1 /*

     2  * Copyright © 2007,2008,2009,2010  Red Hat, Inc.

     3  * Copyright © 2010,2012  Google, Inc.

     4  *

     5  *  This is part of HarfBuzz, a text shaping library.

     6  *

     7  * Permission is hereby granted, without written agreement and without

     8  * license or royalty fees, to use, copy, modify, and distribute this

     9  * software and its documentation for any purpose, provided that the

    10  * above copyright notice and the following two paragraphs appear in

    11  * all copies of this software.

    12  *

    13  * IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR

    14  * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES

    15  * ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN

    16  * IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH

    17  * DAMAGE.

    18  *

    19  * THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,

    20  * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND

    21  * FITNESS FOR A PARTICULAR PURPOSE.  THE SOFTWARE PROVIDED HEREUNDER IS

    22  * ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO

    23  * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.

    24  *

    25  * Red Hat Author(s): Behdad Esfahbod

    26  * Google Author(s): Behdad Esfahbod

    27  */

    28 

    29 #ifndef HB_OT_LAYOUT_GSUBGPOS_PRIVATE_HH

    30 #define HB_OT_LAYOUT_GSUBGPOS_PRIVATE_HH

    31 

    32 #include "hb-buffer-private.hh"

    33 #include "hb-ot-layout-gdef-table.hh"

    34 #include "hb-set-private.hh"

    35 

    36 

    37 namespace OT {

    38 

    39 

    40 #ifndef HB_DEBUG_CLOSURE

    41 #define HB_DEBUG_CLOSURE (HB_DEBUG+0)

    42 #endif

    43 

    44 #define TRACE_CLOSURE(this) \

    45         hb_auto_trace_t<HB_DEBUG_CLOSURE, hb_void_t> trace \

    46         (&c->debug_depth, c->get_name (), this, HB_FUNC, \

    47          "");

    48 

    49 struct hb_closure_context_t :

    50        hb_dispatch_context_t<hb_closure_context_t, hb_void_t, HB_DEBUG_CLOSURE>

    51 {

    52   inline const char *get_name (void) { return "CLOSURE"; }

    53   typedef return_t (*recurse_func_t) (hb_closure_context_t *c, unsigned int lookup_index);

    54   template <typename T>

    55   inline return_t dispatch (const T &obj) { obj.closure (this); return HB_VOID; }

    56   static return_t default_return_value (void) { return HB_VOID; }

    57   bool stop_sublookup_iteration (return_t r HB_UNUSED) const { return false; }

    58   return_t recurse (unsigned int lookup_index)

    59   {

    60     if (unlikely (nesting_level_left == 0 || !recurse_func))

    61       return default_return_value ();

    62 

    63     nesting_level_left--;

    64     recurse_func (this, lookup_index);

    65     nesting_level_left++;

    66     return HB_VOID;

    67   }

    68 

    69   hb_face_t *face;

    70   hb_set_t *glyphs;

    71   recurse_func_t recurse_func;

    72   unsigned int nesting_level_left;

    73   unsigned int debug_depth;

    74 

    75   hb_closure_context_t (hb_face_t *face_,

    76                         hb_set_t *glyphs_,

    77                         unsigned int nesting_level_left_ = HB_MAX_NESTING_LEVEL) :

    78                           face (face_),

    79                           glyphs (glyphs_),

    80                           recurse_func (NULL),

    81                           nesting_level_left (nesting_level_left_),

    82                           debug_depth (0) {}

    83 

    84   void set_recurse_func (recurse_func_t func) { recurse_func = func; }

    85 };

    86 

    87 

    88 

    89 #ifndef HB_DEBUG_WOULD_APPLY

    90 #define HB_DEBUG_WOULD_APPLY (HB_DEBUG+0)

    91 #endif

    92 

    93 #define TRACE_WOULD_APPLY(this) \

    94         hb_auto_trace_t<HB_DEBUG_WOULD_APPLY, bool> trace \

    95         (&c->debug_depth, c->get_name (), this, HB_FUNC, \

    96          "%d glyphs", c->len);

    97 

    98 struct hb_would_apply_context_t :

    99        hb_dispatch_context_t<hb_would_apply_context_t, bool, HB_DEBUG_WOULD_APPLY>

   100 {

   101   inline const char *get_name (void) { return "WOULD_APPLY"; }

   102   template <typename T>

   103   inline return_t dispatch (const T &obj) { return obj.would_apply (this); }

   104   static return_t default_return_value (void) { return false; }

   105   bool stop_sublookup_iteration (return_t r) const { return r; }

   106 

   107   hb_face_t *face;

   108   const hb_codepoint_t *glyphs;

   109   unsigned int len;

   110   bool zero_context;

   111   unsigned int debug_depth;

   112 

   113   hb_would_apply_context_t (hb_face_t *face_,

   114                             const hb_codepoint_t *glyphs_,

   115                             unsigned int len_,

   116                             bool zero_context_) :

   117                               face (face_),

   118                               glyphs (glyphs_),

   119                               len (len_),

   120                               zero_context (zero_context_),

   121                               debug_depth (0) {}

   122 };

   123 

   124 

   125 

   126 #ifndef HB_DEBUG_COLLECT_GLYPHS

   127 #define HB_DEBUG_COLLECT_GLYPHS (HB_DEBUG+0)

   128 #endif

   129 

   130 #define TRACE_COLLECT_GLYPHS(this) \

   131         hb_auto_trace_t<HB_DEBUG_COLLECT_GLYPHS, hb_void_t> trace \

   132         (&c->debug_depth, c->get_name (), this, HB_FUNC, \

   133          "");

   134 

   135 struct hb_collect_glyphs_context_t :

   136        hb_dispatch_context_t<hb_collect_glyphs_context_t, hb_void_t, HB_DEBUG_COLLECT_GLYPHS>

   137 {

   138   inline const char *get_name (void) { return "COLLECT_GLYPHS"; }

   139   typedef return_t (*recurse_func_t) (hb_collect_glyphs_context_t *c, unsigned int lookup_index);

   140   template <typename T>

   141   inline return_t dispatch (const T &obj) { obj.collect_glyphs (this); return HB_VOID; }

   142   static return_t default_return_value (void) { return HB_VOID; }

   143   bool stop_sublookup_iteration (return_t r HB_UNUSED) const { return false; }

   144   return_t recurse (unsigned int lookup_index)

   145   {

   146     if (unlikely (nesting_level_left == 0 || !recurse_func))

   147       return default_return_value ();

   148 

   149     /* Note that GPOS sets recurse_func to NULL already, so it doesn't get

   150      * past the previous check.  For GSUB, we only want to collect the output

   151      * glyphs in the recursion.  If output is not requested, we can go home now.

