gfx/harfbuzz/src/hb-buffer.hh

   1 /*
   2  * Copyright © 1998-2004  David Turner and Werner Lemberg
   3  * Copyright © 2004,2007,2009,2010  Red Hat, Inc.
   4  * Copyright © 2011,2012  Google, Inc.
   5  *
   6  *  This is part of HarfBuzz, a text shaping library.
   7  *
   8  * Permission is hereby granted, without written agreement and without
   9  * license or royalty fees, to use, copy, modify, and distribute this
  10  * software and its documentation for any purpose, provided that the
  11  * above copyright notice and the following two paragraphs appear in
  12  * all copies of this software.
  13  *
  14  * IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR
  15  * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
  16  * ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN
  17  * IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
  18  * DAMAGE.
  19  *
  20  * THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
  21  * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
  22  * FITNESS FOR A PARTICULAR PURPOSE.  THE SOFTWARE PROVIDED HEREUNDER IS
  23  * ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO
  24  * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
  25  *
  26  * Red Hat Author(s): Owen Taylor, Behdad Esfahbod
  27  * Google Author(s): Behdad Esfahbod
  28  */
  29
  30 #ifndef HB_BUFFER_HH
  31 #define HB_BUFFER_HH
  32
  33 #include "hb.hh"
  34 #include "hb-unicode.hh"
  35 #include "hb-set-digest.hh"
  36
  37
  38 static_assert ((sizeof (hb_glyph_info_t) == 20), "");
  39 static_assert ((sizeof (hb_glyph_info_t) == sizeof (hb_glyph_position_t)), "");
  40
  41 HB_MARK_AS_FLAG_T (hb_glyph_flags_t);
  42 HB_MARK_AS_FLAG_T (hb_buffer_flags_t);
  43 HB_MARK_AS_FLAG_T (hb_buffer_serialize_flags_t);
  44 HB_MARK_AS_FLAG_T (hb_buffer_diff_flags_t);
  45
  46 enum hb_buffer_scratch_flags_t {
  47   HB_BUFFER_SCRATCH_FLAG_DEFAULT                        = 0x00000000u,
  48   HB_BUFFER_SCRATCH_FLAG_HAS_NON_ASCII                  = 0x00000001u,
  49   HB_BUFFER_SCRATCH_FLAG_HAS_DEFAULT_IGNORABLES         = 0x00000002u,
  50   HB_BUFFER_SCRATCH_FLAG_HAS_SPACE_FALLBACK             = 0x00000004u,
  51   HB_BUFFER_SCRATCH_FLAG_HAS_GPOS_ATTACHMENT            = 0x00000008u,
  52   HB_BUFFER_SCRATCH_FLAG_HAS_CGJ                        = 0x00000010u,
  53   HB_BUFFER_SCRATCH_FLAG_HAS_GLYPH_FLAGS                = 0x00000020u,
  54   HB_BUFFER_SCRATCH_FLAG_HAS_BROKEN_SYLLABLE            = 0x00000040u,
  55
  56   /* Reserved for shapers' internal use. */
  57   HB_BUFFER_SCRATCH_FLAG_SHAPER0                        = 0x01000000u,
  58   HB_BUFFER_SCRATCH_FLAG_SHAPER1                        = 0x02000000u,
  59   HB_BUFFER_SCRATCH_FLAG_SHAPER2                        = 0x04000000u,
  60   HB_BUFFER_SCRATCH_FLAG_SHAPER3                        = 0x08000000u,
  61 };
  62 HB_MARK_AS_FLAG_T (hb_buffer_scratch_flags_t);
  63
  64
  65 /*
  66  * hb_buffer_t
  67  */
  68
  69 struct hb_buffer_t
  70 {
  71   hb_object_header_t header;
  72
  73   /*
  74    * Information about how the text in the buffer should be treated.
