text: /*
   * Copyright © 1998-2004  David Turner and Werner Lemberg
   * Copyright © 2006  Behdad Esfahbod
   * 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
   */
  
  #include "hb-open-type-private.hh"
  #include "hb-ot-layout-private.hh"
  #include "hb-ot-map-private.hh"
  
  #include "hb-ot-layout-gdef-table.hh"
  #include "hb-ot-layout-gsub-table.hh"
  #include "hb-ot-layout-gpos-table.hh"
  
  // Just so we compile them; unused otherwise:
  #include "hb-ot-layout-base-table.hh"
  #include "hb-ot-layout-jstf-table.hh"
  #include "hb-ot-color-colr-table.hh"
  #include "hb-ot-color-cpal-table.hh"
  #include "hb-ot-color-sbix-table.hh"
  #include "hb-ot-color-svg-table.hh"
  #include "hb-ot-name-table.hh"
  #include "hb-map-private.hh"
  
  
  hb_ot_layout_t *
  _hb_ot_layout_create (hb_face_t *face)
  {
    hb_ot_layout_t *layout = (hb_ot_layout_t *) calloc (1, sizeof (hb_ot_layout_t));
    if (unlikely (!layout))
      return nullptr;
  
    layout->gdef_blob = OT::Sanitizer<OT::GDEF>().sanitize (face->reference_table (HB_OT_TAG_GDEF));
    layout->gdef = layout->gdef_blob->as<OT::GDEF> ();
  
    layout->gsub_blob = OT::Sanitizer<OT::GSUB>().sanitize (face->reference_table (HB_OT_TAG_GSUB));
    layout->gsub = layout->gsub_blob->as<OT::GSUB> ();
  
    layout->gpos_blob = OT::Sanitizer<OT::GPOS>().sanitize (face->reference_table (HB_OT_TAG_GPOS));
    layout->gpos = layout->gpos_blob->as<OT::GPOS> ();
  
    layout->math.init (face);
    layout->fvar.init (face);
    layout->avar.init (face);
  
