text: /*
   * Copyright © 2012,2013  Mozilla Foundation.
   * 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.
   *
   * Mozilla Author(s): Jonathan Kew
   * Google Author(s): Behdad Esfahbod
   */
  
  #define HB_SHAPER coretext
  
  #include "hb-private.hh"
  #include "hb-debug.hh"
  #include "hb-shaper-impl-private.hh"
  
  #include "hb-coretext.h"
  #include <math.h>
  
  /* https://developer.apple.com/documentation/coretext/1508745-ctfontcreatewithgraphicsfont */
  #define HB_CORETEXT_DEFAULT_FONT_SIZE 12.f
  
  static CGFloat
  coretext_font_size (float ptem)
  {
    /* CoreText points are CSS pixels (96 per inch),
     * NOT typographic points (72 per inch).
     *
     * https://developer.apple.com/library/content/documentation/GraphicsAnimation/Conceptual/HighResolutionOSX/Explained/Explained.html
     */
    ptem *= 96.f / 72.f;
    return ptem <= 0.f ? HB_CORETEXT_DEFAULT_FONT_SIZE : ptem;
  }
  
  static void
  release_table_data (void *user_data)
  {
    CFDataRef cf_data = reinterpret_cast<CFDataRef> (user_data);
    CFRelease(cf_data);
  }
  
  static hb_blob_t *
  reference_table  (hb_face_t *face HB_UNUSED, hb_tag_t tag, void *user_data)
  {
    CGFontRef cg_font = reinterpret_cast<CGFontRef> (user_data);
    CFDataRef cf_data = CGFontCopyTableForTag (cg_font, tag);
    if (unlikely (!cf_data))
      return nullptr;
  
    const char *data = reinterpret_cast<const char*> (CFDataGetBytePtr (cf_data));
    const size_t length = CFDataGetLength (cf_data);
    if (!data || !length)
      return nullptr;
  
    return hb_blob_create (data, length, HB_MEMORY_MODE_READONLY,
  			 reinterpret_cast<void *> (const_cast<__CFData *> (cf_data)),
  			 release_table_data);
  }
  
  static void
  _hb_cg_font_release (void *data)
  {
    CGFontRelease ((CGFontRef) data);
  }
  
  
  HB_SHAPER_DATA_ENSURE_DEFINE(coretext, face)
  HB_SHAPER_DATA_ENSURE_DEFINE_WITH_CONDITION(coretext, font,
  	fabs (CTFontGetSize((CTFontRef) data) - coretext_font_size (font->ptem)) <= .5
  )
  
  static CTFontDescriptorRef
  get_last_resort_font_desc (void)
  {
    // TODO Handle allocation failures?
    CTFontDescriptorRef last_resort = CTFontDescriptorCreateWithNameAndSize (CFSTR("LastResort"), 0);
    CFArrayRef cascade_list = CFArrayCreate (kCFAllocatorDefault,
  					   (const void **) &last_resort,
  					   1,
  					   &kCFTypeArrayCallBacks);
    CFRelease (last_resort);
    CFDictionaryRef attributes = CFDictionaryCreate (kCFAllocatorDefault,
  						   (const void **) &kCTFontCascadeListAttribute,
  						   (const void **) &cascade_list,
  						   1,
  						   &kCFTypeDictionaryKeyCallBacks,
  						   &kCFTypeDictionaryValueCallBacks);
    CFRelease (cascade_list);
  
    CTFontDescriptorRef font_desc = CTFontDescriptorCreateWithAttributes (attributes);
    CFRelease (attributes);
    return font_desc;
  }
  
  static void
  release_data (void *info, const void *data, size_t size)
  {
    assert (hb_blob_get_length ((hb_blob_t *) info) == size &&
            hb_blob_get_data ((hb_blob_t *) info, nullptr) == data);
  
    hb_blob_destroy ((hb_blob_t *) info);
  }
  
  static CGFontRef
  create_cg_font (hb_face_t *face)
  {
    CGFontRef cg_font = nullptr;
    if (face->destroy == _hb_cg_font_release)
    {
      cg_font = CGFontRetain ((CGFontRef) face->user_data);
    }
    else
    {
      hb_blob_t *blob = hb_face_reference_blob (face);
      unsigned int blob_length;
      const char *blob_data = hb_blob_get_data (blob, &blob_length);
      if (unlikely (!blob_length))
        DEBUG_MSG (CORETEXT, face, "Face has empty blob");
  