  75    */
  76
  77   hb_unicode_funcs_t *unicode; /* Unicode functions */
  78   hb_buffer_flags_t flags; /* BOT / EOT / etc. */
  79   hb_buffer_cluster_level_t cluster_level;
  80   hb_codepoint_t replacement; /* U+FFFD or something else. */
  81   hb_codepoint_t invisible; /* 0 or something else. */
  82   hb_codepoint_t not_found; /* 0 or something else. */
  83
  84   /*
  85    * Buffer contents
  86    */
  87
  88   hb_buffer_content_type_t content_type;
  89   hb_segment_properties_t props; /* Script, language, direction */
  90
  91   bool successful; /* Allocations successful */
  92   bool shaping_failed; /* Shaping failure */
  93   bool have_output; /* Whether we have an output buffer going on */
  94   bool have_positions; /* Whether we have positions */
  95
  96   unsigned int idx; /* Cursor into ->info and ->pos arrays */
  97   unsigned int len; /* Length of ->info and ->pos arrays */
  98   unsigned int out_len; /* Length of ->out_info array if have_output */
  99
 100   unsigned int allocated; /* Length of allocated arrays */
 101   hb_glyph_info_t     *info;
 102   hb_glyph_info_t     *out_info;
 103   hb_glyph_position_t *pos;
 104
 105   /* Text before / after the main buffer contents.
 106    * Always in Unicode, and ordered outward.
 107    * Index 0 is for "pre-context", 1 for "post-context". */
 108   static constexpr unsigned CONTEXT_LENGTH = 5u;
 109   hb_codepoint_t context[2][CONTEXT_LENGTH];
 110   unsigned int context_len[2];
 111
 112
 113   /*
 114    * Managed by enter / leave
 115    */
 116
 117   uint8_t allocated_var_bits;
 118   uint8_t serial;
 119   hb_buffer_scratch_flags_t scratch_flags; /* Have space-fallback, etc. */
 120   unsigned int max_len; /* Maximum allowed len. */
 121   int max_ops; /* Maximum allowed operations. */
 122   /* The bits here reflect current allocations of the bytes in glyph_info_t's var1 and var2. */
 123
 124
 125   /*
 126    * Messaging callback
 127    */
 128
 129 #ifndef HB_NO_BUFFER_MESSAGE
 130   hb_buffer_message_func_t message_func;
 131   void *message_data;
 132   hb_destroy_func_t message_destroy;
 133   unsigned message_depth; /* How deeply are we inside a message callback? */
 134 #else
 135   static constexpr unsigned message_depth = 0u;
 136 #endif
 137
 138
 139
 140   /* Methods */
 141
 142   HB_NODISCARD bool in_error () const { return !successful; }
 143
 144   void allocate_var (unsigned int start, unsigned int count)
 145   {
 146     unsigned int end = start + count;
 147     assert (end <= 8);
 148     unsigned int bits = (1u<<end) - (1u<<start);
 149     assert (0 == (allocated_var_bits & bits));
 150     allocated_var_bits |= bits;
 151   }
 152   bool try_allocate_var (unsigned int start, unsigned int count)
 153   {
 154     unsigned int end = start + count;
 155     assert (end <= 8);
 156     unsigned int bits = (1u<<end) - (1u<<start);
 157     if (allocated_var_bits & bits)
 158       return false;
 159     allocated_var_bits |= bits;
 160     return true;
 161   }
 162   void deallocate_var (unsigned int start, unsigned int count)
 163   {
 164     unsigned int end = start + count;
 165     assert (end <= 8);
 166     unsigned int bits = (1u<<end) - (1u<<start);
 167     assert (bits == (allocated_var_bits & bits));
 168     allocated_var_bits &= ~bits;
 169   }
 170   void assert_var (unsigned int start, unsigned int count)
 171   {
 172     unsigned int end = start + count;
 173     assert (end <= 8);
 174     HB_UNUSED unsigned int bits = (1u<<end) - (1u<<start);
 175     assert (bits == (allocated_var_bits & bits));
 176   }
 177   void deallocate_var_all ()
 178   {
 179     allocated_var_bits = 0;
 180   }
 181