    {
      /*
       * The ugly business of blacklisting individual fonts' tables happen here!
       * See this thread for why we finally had to bend in and do this:
       * https://lists.freedesktop.org/archives/harfbuzz/2016-February/005489.html
       */
      unsigned int gdef_len = layout->gdef_blob->length;
      unsigned int gsub_len = layout->gsub_blob->length;
      unsigned int gpos_len = layout->gpos_blob->length;
      if (0
        /* sha1sum:c5ee92f0bca4bfb7d06c4d03e8cf9f9cf75d2e8a Windows 7? timesi.ttf */
        || (442 == gdef_len && 42038 == gpos_len && 2874 == gsub_len)
        /* sha1sum:37fc8c16a0894ab7b749e35579856c73c840867b Windows 7? timesbi.ttf */
        || (430 == gdef_len && 40662 == gpos_len && 2874 == gsub_len)
        /* sha1sum:19fc45110ea6cd3cdd0a5faca256a3797a069a80 Windows 7 timesi.ttf */
        || (442 == gdef_len && 39116 == gpos_len && 2874 == gsub_len)
        /* sha1sum:6d2d3c9ed5b7de87bc84eae0df95ee5232ecde26 Windows 7 timesbi.ttf */
        || (430 == gdef_len && 39374 == gpos_len && 2874 == gsub_len)
        /* sha1sum:8583225a8b49667c077b3525333f84af08c6bcd8 OS X 10.11.3 Times New Roman Italic.ttf */
        || (490 == gdef_len && 41638 == gpos_len && 3046 == gsub_len)
        /* sha1sum:ec0f5a8751845355b7c3271d11f9918a966cb8c9 OS X 10.11.3 Times New Roman Bold Italic.ttf */
        || (478 == gdef_len && 41902 == gpos_len && 3046 == gsub_len)
      )
      {
        /* In certain versions of Times New Roman Italic and Bold Italic,
         * ASCII double quotation mark U+0022, mapped to glyph 5, has wrong
         * glyph class 3 (mark) in GDEF.  Nuke the GDEF to avoid zero-width
         * double-quote.  See:
         * https://lists.freedesktop.org/archives/harfbuzz/2016-February/005489.html
         */
       if (3 == layout->gdef->get_glyph_class (5))
         layout->gdef = &Null(OT::GDEF);
      }
      else if (0
        /* sha1sum:96eda93f7d33e79962451c6c39a6b51ee893ce8c  tahoma.ttf from Windows 8 */
        || (898 == gdef_len && 46470 == gpos_len && 12554 == gsub_len)
        /* sha1sum:20928dc06014e0cd120b6fc942d0c3b1a46ac2bc  tahomabd.ttf from Windows 8 */
        || (910 == gdef_len && 47732 == gpos_len && 12566 == gsub_len)
        /* sha1sum:4f95b7e4878f60fa3a39ca269618dfde9721a79e  tahoma.ttf from Windows 8.1 */
        || (928 == gdef_len && 59332 == gpos_len && 23298 == gsub_len)
        /* sha1sum:6d400781948517c3c0441ba42acb309584b73033  tahomabd.ttf from Windows 8.1 */
        || (940 == gdef_len && 60732 == gpos_len && 23310 == gsub_len)
        /* tahoma.ttf v6.04 from Windows 8.1 x64, see https://bugzilla.mozilla.org/show_bug.cgi?id=1279925 */
        || (964 == gdef_len && 60072 == gpos_len && 23836 == gsub_len)
        /* tahomabd.ttf v6.04 from Windows 8.1 x64, see https://bugzilla.mozilla.org/show_bug.cgi?id=1279925 */
        || (976 == gdef_len && 61456 == gpos_len && 23832 == gsub_len)
        /* sha1sum:e55fa2dfe957a9f7ec26be516a0e30b0c925f846  tahoma.ttf from Windows 10 */
        || (994 == gdef_len && 60336 == gpos_len && 24474 == gsub_len)
        /* sha1sum:7199385abb4c2cc81c83a151a7599b6368e92343  tahomabd.ttf from Windows 10 */
        || (1006 == gdef_len && 61740 == gpos_len && 24470 == gsub_len)
        /* tahoma.ttf v6.91 from Windows 10 x64, see https://bugzilla.mozilla.org/show_bug.cgi?id=1279925 */
        || (1006 == gdef_len && 61346 == gpos_len && 24576 == gsub_len)
        /* tahomabd.ttf v6.91 from Windows 10 x64, see https://bugzilla.mozilla.org/show_bug.cgi?id=1279925 */
        || (1018 == gdef_len && 62828 == gpos_len && 24572 == gsub_len)
        /* sha1sum:b9c84d820c49850d3d27ec498be93955b82772b5  tahoma.ttf from Windows 10 AU */
        || (1006 == gdef_len && 61352 == gpos_len && 24576 == gsub_len)
        /* sha1sum:2bdfaab28174bdadd2f3d4200a30a7ae31db79d2  tahomabd.ttf from Windows 10 AU */
        || (1018 == gdef_len && 62834 == gpos_len && 24572 == gsub_len)
        /* sha1sum:b0d36cf5a2fbe746a3dd277bffc6756a820807a7  Tahoma.ttf from Mac OS X 10.9 */
        || (832 == gdef_len && 47162 == gpos_len && 7324 == gsub_len)
        /* sha1sum:12fc4538e84d461771b30c18b5eb6bd434e30fba  Tahoma Bold.ttf from Mac OS X 10.9 */
        || (844 == gdef_len && 45474 == gpos_len && 7302 == gsub_len)
        /* sha1sum:eb8afadd28e9cf963e886b23a30b44ab4fd83acc  himalaya.ttf from Windows 7 */
        || (180 == gdef_len && 7254 == gpos_len && 13054 == gsub_len)
        /* sha1sum:73da7f025b238a3f737aa1fde22577a6370f77b0  himalaya.ttf from Windows 8 */
        || (192 == gdef_len && 7254 == gpos_len && 12638 == gsub_len)
        /* sha1sum:6e80fd1c0b059bbee49272401583160dc1e6a427  himalaya.ttf from Windows 8.1 */
        || (192 == gdef_len && 7254 == gpos_len && 12690 == gsub_len)
        /* 8d9267aea9cd2c852ecfb9f12a6e834bfaeafe44  cantarell-fonts-0.0.21/otf/Cantarell-Regular.otf */
        /* 983988ff7b47439ab79aeaf9a45bd4a2c5b9d371  cantarell-fonts-0.0.21/otf/Cantarell-Oblique.otf */
        || (188 == gdef_len && 3852 == gpos_len && 248 == gsub_len)
        /* 2c0c90c6f6087ffbfea76589c93113a9cbb0e75f  cantarell-fonts-0.0.21/otf/Cantarell-Bold.otf */
        /* 55461f5b853c6da88069ffcdf7f4dd3f8d7e3e6b  cantarell-fonts-0.0.21/otf/Cantarell-Bold-Oblique.otf */
        || (188 == gdef_len && 3426 == gpos_len && 264 == gsub_len)
        /* d125afa82a77a6475ac0e74e7c207914af84b37a padauk-2.80/Padauk.ttf RHEL 7.2 */
        || (1058 == gdef_len && 11818 == gpos_len && 47032 == gsub_len)
        /* 0f7b80437227b90a577cc078c0216160ae61b031 padauk-2.80/Padauk-Bold.ttf RHEL 7.2*/
        || (1046 == gdef_len && 12600 == gpos_len && 47030 == gsub_len)
        /* d3dde9aa0a6b7f8f6a89ef1002e9aaa11b882290 padauk-2.80/Padauk.ttf Ubuntu 16.04 */
        || (1058 == gdef_len && 16770 == gpos_len && 71796 == gsub_len)
        /* 5f3c98ccccae8a953be2d122c1b3a77fd805093f padauk-2.80/Padauk-Bold.ttf Ubuntu 16.04 */
        || (1046 == gdef_len && 17862 == gpos_len && 71790 == gsub_len)
        /* 6c93b63b64e8b2c93f5e824e78caca555dc887c7 padauk-2.80/Padauk-book.ttf */
        || (1046 == gdef_len && 17112 == gpos_len && 71788 == gsub_len)
        /* d89b1664058359b8ec82e35d3531931125991fb9 padauk-2.80/Padauk-bookbold.ttf */
        || (1058 == gdef_len && 17514 == gpos_len && 71794 == gsub_len)
        /* 824cfd193aaf6234b2b4dc0cf3c6ef576c0d00ef padauk-3.0/Padauk-book.ttf */
        || (1330 == gdef_len && 57938 == gpos_len && 109904 == gsub_len)
        /* 91fcc10cf15e012d27571e075b3b4dfe31754a8a padauk-3.0/Padauk-bookbold.ttf */
        || (1330 == gdef_len && 58972 == gpos_len && 109904 == gsub_len)
        /* sha1sum: c26e41d567ed821bed997e937bc0c41435689e85  Padauk.ttf
         *  "Padauk Regular" "Version 2.5", see https://crbug.com/681813 */
        || (1004 == gdef_len && 14836 == gpos_len && 59092 == gsub_len)
      )
      {
        /* Many versions of Tahoma have bad GDEF tables that incorrectly classify some spacing marks
         * such as certain IPA symbols as glyph class 3. So do older versions of Microsoft Himalaya,
         * and the version of Cantarell shipped by Ubuntu 16.04.
         * Nuke the GDEF tables of these fonts to avoid unwanted width-zeroing.
         * See https://bugzilla.mozilla.org/show_bug.cgi?id=1279925
         *     https://bugzilla.mozilla.org/show_bug.cgi?id=1279693
         *     https://bugzilla.mozilla.org/show_bug.cgi?id=1279875
         */
        layout->gdef = &Null(OT::GDEF);
      }
    }
  
    layout->gsub_lookup_count = layout->gsub->get_lookup_count ();
    layout->gpos_lookup_count = layout->gpos->get_lookup_count ();
  
    layout->gsub_accels = (hb_ot_layout_lookup_accelerator_t *) calloc (layout->gsub->get_lookup_count (), sizeof (hb_ot_layout_lookup_accelerator_t));
    layout->gpos_accels = (hb_ot_layout_lookup_accelerator_t *) calloc (layout->gpos->get_lookup_count (), sizeof (hb_ot_layout_lookup_accelerator_t));
  
    if (unlikely ((layout->gsub_lookup_count && !layout->gsub_accels) ||
                  (layout->gpos_lookup_count && !layout->gpos_accels)))
    {
      _hb_ot_layout_destroy (layout);
      return nullptr;
    }
  