      CGDataProviderRef provider = CGDataProviderCreateWithData (blob, blob_data, blob_length, &release_data);
      if (likely (provider))
      {
        cg_font = CGFontCreateWithDataProvider (provider);
        if (unlikely (!cg_font))
  	DEBUG_MSG (CORETEXT, face, "Face CGFontCreateWithDataProvider() failed");
        CGDataProviderRelease (provider);
      }
    }
    return cg_font;
  }
  
  static CTFontRef
  create_ct_font (CGFontRef cg_font, CGFloat font_size)
  {
    CTFontRef ct_font = nullptr;
  
    /* CoreText does not enable trak table usage / tracking when creating a CTFont
     * using CTFontCreateWithGraphicsFont. The only way of enabling tracking seems
     * to be through the CTFontCreateUIFontForLanguage call. */
    CFStringRef cg_postscript_name = CGFontCopyPostScriptName (cg_font);
    if (CFStringHasPrefix (cg_postscript_name, CFSTR (".SFNSText")) ||
        CFStringHasPrefix (cg_postscript_name, CFSTR (".SFNSDisplay")))
    {
      CTFontUIFontType font_type = kCTFontUIFontSystem;
      if (CFStringHasSuffix (cg_postscript_name, CFSTR ("-Bold")))
        font_type = kCTFontUIFontEmphasizedSystem;
  
      ct_font = CTFontCreateUIFontForLanguage (font_type, font_size, nullptr);
      CFStringRef ct_result_name = CTFontCopyPostScriptName(ct_font);
      if (CFStringCompare (ct_result_name, cg_postscript_name, 0) != kCFCompareEqualTo)
      {
        CFRelease(ct_font);
        ct_font = nullptr;
      }
      CFRelease (ct_result_name);
    }
    CFRelease (cg_postscript_name);
  
    if (!ct_font)
      ct_font = CTFontCreateWithGraphicsFont (cg_font, font_size, nullptr, nullptr);
  
    if (unlikely (!ct_font)) {
      DEBUG_MSG (CORETEXT, cg_font, "Font CTFontCreateWithGraphicsFont() failed");
      return nullptr;
    }
  
    /* crbug.com/576941 and crbug.com/625902 and the investigation in the latter
     * bug indicate that the cascade list reconfiguration occasionally causes
     * crashes in CoreText on OS X 10.9, thus let's skip this step on older
     * operating system versions. Except for the emoji font, where _not_
     * reconfiguring the cascade list causes CoreText crashes. For details, see
     * crbug.com/549610 */
    // 0x00070000 stands for "kCTVersionNumber10_10", see CoreText.h
    if (&CTGetCoreTextVersion != nullptr && CTGetCoreTextVersion() < 0x00070000) {
      CFStringRef fontName = CTFontCopyPostScriptName (ct_font);
      bool isEmojiFont = CFStringCompare (fontName, CFSTR("AppleColorEmoji"), 0) == kCFCompareEqualTo;
      CFRelease (fontName);
      if (!isEmojiFont)
        return ct_font;
    }
  
    CFURLRef original_url = (CFURLRef)CTFontCopyAttribute(ct_font, kCTFontURLAttribute);
  