   152      *

   153      * Note further, that the above is not exactly correct.  A recursed lookup

   154      * is allowed to match input that is not matched in the context, but that's

   155      * not how most fonts are built.  It's possible to relax that and recurse

   156      * with all sets here if it proves to be an issue.

   157      */

   158 

   159     if (output == hb_set_get_empty ())

   160       return HB_VOID;

   161 

   162     /* Return if new lookup was recursed to before. */

   163     if (recursed_lookups.has (lookup_index))

   164       return HB_VOID;

   165 

   166     hb_set_t *old_before = before;

   167     hb_set_t *old_input  = input;

   168     hb_set_t *old_after  = after;

   169     before = input = after = hb_set_get_empty ();

   170 

   171     nesting_level_left--;

   172     recurse_func (this, lookup_index);

   173     nesting_level_left++;

   174 

   175     before = old_before;

   176     input  = old_input;

   177     after  = old_after;

   178 

   179     recursed_lookups.add (lookup_index);

   180 

   181     return HB_VOID;

   182   }

   183 

   184   hb_face_t *face;

   185   hb_set_t *before;

   186   hb_set_t *input;

   187   hb_set_t *after;

   188   hb_set_t *output;

   189   recurse_func_t recurse_func;

   190   hb_set_t recursed_lookups;

   191   unsigned int nesting_level_left;

   192   unsigned int debug_depth;

   193 

   194   hb_collect_glyphs_context_t (hb_face_t *face_,

   195                                hb_set_t  *glyphs_before, /* OUT. May be NULL */

   196                                hb_set_t  *glyphs_input,  /* OUT. May be NULL */

   197                                hb_set_t  *glyphs_after,  /* OUT. May be NULL */

   198                                hb_set_t  *glyphs_output, /* OUT. May be NULL */

   199                                unsigned int nesting_level_left_ = HB_MAX_NESTING_LEVEL) :

   200                               face (face_),

   201                               before (glyphs_before ? glyphs_before : hb_set_get_empty ()),

   202                               input  (glyphs_input  ? glyphs_input  : hb_set_get_empty ()),

   203                               after  (glyphs_after  ? glyphs_after  : hb_set_get_empty ()),

   204                               output (glyphs_output ? glyphs_output : hb_set_get_empty ()),

   205                               recurse_func (NULL),

   206                               recursed_lookups (),

   207                               nesting_level_left (nesting_level_left_),

   208                               debug_depth (0)

   209   {

   210     recursed_lookups.init ();

   211   }

   212   ~hb_collect_glyphs_context_t (void)

   213   {

   214     recursed_lookups.fini ();

   215   }

   216 

   217   void set_recurse_func (recurse_func_t func) { recurse_func = func; }

   218 };

   219 

   220 

   221 

   222 #ifndef HB_DEBUG_GET_COVERAGE

   223 #define HB_DEBUG_GET_COVERAGE (HB_DEBUG+0)

   224 #endif

   225 

   226 /* XXX Can we remove this? */

   227 

   228 template <typename set_t>

   229 struct hb_add_coverage_context_t :

   230        hb_dispatch_context_t<hb_add_coverage_context_t<set_t>, const Coverage &, HB_DEBUG_GET_COVERAGE>

   231 {

   232   inline const char *get_name (void) { return "GET_COVERAGE"; }

   233   typedef const Coverage &return_t;

   234   template <typename T>

   235   inline return_t dispatch (const T &obj) { return obj.get_coverage (); }

   236   static return_t default_return_value (void) { return Null(Coverage); }

   237   bool stop_sublookup_iteration (return_t r) const

   238   {

   239     r.add_coverage (set);

   240     return false;

   241   }

   242 

   243   hb_add_coverage_context_t (set_t *set_) :

   244                             set (set_),

   245                             debug_depth (0) {}

   246 

   247   set_t *set;

   248   unsigned int debug_depth;

   249 };

   250 

   251 

   252 

   253 #ifndef HB_DEBUG_APPLY

   254 #define HB_DEBUG_APPLY (HB_DEBUG+0)

   255 #endif

   256 

   257 #define TRACE_APPLY(this) \

   258         hb_auto_trace_t<HB_DEBUG_APPLY, bool> trace \

   259         (&c->debug_depth, c->get_name (), this, HB_FUNC, \

   260          "idx %d gid %u lookup %d", \

   261          c->buffer->idx, c->buffer->cur().codepoint, (int) c->lookup_index);

   262 

   263 struct hb_apply_context_t :

   264        hb_dispatch_context_t<hb_apply_context_t, bool, HB_DEBUG_APPLY>

   265 {

   266   struct matcher_t

   267   {

   268     inline matcher_t (void) :

   269              lookup_props (0),

   270              ignore_zwnj (false),

   271              ignore_zwj (false),

   272              mask (-1),

   273 #define arg1(arg) (arg) /* Remove the macro to see why it's needed! */

   274              syllable arg1(0),

   275 #undef arg1

   276              match_func (NULL),

   277              match_data (NULL) {};

   278 

   279     typedef bool (*match_func_t) (hb_codepoint_t glyph_id, const USHORT &value, const void *data);

   280 

   281     inline void set_ignore_zwnj (bool ignore_zwnj_) { ignore_zwnj = ignore_zwnj_; }

   282     inline void set_ignore_zwj (bool ignore_zwj_) { ignore_zwj = ignore_zwj_; }

   283     inline void set_lookup_props (unsigned int lookup_props_) { lookup_props = lookup_props_; }