 182   hb_glyph_info_t &cur (unsigned int i = 0) { return info[idx + i]; }
 183   hb_glyph_info_t cur (unsigned int i = 0) const { return info[idx + i]; }
 184
 185   hb_glyph_position_t &cur_pos (unsigned int i = 0) { return pos[idx + i]; }
 186   hb_glyph_position_t cur_pos (unsigned int i = 0) const { return pos[idx + i]; }
 187
 188   hb_glyph_info_t &prev ()      { return out_info[out_len ? out_len - 1 : 0]; }
 189   hb_glyph_info_t prev () const { return out_info[out_len ? out_len - 1 : 0]; }
 190
 191   hb_set_digest_t digest () const
 192   {
 193     hb_set_digest_t d;
 194     d.init ();
 195     d.add_array (&info[0].codepoint, len, sizeof (info[0]));
 196     return d;
 197   }
 198
 199   HB_INTERNAL void similar (const hb_buffer_t &src);
 200   HB_INTERNAL void reset ();
 201   HB_INTERNAL void clear ();
 202
 203   /* Called around shape() */
 204   HB_INTERNAL void enter ();
 205   HB_INTERNAL void leave ();
 206
 207 #ifndef HB_NO_BUFFER_VERIFY
 208   HB_INTERNAL
 209 #endif
 210   bool verify (hb_buffer_t        *text_buffer,
 211                hb_font_t          *font,
 212                const hb_feature_t *features,
 213                unsigned int        num_features,
 214                const char * const *shapers)
 215 #ifndef HB_NO_BUFFER_VERIFY
 216   ;
 217 #else
 218   { return true; }
 219 #endif
 220
 221   unsigned int backtrack_len () const { return have_output ? out_len : idx; }
 222   unsigned int lookahead_len () const { return len - idx; }
 223   uint8_t next_serial () { return ++serial ? serial : ++serial; }
 224
 225   HB_INTERNAL void add (hb_codepoint_t  codepoint,
 226                         unsigned int    cluster);
 227   HB_INTERNAL void add_info (const hb_glyph_info_t &glyph_info);
 228
 229   void reverse_range (unsigned start, unsigned end)
 230   {
 231     hb_array_t<hb_glyph_info_t> (info, len).reverse (start, end);
 232     if (have_positions)
 233       hb_array_t<hb_glyph_position_t> (pos, len).reverse (start, end);
 234   }
 235   void reverse () { reverse_range (0, len); }
 236
 237   template <typename FuncType>
 238   void reverse_groups (const FuncType& group,
 239                        bool merge_clusters = false)
 240   {
 241     if (unlikely (!len))
 242       return;
 243
 244     unsigned start = 0;
 245     unsigned i;
 246     for (i = 1; i < len; i++)
 247     {
 248       if (!group (info[i - 1], info[i]))
 249       {
 250         if (merge_clusters)
 251           this->merge_clusters (start, i);
 252         reverse_range (start, i);
 253         start = i;
 254       }
 255     }
 256     if (merge_clusters)
 257       this->merge_clusters (start, i);
 258     reverse_range (start, i);
 259
 260     reverse ();
 261   }
 262
 263   template <typename FuncType>
 264   unsigned group_end (unsigned start, const FuncType& group) const
 265   {
 266     while (++start < len && group (info[start - 1], info[start]))
 267       ;
 268
 269     return start;
 270   }
 271
 272   static bool _cluster_group_func (const hb_glyph_info_t& a,
 273                                    const hb_glyph_info_t& b)
 274   { return a.cluster == b.cluster; }
 275
 276   void reverse_clusters () { reverse_groups (_cluster_group_func); }
 277
 278   HB_INTERNAL void guess_segment_properties ();
 279
 280   HB_INTERNAL bool sync ();
 281   HB_INTERNAL int sync_so_far ();
 282   HB_INTERNAL void clear_output ();
 283   HB_INTERNAL void clear_positions ();
 284
 285   template <typename T>
 286   HB_NODISCARD bool replace_glyphs (unsigned int num_in,
 287                                     unsigned int num_out,
 288                                     const T *glyph_data)
 289   {
