text: /*
   * Copyright © 2007,2008,2009  Red Hat, Inc.
   * Copyright © 2012,2013  Google, Inc.
   *
   *  This is part of HarfBuzz, a text shaping library.
   *
   * Permission is hereby granted, without written agreement and without
   * license or royalty fees, to use, copy, modify, and distribute this
   * software and its documentation for any purpose, provided that the
   * above copyright notice and the following two paragraphs appear in
   * all copies of this software.
   *
   * IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR
   * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
   * ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN
   * IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
   * DAMAGE.
   *
   * THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
   * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
   * FITNESS FOR A PARTICULAR PURPOSE.  THE SOFTWARE PROVIDED HEREUNDER IS
   * ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO
   * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
   *
   * Red Hat Author(s): Behdad Esfahbod
   * Google Author(s): Behdad Esfahbod
   */
  
  #ifndef HB_OT_LAYOUT_PRIVATE_HH
  #define HB_OT_LAYOUT_PRIVATE_HH
  
  #include "hb-private.hh"
  
  #include "hb-font-private.hh"
  #include "hb-buffer-private.hh"
  #include "hb-set-private.hh"
  #include "hb-open-type-private.hh"
  
  
  /* Private API corresponding to hb-ot-layout.h: */
  
  HB_INTERNAL hb_bool_t
  hb_ot_layout_table_find_feature (hb_face_t    *face,
  				 hb_tag_t      table_tag,
  				 hb_tag_t      feature_tag,
  				 unsigned int *feature_index);
  
  
  /*
   * GDEF
   */
  
  enum hb_ot_layout_glyph_props_flags_t
  {
    /* The following three match LookupFlags::Ignore* numbers. */
    HB_OT_LAYOUT_GLYPH_PROPS_BASE_GLYPH	= 0x02u,
    HB_OT_LAYOUT_GLYPH_PROPS_LIGATURE	= 0x04u,
    HB_OT_LAYOUT_GLYPH_PROPS_MARK		= 0x08u,
  
    /* The following are used internally; not derived from GDEF. */
    HB_OT_LAYOUT_GLYPH_PROPS_SUBSTITUTED	= 0x10u,
    HB_OT_LAYOUT_GLYPH_PROPS_LIGATED	= 0x20u,
    HB_OT_LAYOUT_GLYPH_PROPS_MULTIPLIED	= 0x40u,
  
    HB_OT_LAYOUT_GLYPH_PROPS_PRESERVE     = HB_OT_LAYOUT_GLYPH_PROPS_SUBSTITUTED |
  					  HB_OT_LAYOUT_GLYPH_PROPS_LIGATED |
  					  HB_OT_LAYOUT_GLYPH_PROPS_MULTIPLIED
  };
  HB_MARK_AS_FLAG_T (hb_ot_layout_glyph_props_flags_t);
  
  
  /*
   * GSUB/GPOS
   */
  
  HB_INTERNAL hb_bool_t
  hb_ot_layout_lookup_would_substitute_fast (hb_face_t            *face,
  					   unsigned int          lookup_index,
  					   const hb_codepoint_t *glyphs,
  					   unsigned int          glyphs_length,
  					   hb_bool_t             zero_context);
  
  
  /* Should be called before all the substitute_lookup's are done. */
  HB_INTERNAL void
  hb_ot_layout_substitute_start (hb_font_t    *font,
  			       hb_buffer_t  *buffer);
  
  
  struct hb_ot_layout_lookup_accelerator_t;
  
  namespace OT {
    struct hb_apply_context_t;
    struct SubstLookup;
  }
  
  HB_INTERNAL void
  hb_ot_layout_substitute_lookup (OT::hb_apply_context_t *c,
  				const OT::SubstLookup &lookup,
  				const hb_ot_layout_lookup_accelerator_t &accel);
  
  
  /* Should be called before all the position_lookup's are done. */
  HB_INTERNAL void
  hb_ot_layout_position_start (hb_font_t    *font,
  			     hb_buffer_t  *buffer);
  