   284     inline void set_mask (hb_mask_t mask_) { mask = mask_; }

   285     inline void set_syllable (uint8_t syllable_)  { syllable = syllable_; }

   286     inline void set_match_func (match_func_t match_func_,

   287                                 const void *match_data_)

   288     { match_func = match_func_; match_data = match_data_; }

   289 

   290     enum may_match_t {

   291       MATCH_NO,

   292       MATCH_YES,

   293       MATCH_MAYBE

   294     };

   295 

   296     inline may_match_t may_match (const hb_glyph_info_t &info,

   297                                   const USHORT          *glyph_data) const

   298     {

   299       if (!(info.mask & mask) ||

   300           (syllable && syllable != info.syllable ()))

   301         return MATCH_NO;

   302 

   303       if (match_func)

   304         return match_func (info.codepoint, *glyph_data, match_data) ? MATCH_YES : MATCH_NO;

   305 

   306       return MATCH_MAYBE;

   307     }

   308 

   309     enum may_skip_t {

   310       SKIP_NO,

   311       SKIP_YES,

   312       SKIP_MAYBE

   313     };

   314 

   315     inline may_skip_t

   316     may_skip (const hb_apply_context_t *c,

   317               const hb_glyph_info_t    &info) const

   318     {

   319       if (!c->check_glyph_property (&info, lookup_props))

   320         return SKIP_YES;

   321 

   322       if (unlikely (_hb_glyph_info_is_default_ignorable_and_not_fvs (&info) &&

   323                     (ignore_zwnj || !_hb_glyph_info_is_zwnj (&info)) &&

   324                     (ignore_zwj || !_hb_glyph_info_is_zwj (&info))))

   325         return SKIP_MAYBE;

   326 

   327       return SKIP_NO;

   328     }

   329 

   330     protected:

   331     unsigned int lookup_props;

   332     bool ignore_zwnj;

   333     bool ignore_zwj;

   334     hb_mask_t mask;

   335     uint8_t syllable;

   336     match_func_t match_func;

   337     const void *match_data;

   338   };

   339 

   340   struct skipping_iterator_t

   341   {

   342     inline void init (hb_apply_context_t *c_, bool context_match = false)

   343     {

   344       c = c_;

   345       match_glyph_data = NULL,

   346       matcher.set_match_func (NULL, NULL);

   347       matcher.set_lookup_props (c->lookup_props);

   348       /* Ignore ZWNJ if we are matching GSUB context, or matching GPOS. */

   349       matcher.set_ignore_zwnj (context_match || c->table_index == 1);

   350       /* Ignore ZWJ if we are matching GSUB context, or matching GPOS, or if asked to. */

   351       matcher.set_ignore_zwj (context_match || c->table_index == 1 || c->auto_zwj);

   352       matcher.set_mask (context_match ? -1 : c->lookup_mask);

   353     }

   354     inline void set_lookup_props (unsigned int lookup_props)

   355     {

   356       matcher.set_lookup_props (lookup_props);

   357     }

   358     inline void set_match_func (matcher_t::match_func_t match_func_,

   359                                 const void *match_data_,

   360                                 const USHORT glyph_data[])

   361     {

   362       matcher.set_match_func (match_func_, match_data_);

   363       match_glyph_data = glyph_data;

   364     }

   365 

   366     inline void reset (unsigned int start_index_,

   367                        unsigned int num_items_)

   368     {

   369       idx = start_index_;

   370       num_items = num_items_;

   371       end = c->buffer->len;

   372       matcher.set_syllable (start_index_ == c->buffer->idx ? c->buffer->cur().syllable () : 0);

   373     }

   374 

   375     inline void reject (void) { num_items++; match_glyph_data--; }

   376 

   377     inline bool next (void)

   378     {

   379       assert (num_items > 0);

   380       while (idx + num_items < end)

   381       {

   382         idx++;

   383         const hb_glyph_info_t &info = c->buffer->info[idx];

   384 

   385         matcher_t::may_skip_t skip = matcher.may_skip (c, info);

   386         if (unlikely (skip == matcher_t::SKIP_YES))

   387           continue;

   388 

   389         matcher_t::may_match_t match = matcher.may_match (info, match_glyph_data);

   390         if (match == matcher_t::MATCH_YES ||

   391             (match == matcher_t::MATCH_MAYBE &&

   392              skip == matcher_t::SKIP_NO))

   393         {

   394           num_items--;

   395           match_glyph_data++;

   396           return true;

   397         }

   398 

   399         if (skip == matcher_t::SKIP_NO)

   400           return false;

   401       }

   402       return false;

   403     }

   404     inline bool prev (void)

   405     {

   406       assert (num_items > 0);

   407       while (idx >= num_items)

   408       {

   409         idx--;

   410         const hb_glyph_info_t &info = c->buffer->out_info[idx];

   411 

   412         matcher_t::may_skip_t skip = matcher.may_skip (c, info);

   413         if (unlikely (skip == matcher_t::SKIP_YES))

   414           continue;

   415 

   416         matcher_t::may_match_t match = matcher.may_match (info, match_glyph_data);

   417         if (match == matcher_t::MATCH_YES ||

   418             (match == matcher_t::MATCH_MAYBE &&

   419              skip == matcher_t::SKIP_NO))

   420         {

   421           num_items--;

   422           match_glyph_data++;

   423           return true;

   424         }

   425 

   426         if (skip == matcher_t::SKIP_NO)

   427           return false;

   428       }

   429       return false;

   430     }

   431 

   432     unsigned int idx;

   433     protected:

   434     hb_apply_context_t *c;

   435     matcher_t matcher;

   436     const USHORT *match_glyph_data;

   437 

   438     unsigned int num_items;

   439     unsigned int end;

   440   };

   441 

   442 

   443   inline const char *get_name (void) { return "APPLY"; }

   444   typedef return_t (*recurse_func_t) (hb_apply_context_t *c, unsigned int lookup_index);

   445   template <typename T>

   446   inline return_t dispatch (const T &obj) { return obj.apply (this); }

   447   static return_t default_return_value (void) { return false; }

   448   bool stop_sublookup_iteration (return_t r) const { return r; }

   449   return_t recurse (unsigned int lookup_index)