    for (unsigned int i = 0; i < layout->gsub_lookup_count; i++)
      layout->gsub_accels[i].init (layout->gsub->get_lookup (i));
    for (unsigned int i = 0; i < layout->gpos_lookup_count; i++)
      layout->gpos_accels[i].init (layout->gpos->get_lookup (i));
  
    return layout;
  }
  
  void
  _hb_ot_layout_destroy (hb_ot_layout_t *layout)
  {
    if (layout->gsub_accels)
      for (unsigned int i = 0; i < layout->gsub_lookup_count; i++)
        layout->gsub_accels[i].fini ();
    if (layout->gpos_accels)
      for (unsigned int i = 0; i < layout->gpos_lookup_count; i++)
        layout->gpos_accels[i].fini ();
  
    free (layout->gsub_accels);
    free (layout->gpos_accels);
  
    hb_blob_destroy (layout->gdef_blob);
    hb_blob_destroy (layout->gsub_blob);
    hb_blob_destroy (layout->gpos_blob);
  
    layout->math.fini ();
    layout->fvar.fini ();
    layout->avar.fini ();
  
    free (layout);
  }
  
  // static inline const OT::BASE&
  // _get_base (hb_face_t *face)
  // {
  //   if (unlikely (!hb_ot_shaper_face_data_ensure (face))) return Null(OT::BASE);
  //   hb_ot_layout_t * layout = hb_ot_layout_from_face (face);
  //   return *(layout->base.get ());
  // }
  
  static inline const OT::GDEF&
  _get_gdef (hb_face_t *face)
  {
    if (unlikely (!hb_ot_shaper_face_data_ensure (face))) return Null(OT::GDEF);
    return *hb_ot_layout_from_face (face)->gdef;
  }
  static inline const OT::GSUB&
  _get_gsub (hb_face_t *face)
  {
    if (unlikely (!hb_ot_shaper_face_data_ensure (face))) return Null(OT::GSUB);
    return *hb_ot_layout_from_face (face)->gsub;
  }
  static inline const OT::GPOS&
  _get_gpos (hb_face_t *face)
  {
    if (unlikely (!hb_ot_shaper_face_data_ensure (face))) return Null(OT::GPOS);
    return *hb_ot_layout_from_face (face)->gpos;
  }
  
  /*
   * GDEF
   */
  
  hb_bool_t
  hb_ot_layout_has_glyph_classes (hb_face_t *face)
  {
    return _get_gdef (face).has_glyph_classes ();
  }
  
  /**
   * hb_ot_layout_get_glyph_class:
   *
   * Since: 0.9.7
   **/
  hb_ot_layout_glyph_class_t
  hb_ot_layout_get_glyph_class (hb_face_t      *face,
                                hb_codepoint_t  glyph)
  {
    return (hb_ot_layout_glyph_class_t) _get_gdef (face).get_glyph_class (glyph);
  }
  
  /**
   * hb_ot_layout_get_glyphs_in_class:
   *
   * Since: 0.9.7
   **/
  void
  hb_ot_layout_get_glyphs_in_class (hb_face_t                  *face,
                                    hb_ot_layout_glyph_class_t  klass,
                                    hb_set_t                   *glyphs /* OUT */)
  {
    return _get_gdef (face).get_glyphs_in_class (klass, glyphs);
  }
  
  unsigned int
  hb_ot_layout_get_attach_points (hb_face_t      *face,
                                  hb_codepoint_t  glyph,
                                  unsigned int    start_offset,
                                  unsigned int   *point_count /* IN/OUT */,
                                  unsigned int   *point_array /* OUT */)
  {
    return _get_gdef (face).get_attach_points (glyph, start_offset, point_count, point_array);
  }
  
  unsigned int
  hb_ot_layout_get_ligature_carets (hb_font_t      *font,
                                    hb_direction_t  direction,
                                    hb_codepoint_t  glyph,
                                    unsigned int    start_offset,
                                    unsigned int   *caret_count /* IN/OUT */,
                                    hb_position_t  *caret_array /* OUT */)
  {
    return _get_gdef (font->face).get_lig_carets (font, direction, glyph, start_offset, caret_count, caret_array);
  }
  
  
  /*
   * GSUB/GPOS
   */
  
  static const OT::GSUBGPOS&
  get_gsubgpos_table (hb_face_t *face,
                      hb_tag_t   table_tag)
  {
    switch (table_tag) {
      case HB_OT_TAG_GSUB: return _get_gsub (face);
      case HB_OT_TAG_GPOS: return _get_gpos (face);
      default:             return Null(OT::GSUBGPOS);
    }
  }
  
  
  unsigned int
  hb_ot_layout_table_get_script_tags (hb_face_t    *face,
                                      hb_tag_t      table_tag,
                                      unsigned int  start_offset,
                                      unsigned int *script_count /* IN/OUT */,
                                      hb_tag_t     *script_tags /* OUT */)
  {
    const OT::GSUBGPOS &g = get_gsubgpos_table (face, table_tag);
  
    return g.get_script_tags (start_offset, script_count, script_tags);
  }
  
  #define HB_OT_TAG_LATIN_SCRIPT          HB_TAG ('l', 'a', 't', 'n')
  
  hb_bool_t
  hb_ot_layout_table_find_script (hb_face_t    *face,
                                  hb_tag_t      table_tag,
                                  hb_tag_t      script_tag,
                                  unsigned int *script_index)
  {
    static_assert ((OT::Index::NOT_FOUND_INDEX == HB_OT_LAYOUT_NO_SCRIPT_INDEX), "");
    const OT::GSUBGPOS &g = get_gsubgpos_table (face, table_tag);
  
    if (g.find_script_index (script_tag, script_index))
      return true;
  
    /* try finding 'DFLT' */
    if (g.find_script_index (HB_OT_TAG_DEFAULT_SCRIPT, script_index))
      return false;
  
    /* try with 'dflt'; MS site has had typos and many fonts use it now :(.
     * including many versions of DejaVu Sans Mono! */
    if (g.find_script_index (HB_OT_TAG_DEFAULT_LANGUAGE, script_index))
      return false;
  