  /* Should be called after all the position_lookup's are done, to finish advances. */
  HB_INTERNAL void
  hb_ot_layout_position_finish_advances (hb_font_t    *font,
  				       hb_buffer_t  *buffer);
  
  /* Should be called after hb_ot_layout_position_finish_advances, to finish offsets. */
  HB_INTERNAL void
  hb_ot_layout_position_finish_offsets (hb_font_t    *font,
  				      hb_buffer_t  *buffer);
  
  
  
  /*
   * hb_ot_layout_t
   */
  
  namespace OT {
    struct GDEF;
    struct GSUB;
    struct GPOS;
    struct MATH;
    struct fvar;
    struct avar;
  }
  
  struct hb_ot_layout_lookup_accelerator_t
  {
    template <typename TLookup>
    inline void init (const TLookup &lookup)
    {
      digest.init ();
      lookup.add_coverage (&digest);
    }
  
    inline void fini (void)
    {
    }
  
    inline bool may_have (hb_codepoint_t g) const {
      return digest.may_have (g);
    }
  
    private:
    hb_set_digest_t digest;
  };
  
  struct hb_ot_layout_t
  {
    hb_blob_t *gdef_blob;
    hb_blob_t *gsub_blob;
    hb_blob_t *gpos_blob;
  
    const struct OT::GDEF *gdef;
    const struct OT::GSUB *gsub;
    const struct OT::GPOS *gpos;
  
    /* TODO Move the following out of this struct. */
    OT::hb_lazy_table_loader_t<struct OT::MATH> math;
    OT::hb_lazy_table_loader_t<struct OT::fvar> fvar;
    OT::hb_lazy_table_loader_t<struct OT::avar> avar;
  
    unsigned int gsub_lookup_count;
    unsigned int gpos_lookup_count;
  
    hb_ot_layout_lookup_accelerator_t *gsub_accels;
    hb_ot_layout_lookup_accelerator_t *gpos_accels;
  };
  
  
  HB_INTERNAL hb_ot_layout_t *
  _hb_ot_layout_create (hb_face_t *face);
  
  HB_INTERNAL void
  _hb_ot_layout_destroy (hb_ot_layout_t *layout);
  
  
  #define hb_ot_layout_from_face(face) ((hb_ot_layout_t *) face->shaper_data.ot)
  
  
  /*
   * Buffer var routines.
   */
  
  /* buffer var allocations, used during the entire shaping process */
  #define unicode_props()		var2.u16[0]
  
  /* buffer var allocations, used during the GSUB/GPOS processing */
  #define glyph_props()		var1.u16[0] /* GDEF glyph properties */
  #define lig_props()		var1.u8[2] /* GSUB/GPOS ligature tracking */
  #define syllable()		var1.u8[3] /* GSUB/GPOS shaping boundaries */
  
  
  /* Loop over syllables. Based on foreach_cluster(). */
  #define foreach_syllable(buffer, start, end) \
    for (unsigned int \
         _count = buffer->len, \
         start = 0, end = _count ? _next_syllable (buffer, 0) : 0; \
         start < _count; \
         start = end, end = _next_syllable (buffer, start))
  
  static inline unsigned int
  _next_syllable (hb_buffer_t *buffer, unsigned int start)
  {
    hb_glyph_info_t *info = buffer->info;
    unsigned int count = buffer->len;
  
    unsigned int syllable = info[start].syllable();
    while (++start < count && syllable == info[start].syllable())
      ;
  
    return start;
  }
  
  
  /* unicode_props */
  
  /* Design:
   * unicode_props() is a two-byte number.  The low byte includes:
   * - General_Category: 5 bits.
   * - A bit each for:
   *   * Is it Default_Ignorable(); we have a modified Default_Ignorable().
   *   * Whether it's one of the three Mongolian Free Variation Selectors.
   *   * One free bit right now.
   *
   * The high-byte has different meanings, switched by the Gen-Cat:
   * - For Mn,Mc,Me: the modified Combining_Class.
   * - For Cf: whether it's ZWJ, ZWNJ, or something else.
   * - For Ws: index of which space character this is, if space fallback
   *   is needed, ie. we don't set this by default, only if asked to.
   */
  
  enum hb_unicode_props_flags_t {
    UPROPS_MASK_GEN_CAT	= 0x001Fu,
    UPROPS_MASK_IGNORABLE	= 0x0020u,
    UPROPS_MASK_HIDDEN	= 0x0040u, /* MONGOLIAN FREE VARIATION SELECTOR 1..3,
                                      * or TAG characters */
  