    /* Create font copy with cascade list that has LastResort first; this speeds up CoreText
     * font fallback which we don't need anyway. */
    {
      CTFontDescriptorRef last_resort_font_desc = get_last_resort_font_desc ();
      CTFontRef new_ct_font = CTFontCreateCopyWithAttributes (ct_font, 0.0, nullptr, last_resort_font_desc);
      CFRelease (last_resort_font_desc);
      if (new_ct_font)
      {
        /* The CTFontCreateCopyWithAttributes call fails to stay on the same font
         * when reconfiguring the cascade list and may switch to a different font
         * when there are fonts that go by the same name, since the descriptor is
         * just name and size.
         *
         * Avoid reconfiguring the cascade lists if the new font is outside the
         * system locations that we cannot access from the sandboxed renderer
         * process in Blink. This can be detected by the new file URL location
         * that the newly found font points to. */
        CFURLRef new_url = (CFURLRef) CTFontCopyAttribute (new_ct_font, kCTFontURLAttribute);
        // Keep reconfigured font if URL cannot be retrieved (seems to be the case
        // on Mac OS 10.12 Sierra), speculative fix for crbug.com/625606
        if (!original_url || !new_url || CFEqual (original_url, new_url)) {
          CFRelease (ct_font);
          ct_font = new_ct_font;
        } else {
          CFRelease (new_ct_font);
          DEBUG_MSG (CORETEXT, ct_font, "Discarding reconfigured CTFont, location changed.");
        }
        if (new_url)
          CFRelease (new_url);
      }
      else
        DEBUG_MSG (CORETEXT, ct_font, "Font copy with empty cascade list failed");
    }
  
    if (original_url)
      CFRelease (original_url);
    return ct_font;
  }
  
  hb_coretext_shaper_face_data_t *
  _hb_coretext_shaper_face_data_create (hb_face_t *face)
  {
    CGFontRef cg_font = create_cg_font (face);
  
    if (unlikely (!cg_font))
    {
      DEBUG_MSG (CORETEXT, face, "CGFont creation failed..");
      return nullptr;
    }
  
    return (hb_coretext_shaper_face_data_t *) cg_font;
  }
  
  void
  _hb_coretext_shaper_face_data_destroy (hb_coretext_shaper_face_data_t *data)
  {
    CFRelease ((CGFontRef) data);
  }
  
  hb_face_t *
  hb_coretext_face_create (CGFontRef cg_font)
  {
    return hb_face_create_for_tables (reference_table, CGFontRetain (cg_font), _hb_cg_font_release);
  }
  
  /*
   * Since: 0.9.10
   */
  CGFontRef
  hb_coretext_face_get_cg_font (hb_face_t *face)
  {
    if (unlikely (!hb_coretext_shaper_face_data_ensure (face))) return nullptr;
    return (CGFontRef) HB_SHAPER_DATA_GET (face);
  }
  
  
  hb_coretext_shaper_font_data_t *
  _hb_coretext_shaper_font_data_create (hb_font_t *font)
  {
    hb_face_t *face = font->face;
    if (unlikely (!hb_coretext_shaper_face_data_ensure (face))) return nullptr;
    CGFontRef cg_font = (CGFontRef) HB_SHAPER_DATA_GET (face);
  
    CTFontRef ct_font = create_ct_font (cg_font, coretext_font_size (font->ptem));
  
    if (unlikely (!ct_font))
    {
      DEBUG_MSG (CORETEXT, font, "CGFont creation failed..");
      return nullptr;
    }
  
    return (hb_coretext_shaper_font_data_t *) ct_font;
  }
  
  void
  _hb_coretext_shaper_font_data_destroy (hb_coretext_shaper_font_data_t *data)
  {
    CFRelease ((CTFontRef) data);
  }
  
  /*
   * Since: 1.7.2
   */
  hb_font_t *
  hb_coretext_font_create (CTFontRef ct_font)
  {
    CGFontRef cg_font = CTFontCopyGraphicsFont (ct_font, 0);
    hb_face_t *face = hb_coretext_face_create (cg_font);
    CFRelease (cg_font);
    hb_font_t *font = hb_font_create (face);
    hb_face_destroy (face);
  
    if (unlikely (hb_object_is_inert (font)))
      return font;
  