    /* try with 'latn'; some old fonts put their features there even though
       they're really trying to support Thai, for example :( */
    if (g.find_script_index (HB_OT_TAG_LATIN_SCRIPT, script_index))
      return false;
  
    if (script_index) *script_index = HB_OT_LAYOUT_NO_SCRIPT_INDEX;
    return false;
  }
  
  hb_bool_t
  hb_ot_layout_table_choose_script (hb_face_t      *face,
                                    hb_tag_t        table_tag,
                                    const hb_tag_t *script_tags,
                                    unsigned int   *script_index,
                                    hb_tag_t       *chosen_script)
  {
    static_assert ((OT::Index::NOT_FOUND_INDEX == HB_OT_LAYOUT_NO_SCRIPT_INDEX), "");
    const OT::GSUBGPOS &g = get_gsubgpos_table (face, table_tag);
  
    while (*script_tags)
    {
      if (g.find_script_index (*script_tags, script_index)) {
        if (chosen_script)
          *chosen_script = *script_tags;
        return true;
      }
      script_tags++;
    }
  
    /* try finding 'DFLT' */
    if (g.find_script_index (HB_OT_TAG_DEFAULT_SCRIPT, script_index)) {
      if (chosen_script)
        *chosen_script = HB_OT_TAG_DEFAULT_SCRIPT;
      return false;
    }
  
    /* try with 'dflt'; MS site has had typos and many fonts use it now :( */
    if (g.find_script_index (HB_OT_TAG_DEFAULT_LANGUAGE, script_index)) {
      if (chosen_script)
        *chosen_script = HB_OT_TAG_DEFAULT_LANGUAGE;
      return false;
    }
  
    /* try with 'latn'; some old fonts put their features there even though
       they're really trying to support Thai, for example :( */
    if (g.find_script_index (HB_OT_TAG_LATIN_SCRIPT, script_index)) {
      if (chosen_script)
        *chosen_script = HB_OT_TAG_LATIN_SCRIPT;
      return false;
    }
  
    if (script_index) *script_index = HB_OT_LAYOUT_NO_SCRIPT_INDEX;
    if (chosen_script)
      *chosen_script = HB_OT_LAYOUT_NO_SCRIPT_INDEX;
    return false;
  }
  
  unsigned int
  hb_ot_layout_table_get_feature_tags (hb_face_t    *face,
                                       hb_tag_t      table_tag,
                                       unsigned int  start_offset,
                                       unsigned int *feature_count /* IN/OUT */,
                                       hb_tag_t     *feature_tags /* OUT */)
  {
    const OT::GSUBGPOS &g = get_gsubgpos_table (face, table_tag);
  
    return g.get_feature_tags (start_offset, feature_count, feature_tags);
  }
  
  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)
  {
    static_assert ((OT::Index::NOT_FOUND_INDEX == HB_OT_LAYOUT_NO_FEATURE_INDEX), "");
    const OT::GSUBGPOS &g = get_gsubgpos_table (face, table_tag);
  
    unsigned int num_features = g.get_feature_count ();
    for (unsigned int i = 0; i < num_features; i++)
    {
      if (feature_tag == g.get_feature_tag (i)) {
        if (feature_index) *feature_index = i;
        return true;
      }
    }
  
    if (feature_index) *feature_index = HB_OT_LAYOUT_NO_FEATURE_INDEX;
    return false;
  }
  
  
  unsigned int
  hb_ot_layout_script_get_language_tags (hb_face_t    *face,
                                         hb_tag_t      table_tag,
                                         unsigned int  script_index,
                                         unsigned int  start_offset,
                                         unsigned int *language_count /* IN/OUT */,
                                         hb_tag_t     *language_tags /* OUT */)
  {
    const OT::Script &s = get_gsubgpos_table (face, table_tag).get_script (script_index);
  
    return s.get_lang_sys_tags (start_offset, language_count, language_tags);
  }
  
  hb_bool_t
  hb_ot_layout_script_find_language (hb_face_t    *face,
                                     hb_tag_t      table_tag,
                                     unsigned int  script_index,
                                     hb_tag_t      language_tag,
                                     unsigned int *language_index)
  {
    static_assert ((OT::Index::NOT_FOUND_INDEX == HB_OT_LAYOUT_DEFAULT_LANGUAGE_INDEX), "");
    const OT::Script &s = get_gsubgpos_table (face, table_tag).get_script (script_index);
  
    if (s.find_lang_sys_index (language_tag, language_index))
      return true;
  
    /* try with 'dflt'; MS site has had typos and many fonts use it now :( */
    if (s.find_lang_sys_index (HB_OT_TAG_DEFAULT_LANGUAGE, language_index))
      return false;
  
    if (language_index) *language_index = HB_OT_LAYOUT_DEFAULT_LANGUAGE_INDEX;
    return false;
  }
  
  hb_bool_t
  hb_ot_layout_language_get_required_feature_index (hb_face_t    *face,
                                                    hb_tag_t      table_tag,
                                                    unsigned int  script_index,
                                                    unsigned int  language_index,
                                                    unsigned int *feature_index)
  {
    return hb_ot_layout_language_get_required_feature (face,
                                                       table_tag,
                                                       script_index,
                                                       language_index,
                                                       feature_index,
                                                       nullptr);
  }
  
  /**
   * hb_ot_layout_language_get_required_feature:
   *
   * Since: 0.9.30
   **/
  hb_bool_t
  hb_ot_layout_language_get_required_feature (hb_face_t    *face,
                                              hb_tag_t      table_tag,
                                              unsigned int  script_index,
                                              unsigned int  language_index,
                                              unsigned int *feature_index,
                                              hb_tag_t     *feature_tag)
  {
    const OT::GSUBGPOS &g = get_gsubgpos_table (face, table_tag);
    const OT::LangSys &l = g.get_script (script_index).get_lang_sys (language_index);
  
    unsigned int index = l.get_required_feature_index ();
    if (feature_index) *feature_index = index;
    if (feature_tag) *feature_tag = g.get_feature_tag (index);
  
    return l.has_required_feature ();
  }
  
  unsigned int
  hb_ot_layout_language_get_feature_indexes (hb_face_t    *face,
                                             hb_tag_t      table_tag,
                                             unsigned int  script_index,
                                             unsigned int  language_index,
                                             unsigned int  start_offset,
                                             unsigned int *feature_count /* IN/OUT */,
                                             unsigned int *feature_indexes /* OUT */)
  {
    const OT::GSUBGPOS &g = get_gsubgpos_table (face, table_tag);
    const OT::LangSys &l = g.get_script (script_index).get_lang_sys (language_index);
  