 290     if (unlikely (!make_room_for (num_in, num_out))) return false;
 291
 292     assert (idx + num_in <= len);
 293
 294     merge_clusters (idx, idx + num_in);
 295
 296     hb_glyph_info_t &orig_info = idx < len ? cur() : prev();
 297
 298     hb_glyph_info_t *pinfo = &out_info[out_len];
 299     for (unsigned int i = 0; i < num_out; i++)
 300     {
 301       *pinfo = orig_info;
 302       pinfo->codepoint = glyph_data[i];
 303       pinfo++;
 304     }
 305
 306     idx  += num_in;
 307     out_len += num_out;
 308     return true;
 309   }
 310
 311   HB_NODISCARD bool replace_glyph (hb_codepoint_t glyph_index)
 312   { return replace_glyphs (1, 1, &glyph_index); }
 313
 314   /* Makes a copy of the glyph at idx to output and replace glyph_index */
 315   HB_NODISCARD bool output_glyph (hb_codepoint_t glyph_index)
 316   { return replace_glyphs (0, 1, &glyph_index); }
 317
 318   HB_NODISCARD bool output_info (const hb_glyph_info_t &glyph_info)
 319   {
 320     if (unlikely (!make_room_for (0, 1))) return false;
 321
 322     out_info[out_len] = glyph_info;
 323
 324     out_len++;
 325     return true;
 326   }
 327   /* Copies glyph at idx to output but doesn't advance idx */
 328   HB_NODISCARD bool copy_glyph ()
 329   {
 330     /* Extra copy because cur()'s return can be freed within
 331      * output_info() call if buffer reallocates. */
 332     return output_info (hb_glyph_info_t (cur()));
 333   }
 334
 335   /* Copies glyph at idx to output and advance idx.
 336    * If there's no output, just advance idx. */
 337   HB_NODISCARD bool next_glyph ()
 338   {
 339     if (have_output)
 340     {
 341       if (out_info != info || out_len != idx)
 342       {
 343         if (unlikely (!make_room_for (1, 1))) return false;
 344         out_info[out_len] = info[idx];
 345       }
 346       out_len++;
 347     }
 348
 349     idx++;
 350     return true;
 351   }
 352   /* Copies n glyphs at idx to output and advance idx.
 353    * If there's no output, just advance idx. */
 354   HB_NODISCARD bool next_glyphs (unsigned int n)
 355   {
 356     if (have_output)
 357     {
 358       if (out_info != info || out_len != idx)
 359       {
 360         if (unlikely (!make_room_for (n, n))) return false;
 361         memmove (out_info + out_len, info + idx, n * sizeof (out_info[0]));
 362       }
 363       out_len += n;
 364     }
 365
 366     idx += n;
 367     return true;
 368   }
 369   /* Advance idx without copying to output. */
 370   void skip_glyph () { idx++; }
 371   void reset_masks (hb_mask_t mask)
 372   {
 373     for (unsigned int j = 0; j < len; j++)
 374       info[j].mask = mask;
 375   }
 376   void add_masks (hb_mask_t mask)
 377   {
 378     for (unsigned int j = 0; j < len; j++)
 379       info[j].mask |= mask;
 380   }
 381   HB_INTERNAL void set_masks (hb_mask_t value, hb_mask_t mask,
 382                               unsigned int cluster_start, unsigned int cluster_end);
 383
 384   void merge_clusters (unsigned int start, unsigned int end)
 385   {
 386     if (end - start < 2)
 387       return;
 388     merge_clusters_impl (start, end);
 389   }
 390   HB_INTERNAL void merge_clusters_impl (unsigned int start, unsigned int end);
 391   HB_INTERNAL void merge_out_clusters (unsigned int start, unsigned int end);
 392   /* Merge clusters for deleting current glyph, and skip it. */
 393   HB_INTERNAL void delete_glyph ();
 394   HB_INTERNAL void delete_glyphs_inplace (bool (*filter) (const hb_glyph_info_t *info));
 395
 396
 397
 398   /* Adds glyph flags in mask to infos with clusters between start and end.
 399    * The start index will be from out-buffer if from_out_buffer is true.