   450   {

   451     if (unlikely (nesting_level_left == 0 || !recurse_func))

   452       return default_return_value ();

   453 

   454     nesting_level_left--;

   455     bool ret = recurse_func (this, lookup_index);

   456     nesting_level_left++;

   457     return ret;

   458   }

   459 

   460   unsigned int table_index; /* GSUB/GPOS */

   461   hb_font_t *font;

   462   hb_face_t *face;

   463   hb_buffer_t *buffer;

   464   hb_direction_t direction;

   465   hb_mask_t lookup_mask;

   466   bool auto_zwj;

   467   recurse_func_t recurse_func;

   468   unsigned int nesting_level_left;

   469   unsigned int lookup_props;

   470   const GDEF &gdef;

   471   bool has_glyph_classes;

   472   const VariationStore &var_store;

   473   skipping_iterator_t iter_input, iter_context;

   474   unsigned int lookup_index;

   475   unsigned int debug_depth;

   476 

   477 

   478   hb_apply_context_t (unsigned int table_index_,

   479                       hb_font_t *font_,

   480                       hb_buffer_t *buffer_) :

   481                         table_index (table_index_),

   482                         font (font_), face (font->face), buffer (buffer_),

   483                         direction (buffer_->props.direction),

   484                         lookup_mask (1),

   485                         auto_zwj (true),

   486                         recurse_func (NULL),

   487                         nesting_level_left (HB_MAX_NESTING_LEVEL),

   488                         lookup_props (0),

   489                         gdef (*hb_ot_layout_from_face (face)->gdef),

   490                         has_glyph_classes (gdef.has_glyph_classes ()),

   491                         var_store (gdef.get_var_store ()),

   492                         iter_input (),

   493                         iter_context (),

   494                         lookup_index ((unsigned int) -1),

   495                         debug_depth (0) {}

   496 

   497   inline void set_lookup_mask (hb_mask_t mask) { lookup_mask = mask; }

   498   inline void set_auto_zwj (bool auto_zwj_) { auto_zwj = auto_zwj_; }

   499   inline void set_recurse_func (recurse_func_t func) { recurse_func = func; }

   500   inline void set_lookup_index (unsigned int lookup_index_) { lookup_index = lookup_index_; }

   501   inline void set_lookup_props (unsigned int lookup_props_)

   502   {

   503     lookup_props = lookup_props_;

   504     iter_input.init (this, false);

   505     iter_context.init (this, true);

   506   }

   507 

   508   inline bool

   509   match_properties_mark (hb_codepoint_t  glyph,

   510                          unsigned int    glyph_props,

   511                          unsigned int    match_props) const

   512   {

   513     /* If using mark filtering sets, the high short of

   514      * match_props has the set index.

   515      */

   516     if (match_props & LookupFlag::UseMarkFilteringSet)

   517       return gdef.mark_set_covers (match_props >> 16, glyph);

   518 

   519     /* The second byte of match_props has the meaning

   520      * "ignore marks of attachment type different than

   521      * the attachment type specified."

   522      */

   523     if (match_props & LookupFlag::MarkAttachmentType)

   524       return (match_props & LookupFlag::MarkAttachmentType) == (glyph_props & LookupFlag::MarkAttachmentType);

   525 

   526     return true;

   527   }

   528 

   529   inline bool

   530   check_glyph_property (const hb_glyph_info_t *info,

   531                         unsigned int  match_props) const

   532   {

   533     hb_codepoint_t glyph = info->codepoint;

   534     unsigned int glyph_props = _hb_glyph_info_get_glyph_props (info);

   535 

   536     /* Not covered, if, for example, glyph class is ligature and

   537      * match_props includes LookupFlags::IgnoreLigatures

   538      */

   539     if (glyph_props & match_props & LookupFlag::IgnoreFlags)

   540       return false;

   541 

   542     if (unlikely (glyph_props & HB_OT_LAYOUT_GLYPH_PROPS_MARK))

   543       return match_properties_mark (glyph, glyph_props, match_props);

   544 

   545     return true;

   546   }

   547 

   548   inline void _set_glyph_props (hb_codepoint_t glyph_index,

   549                           unsigned int class_guess = 0,

   550                           bool ligature = false,

   551                           bool component = false) const

   552   {

   553     unsigned int add_in = _hb_glyph_info_get_glyph_props (&buffer->cur()) &

   554                           HB_OT_LAYOUT_GLYPH_PROPS_PRESERVE;

   555     add_in |= HB_OT_LAYOUT_GLYPH_PROPS_SUBSTITUTED;

   556     if (ligature)

   557     {

   558       add_in |= HB_OT_LAYOUT_GLYPH_PROPS_LIGATED;

   559       /* In the only place that the MULTIPLIED bit is used, Uniscribe

   560        * seems to only care about the "last" transformation between

   561        * Ligature and Multiple substitions.  Ie. if you ligate, expand,

   562        * and ligate again, it forgives the multiplication and acts as

   563        * if only ligation happened.  As such, clear MULTIPLIED bit.

   564        */

   565       add_in &= ~HB_OT_LAYOUT_GLYPH_PROPS_MULTIPLIED;

   566     }

   567     if (component)

   568       add_in |= HB_OT_LAYOUT_GLYPH_PROPS_MULTIPLIED;

   569     if (likely (has_glyph_classes))

   570       _hb_glyph_info_set_glyph_props (&buffer->cur(), add_in | gdef.get_glyph_props (glyph_index));

   571     else if (class_guess)

   572       _hb_glyph_info_set_glyph_props (&buffer->cur(), add_in | class_guess);

   573   }

   574 

   575   inline void replace_glyph (hb_codepoint_t glyph_index) const

   576   {

   577     _set_glyph_props (glyph_index);

   578     buffer->replace_glyph (glyph_index);

   579   }

   580   inline void replace_glyph_inplace (hb_codepoint_t glyph_index) const

   581   {

   582     _set_glyph_props (glyph_index);

   583     buffer->cur().codepoint = glyph_index;

   584   }

   585   inline void replace_glyph_with_ligature (hb_codepoint_t glyph_index,

   586                                            unsigned int class_guess) const

   587   {

   588     _set_glyph_props (glyph_index, class_guess, true);