    return l.get_feature_indexes (start_offset, feature_count, feature_indexes);
  }
  
  unsigned int
  hb_ot_layout_language_get_feature_tags (hb_face_t    *face,
                                          hb_tag_t      table_tag,
                                          unsigned int  script_index,
                                          unsigned int  language_index,
                                          unsigned int  start_offset,
                                          unsigned int *feature_count /* IN/OUT */,
                                          hb_tag_t     *feature_tags /* OUT */)
  {
    const OT::GSUBGPOS &g = get_gsubgpos_table (face, table_tag);
    const OT::LangSys &l = g.get_script (script_index).get_lang_sys (language_index);
  
    static_assert ((sizeof (unsigned int) == sizeof (hb_tag_t)), "");
    unsigned int ret = l.get_feature_indexes (start_offset, feature_count, (unsigned int *) feature_tags);
  
    if (feature_tags) {
      unsigned int count = *feature_count;
      for (unsigned int i = 0; i < count; i++)
        feature_tags[i] = g.get_feature_tag ((unsigned int) feature_tags[i]);
    }
  
    return ret;
  }
  
  
  hb_bool_t
  hb_ot_layout_language_find_feature (hb_face_t    *face,
                                      hb_tag_t      table_tag,
                                      unsigned int  script_index,
                                      unsigned int  language_index,
                                      hb_tag_t      feature_tag,
                                      unsigned int *feature_index)
  {
    static_assert ((OT::Index::NOT_FOUND_INDEX == HB_OT_LAYOUT_NO_FEATURE_INDEX), "");
    const OT::GSUBGPOS &g = get_gsubgpos_table (face, table_tag);
    const OT::LangSys &l = g.get_script (script_index).get_lang_sys (language_index);
  
    unsigned int num_features = l.get_feature_count ();
    for (unsigned int i = 0; i < num_features; i++) {
      unsigned int f_index = l.get_feature_index (i);
  
      if (feature_tag == g.get_feature_tag (f_index)) {
        if (feature_index) *feature_index = f_index;
        return true;
      }
    }
  
    if (feature_index) *feature_index = HB_OT_LAYOUT_NO_FEATURE_INDEX;
    return false;
  }
  
  /**
   * hb_ot_layout_feature_get_lookups:
   *
   * Since: 0.9.7
   **/
  unsigned int
  hb_ot_layout_feature_get_lookups (hb_face_t    *face,
                                    hb_tag_t      table_tag,
                                    unsigned int  feature_index,
                                    unsigned int  start_offset,
                                    unsigned int *lookup_count /* IN/OUT */,
                                    unsigned int *lookup_indexes /* OUT */)
  {
    return hb_ot_layout_feature_with_variations_get_lookups (face,
                                                             table_tag,
                                                             feature_index,
                                                             HB_OT_LAYOUT_NO_VARIATIONS_INDEX,
                                                             start_offset,
                                                             lookup_count,
                                                             lookup_indexes);
  }
  
  /**
   * hb_ot_layout_table_get_lookup_count:
   *
   * Since: 0.9.22
   **/
  unsigned int
  hb_ot_layout_table_get_lookup_count (hb_face_t    *face,
                                       hb_tag_t      table_tag)
  {
    if (unlikely (!hb_ot_shaper_face_data_ensure (face))) return 0;
    switch (table_tag)
    {
      case HB_OT_TAG_GSUB:
      {
        return hb_ot_layout_from_face (face)->gsub_lookup_count;
      }
      case HB_OT_TAG_GPOS:
      {
        return hb_ot_layout_from_face (face)->gpos_lookup_count;
      }
    }
    return 0;
  }
  
  static void
  _hb_ot_layout_collect_lookups_lookups (hb_face_t      *face,
                                         hb_tag_t        table_tag,
                                         unsigned int    feature_index,
                                         hb_set_t       *lookup_indexes /* OUT */)
  {
    unsigned int lookup_indices[32];
    unsigned int offset, len;
  
    offset = 0;
    do {
      len = ARRAY_LENGTH (lookup_indices);
      hb_ot_layout_feature_get_lookups (face,
                                        table_tag,
                                        feature_index,
                                        offset, &len,
                                        lookup_indices);
  
      for (unsigned int i = 0; i < len; i++)
        lookup_indexes->add (lookup_indices[i]);
  
      offset += len;
    } while (len == ARRAY_LENGTH (lookup_indices));
  }
  
  static void
  _hb_ot_layout_collect_lookups_features (hb_face_t      *face,
                                          hb_tag_t        table_tag,
                                          unsigned int    script_index,
                                          unsigned int    language_index,
                                          const hb_tag_t *features,
                                          hb_set_t       *lookup_indexes /* OUT */)
  {
    if (!features)
    {
      unsigned int required_feature_index;
      if (hb_ot_layout_language_get_required_feature (face,
                                                      table_tag,
                                                      script_index,
                                                      language_index,
                                                      &required_feature_index,
                                                      nullptr))
        _hb_ot_layout_collect_lookups_lookups (face,
                                               table_tag,
                                               required_feature_index,
                                               lookup_indexes);
  
      /* All features */
      unsigned int feature_indices[32];
      unsigned int offset, len;
  
      offset = 0;
      do {
        len = ARRAY_LENGTH (feature_indices);
        hb_ot_layout_language_get_feature_indexes (face,
                                                   table_tag,
                                                   script_index,
                                                   language_index,
                                                   offset, &len,
                                                   feature_indices);
  
        for (unsigned int i = 0; i < len; i++)
          _hb_ot_layout_collect_lookups_lookups (face,
                                                 table_tag,
                                                 feature_indices[i],
                                                 lookup_indexes);
  
        offset += len;
      } while (len == ARRAY_LENGTH (feature_indices));
    }
    else
    {
      for (; *features; features++)
      {
        unsigned int feature_index;
        if (hb_ot_layout_language_find_feature (face,
                                                table_tag,
                                                script_index,
                                                language_index,
                                                *features,
                                                &feature_index))
          _hb_ot_layout_collect_lookups_lookups (face,
                                                 table_tag,
                                                 feature_index,
                                                 lookup_indexes);
      }
    }
  }
  
  static void
  _hb_ot_layout_collect_lookups_languages (hb_face_t      *face,
                                           hb_tag_t        table_tag,
                                           unsigned int    script_index,
                                           const hb_tag_t *languages,
                                           const hb_tag_t *features,
                                           hb_set_t       *lookup_indexes /* OUT */)
  {
    _hb_ot_layout_collect_lookups_features (face,
                                            table_tag,
                                            script_index,
                                            HB_OT_LAYOUT_DEFAULT_LANGUAGE_INDEX,
                                            features,
                                            lookup_indexes);
  