 400    * If interior is true, then the cluster having the minimum value is skipped. */
 401   void _set_glyph_flags (hb_mask_t mask,
 402                          unsigned start = 0,
 403                          unsigned end = (unsigned) -1,
 404                          bool interior = false,
 405                          bool from_out_buffer = false)
 406   {
 407     end = hb_min (end, len);
 408
 409     if (interior && !from_out_buffer && end - start < 2)
 410       return;
 411
 412     scratch_flags |= HB_BUFFER_SCRATCH_FLAG_HAS_GLYPH_FLAGS;
 413
 414     if (!from_out_buffer || !have_output)
 415     {
 416       if (!interior)
 417       {
 418         for (unsigned i = start; i < end; i++)
 419           info[i].mask |= mask;
 420       }
 421       else
 422       {
 423         unsigned cluster = _infos_find_min_cluster (info, start, end);
 424         _infos_set_glyph_flags (info, start, end, cluster, mask);
 425       }
 426     }
 427     else
 428     {
 429       assert (start <= out_len);
 430       assert (idx <= end);
 431
 432       if (!interior)
 433       {
 434         for (unsigned i = start; i < out_len; i++)
 435           out_info[i].mask |= mask;
 436         for (unsigned i = idx; i < end; i++)
 437           info[i].mask |= mask;
 438       }
 439       else
 440       {
 441         unsigned cluster = _infos_find_min_cluster (info, idx, end);
 442         cluster = _infos_find_min_cluster (out_info, start, out_len, cluster);
 443
 444         _infos_set_glyph_flags (out_info, start, out_len, cluster, mask);
 445         _infos_set_glyph_flags (info, idx, end, cluster, mask);
 446       }
 447     }
 448   }
 449
 450   void unsafe_to_break (unsigned int start = 0, unsigned int end = -1)
 451   {
 452     _set_glyph_flags (HB_GLYPH_FLAG_UNSAFE_TO_BREAK | HB_GLYPH_FLAG_UNSAFE_TO_CONCAT,
 453                       start, end,
 454                       true);
 455   }
 456   void safe_to_insert_tatweel (unsigned int start = 0, unsigned int end = -1)
 457   {
 458     if ((flags & HB_BUFFER_FLAG_PRODUCE_SAFE_TO_INSERT_TATWEEL) == 0)
 459     {
 460       unsafe_to_break (start, end);
 461       return;
 462     }
 463     _set_glyph_flags (HB_GLYPH_FLAG_SAFE_TO_INSERT_TATWEEL,
 464                       start, end,
 465                       true);
 466   }
 467 #ifndef HB_OPTIMIZE_SIZE
 468   HB_ALWAYS_INLINE
 469 #endif
 470   void unsafe_to_concat (unsigned int start = 0, unsigned int end = -1)
 471   {
 472     if (likely ((flags & HB_BUFFER_FLAG_PRODUCE_UNSAFE_TO_CONCAT) == 0))
 473       return;
 474     _set_glyph_flags (HB_GLYPH_FLAG_UNSAFE_TO_CONCAT,
 475                       start, end,
 476                       false);
 477   }
 478   void unsafe_to_break_from_outbuffer (unsigned int start = 0, unsigned int end = -1)
 479   {
 480     _set_glyph_flags (HB_GLYPH_FLAG_UNSAFE_TO_BREAK | HB_GLYPH_FLAG_UNSAFE_TO_CONCAT,
 481                       start, end,
 482                       true, true);
 483   }
 484 #ifndef HB_OPTIMIZE_SIZE
 485   HB_ALWAYS_INLINE
 486 #endif
 487   void unsafe_to_concat_from_outbuffer (unsigned int start = 0, unsigned int end = -1)
 488   {
 489     if (likely ((flags & HB_BUFFER_FLAG_PRODUCE_UNSAFE_TO_CONCAT) == 0))
 490       return;
 491     _set_glyph_flags (HB_GLYPH_FLAG_UNSAFE_TO_CONCAT,
 492                       start, end,