    /* If GEN_CAT=FORMAT, top byte masks: */
    UPROPS_MASK_Cf_ZWJ	= 0x0100u,
    UPROPS_MASK_Cf_ZWNJ	= 0x0200u
  };
  HB_MARK_AS_FLAG_T (hb_unicode_props_flags_t);
  
  static inline void
  _hb_glyph_info_set_unicode_props (hb_glyph_info_t *info, hb_buffer_t *buffer)
  {
    hb_unicode_funcs_t *unicode = buffer->unicode;
    unsigned int u = info->codepoint;
    unsigned int gen_cat = (unsigned int) unicode->general_category (u);
    unsigned int props = gen_cat;
  
    if (u >= 0x80)
    {
      buffer->scratch_flags |= HB_BUFFER_SCRATCH_FLAG_HAS_NON_ASCII;
      if (unlikely (unicode->is_default_ignorable (u)))
      {
        buffer->scratch_flags |= HB_BUFFER_SCRATCH_FLAG_HAS_DEFAULT_IGNORABLES;
        props |=  UPROPS_MASK_IGNORABLE;
        if (u == 0x200Cu) props |= UPROPS_MASK_Cf_ZWNJ;
        if (u == 0x200Du) props |= UPROPS_MASK_Cf_ZWJ;
        /* Mongolian Free Variation Selectors need to be remembered
         * because although we need to hide them like default-ignorables,
         * they need to non-ignorable during shaping.  This is similar to
         * what we do for joiners in Indic-like shapers, but since the
         * FVSes are GC=Mn, we have use a separate bit to remember them.
         * Fixes:
         * https://github.com/behdad/harfbuzz/issues/234
         */
        if (unlikely (hb_in_range (u, 0x180Bu, 0x180Du))) props |= UPROPS_MASK_HIDDEN;
        /* TAG characters need similar treatment. Fixes:
         * https://github.com/behdad/harfbuzz/issues/463
         */
        if (unlikely (hb_in_range (u, 0xE0020u, 0xE007Fu))) props |= UPROPS_MASK_HIDDEN;
      }
      else if (unlikely (HB_UNICODE_GENERAL_CATEGORY_IS_NON_ENCLOSING_MARK_OR_MODIFIER_SYMBOL (gen_cat)))
      {
        /* The above check is just an optimization to let in only things we need further
         * processing on. */
  
        /* Only Mn and Mc can have non-zero ccc:
         * http://www.unicode.org/policies/stability_policy.html#Property_Value
         * """
         * Canonical_Combining_Class, General_Category
         * All characters other than those with General_Category property values
         * Spacing_Mark (Mc) and Nonspacing_Mark (Mn) have the Canonical_Combining_Class
         * property value 0.
         * 1.1.5+
         * """
         *
         * Also, all Mn's that are Default_Ignorable, have ccc=0, hence
         * the "else if".
         */
        props |= unicode->modified_combining_class (info->codepoint)<<8;
  
        /* Recategorize emoji skin-tone modifiers as Unicode mark, so they
         * behave correctly in non-native directionality.  They originally
         * are MODIFIER_SYMBOL.  Fixes:
         * https://github.com/behdad/harfbuzz/issues/169
         */
        if (unlikely (hb_in_range (u, 0x1F3FBu, 0x1F3FFu)))
        {
  	props = gen_cat = HB_UNICODE_GENERAL_CATEGORY_ENCLOSING_MARK;
        }
      }
    }
  
    info->unicode_props() = props;
  }
  
  static inline void
  _hb_glyph_info_set_general_category (hb_glyph_info_t *info,
  				     hb_unicode_general_category_t gen_cat)
  {
    /* Clears top-byte. */
    info->unicode_props() = (unsigned int) gen_cat | (info->unicode_props() & (0xFF & ~UPROPS_MASK_GEN_CAT));
  }
  