   589     buffer->replace_glyph (glyph_index);

   590   }

   591   inline void output_glyph_for_component (hb_codepoint_t glyph_index,

   592                                           unsigned int class_guess) const

   593   {

   594     _set_glyph_props (glyph_index, class_guess, false, true);

   595     buffer->output_glyph (glyph_index);

   596   }

   597 };

   598 

   599 

   600 

   601 typedef bool (*intersects_func_t) (hb_set_t *glyphs, const USHORT &value, const void *data);

   602 typedef void (*collect_glyphs_func_t) (hb_set_t *glyphs, const USHORT &value, const void *data);

   603 typedef bool (*match_func_t) (hb_codepoint_t glyph_id, const USHORT &value, const void *data);

   604 

   605 struct ContextClosureFuncs

   606 {

   607   intersects_func_t intersects;

   608 };

   609 struct ContextCollectGlyphsFuncs

   610 {

   611   collect_glyphs_func_t collect;

   612 };

   613 struct ContextApplyFuncs

   614 {

   615   match_func_t match;

   616 };

   617 

   618 

   619 static inline bool intersects_glyph (hb_set_t *glyphs, const USHORT &value, const void *data HB_UNUSED)

   620 {

   621   return glyphs->has (value);

   622 }

   623 static inline bool intersects_class (hb_set_t *glyphs, const USHORT &value, const void *data)

   624 {

   625   const ClassDef &class_def = *reinterpret_cast<const ClassDef *>(data);

   626   return class_def.intersects_class (glyphs, value);

   627 }

   628 static inline bool intersects_coverage (hb_set_t *glyphs, const USHORT &value, const void *data)

   629 {

   630   const OffsetTo<Coverage> &coverage = (const OffsetTo<Coverage>&)value;

   631   return (data+coverage).intersects (glyphs);

   632 }

   633 

   634 static inline bool intersects_array (hb_closure_context_t *c,

   635                                      unsigned int count,

   636                                      const USHORT values[],

   637                                      intersects_func_t intersects_func,

   638                                      const void *intersects_data)

   639 {

   640   for (unsigned int i = 0; i < count; i++)

   641     if (likely (!intersects_func (c->glyphs, values[i], intersects_data)))

   642       return false;

   643   return true;

   644 }

   645 

   646 

   647 static inline void collect_glyph (hb_set_t *glyphs, const USHORT &value, const void *data HB_UNUSED)

   648 {

   649   glyphs->add (value);

   650 }

   651 static inline void collect_class (hb_set_t *glyphs, const USHORT &value, const void *data)

   652 {

   653   const ClassDef &class_def = *reinterpret_cast<const ClassDef *>(data);

   654   class_def.add_class (glyphs, value);

   655 }

   656 static inline void collect_coverage (hb_set_t *glyphs, const USHORT &value, const void *data)

   657 {

   658   const OffsetTo<Coverage> &coverage = (const OffsetTo<Coverage>&)value;

   659   (data+coverage).add_coverage (glyphs);

   660 }

   661 static inline void collect_array (hb_collect_glyphs_context_t *c HB_UNUSED,

   662                                   hb_set_t *glyphs,

   663                                   unsigned int count,

   664                                   const USHORT values[],

   665                                   collect_glyphs_func_t collect_func,

   666                                   const void *collect_data)

   667 {

   668   for (unsigned int i = 0; i < count; i++)

   669     collect_func (glyphs, values[i], collect_data);

   670 }

   671 

   672 

   673 static inline bool match_glyph (hb_codepoint_t glyph_id, const USHORT &value, const void *data HB_UNUSED)

   674 {

   675   return glyph_id == value;

   676 }

   677 static inline bool match_class (hb_codepoint_t glyph_id, const USHORT &value, const void *data)

   678 {

   679   const ClassDef &class_def = *reinterpret_cast<const ClassDef *>(data);

   680   return class_def.get_class (glyph_id) == value;

   681 }

   682 static inline bool match_coverage (hb_codepoint_t glyph_id, const USHORT &value, const void *data)

   683 {

   684   const OffsetTo<Coverage> &coverage = (const OffsetTo<Coverage>&)value;

   685   return (data+coverage).get_coverage (glyph_id) != NOT_COVERED;

   686 }

   687 

   688 static inline bool would_match_input (hb_would_apply_context_t *c,

   689                                       unsigned int count, /* Including the first glyph (not matched) */

   690                                       const USHORT input[], /* Array of input values--start with second glyph */

   691                                       match_func_t match_func,

   692                                       const void *match_data)

   693 {

   694   if (count != c->len)

   695     return false;

   696 

   697   for (unsigned int i = 1; i < count; i++)

   698     if (likely (!match_func (c->glyphs[i], input[i - 1], match_data)))

   699       return false;

   700 

   701   return true;

   702 }

   703 static inline bool match_input (hb_apply_context_t *c,

   704                                 unsigned int count, /* Including the first glyph (not matched) */

   705                                 const USHORT input[], /* Array of input values--start with second glyph */

   706                                 match_func_t match_func,

   707                                 const void *match_data,

   708                                 unsigned int *end_offset,

   709                                 unsigned int match_positions[HB_MAX_CONTEXT_LENGTH],

   710                                 bool *p_is_mark_ligature = NULL,

   711                                 unsigned int *p_total_component_count = NULL)

   712 {

   713   TRACE_APPLY (NULL);

   714 

   715   if (unlikely (count > HB_MAX_CONTEXT_LENGTH)) return_trace (false);

   716 

   717   hb_buffer_t *buffer = c->buffer;

   718 

   719   hb_apply_context_t::skipping_iterator_t &skippy_iter = c->iter_input;

   720   skippy_iter.reset (buffer->idx, count - 1);

   721   skippy_iter.set_match_func (match_func, match_data, input);

   722 

   723   /*

   724    * This is perhaps the trickiest part of OpenType...  Remarks:

   725    *

   726    * - If all components of the ligature were marks, we call this a mark ligature.

   727    *

   728    * - If there is no GDEF, and the ligature is NOT a mark ligature, we categorize

   729    *   it as a ligature glyph.

