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      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_PRIVATE_HH
     31 #define HB_BUFFER_PRIVATE_HH
     32 
     33 #include "hb-private.hh"
     34 #include "hb-object-private.hh"
     35 #include "hb-unicode-private.hh"
     36 
     37 
     38 #ifndef HB_BUFFER_MAX_EXPANSION_FACTOR
     39 #define HB_BUFFER_MAX_EXPANSION_FACTOR 32
     40 #endif
     41 #ifndef HB_BUFFER_MAX_LEN_MIN
     42 #define HB_BUFFER_MAX_LEN_MIN 8192
     43 #endif
     44 #ifndef HB_BUFFER_MAX_LEN_DEFAULT
     45 #define HB_BUFFER_MAX_LEN_DEFAULT 0x3FFFFFFF /* Shaping more than a billion chars? Let us know! */
     46 #endif
     47 
     48 ASSERT_STATIC (sizeof (hb_glyph_info_t) == 20);
     49 ASSERT_STATIC (sizeof (hb_glyph_info_t) == sizeof (hb_glyph_position_t));
     50 
     51 HB_MARK_AS_FLAG_T (hb_buffer_flags_t);
     52 HB_MARK_AS_FLAG_T (hb_buffer_serialize_flags_t);
     53 
     54 enum hb_buffer_scratch_flags_t {
     55   HB_BUFFER_SCRATCH_FLAG_DEFAULT			= 0x00000000u,
     56   HB_BUFFER_SCRATCH_FLAG_HAS_NON_ASCII			= 0x00000001u,
     57   HB_BUFFER_SCRATCH_FLAG_HAS_DEFAULT_IGNORABLES		= 0x00000002u,
     58   HB_BUFFER_SCRATCH_FLAG_HAS_SPACE_FALLBACK		= 0x00000004u,
     59   HB_BUFFER_SCRATCH_FLAG_HAS_GPOS_ATTACHMENT		= 0x00000008u,
     60   /* Reserved for complex shapers' internal use. */
     61   HB_BUFFER_SCRATCH_FLAG_COMPLEX0			= 0x01000000u,
     62   HB_BUFFER_SCRATCH_FLAG_COMPLEX1			= 0x02000000u,
     63   HB_BUFFER_SCRATCH_FLAG_COMPLEX2			= 0x04000000u,
     64   HB_BUFFER_SCRATCH_FLAG_COMPLEX3			= 0x08000000u,
     65 };
     66 HB_MARK_AS_FLAG_T (hb_buffer_scratch_flags_t);
     67 
     68 
     69 /*
     70  * hb_buffer_t
     71  */
     72 
     73 struct hb_buffer_t {
     74   hb_object_header_t header;
     75   ASSERT_POD ();
     76 
     77   /* Information about how the text in the buffer should be treated */
     78   hb_unicode_funcs_t *unicode; /* Unicode functions */
     79   hb_buffer_flags_t flags; /* BOT / EOT / etc. */
     80   hb_buffer_cluster_level_t cluster_level;
     81   hb_codepoint_t replacement; /* U+FFFD or something else. */
     82   hb_buffer_scratch_flags_t scratch_flags; /* Have space-flallback, etc. */
     83   unsigned int max_len; /* Maximum allowed len. */
     84 
     85   /* Buffer contents */
     86   hb_buffer_content_type_t content_type;
     87   hb_segment_properties_t props; /* Script, language, direction */
     88 
     89   bool in_error; /* Allocation failed */
     90   bool have_output; /* Whether we have an output buffer going on */
     91   bool have_positions; /* Whether we have positions */
     92 
     93   unsigned int idx; /* Cursor into ->info and ->pos arrays */
     94   unsigned int len; /* Length of ->info and ->pos arrays */
     95   unsigned int out_len; /* Length of ->out array if have_output */
     96 
     97   unsigned int allocated; /* Length of allocated arrays */
     98   hb_glyph_info_t     *info;
     99   hb_glyph_info_t     *out_info;
    100   hb_glyph_position_t *pos;
    101 
    102   inline hb_glyph_info_t &cur (unsigned int i = 0) { return info[idx + i]; }
    103   inline hb_glyph_info_t cur (unsigned int i = 0) const { return info[idx + i]; }
    104 
    105   inline hb_glyph_position_t &cur_pos (unsigned int i = 0) { return pos[idx + i]; }
    106   inline hb_glyph_position_t cur_pos (unsigned int i = 0) const { return pos[idx + i]; }
    107 
    108   inline hb_glyph_info_t &prev (void) { return out_info[out_len ? out_len - 1 : 0]; }
    109   inline hb_glyph_info_t prev (void) const { return out_info[out_len ? out_len - 1 : 0]; }
    110 
    111   inline bool has_separate_output (void) const { return info != out_info; }
    112 
    113   unsigned int serial;
    114 
    115   /* Text before / after the main buffer contents.