  static inline hb_unicode_general_category_t
  _hb_glyph_info_get_general_category (const hb_glyph_info_t *info)
  {
    return (hb_unicode_general_category_t) (info->unicode_props() & UPROPS_MASK_GEN_CAT);
  }
  
  static inline bool
  _hb_glyph_info_is_unicode_mark (const hb_glyph_info_t *info)
  {
    return HB_UNICODE_GENERAL_CATEGORY_IS_MARK (info->unicode_props() & UPROPS_MASK_GEN_CAT);
  }
  static inline void
  _hb_glyph_info_set_modified_combining_class (hb_glyph_info_t *info,
  					     unsigned int modified_class)
  {
    if (unlikely (!_hb_glyph_info_is_unicode_mark (info)))
      return;
    info->unicode_props() = (modified_class<<8) | (info->unicode_props() & 0xFF);
  }
  static inline unsigned int
  _hb_glyph_info_get_modified_combining_class (const hb_glyph_info_t *info)
  {
    return _hb_glyph_info_is_unicode_mark (info) ? info->unicode_props()>>8 : 0;
  }
  
  static inline bool
  _hb_glyph_info_is_unicode_space (const hb_glyph_info_t *info)
  {
    return _hb_glyph_info_get_general_category (info) ==
  	 HB_UNICODE_GENERAL_CATEGORY_SPACE_SEPARATOR;
  }
  static inline void
  _hb_glyph_info_set_unicode_space_fallback_type (hb_glyph_info_t *info, hb_unicode_funcs_t::space_t s)
  {
    if (unlikely (!_hb_glyph_info_is_unicode_space (info)))
      return;
    info->unicode_props() = (((unsigned int) s)<<8) | (info->unicode_props() & 0xFF);
  }
  static inline hb_unicode_funcs_t::space_t
  _hb_glyph_info_get_unicode_space_fallback_type (const hb_glyph_info_t *info)
  {
    return _hb_glyph_info_is_unicode_space (info) ?
  	 (hb_unicode_funcs_t::space_t) (info->unicode_props()>>8) :
  	 hb_unicode_funcs_t::NOT_SPACE;
  }
  
  static inline bool _hb_glyph_info_ligated (const hb_glyph_info_t *info);
  
  static inline hb_bool_t
  _hb_glyph_info_is_default_ignorable (const hb_glyph_info_t *info)
  {
    return (info->unicode_props() & UPROPS_MASK_IGNORABLE) &&
  	 !_hb_glyph_info_ligated (info);
  }
  static inline hb_bool_t
  _hb_glyph_info_is_default_ignorable_and_not_hidden (const hb_glyph_info_t *info)
  {
    return ((info->unicode_props() & (UPROPS_MASK_IGNORABLE|UPROPS_MASK_HIDDEN))
  	  == UPROPS_MASK_IGNORABLE) &&
  	 !_hb_glyph_info_ligated (info);
  }
  
  static inline bool
  _hb_glyph_info_is_unicode_format (const hb_glyph_info_t *info)
  {
    return _hb_glyph_info_get_general_category (info) ==
  	 HB_UNICODE_GENERAL_CATEGORY_FORMAT;
  }
  static inline hb_bool_t
  _hb_glyph_info_is_zwnj (const hb_glyph_info_t *info)
  {
    return _hb_glyph_info_is_unicode_format (info) && (info->unicode_props() & UPROPS_MASK_Cf_ZWNJ);
  }
  static inline hb_bool_t
  _hb_glyph_info_is_zwj (const hb_glyph_info_t *info)
  {
    return _hb_glyph_info_is_unicode_format (info) && (info->unicode_props() & UPROPS_MASK_Cf_ZWJ);
  }
  static inline hb_bool_t
  _hb_glyph_info_is_joiner (const hb_glyph_info_t *info)
  {
    return _hb_glyph_info_is_unicode_format (info) && (info->unicode_props() & (UPROPS_MASK_Cf_ZWNJ|UPROPS_MASK_Cf_ZWJ));
  }
  static inline void
  _hb_glyph_info_flip_joiners (hb_glyph_info_t *info)
  {
    if (!_hb_glyph_info_is_unicode_format (info))
      return;
    info->unicode_props() ^= UPROPS_MASK_Cf_ZWNJ | UPROPS_MASK_Cf_ZWJ;
  }
  