    /* Let there be dragons here... */
    HB_SHAPER_DATA_GET (font) = (hb_coretext_shaper_font_data_t *) CFRetain (ct_font);
  
    return font;
  }
  
  CTFontRef
  hb_coretext_font_get_ct_font (hb_font_t *font)
  {
    if (unlikely (!hb_coretext_shaper_font_data_ensure (font))) return nullptr;
    return (CTFontRef) HB_SHAPER_DATA_GET (font);
  }
  
  
  
  /*
   * shaper shape_plan data
   */
  
  struct hb_coretext_shaper_shape_plan_data_t {};
  
  hb_coretext_shaper_shape_plan_data_t *
  _hb_coretext_shaper_shape_plan_data_create (hb_shape_plan_t    *shape_plan HB_UNUSED,
  					     const hb_feature_t *user_features HB_UNUSED,
  					     unsigned int        num_user_features HB_UNUSED,
  					     const int          *coords HB_UNUSED,
  					     unsigned int        num_coords HB_UNUSED)
  {
    return (hb_coretext_shaper_shape_plan_data_t *) HB_SHAPER_DATA_SUCCEEDED;
  }
  
  void
  _hb_coretext_shaper_shape_plan_data_destroy (hb_coretext_shaper_shape_plan_data_t *data HB_UNUSED)
  {
  }
  
  
  /*
   * shaper
   */
  
  struct feature_record_t {
    unsigned int feature;
    unsigned int setting;
  };
  
  struct active_feature_t {
    feature_record_t rec;
    unsigned int order;
  
    static int cmp (const void *pa, const void *pb) {
      const active_feature_t *a = (const active_feature_t *) pa;
      const active_feature_t *b = (const active_feature_t *) pb;
      return a->rec.feature < b->rec.feature ? -1 : a->rec.feature > b->rec.feature ? 1 :
  	   a->order < b->order ? -1 : a->order > b->order ? 1 :
  	   a->rec.setting < b->rec.setting ? -1 : a->rec.setting > b->rec.setting ? 1 :
  	   0;
    }
    bool operator== (const active_feature_t *f) {
      return cmp (this, f) == 0;
    }
  };
  
  struct feature_event_t {
    unsigned int index;
    bool start;
    active_feature_t feature;
  
    static int cmp (const void *pa, const void *pb) {
      const feature_event_t *a = (const feature_event_t *) pa;
      const feature_event_t *b = (const feature_event_t *) pb;
      return a->index < b->index ? -1 : a->index > b->index ? 1 :
  	   a->start < b->start ? -1 : a->start > b->start ? 1 :
  	   active_feature_t::cmp (&a->feature, &b->feature);
    }
  };
  
  struct range_record_t {
    CTFontRef font;
    unsigned int index_first; /* == start */
    unsigned int index_last;  /* == end - 1 */
  };
  