    116    * Always in Unicode, and ordered outward.
    117    * Index 0 is for "pre-context", 1 for "post-context". */
    118   static const unsigned int CONTEXT_LENGTH = 5;
    119   hb_codepoint_t context[2][CONTEXT_LENGTH];
    120   unsigned int context_len[2];
    121 
    122   /* Debugging API */
    123   hb_buffer_message_func_t message_func;
    124   void *message_data;
    125   hb_destroy_func_t message_destroy;
    126 
    127   /* Internal debugging. */
    128   /* The bits here reflect current allocations of the bytes in glyph_info_t's var1 and var2. */
    129 #ifndef HB_NDEBUG
    130   uint8_t allocated_var_bits;
    131 #endif
    132   inline void allocate_var (unsigned int start, unsigned int count)
    133   {
    134 #ifndef HB_NDEBUG
    135     unsigned int end = start + count;
    136     assert (end <= 8);
    137     unsigned int bits = (1u<<end) - (1u<<start);
    138     assert (0 == (allocated_var_bits & bits));
    139     allocated_var_bits |= bits;
    140 #endif
    141   }
    142   inline void deallocate_var (unsigned int start, unsigned int count)
    143   {
    144 #ifndef HB_NDEBUG
    145     unsigned int end = start + count;
    146     assert (end <= 8);
    147     unsigned int bits = (1u<<end) - (1u<<start);
    148     assert (bits == (allocated_var_bits & bits));
    149     allocated_var_bits &= ~bits;
    150 #endif
    151   }
    152   inline void assert_var (unsigned int start, unsigned int count)
    153   {
    154 #ifndef HB_NDEBUG
    155     unsigned int end = start + count;
    156     assert (end <= 8);
    157     unsigned int bits = (1u<<end) - (1u<<start);
    158     assert (bits == (allocated_var_bits & bits));
    159 #endif
    160   }
    161   inline void deallocate_var_all (void)
    162   {
    163 #ifndef HB_NDEBUG
    164     allocated_var_bits = 0;
    165 #endif
    166   }
    167 
    168 
    169   /* Methods */
    170 
    171   HB_INTERNAL void reset (void);
    172   HB_INTERNAL void clear (void);
    173 
    174   inline unsigned int backtrack_len (void) const
    175   { return have_output? out_len : idx; }
    176   inline unsigned int lookahead_len (void) const
    177   { return len - idx; }
    178   inline unsigned int next_serial (void) { return serial++; }
    179 
    180   HB_INTERNAL void add (hb_codepoint_t  codepoint,
    181 			unsigned int    cluster);
    182   HB_INTERNAL void add_info (const hb_glyph_info_t &glyph_info);
    183 
    184   HB_INTERNAL void reverse_range (unsigned int start, unsigned int end);
    185   HB_INTERNAL void reverse (void);
    186   HB_INTERNAL void reverse_clusters (void);
    187   HB_INTERNAL void guess_segment_properties (void);
    188 
    189   HB_INTERNAL void swap_buffers (void);
    190   HB_INTERNAL void remove_output (void);
    191   HB_INTERNAL void clear_output (void);
    192   HB_INTERNAL void clear_positions (void);
    193 
    194   HB_INTERNAL void replace_glyphs (unsigned int num_in,
    195 				   unsigned int num_out,
    196 				   const hb_codepoint_t *glyph_data);
    197 
    198   HB_INTERNAL void replace_glyph (hb_codepoint_t glyph_index);
    199   /* Makes a copy of the glyph at idx to output and replace glyph_index */
    200   HB_INTERNAL void output_glyph (hb_codepoint_t glyph_index);
    201   HB_INTERNAL void output_info (const hb_glyph_info_t &glyph_info);
    202   /* Copies glyph at idx to output but doesn't advance idx */
    203   HB_INTERNAL void copy_glyph (void);
    204   HB_INTERNAL bool move_to (unsigned int i); /* i is output-buffer index. */
    205   /* Copies glyph at idx to output and advance idx.