  /* lig_props: aka lig_id / lig_comp
   *
   * When a ligature is formed:
   *
   *   - The ligature glyph and any marks in between all the same newly allocated
   *     lig_id,
   *   - The ligature glyph will get lig_num_comps set to the number of components
   *   - The marks get lig_comp > 0, reflecting which component of the ligature
   *     they were applied to.
   *   - This is used in GPOS to attach marks to the right component of a ligature
   *     in MarkLigPos,
   *   - Note that when marks are ligated together, much of the above is skipped
   *     and the current lig_id reused.
   *
   * When a multiple-substitution is done:
   *
   *   - All resulting glyphs will have lig_id = 0,
   *   - The resulting glyphs will have lig_comp = 0, 1, 2, ... respectively.
   *   - This is used in GPOS to attach marks to the first component of a
   *     multiple substitution in MarkBasePos.
   *
   * The numbers are also used in GPOS to do mark-to-mark positioning only
   * to marks that belong to the same component of the same ligature.
   */
  
  static inline void
  _hb_glyph_info_clear_lig_props (hb_glyph_info_t *info)
  {
    info->lig_props() = 0;
  }
  
  #define IS_LIG_BASE 0x10
  
  static inline void
  _hb_glyph_info_set_lig_props_for_ligature (hb_glyph_info_t *info,
  					   unsigned int lig_id,
  					   unsigned int lig_num_comps)
  {
    info->lig_props() = (lig_id << 5) | IS_LIG_BASE | (lig_num_comps & 0x0F);
  }
  
  static inline void
  _hb_glyph_info_set_lig_props_for_mark (hb_glyph_info_t *info,
  				       unsigned int lig_id,
  				       unsigned int lig_comp)
  {
    info->lig_props() = (lig_id << 5) | (lig_comp & 0x0F);
  }
  
  static inline void
  _hb_glyph_info_set_lig_props_for_component (hb_glyph_info_t *info, unsigned int comp)
  {
    _hb_glyph_info_set_lig_props_for_mark (info, 0, comp);
  }
  
  static inline unsigned int
  _hb_glyph_info_get_lig_id (const hb_glyph_info_t *info)
  {
    return info->lig_props() >> 5;
  }
  
  static inline bool
  _hb_glyph_info_ligated_internal (const hb_glyph_info_t *info)
  {
    return !!(info->lig_props() & IS_LIG_BASE);
  }
  
  static inline unsigned int
  _hb_glyph_info_get_lig_comp (const hb_glyph_info_t *info)
  {
    if (_hb_glyph_info_ligated_internal (info))
      return 0;
    else
      return info->lig_props() & 0x0F;
  }
  
  static inline unsigned int
  _hb_glyph_info_get_lig_num_comps (const hb_glyph_info_t *info)
  {
    if ((info->glyph_props() & HB_OT_LAYOUT_GLYPH_PROPS_LIGATURE) &&
        _hb_glyph_info_ligated_internal (info))
      return info->lig_props() & 0x0F;
    else
      return 1;
  }
  
  static inline uint8_t
  _hb_allocate_lig_id (hb_buffer_t *buffer) {
    uint8_t lig_id = buffer->next_serial () & 0x07;
    if (unlikely (!lig_id))
      lig_id = _hb_allocate_lig_id (buffer); /* in case of overflow */
    return lig_id;
  }
  