  
  /* The following enum members are added in OS X 10.8. */
  #define kAltHalfWidthTextSelector		6
  #define kAltProportionalTextSelector		5
  #define kAlternateHorizKanaOffSelector		1
  #define kAlternateHorizKanaOnSelector		0
  #define kAlternateKanaType			34
  #define kAlternateVertKanaOffSelector		3
  #define kAlternateVertKanaOnSelector		2
  #define kCaseSensitiveLayoutOffSelector		1
  #define kCaseSensitiveLayoutOnSelector		0
  #define kCaseSensitiveLayoutType		33
  #define kCaseSensitiveSpacingOffSelector	3
  #define kCaseSensitiveSpacingOnSelector		2
  #define kContextualAlternatesOffSelector	1
  #define kContextualAlternatesOnSelector		0
  #define kContextualAlternatesType		36
  #define kContextualLigaturesOffSelector		19
  #define kContextualLigaturesOnSelector		18
  #define kContextualSwashAlternatesOffSelector	5
  #define kContextualSwashAlternatesOnSelector	4
  #define kDefaultLowerCaseSelector		0
  #define kDefaultUpperCaseSelector		0
  #define kHistoricalLigaturesOffSelector		21
  #define kHistoricalLigaturesOnSelector		20
  #define kHojoCharactersSelector			12
  #define kJIS2004CharactersSelector		11
  #define kLowerCasePetiteCapsSelector		2
  #define kLowerCaseSmallCapsSelector		1
  #define kLowerCaseType				37
  #define kMathematicalGreekOffSelector		11
  #define kMathematicalGreekOnSelector		10
  #define kNLCCharactersSelector			13
  #define kQuarterWidthTextSelector		4
  #define kScientificInferiorsSelector		4
  #define kStylisticAltEightOffSelector		17
  #define kStylisticAltEightOnSelector		16
  #define kStylisticAltEighteenOffSelector	37
  #define kStylisticAltEighteenOnSelector		36
  #define kStylisticAltElevenOffSelector		23
  #define kStylisticAltElevenOnSelector		22
  #define kStylisticAltFifteenOffSelector		31
  #define kStylisticAltFifteenOnSelector		30
  #define kStylisticAltFiveOffSelector		11
  #define kStylisticAltFiveOnSelector		10
  #define kStylisticAltFourOffSelector		9
  #define kStylisticAltFourOnSelector		8
  #define kStylisticAltFourteenOffSelector	29
  #define kStylisticAltFourteenOnSelector		28
  #define kStylisticAltNineOffSelector		19
  #define kStylisticAltNineOnSelector		18
  #define kStylisticAltNineteenOffSelector	39
  #define kStylisticAltNineteenOnSelector		38
  #define kStylisticAltOneOffSelector		3
  #define kStylisticAltOneOnSelector		2
  #define kStylisticAltSevenOffSelector		15
  #define kStylisticAltSevenOnSelector		14
  #define kStylisticAltSeventeenOffSelector	35
  #define kStylisticAltSeventeenOnSelector	34
  #define kStylisticAltSixOffSelector		13
  #define kStylisticAltSixOnSelector		12
  #define kStylisticAltSixteenOffSelector		33
  #define kStylisticAltSixteenOnSelector		32
  #define kStylisticAltTenOffSelector		21
  #define kStylisticAltTenOnSelector		20
  #define kStylisticAltThirteenOffSelector	27
  #define kStylisticAltThirteenOnSelector		26
  #define kStylisticAltThreeOffSelector		7
  #define kStylisticAltThreeOnSelector		6
  #define kStylisticAltTwelveOffSelector		25
  #define kStylisticAltTwelveOnSelector		24
  #define kStylisticAltTwentyOffSelector		41
  #define kStylisticAltTwentyOnSelector		40
  #define kStylisticAltTwoOffSelector		5
  #define kStylisticAltTwoOnSelector		4
  #define kStylisticAlternativesType		35
  #define kSwashAlternatesOffSelector		3
  #define kSwashAlternatesOnSelector		2
  #define kThirdWidthTextSelector			3
  #define kTraditionalNamesCharactersSelector	14
  #define kUpperCasePetiteCapsSelector		2
  #define kUpperCaseSmallCapsSelector		1
  #define kUpperCaseType				38
  