 493                       false, true);
 494   }
 495
 496
 497   /* Internal methods */
 498   HB_NODISCARD HB_INTERNAL bool move_to (unsigned int i); /* i is output-buffer index. */
 499
 500   HB_NODISCARD HB_INTERNAL bool enlarge (unsigned int size);
 501
 502   HB_NODISCARD bool resize (unsigned length)
 503   {
 504     assert (!have_output);
 505     if (unlikely (!ensure (length))) return false;
 506     len = length;
 507     return true;
 508   }
 509   HB_NODISCARD bool ensure (unsigned int size)
 510   { return likely (!size || size < allocated) ? true : enlarge (size); }
 511
 512   HB_NODISCARD bool ensure_inplace (unsigned int size)
 513   { return likely (!size || size < allocated); }
 514
 515   void assert_glyphs ()
 516   {
 517     assert ((content_type == HB_BUFFER_CONTENT_TYPE_GLYPHS) ||
 518             (!len && (content_type == HB_BUFFER_CONTENT_TYPE_INVALID)));
 519   }
 520   void assert_unicode ()
 521   {
 522     assert ((content_type == HB_BUFFER_CONTENT_TYPE_UNICODE) ||
 523             (!len && (content_type == HB_BUFFER_CONTENT_TYPE_INVALID)));
 524   }
 525   HB_NODISCARD bool ensure_glyphs ()
 526   {
 527     if (unlikely (content_type != HB_BUFFER_CONTENT_TYPE_GLYPHS))
 528     {
 529       if (content_type != HB_BUFFER_CONTENT_TYPE_INVALID)
 530         return false;
 531       assert (len == 0);
 532       content_type = HB_BUFFER_CONTENT_TYPE_GLYPHS;
 533     }
 534     return true;
 535   }
 536   HB_NODISCARD bool ensure_unicode ()
 537   {
 538     if (unlikely (content_type != HB_BUFFER_CONTENT_TYPE_UNICODE))
 539     {
 540       if (content_type != HB_BUFFER_CONTENT_TYPE_INVALID)
 541         return false;
 542       assert (len == 0);
 543       content_type = HB_BUFFER_CONTENT_TYPE_UNICODE;
 544     }
 545     return true;
 546   }
 547
 548   HB_NODISCARD HB_INTERNAL bool make_room_for (unsigned int num_in, unsigned int num_out);
 549   HB_NODISCARD HB_INTERNAL bool shift_forward (unsigned int count);
 550
 551   typedef long scratch_buffer_t;
 552   HB_INTERNAL scratch_buffer_t *get_scratch_buffer (unsigned int *size);
 553
 554   void clear_context (unsigned int side) { context_len[side] = 0; }
 555
 556   HB_INTERNAL void sort (unsigned int start, unsigned int end, int(*compar)(const hb_glyph_info_t *, const hb_glyph_info_t *));
 557
 558   bool messaging ()
 559   {
 560 #ifdef HB_NO_BUFFER_MESSAGE
 561     return false;
 562 #else
 563     return unlikely (message_func);
 564 #endif
 565   }
 566   bool message (hb_font_t *font, const char *fmt, ...) HB_PRINTF_FUNC(3, 4)
 567   {
 568 #ifdef HB_NO_BUFFER_MESSAGE
 569     return true;
 570 #else
 571     if (likely (!messaging ()))
 572       return true;
 573
 574     va_list ap;
 575     va_start (ap, fmt);
 576     bool ret = message_impl (font, fmt, ap);
 577     va_end (ap);
 578
 579     return ret;
 580 #endif
 581   }
 582   HB_INTERNAL bool message_impl (hb_font_t *font, const char *fmt, va_list ap) HB_PRINTF_FUNC(3, 0);
 583
 584   static void
 585   set_cluster (hb_glyph_info_t &inf, unsigned int cluster, unsigned int mask = 0)
 586   {
 587     if (inf.cluster != cluster)
 588       inf.mask = (inf.mask & ~HB_GLYPH_FLAG_DEFINED) | (mask & HB_GLYPH_FLAG_DEFINED);
 589     inf.cluster = cluster;
 590   }
 591   void
 592   _infos_set_glyph_flags (hb_glyph_info_t *infos,