  /* glyph_props: */
  
  static inline void
  _hb_glyph_info_set_glyph_props (hb_glyph_info_t *info, unsigned int props)
  {
    info->glyph_props() = props;
  }
  
  static inline unsigned int
  _hb_glyph_info_get_glyph_props (const hb_glyph_info_t *info)
  {
    return info->glyph_props();
  }
  
  static inline bool
  _hb_glyph_info_is_base_glyph (const hb_glyph_info_t *info)
  {
    return !!(info->glyph_props() & HB_OT_LAYOUT_GLYPH_PROPS_BASE_GLYPH);
  }
  
  static inline bool
  _hb_glyph_info_is_ligature (const hb_glyph_info_t *info)
  {
    return !!(info->glyph_props() & HB_OT_LAYOUT_GLYPH_PROPS_LIGATURE);
  }
  
  static inline bool
  _hb_glyph_info_is_mark (const hb_glyph_info_t *info)
  {
    return !!(info->glyph_props() & HB_OT_LAYOUT_GLYPH_PROPS_MARK);
  }
  
  static inline bool
  _hb_glyph_info_substituted (const hb_glyph_info_t *info)
  {
    return !!(info->glyph_props() & HB_OT_LAYOUT_GLYPH_PROPS_SUBSTITUTED);
  }
  
  static inline bool
  _hb_glyph_info_ligated (const hb_glyph_info_t *info)
  {
    return !!(info->glyph_props() & HB_OT_LAYOUT_GLYPH_PROPS_LIGATED);
  }
  
  static inline bool
  _hb_glyph_info_multiplied (const hb_glyph_info_t *info)
  {
    return !!(info->glyph_props() & HB_OT_LAYOUT_GLYPH_PROPS_MULTIPLIED);
  }
  
  static inline bool
  _hb_glyph_info_ligated_and_didnt_multiply (const hb_glyph_info_t *info)
  {
    return _hb_glyph_info_ligated (info) && !_hb_glyph_info_multiplied (info);
  }
  
  static inline void
  _hb_glyph_info_clear_ligated_and_multiplied (hb_glyph_info_t *info)
  {
    info->glyph_props() &= ~(HB_OT_LAYOUT_GLYPH_PROPS_LIGATED |
  			   HB_OT_LAYOUT_GLYPH_PROPS_MULTIPLIED);
  }
  
  static inline void
  _hb_glyph_info_clear_substituted (hb_glyph_info_t *info)
  {
    info->glyph_props() &= ~(HB_OT_LAYOUT_GLYPH_PROPS_SUBSTITUTED);
  }
  
  
  /* Allocation / deallocation. */
  
  static inline void
  _hb_buffer_allocate_unicode_vars (hb_buffer_t *buffer)
  {
    HB_BUFFER_ALLOCATE_VAR (buffer, unicode_props);
  }
  
  static inline void
  _hb_buffer_deallocate_unicode_vars (hb_buffer_t *buffer)
  {
    HB_BUFFER_DEALLOCATE_VAR (buffer, unicode_props);
  }
  
  static inline void
  _hb_buffer_assert_unicode_vars (hb_buffer_t *buffer)
  {
    HB_BUFFER_ASSERT_VAR (buffer, unicode_props);
  }
  
  static inline void
  _hb_buffer_allocate_gsubgpos_vars (hb_buffer_t *buffer)
  {
    HB_BUFFER_ALLOCATE_VAR (buffer, glyph_props);
    HB_BUFFER_ALLOCATE_VAR (buffer, lig_props);
    HB_BUFFER_ALLOCATE_VAR (buffer, syllable);
  }
  
  static inline void
  _hb_buffer_deallocate_gsubgpos_vars (hb_buffer_t *buffer)
  {
    HB_BUFFER_DEALLOCATE_VAR (buffer, syllable);
    HB_BUFFER_DEALLOCATE_VAR (buffer, lig_props);
    HB_BUFFER_DEALLOCATE_VAR (buffer, glyph_props);
  }
  
  static inline void
  _hb_buffer_assert_gsubgpos_vars (hb_buffer_t *buffer)
  {
    HB_BUFFER_ASSERT_VAR (buffer, glyph_props);
    HB_BUFFER_ASSERT_VAR (buffer, lig_props);
    HB_BUFFER_ASSERT_VAR (buffer, syllable);
  }
  
  /* Make sure no one directly touches our props... */
  #undef unicode_props0
  #undef unicode_props1
  #undef lig_props
  #undef glyph_props
  
  #endif /* HB_OT_LAYOUT_PRIVATE_HH */
  