    if (!languages)
    {
      /* All languages */
      unsigned int count = hb_ot_layout_script_get_language_tags (face,
                                                                  table_tag,
                                                                  script_index,
                                                                  0, nullptr, nullptr);
      for (unsigned int language_index = 0; language_index < count; language_index++)
        _hb_ot_layout_collect_lookups_features (face,
                                                table_tag,
                                                script_index,
                                                language_index,
                                                features,
                                                lookup_indexes);
    }
    else
    {
      for (; *languages; languages++)
      {
        unsigned int language_index;
        if (hb_ot_layout_script_find_language (face,
                                               table_tag,
                                               script_index,
                                               *languages,
                                               &language_index))
          _hb_ot_layout_collect_lookups_features (face,
                                                  table_tag,
                                                  script_index,
                                                  language_index,
                                                  features,
                                                  lookup_indexes);
      }
    }
  }
  
  /**
   * hb_ot_layout_collect_lookups:
   *
   * Since: 0.9.8
   **/
  void
  hb_ot_layout_collect_lookups (hb_face_t      *face,
                                hb_tag_t        table_tag,
                                const hb_tag_t *scripts,
                                const hb_tag_t *languages,
                                const hb_tag_t *features,
                                hb_set_t       *lookup_indexes /* OUT */)
  {
    if (!scripts)
    {
      /* All scripts */
      unsigned int count = hb_ot_layout_table_get_script_tags (face,
                                                               table_tag,
                                                               0, nullptr, nullptr);
      for (unsigned int script_index = 0; script_index < count; script_index++)
        _hb_ot_layout_collect_lookups_languages (face,
                                                 table_tag,
                                                 script_index,
                                                 languages,
                                                 features,
                                                 lookup_indexes);
    }
    else
    {
      for (; *scripts; scripts++)
      {
        unsigned int script_index;
        if (hb_ot_layout_table_find_script (face,
                                            table_tag,
                                            *scripts,
                                            &script_index))
          _hb_ot_layout_collect_lookups_languages (face,
                                                   table_tag,
                                                   script_index,
                                                   languages,
                                                   features,
                                                   lookup_indexes);
      }
    }
  }
  
  /**
   * hb_ot_layout_lookup_collect_glyphs:
   *
   * Since: 0.9.7
   **/
  void
  hb_ot_layout_lookup_collect_glyphs (hb_face_t    *face,
                                      hb_tag_t      table_tag,
                                      unsigned int  lookup_index,
                                      hb_set_t     *glyphs_before, /* OUT. May be nullptr */
                                      hb_set_t     *glyphs_input,  /* OUT. May be nullptr */
                                      hb_set_t     *glyphs_after,  /* OUT. May be nullptr */
                                      hb_set_t     *glyphs_output  /* OUT. May be nullptr */)
  {
    if (unlikely (!hb_ot_shaper_face_data_ensure (face))) return;
  
    OT::hb_collect_glyphs_context_t c (face,
                                       glyphs_before,
                                       glyphs_input,
                                       glyphs_after,
                                       glyphs_output);
  
    switch (table_tag)
    {
      case HB_OT_TAG_GSUB:
      {
        const OT::SubstLookup& l = hb_ot_layout_from_face (face)->gsub->get_lookup (lookup_index);
        l.collect_glyphs (&c);
        return;
      }
      case HB_OT_TAG_GPOS:
      {
        const OT::PosLookup& l = hb_ot_layout_from_face (face)->gpos->get_lookup (lookup_index);
        l.collect_glyphs (&c);
        return;
      }
    }
  }
  
  
  /* Variations support */
  
  hb_bool_t
  hb_ot_layout_table_find_feature_variations (hb_face_t    *face,
                                              hb_tag_t      table_tag,
                                              const int    *coords,
                                              unsigned int  num_coords,
                                              unsigned int *variations_index /* out */)
  {
    const OT::GSUBGPOS &g = get_gsubgpos_table (face, table_tag);
  
    return g.find_variations_index (coords, num_coords, variations_index);
  }
  
  unsigned int
  hb_ot_layout_feature_with_variations_get_lookups (hb_face_t    *face,
                                                    hb_tag_t      table_tag,
                                                    unsigned int  feature_index,
                                                    unsigned int  variations_index,
                                                    unsigned int  start_offset,
                                                    unsigned int *lookup_count /* IN/OUT */,
                                                    unsigned int *lookup_indexes /* OUT */)
  {
    static_assert ((OT::FeatureVariations::NOT_FOUND_INDEX == HB_OT_LAYOUT_NO_VARIATIONS_INDEX), "");
    const OT::GSUBGPOS &g = get_gsubgpos_table (face, table_tag);
  
    const OT::Feature &f = g.get_feature_variation (feature_index, variations_index);
  
    return f.get_lookup_indexes (start_offset, lookup_count, lookup_indexes);
  }
  
  
  /*
   * OT::GSUB
   */
  
  hb_bool_t
  hb_ot_layout_has_substitution (hb_face_t *face)
  {
    return &_get_gsub (face) != &Null(OT::GSUB);
  }
  
  /**
   * hb_ot_layout_lookup_would_substitute:
   *
   * Since: 0.9.7
   **/
  hb_bool_t
  hb_ot_layout_lookup_would_substitute (hb_face_t            *face,
                                        unsigned int          lookup_index,
                                        const hb_codepoint_t *glyphs,
                                        unsigned int          glyphs_length,
                                        hb_bool_t             zero_context)
  {
    if (unlikely (!hb_ot_shaper_face_data_ensure (face))) return false;
    return hb_ot_layout_lookup_would_substitute_fast (face, lookup_index, glyphs, glyphs_length, zero_context);
  }
  
  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)
  {
    if (unlikely (lookup_index >= hb_ot_layout_from_face (face)->gsub_lookup_count)) return false;
    OT::hb_would_apply_context_t c (face, glyphs, glyphs_length, (bool) zero_context);
  
    const OT::SubstLookup& l = hb_ot_layout_from_face (face)->gsub->get_lookup (lookup_index);
  
    return l.would_apply (&c, &hb_ot_layout_from_face (face)->gsub_accels[lookup_index]);
  }
  
  void
  hb_ot_layout_substitute_start (hb_font_t *font, hb_buffer_t *buffer)
  {
    OT::GSUB::substitute_start (font, buffer);
  }
  
