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