   730    *

   731    * - Ligatures cannot be formed across glyphs attached to different components

   732    *   of previous ligatures.  Eg. the sequence is LAM,SHADDA,LAM,FATHA,HEH, and

   733    *   LAM,LAM,HEH form a ligature, leaving SHADDA,FATHA next to eachother.

   734    *   However, it would be wrong to ligate that SHADDA,FATHA sequence.o

   735    *   There is an exception to this: If a ligature tries ligating with marks that

   736    *   belong to it itself, go ahead, assuming that the font designer knows what

   737    *   they are doing (otherwise it can break Indic stuff when a matra wants to

   738    *   ligate with a conjunct...)

   739    */

   740 

   741   bool is_mark_ligature = _hb_glyph_info_is_mark (&buffer->cur());

   742 

   743   unsigned int total_component_count = 0;

   744   total_component_count += _hb_glyph_info_get_lig_num_comps (&buffer->cur());

   745 

   746   unsigned int first_lig_id = _hb_glyph_info_get_lig_id (&buffer->cur());

   747   unsigned int first_lig_comp = _hb_glyph_info_get_lig_comp (&buffer->cur());

   748 

   749   match_positions[0] = buffer->idx;

   750   for (unsigned int i = 1; i < count; i++)

   751   {

   752     if (!skippy_iter.next ()) return_trace (false);

   753 

   754     match_positions[i] = skippy_iter.idx;

   755 

   756     unsigned int this_lig_id = _hb_glyph_info_get_lig_id (&buffer->info[skippy_iter.idx]);

   757     unsigned int this_lig_comp = _hb_glyph_info_get_lig_comp (&buffer->info[skippy_iter.idx]);

   758 

   759     if (first_lig_id && first_lig_comp) {

   760       /* If first component was attached to a previous ligature component,

   761        * all subsequent components should be attached to the same ligature

   762        * component, otherwise we shouldn't ligate them. */

   763       if (first_lig_id != this_lig_id || first_lig_comp != this_lig_comp)

   764         return_trace (false);

   765     } else {

   766       /* If first component was NOT attached to a previous ligature component,

   767        * all subsequent components should also NOT be attached to any ligature

   768        * component, unless they are attached to the first component itself! */

   769       if (this_lig_id && this_lig_comp && (this_lig_id != first_lig_id))

   770         return_trace (false);

   771     }

   772 

   773     is_mark_ligature = is_mark_ligature && _hb_glyph_info_is_mark (&buffer->info[skippy_iter.idx]);

   774     total_component_count += _hb_glyph_info_get_lig_num_comps (&buffer->info[skippy_iter.idx]);

   775   }

   776 

   777   *end_offset = skippy_iter.idx - buffer->idx + 1;

   778 

   779   if (p_is_mark_ligature)

   780     *p_is_mark_ligature = is_mark_ligature;

   781 

   782   if (p_total_component_count)

   783     *p_total_component_count = total_component_count;

   784 

   785   return_trace (true);

   786 }

   787 static inline bool ligate_input (hb_apply_context_t *c,

   788                                  unsigned int count, /* Including the first glyph */

   789                                  unsigned int match_positions[HB_MAX_CONTEXT_LENGTH], /* Including the first glyph */

   790                                  unsigned int match_length,

   791                                  hb_codepoint_t lig_glyph,

   792                                  bool is_mark_ligature,

   793                                  unsigned int total_component_count)

   794 {

   795   TRACE_APPLY (NULL);

   796 

   797   hb_buffer_t *buffer = c->buffer;

   798 

   799   buffer->merge_clusters (buffer->idx, buffer->idx + match_length);

   800 

   801   /*

   802    * - If it *is* a mark ligature, we don't allocate a new ligature id, and leave

   803    *   the ligature to keep its old ligature id.  This will allow it to attach to

   804    *   a base ligature in GPOS.  Eg. if the sequence is: LAM,LAM,SHADDA,FATHA,HEH,

   805    *   and LAM,LAM,HEH for a ligature, they will leave SHADDA and FATHA wit a

   806    *   ligature id and component value of 2.  Then if SHADDA,FATHA form a ligature

   807    *   later, we don't want them to lose their ligature id/component, otherwise

   808    *   GPOS will fail to correctly position the mark ligature on top of the

   809    *   LAM,LAM,HEH ligature.  See:

   810    *     https://bugzilla.gnome.org/show_bug.cgi?id=676343

   811    *

   812    * - If a ligature is formed of components that some of which are also ligatures

   813    *   themselves, and those ligature components had marks attached to *their*

   814    *   components, we have to attach the marks to the new ligature component

   815    *   positions!  Now *that*'s tricky!  And these marks may be following the

   816    *   last component of the whole sequence, so we should loop forward looking

   817    *   for them and update them.

   818    *

   819    *   Eg. the sequence is LAM,LAM,SHADDA,FATHA,HEH, and the font first forms a

   820    *   'calt' ligature of LAM,HEH, leaving the SHADDA and FATHA with a ligature

   821    *   id and component == 1.  Now, during 'liga', the LAM and the LAM-HEH ligature

   822    *   form a LAM-LAM-HEH ligature.  We need to reassign the SHADDA and FATHA to

   823    *   the new ligature with a component value of 2.

   824    *

   825    *   This in fact happened to a font...  See:

   826    *   https://bugzilla.gnome.org/show_bug.cgi?id=437633

   827    */

   828 

   829   unsigned int klass = is_mark_ligature ? 0 : HB_OT_LAYOUT_GLYPH_PROPS_LIGATURE;

   830   unsigned int lig_id = is_mark_ligature ? 0 : _hb_allocate_lig_id (buffer);

   831   unsigned int last_lig_id = _hb_glyph_info_get_lig_id (&buffer->cur());

   832   unsigned int last_num_components = _hb_glyph_info_get_lig_num_comps (&buffer->cur());

   833   unsigned int components_so_far = last_num_components;

   834 

   835   if (!is_mark_ligature)

   836   {

   837     _hb_glyph_info_set_lig_props_for_ligature (&buffer->cur(), lig_id, total_component_count);

