in_error)) return;
 194     /* TODO Speedup */
 195     for (unsigned int i = a; i < b + 1; i++)
 196       del (i);
 197   }
 198   inline bool has (hb_codepoint_t g) const
 199   {
 200     if (unlikely (g > MAX_G)) return false;
 201     return !!(elt (g) & mask (g));
 202   }
 203   inline bool intersects (hb_codepoint_t first,
 204                           hb_codepoint_t last) const
 205   {
 206     if (unlikely (first > MAX_G)) return false;
 207     if (unlikely (last  > MAX_G)) last = MAX_G;
 208     unsigned int end = last + 1;
 209     for (hb_codepoint_t i = first; i < end; i++)
 210       if (has (i))
 211         return true;
 212     return false;
 213   }
 214   inline bool is_equal (const hb_set_t *other) const
 215   {
 216     for (unsigned int i = 0; i < ELTS; i++)
 217       if (elts[i] != other->elts[i])
 218         return false;
 219     return true;
 220   }
 221   inline void set (const hb_set_t *other)
 222   {
 223     if (unlikely (in_error)) return;
 224     for (unsigned int i = 0; i < ELTS; i++)
 225       elts[i] = other->elts[i];
 226   }
 227   inline void union_ (const hb_set_t *other)
 228   {
 229     if (unlikely (in_error)) return;
 230     for (unsigned int i = 0; i < ELTS; i++)
 231       elts[i] |= other->elts[i];
 232   }
 233   inline void intersect (const hb_set_t *other)
 234   {
 235     if (unlikely (in_error)) return;
 236     for (unsigned int i = 0; i < ELTS; i++)
 237       elts[i] &= other->elts[i];
 238   }
 239   inline void subtract (const hb_set_t *other)
 240   {
 241     if (unlikely (in_error)) return;
 242     for (unsigned int i = 0; i < ELTS; i++)
 243       elts[i] &= ~other->elts[i];
 244   }
 245   inline void symmetric_difference (const hb_set_t *other)
 246   {
 247     if (unlikely (in_error)) return;
 248     for (unsigned int i = 0; i < ELTS; i++)
 249       elts[i] ^= other->elts[i];
 250   }
 251   inline void invert (void)
 252   {
 253     if (unlikely (in_error)) return;
 254     for (unsigned int i = 0; i < ELTS; i++)
 255       elts[i] = ~elts[i];
 256   }
 257   inline bool next (hb_codepoint_t *codepoint) const
 258   {
 259     if (unlikely (*codepoint == INVALID)) {
 260       hb_codepoint_t i = get_min ();
 261       if (i != INVALID) {
 262         *codepoint = i;
 263         return true;
 264       } else {
 265         *codepoint = INVALID;
 266         return false;
 267       }
 268     }
 269     for (hb_codepoint_t i = *codepoint + 1; i < MAX_G + 1; i++)
 270       if (has (i)) {
 271         *codepoint = i;
 272         return true;
 273       }
 274     *codepoint = INVALID;
 275     return false;
 276   }
 277   inline bool next_range (hb_codepoint_t *first, hb_codepoint_t *last) const
 278   {
 279     hb_codepoint_t i;
 280
 281     i = *last;
 282     if (!next (&i))
 283     {
 284       *last = *first = INVALID;
 285       return false;
 286     }
 287
 288     *last = *first = i;
 289     while (next (&i) && i == *last + 1)
 290       (*last)++;
 291
 292     return true;
 293   }
 294
 295   inline unsigned int get_population (void) const
 296   {
 297     unsigned int count = 0;
 298     for (unsigned int i = 0; i < ELTS; i++)
 299       count += _hb_popcount32 (elts[i]);
 300     return count;
 301   }
 302   inline hb_codepoint_t get_min (void) const
 303   {
 304     for (unsigned int i = 0; i < ELTS; i++)
 305       if (elts[i])
 306         for (unsigned int j = 0; j < BITS; j++)
 307           if (elts[i] & (1 << j))
 308             return i * BITS + j;
 309     return INVALID;
 310   }
 311   inline hb_codepoint_t get_max (void) const
 312   {
 313     for (unsigned int i = ELTS; i; i--)
 314       if (elts[i - 1])
 315         for (unsigned int j = BITS; j; j--)
 316           if (elts[i - 1] & (1 << (j - 1)))
 317             return (i - 1) * BITS + (j - 1);
 318     return INVALID;
 319   }
 320
 321   typedef uint32_t elt_t;
 322   static const unsigned int MAX_G = 65536 - 1; /* XXX Fix this... */
 323   static const unsigned int SHIFT = 5;
 324   static const unsigned int BITS = (1 << SHIFT);
 325   static const unsigned int MASK = BITS - 1;
 326   static const unsigned int ELTS = (MAX_G + 1 + (BITS - 1)) / BITS;
 327   static  const hb_codepoint_t INVALID = HB_SET_VALUE_INVALID;
 328
 329   elt_t &elt (hb_codepoint_t g) { return elts[g >> SHIFT]; }
 330   elt_t elt (hb_codepoint_t g) const { return elts[g >> SHIFT]; }
 331   elt_t mask (hb_codepoint_t g) const { return elt_t (1) << (g & MASK); }
 332
 333   elt_t elts[ELTS]; /* XXX 8kb */
 334
 335   ASSERT_STATIC (sizeof (elt_t) * 8 == BITS);
 336   ASSERT_STATIC (sizeof (elt_t) * 8 * ELTS > MAX_G);
 337 };
 338
 339
 340
 341 #endif /* HB_SET_PRIVATE_HH */