    206    * If there's no output, just advance idx. */
    207   inline void
    208   next_glyph (void)
    209   {
    210     if (have_output)
    211     {
    212       if (unlikely (out_info != info || out_len != idx)) {
    213 	if (unlikely (!make_room_for (1, 1))) return;
    214 	out_info[out_len] = info[idx];
    215       }
    216       out_len++;
    217     }
    218 
    219     idx++;
    220   }
    221 
    222   /* Advance idx without copying to output. */
    223   inline void skip_glyph (void) { idx++; }
    224 
    225   inline void reset_masks (hb_mask_t mask)
    226   {
    227     for (unsigned int j = 0; j < len; j++)
    228       info[j].mask = mask;
    229   }
    230   inline void add_masks (hb_mask_t mask)
    231   {
    232     for (unsigned int j = 0; j < len; j++)
    233       info[j].mask |= mask;
    234   }
    235   HB_INTERNAL void set_masks (hb_mask_t value,
    236 			      hb_mask_t mask,
    237 			      unsigned int cluster_start,
    238 			      unsigned int cluster_end);
    239 
    240   HB_INTERNAL void merge_clusters (unsigned int start,
    241 				   unsigned int end)
    242   {
    243     if (end - start < 2)
    244       return;
    245     merge_clusters_impl (start, end);
    246   }
    247   HB_INTERNAL void merge_clusters_impl (unsigned int start,
    248 					unsigned int end);
    249   HB_INTERNAL void merge_out_clusters (unsigned int start,
    250 				       unsigned int end);
    251   /* Merge clusters for deleting current glyph, and skip it. */
    252   HB_INTERNAL void delete_glyph (void);
    253 
    254   /* Internal methods */
    255   HB_INTERNAL bool enlarge (unsigned int size);
    256 
    257   inline bool ensure (unsigned int size)
    258   { return likely (!size || size < allocated) ? true : enlarge (size); }
    259 
    260   inline bool ensure_inplace (unsigned int size)
    261   { return likely (!size || size < allocated); }
    262 
    263   HB_INTERNAL bool make_room_for (unsigned int num_in, unsigned int num_out);
    264   HB_INTERNAL bool shift_forward (unsigned int count);
    265 
    266   typedef long scratch_buffer_t;
    267   HB_INTERNAL scratch_buffer_t *get_scratch_buffer (unsigned int *size);
    268 
    269   inline void clear_context (unsigned int side) { context_len[side] = 0; }
    270 
    271   HB_INTERNAL void sort (unsigned int start, unsigned int end, int(*compar)(const hb_glyph_info_t *, const hb_glyph_info_t *));
    272 
    273   inline bool messaging (void) { return unlikely (message_func); }
    274   inline bool message (hb_font_t *font, const char *fmt, ...) HB_PRINTF_FUNC(3, 4)
    275   {
    276     if (!messaging ())
    277       return true;
    278     va_list ap;
    279     va_start (ap, fmt);
    280     bool ret = message_impl (font, fmt, ap);
    281     va_end (ap);
    282     return ret;
    283   }
    284   HB_INTERNAL bool message_impl (hb_font_t *font, const char *fmt, va_list ap) HB_PRINTF_FUNC(3, 0);
    285 };
    286 
    287 
    288 #define HB_BUFFER_XALLOCATE_VAR(b, func, var) \
    289   b->func (offsetof (hb_glyph_info_t, var) - offsetof(hb_glyph_info_t, var1), \
    290 	   sizeof (b->info[0].var))
    291 #define HB_BUFFER_ALLOCATE_VAR(b, var)		HB_BUFFER_XALLOCATE_VAR (b, allocate_var,   var ())
    292 #define HB_BUFFER_DEALLOCATE_VAR(b, var)	HB_BUFFER_XALLOCATE_VAR (b, deallocate_var, var ())
    293 #define HB_BUFFER_ASSERT_VAR(b, var)		HB_BUFFER_XALLOCATE_VAR (b, assert_var,     var ())
    294 
    295 
    296 #endif /* HB_BUFFER_PRIVATE_HH */
    297