 593                           unsigned int start, unsigned int end,
 594                           unsigned int cluster,
 595                           hb_mask_t mask)
 596   {
 597     if (unlikely (start == end))
 598       return;
 599
 600     unsigned cluster_first = infos[start].cluster;
 601     unsigned cluster_last = infos[end - 1].cluster;
 602
 603     if (cluster_level == HB_BUFFER_CLUSTER_LEVEL_CHARACTERS ||
 604         (cluster != cluster_first && cluster != cluster_last))
 605     {
 606       for (unsigned int i = start; i < end; i++)
 607         if (cluster != infos[i].cluster)
 608         {
 609           scratch_flags |= HB_BUFFER_SCRATCH_FLAG_HAS_GLYPH_FLAGS;
 610           infos[i].mask |= mask;
 611         }
 612       return;
 613     }
 614
 615     /* Monotone clusters */
 616
 617     if (cluster == cluster_first)
 618     {
 619       for (unsigned int i = end; start < i && infos[i - 1].cluster != cluster_first; i--)
 620       {
 621         scratch_flags |= HB_BUFFER_SCRATCH_FLAG_HAS_GLYPH_FLAGS;
 622         infos[i - 1].mask |= mask;
 623       }
 624     }
 625     else /* cluster == cluster_last */
 626     {
 627       for (unsigned int i = start; i < end && infos[i].cluster != cluster_last; i++)
 628       {
 629         scratch_flags |= HB_BUFFER_SCRATCH_FLAG_HAS_GLYPH_FLAGS;
 630         infos[i].mask |= mask;
 631       }
 632     }
 633   }
 634   unsigned
 635   _infos_find_min_cluster (const hb_glyph_info_t *infos,
 636                            unsigned start, unsigned end,
 637                            unsigned cluster = UINT_MAX)
 638   {
 639     if (unlikely (start == end))
 640       return cluster;
 641
 642     if (cluster_level == HB_BUFFER_CLUSTER_LEVEL_CHARACTERS)
 643     {
 644       for (unsigned int i = start; i < end; i++)
 645         cluster = hb_min (cluster, infos[i].cluster);
 646       return cluster;
 647     }
 648
 649     return hb_min (cluster, hb_min (infos[start].cluster, infos[end - 1].cluster));
 650   }
 651
 652   void clear_glyph_flags (hb_mask_t mask = 0)
 653   {
 654     for (unsigned int i = 0; i < len; i++)
 655       info[i].mask = (info[i].mask & ~HB_GLYPH_FLAG_DEFINED) | (mask & HB_GLYPH_FLAG_DEFINED);
 656   }
 657 };
 658 DECLARE_NULL_INSTANCE (hb_buffer_t);
 659
 660
 661 #define foreach_group(buffer, start, end, group_func) \
 662   for (unsigned int \
 663        _count = buffer->len, \
 664        start = 0, end = _count ? buffer->group_end (0, group_func) : 0; \
 665        start < _count; \
 666        start = end, end = buffer->group_end (start, group_func))
 667
 668 #define foreach_cluster(buffer, start, end) \
 669         foreach_group (buffer, start, end, hb_buffer_t::_cluster_group_func)
 670
 671
 672 #define HB_BUFFER_XALLOCATE_VAR(b, func, var) \
 673   b->func (offsetof (hb_glyph_info_t, var) - offsetof(hb_glyph_info_t, var1), \
 674            sizeof (b->info[0].var))
 675 #define HB_BUFFER_ALLOCATE_VAR(b, var)          HB_BUFFER_XALLOCATE_VAR (b, allocate_var,     var ())
 676 #define HB_BUFFER_TRY_ALLOCATE_VAR(b, var)      HB_BUFFER_XALLOCATE_VAR (b, try_allocate_var, var ())
 677 #define HB_BUFFER_DEALLOCATE_VAR(b, var)        HB_BUFFER_XALLOCATE_VAR (b, deallocate_var,   var ())
 678 #define HB_BUFFER_ASSERT_VAR(b, var)            HB_BUFFER_XALLOCATE_VAR (b, assert_var,       var ())
 679
 680
 681 #endif /* HB_BUFFER_HH */