  /**
   * hb_ot_layout_lookup_substitute_closure:
   *
   * Since: 0.9.7
   **/
  void
  hb_ot_layout_lookup_substitute_closure (hb_face_t    *face,
                                          unsigned int  lookup_index,
                                          hb_set_t     *glyphs)
  {
    hb_auto_t<hb_map_t> done_lookups;
    OT::hb_closure_context_t c (face, glyphs, &done_lookups);
  
    const OT::SubstLookup& l = _get_gsub (face).get_lookup (lookup_index);
  
    l.closure (&c, lookup_index);
  }
  
  /**
   * hb_ot_layout_lookups_substitute_closure:
   *
   * Compute the transitive closure of glyphs needed for all of the
   * provided lookups.
   *
   * Since: 1.8.1
   **/
  void
  hb_ot_layout_lookups_substitute_closure (hb_face_t      *face,
                                           const hb_set_t *lookups,
                                           hb_set_t       *glyphs)
  {
    hb_auto_t<hb_map_t> done_lookups;
    OT::hb_closure_context_t c (face, glyphs, &done_lookups);
    const OT::GSUB& gsub = _get_gsub (face);
  
    unsigned int glyphs_length;
    do
    {
      glyphs_length = glyphs->get_population ();
      if (lookups != nullptr)
      {
        for (hb_codepoint_t lookup_index = HB_SET_VALUE_INVALID; hb_set_next (lookups, &lookup_index);)
          gsub.get_lookup (lookup_index).closure (&c, lookup_index);
      }
      else
      {
        for (unsigned int i = 0; i < gsub.get_lookup_count (); i++)
          gsub.get_lookup (i).closure (&c, i);
      }
    } while (glyphs_length != glyphs->get_population ());
  }
  
  /*
   * OT::GPOS
   */
  
  hb_bool_t
  hb_ot_layout_has_positioning (hb_face_t *face)
  {
    return &_get_gpos (face) != &Null(OT::GPOS);
  }
  
  void
  hb_ot_layout_position_start (hb_font_t *font, hb_buffer_t *buffer)
  {
    OT::GPOS::position_start (font, buffer);
  }
  
  void
  hb_ot_layout_position_finish_advances (hb_font_t *font, hb_buffer_t *buffer)
  {
    OT::GPOS::position_finish_advances (font, buffer);
  }
  
  void
  hb_ot_layout_position_finish_offsets (hb_font_t *font, hb_buffer_t *buffer)
  {
    OT::GPOS::position_finish_offsets (font, buffer);
  }
  
  /**
   * hb_ot_layout_get_size_params:
   *
   * Since: 0.9.10
   **/
  hb_bool_t
  hb_ot_layout_get_size_params (hb_face_t    *face,
                                unsigned int *design_size,       /* OUT.  May be nullptr */
                                unsigned int *subfamily_id,      /* OUT.  May be nullptr */
                                unsigned int *subfamily_name_id, /* OUT.  May be nullptr */
                                unsigned int *range_start,       /* OUT.  May be nullptr */
                                unsigned int *range_end          /* OUT.  May be nullptr */)
  {
    const OT::GPOS &gpos = _get_gpos (face);
    const hb_tag_t tag = HB_TAG ('s','i','z','e');
  
    unsigned int num_features = gpos.get_feature_count ();
    for (unsigned int i = 0; i < num_features; i++)
    {
      if (tag == gpos.get_feature_tag (i))
      {
        const OT::Feature &f = gpos.get_feature (i);
        const OT::FeatureParamsSize &params = f.get_feature_params ().get_size_params (tag);
  
        if (params.designSize)
        {
  #define PARAM(a, A) if (a) *a = params.A
          PARAM (design_size, designSize);
          PARAM (subfamily_id, subfamilyID);
          PARAM (subfamily_name_id, subfamilyNameID);
          PARAM (range_start, rangeStart);
          PARAM (range_end, rangeEnd);
  #undef PARAM
  
          return true;
        }
      }
    }
  
  #define PARAM(a, A) if (a) *a = 0
    PARAM (design_size, designSize);
    PARAM (subfamily_id, subfamilyID);
    PARAM (subfamily_name_id, subfamilyNameID);
    PARAM (range_start, rangeStart);
    PARAM (range_end, rangeEnd);
  #undef PARAM
  
    return false;
  }
  
  
  /*
   * Parts of different types are implemented here such that they have direct
   * access to GSUB/GPOS lookups.
   */
  
  
  struct GSUBProxy
  {
    static const unsigned int table_index = 0;
    static const bool inplace = false;
    typedef OT::SubstLookup Lookup;
  
    GSUBProxy (hb_face_t *face) :
      table (*hb_ot_layout_from_face (face)->gsub),
      accels (hb_ot_layout_from_face (face)->gsub_accels) {}
  
    const OT::GSUB &table;
    const hb_ot_layout_lookup_accelerator_t *accels;
  };
  
  struct GPOSProxy
  {
    static const unsigned int table_index = 1;
    static const bool inplace = true;
    typedef OT::PosLookup Lookup;
  
    GPOSProxy (hb_face_t *face) :
      table (*hb_ot_layout_from_face (face)->gpos),
      accels (hb_ot_layout_from_face (face)->gpos_accels) {}
  
    const OT::GPOS &table;
    const hb_ot_layout_lookup_accelerator_t *accels;
  };
  
  
  struct hb_get_subtables_context_t :
         OT::hb_dispatch_context_t<hb_get_subtables_context_t, hb_void_t, HB_DEBUG_APPLY>
  {
    template <typename Type>
    static inline bool apply_to (const void *obj, OT::hb_ot_apply_context_t *c)
    {
      const Type *typed_obj = (const Type *) obj;
      return typed_obj->apply (c);
    }
  
    typedef bool (*hb_apply_func_t) (const void *obj, OT::hb_ot_apply_context_t *c);
  
    struct hb_applicable_t
    {
      inline void init (const void *obj_, hb_apply_func_t apply_func_)
      {
        obj = obj_;
        apply_func = apply_func_;
      }
  
      inline bool apply (OT::hb_ot_apply_context_t *c) const { return apply_func (obj, c); }
  
      private:
      const void *obj;
      hb_apply_func_t apply_func;
    };
  
    typedef hb_auto_t<hb_vector_t<hb_applicable_t> > array_t;
  