   838     if (_hb_glyph_info_get_general_category (&buffer->cur()) == HB_UNICODE_GENERAL_CATEGORY_NON_SPACING_MARK)

   839     {

   840       _hb_glyph_info_set_general_category (&buffer->cur(), HB_UNICODE_GENERAL_CATEGORY_OTHER_LETTER);

   841     }

   842   }

   843   c->replace_glyph_with_ligature (lig_glyph, klass);

   844 

   845   for (unsigned int i = 1; i < count; i++)

   846   {

   847     while (buffer->idx < match_positions[i] && !buffer->in_error)

   848     {

   849       if (!is_mark_ligature) {

   850         unsigned int this_comp = _hb_glyph_info_get_lig_comp (&buffer->cur());

   851         if (this_comp == 0)

   852           this_comp = last_num_components;

   853         unsigned int new_lig_comp = components_so_far - last_num_components +

   854                                     MIN (this_comp, last_num_components);

   855           _hb_glyph_info_set_lig_props_for_mark (&buffer->cur(), lig_id, new_lig_comp);

   856       }

   857       buffer->next_glyph ();

   858     }

   859 

   860     last_lig_id = _hb_glyph_info_get_lig_id (&buffer->cur());

   861     last_num_components = _hb_glyph_info_get_lig_num_comps (&buffer->cur());

   862     components_so_far += last_num_components;

   863 

   864     /* Skip the base glyph */

   865     buffer->idx++;

   866   }

   867 

   868   if (!is_mark_ligature && last_lig_id) {

   869     /* Re-adjust components for any marks following. */

   870     for (unsigned int i = buffer->idx; i < buffer->len; i++) {

   871       if (last_lig_id == _hb_glyph_info_get_lig_id (&buffer->info[i])) {

   872         unsigned int this_comp = _hb_glyph_info_get_lig_comp (&buffer->info[i]);

   873         if (!this_comp)

   874           break;

   875         unsigned int new_lig_comp = components_so_far - last_num_components +

   876                                     MIN (this_comp, last_num_components);

   877         _hb_glyph_info_set_lig_props_for_mark (&buffer->info[i], lig_id, new_lig_comp);

   878       } else

   879         break;

   880     }

   881   }

   882   return_trace (true);

   883 }

   884 

   885 static inline bool match_backtrack (hb_apply_context_t *c,

   886                                     unsigned int count,

   887                                     const USHORT backtrack[],

   888                                     match_func_t match_func,

   889                                     const void *match_data)

   890 {

   891   TRACE_APPLY (NULL);

   892 

   893   hb_apply_context_t::skipping_iterator_t &skippy_iter = c->iter_context;

   894   skippy_iter.reset (c->buffer->backtrack_len (), count);

   895   skippy_iter.set_match_func (match_func, match_data, backtrack);

   896 

   897   for (unsigned int i = 0; i < count; i++)

   898     if (!skippy_iter.prev ())

   899       return_trace (false);

   900 

   901   return_trace (true);

   902 }

   903 

   904 static inline bool match_lookahead (hb_apply_context_t *c,

   905                                     unsigned int count,

   906                                     const USHORT lookahead[],

   907                                     match_func_t match_func,

   908                                     const void *match_data,

   909                                     unsigned int offset)

   910 {

   911   TRACE_APPLY (NULL);

   912 

   913   hb_apply_context_t::skipping_iterator_t &skippy_iter = c->iter_context;

   914   skippy_iter.reset (c->buffer->idx + offset - 1, count);

   915   skippy_iter.set_match_func (match_func, match_data, lookahead);

   916 

   917   for (unsigned int i = 0; i < count; i++)

   918     if (!skippy_iter.next ())

   919       return_trace (false);

   920 

   921   return_trace (true);

   922 }

   923 

   924 

   925 

   926 struct LookupRecord

   927 {

   928   inline bool sanitize (hb_sanitize_context_t *c) const

   929   {

   930     TRACE_SANITIZE (this);

   931     return_trace (c->check_struct (this));

   932   }

   933 

   934   USHORT        sequenceIndex;          /* Index into current glyph

   935                                          * sequence--first glyph = 0 */

   936   USHORT        lookupListIndex;        /* Lookup to apply to that

   937                                          * position--zero--based */

   938   public:

   939   DEFINE_SIZE_STATIC (4);

   940 };

   941 

   942 

   943 template <typename context_t>

   944 static inline void recurse_lookups (context_t *c,

   945                                     unsigned int lookupCount,

   946                                     const LookupRecord lookupRecord[] /* Array of LookupRecords--in design order */)

   947 {

   948   for (unsigned int i = 0; i < lookupCount; i++)

   949     c->recurse (lookupRecord[i].lookupListIndex);

   950 }

   951 

   952 static inline bool apply_lookup (hb_apply_context_t *c,

   953                                  unsigned int count, /* Including the first glyph */

   954                                  unsigned int match_positions[HB_MAX_CONTEXT_LENGTH], /* Including the first glyph */

   955                                  unsigned int lookupCount,

   956                                  const LookupRecord lookupRecord[], /* Array of LookupRecords--in design order */

   957                                  unsigned int match_length)

   958 {

   959   TRACE_APPLY (NULL);

   960 

   961   hb_buffer_t *buffer = c->buffer;

   962   unsigned int end;

   963 

   964   /* All positions are distance from beginning of *output* buffer.

   965    * Adjust. */

   966   {

   967     unsigned int bl = buffer->backtrack_len ();

   968     end = bl + match_length;

   969 

   970     int delta = bl - buffer->idx;

   971     /* Convert positions to new indexing. */

   972     for (unsigned int j = 0; j < count; j++)

   973       match_positions[j] += delta;

   974   }

   975 

   976   for (unsigned int i = 0; i < lookupCount && !buffer->in_error; i++)

   977   {

   978     unsigned int idx = lookupRecord[i].sequenceIndex;

   979     if (idx >= count)

   980       continue;

   981 

   982     /* Don't recurse to ourself at same position.

   983      * Note that this test is too naive, it doesn't catch longer loops. */

   984     if (idx == 0 && lookupRecord[i].lookupListIndex == c->lookup_index)

   985       continue;

   986 

   987     buffer->move_to (match_positions[idx]);

   988 

   989     unsigned int orig_len = buffer->backtrack_len () + buffer->lookahead_len ();

   990     if (!c->recurse (lookupRecord[i].lookupListIndex))

   991       continue;

   992 

   993     unsigned int new_len = buffer->backtrack_len () + buffer->lookahead_len ();

   994     int delta = new_len - orig_len;

   995 

   996     if (!delta)

   997         continue;

   998 

   999     /* Recursed lookup changed buffer len.  Adjust. */

  1000 

  1001     end = int (end) + delta;

  1002     if (end <= match_positions[idx])

  1003     {

  1004       /* End might end up being smaller than match_positions[idx] if the recursed

  1005        * lookup ended up removing many items, more than we have had matched.

  1006        * Just never rewind end back and get out of here.

  1007        * https://bugs.chromium.org/p/chromium/issues/detail?id=659496 */

  1008       end = match_positions[idx];

  1009       /* There can't be any further changes. */

  1010       break;

  1011     }

  1012 

  1013     unsigned int next = idx + 1; /* next now is the position after the recursed lookup. */

  1014 

  1015     if (delta > 0)

  1016     {

  1017       if (unlikely (delta + count > HB_MAX_CONTEXT_LENGTH))

  1018         break;

  1019     }

  1020     else

  1021     {

  1022       /* NOTE: delta is negative. */

  1023       delta = MAX (delta, (int) next - (int) count);

  1024       next -= delta;

  1025     }

  1026 

  1027     /* Shift! */

  1028     memmove (match_positions + next + delta, match_positions + next,

  1029              (count - next) * sizeof (match_positions[0]));

  1030     next += delta;

  1031     count += delta;

  1032 

  1033     /* Fill in new entries. */

  1034     for (unsigned int j = idx + 1; j < next; j++)

  1035       match_positions[j] = match_positions[j - 1] + 1;

  1036 

  1037     /* And fixup the rest. */

  1038     for (; next < count; next++)

  1039       match_positions[next] += delta;

  1040   }

  1041 

  1042   buffer->move_to (end);

  1043 

  1044   return_trace (true);

  1045 }

  1046 

  1047 

  1048 

  1049 /* Contextual lookups */

  1050 

  1051 struct ContextClosureLookupContext

  1052 {

  1053   ContextClosureFuncs funcs;

  1054   const void *intersects_data;

  1055 };

  1056 

  1057 struct ContextCollectGlyphsLookupContext

  1058 {

  1059   ContextCollectGlyphsFuncs funcs;

  1060   const void *collect_data;

  1061 };

  1062 

  1063 struct ContextApplyLookupContext

  1064 {

  1065   ContextApplyFuncs funcs;

  1066   const void *match_data;

  1067 };

  1068 

  1069 static inline void context_closure_lookup (hb_closure_context_t *c,

  1070                                            unsigned int inputCount, /* Including the first glyph (not matched) */

  1071                                            const USHORT input[], /* Array of input values--start with second glyph */

  1072                                            unsigned int lookupCount,

  1073                                            const LookupRecord lookupRecord[],

  1074                                            ContextClosureLookupContext &lookup_context)

  1075 {

  1076   if (intersects_array (c,

  1077                         inputCount ? inputCount - 1 : 0, input,

  1078                         lookup_context.funcs.intersects, lookup_context.intersects_data))

  1079     recurse_lookups (c,

  1080                      lookupCount, lookupRecord);

  1081 }

  1082 

  1083 static inline void context_collect_glyphs_lookup (hb_collect_glyphs_context_t *c,

  1084                                                   unsigned int inputCount, /* Including the first glyph (not matched) */

  1085                                                   const USHORT input[], /* Array of input values--start with second glyph */

  1086                                                   unsigned int lookupCount,

  1087                                                   const LookupRecord lookupRecord[],

  1088                                                   ContextCollectGlyphsLookupContext &lookup_context)

  1089 {

  1090   collect_array (c, c->input,

  1091                  inputCount ? inputCount - 1 : 0, input,

  1092                  lookup_context.funcs.collect, lookup_context.collect_data);

  1093   recurse_lookups (c,

  1094                    lookupCount, lookupRecord);

  1095 }

  1096 

  1097 static inline bool context_would_apply_lookup (hb_would_apply_context_t *c,

  1098                                                unsigned int inputCount, /* Including the first glyph (not matched) */

  1099                                                const USHORT input[], /* Array of input values--start with second glyph */

  1100                                                unsigned int lookupCount HB_UNUSED,

  1101                                                const LookupRecord lookupRecord[] HB_UNUSED,

  1102                                                ContextApplyLookupContext &lookup_context)

  1103 {

  1104   return would_match_input (c,

  1105                             inputCount, input,

  1106                             lookup_context.funcs.match, lookup_context.match_data);

  1107 }

  1108 static inline bool context_apply_lookup (hb_apply_context_t *c,

  1109                                          unsigned int inputCount, /* Including the first glyph (not matched) */

  1110                                          const USHORT input[], /* Array of input values--start with second glyph */

  1111                                          unsigned int lookupCount,

  1112                                          const LookupRecord lookupRecord[],

  1113                                          ContextApplyLookupContext &lookup_context)

  1114 {

  1115   unsigned int match_length = 0;

  1116   unsigned int match_positions[HB_MAX_CONTEXT_LENGTH];

  1117   return match_input (c,

  1118                       inputCount, input,

  1119                       lookup_context.funcs.match, lookup_context.match_data,

  1120                       &match_length, match_positions)

  1121       && apply_lookup (c,

  1122                        inputCount, match_positions,

  1123                        lookupCount, lookupRecord,

  1124                        match_length);

  1125 }

  1126 

  1127 struct Rule

  1128 {

  1129   inline void closure (hb_closure_context_t *c, ContextClosureLookupContext &lookup_context) const

  1130   {

  1131     TRACE_CLOSURE (this);

  1132     const LookupRecord *lookupRecord = &StructAtOffset<LookupRecord> (inputZ, inputZ[0].static_size * (inputCount ? inputCount - 1 : 0));

  1133     context_closure_lookup (c,

  1134                             inputCount, inputZ,