    /* Dispatch interface. */
    inline const char *get_name (void) { return "GET_SUBTABLES"; }
    template <typename T>
    inline return_t dispatch (const T &obj)
    {
      hb_applicable_t *entry = array.push();
      entry->init (&obj, apply_to<T>);
      return HB_VOID;
    }
    static return_t default_return_value (void) { return HB_VOID; }
    bool stop_sublookup_iteration (return_t r HB_UNUSED) const { return false; }
  
    hb_get_subtables_context_t (array_t &array_) :
                                array (array_),
                                debug_depth (0) {}
  
    array_t &array;
    unsigned int debug_depth;
  };
  
  static inline bool
  apply_forward (OT::hb_ot_apply_context_t *c,
                 const hb_ot_layout_lookup_accelerator_t &accel,
                 const hb_get_subtables_context_t::array_t &subtables)
  {
    bool ret = false;
    hb_buffer_t *buffer = c->buffer;
    while (buffer->idx < buffer->len && buffer->successful)
    {
      bool applied = false;
      if (accel.may_have (buffer->cur().codepoint) &&
          (buffer->cur().mask & c->lookup_mask) &&
          c->check_glyph_property (&buffer->cur(), c->lookup_props))
       {
         for (unsigned int i = 0; i < subtables.len; i++)
           if (subtables[i].apply (c))
           {
             applied = true;
             break;
           }
       }
  
      if (applied)
        ret = true;
      else
        buffer->next_glyph ();
    }
    return ret;
  }
  
  static inline bool
  apply_backward (OT::hb_ot_apply_context_t *c,
                 const hb_ot_layout_lookup_accelerator_t &accel,
                 const hb_get_subtables_context_t::array_t &subtables)
  {
    bool ret = false;
    hb_buffer_t *buffer = c->buffer;
    do
    {
      if (accel.may_have (buffer->cur().codepoint) &&
          (buffer->cur().mask & c->lookup_mask) &&
          c->check_glyph_property (&buffer->cur(), c->lookup_props))
      {
       for (unsigned int i = 0; i < subtables.len; i++)
         if (subtables[i].apply (c))
         {
           ret = true;
           break;
         }
      }
      /* The reverse lookup doesn't "advance" cursor (for good reason). */
      buffer->idx--;
  
    }
    while ((int) buffer->idx >= 0);
    return ret;
  }
  
  template <typename Proxy>
  static inline void
  apply_string (OT::hb_ot_apply_context_t *c,
                const typename Proxy::Lookup &lookup,
                const hb_ot_layout_lookup_accelerator_t &accel)
  {
    hb_buffer_t *buffer = c->buffer;
  
    if (unlikely (!buffer->len || !c->lookup_mask))
      return;
  
    c->set_lookup_props (lookup.get_props ());
  
    hb_get_subtables_context_t::array_t subtables;
    hb_get_subtables_context_t c_get_subtables (subtables);
    lookup.dispatch (&c_get_subtables);
  
    if (likely (!lookup.is_reverse ()))
    {
      /* in/out forward substitution/positioning */
      if (Proxy::table_index == 0)
        buffer->clear_output ();
      buffer->idx = 0;
  
      bool ret;
      ret = apply_forward (c, accel, subtables);
      if (ret)
      {
        if (!Proxy::inplace)
          buffer->swap_buffers ();
        else
          assert (!buffer->has_separate_output ());
      }
    }
    else
    {
      /* in-place backward substitution/positioning */
      if (Proxy::table_index == 0)
        buffer->remove_output ();
      buffer->idx = buffer->len - 1;
  
      apply_backward (c, accel, subtables);
    }
  }
  
  template <typename Proxy>
  inline void hb_ot_map_t::apply (const Proxy &proxy,
                                  const hb_ot_shape_plan_t *plan,
                                  hb_font_t *font,
                                  hb_buffer_t *buffer) const
  {
    const unsigned int table_index = proxy.table_index;
    unsigned int i = 0;
    OT::hb_ot_apply_context_t c (table_index, font, buffer);
    c.set_recurse_func (Proxy::Lookup::apply_recurse_func);
  
    for (unsigned int stage_index = 0; stage_index < stages[table_index].len; stage_index++) {
      const stage_map_t *stage = &stages[table_index][stage_index];
      for (; i < stage->last_lookup; i++)
      {
        unsigned int lookup_index = lookups[table_index][i].index;
        if (!buffer->message (font, "start lookup %d", lookup_index)) continue;
        c.set_lookup_index (lookup_index);
        c.set_lookup_mask (lookups[table_index][i].mask);
        c.set_auto_zwj (lookups[table_index][i].auto_zwj);
        c.set_auto_zwnj (lookups[table_index][i].auto_zwnj);
        apply_string<Proxy> (&c,
                             proxy.table.get_lookup (lookup_index),
                             proxy.accels[lookup_index]);
        (void) buffer->message (font, "end lookup %d", lookup_index);
      }
  
      if (stage->pause_func)
      {
        buffer->clear_output ();
        stage->pause_func (plan, font, buffer);
      }
    }
  }
  
  void hb_ot_map_t::substitute (const hb_ot_shape_plan_t *plan, hb_font_t *font, hb_buffer_t *buffer) const
  {
    GSUBProxy proxy (font->face);
    apply (proxy, plan, font, buffer);
  }
  
  void hb_ot_map_t::position (const hb_ot_shape_plan_t *plan, hb_font_t *font, hb_buffer_t *buffer) const
  {
    GPOSProxy proxy (font->face);
    apply (proxy, plan, font, buffer);
  }
  
  void
  hb_ot_layout_substitute_lookup (OT::hb_ot_apply_context_t *c,
                                  const OT::SubstLookup &lookup,
                                  const hb_ot_layout_lookup_accelerator_t &accel)
  {
    apply_string<GSUBProxy> (c, lookup, accel);
  }
  
  
  
  
  /*
   * OT::BASE
   */
  
  // /**
  //  * hb_ot_base_has_data:
  //  * @face: #hb_face_t to test
  //  *
  //  * This function allows to verify the presence of an OpenType BASE table on the
  //  * face.
  //  *
  //  * Return value: true if face has a BASE table, false otherwise
  //  *
  //  * Since: XXX
  //  **/
  // hb_bool_t
  // hb_ot_base_has_data (hb_face_t *face)
  // {
  //   return &_get_base (face) != &Null(OT::BASE);
  // }
  