  /* Table data courtesy of Apple. */
  static const struct feature_mapping_t {
      FourCharCode otFeatureTag;
      uint16_t aatFeatureType;
      uint16_t selectorToEnable;
      uint16_t selectorToDisable;
  } feature_mappings[] = {
      { 'c2pc',   kUpperCaseType,             kUpperCasePetiteCapsSelector,           kDefaultUpperCaseSelector },
      { 'c2sc',   kUpperCaseType,             kUpperCaseSmallCapsSelector,            kDefaultUpperCaseSelector },
      { 'calt',   kContextualAlternatesType,  kContextualAlternatesOnSelector,        kContextualAlternatesOffSelector },
      { 'case',   kCaseSensitiveLayoutType,   kCaseSensitiveLayoutOnSelector,         kCaseSensitiveLayoutOffSelector },
      { 'clig',   kLigaturesType,             kContextualLigaturesOnSelector,         kContextualLigaturesOffSelector },
      { 'cpsp',   kCaseSensitiveLayoutType,   kCaseSensitiveSpacingOnSelector,        kCaseSensitiveSpacingOffSelector },
      { 'cswh',   kContextualAlternatesType,  kContextualSwashAlternatesOnSelector,   kContextualSwashAlternatesOffSelector },
      { 'dlig',   kLigaturesType,             kRareLigaturesOnSelector,               kRareLigaturesOffSelector },
      { 'expt',   kCharacterShapeType,        kExpertCharactersSelector,              16 },
      { 'frac',   kFractionsType,             kDiagonalFractionsSelector,             kNoFractionsSelector },
      { 'fwid',   kTextSpacingType,           kMonospacedTextSelector,                7 },
      { 'halt',   kTextSpacingType,           kAltHalfWidthTextSelector,              7 },
      { 'hist',   kLigaturesType,             kHistoricalLigaturesOnSelector,         kHistoricalLigaturesOffSelector },
      { 'hkna',   kAlternateKanaType,         kAlternateHorizKanaOnSelector,          kAlternateHorizKanaOffSelector, },
      { 'hlig',   kLigaturesType,             kHistoricalLigaturesOnSelector,         kHistoricalLigaturesOffSelector },
      { 'hngl',   kTransliterationType,       kHanjaToHangulSelector,                 kNoTransliterationSelector },
      { 'hojo',   kCharacterShapeType,        kHojoCharactersSelector,                16 },
      { 'hwid',   kTextSpacingType,           kHalfWidthTextSelector,                 7 },
      { 'ital',   kItalicCJKRomanType,        kCJKItalicRomanOnSelector,              kCJKItalicRomanOffSelector },
      { 'jp04',   kCharacterShapeType,        kJIS2004CharactersSelector,             16 },
      { 'jp78',   kCharacterShapeType,        kJIS1978CharactersSelector,             16 },
      { 'jp83',   kCharacterShapeType,        kJIS1983CharactersSelector,             16 },
      { 'jp90',   kCharacterShapeType,        kJIS1990CharactersSelector,             16 },
      { 'liga',   kLigaturesType,             kCommonLigaturesOnSelector,             kCommonLigaturesOffSelector },
      { 'lnum',   kNumberCaseType,            kUpperCaseNumbersSelector,              2 },
      { 'mgrk',   kMathematicalExtrasType,    kMathematicalGreekOnSelector,           kMathematicalGreekOffSelector },
      { 'nlck',   kCharacterShapeType,        kNLCCharactersSelector,                 16 },
      { 'onum',   kNumberCaseType,            kLowerCaseNumbersSelector,              2 },
      { 'ordn',   kVerticalPositionType,      kOrdinalsSelector,                      kNormalPositionSelector },
      { 'palt',   kTextSpacingType,           kAltProportionalTextSelector,           7 },
      { 'pcap',   kLowerCaseType,             kLowerCasePetiteCapsSelector,           kDefaultLowerCaseSelector },
      { 'pkna',   kTextSpacingType,           kProportionalTextSelector,              7 },
      { 'pnum',   kNumberSpacingType,         kProportionalNumbersSelector,           4 },
      { 'pwid',   kTextSpacingType,           kProportionalTextSelector,              7 },
      { 'qwid',   kTextSpacingType,           kQuarterWidthTextSelector,              7 },
      { 'ruby',   kRubyKanaType,              kRubyKanaOnSelector,                    kRubyKanaOffSelector },
      { 'sinf',   kVerticalPositionType,      kScientificInferiorsSelector,           kNormalPositionSelector },
      { 'smcp',   kLowerCaseType,             kLowerCaseSmallCapsSelector,            kDefaultLowerCaseSelector },
      { 'smpl',   kCharacterShapeType,        kSimplifiedCharactersSelector,          16 },
      { 'ss01',   kStylisticAlternativesType, kStylisticAltOneOnSelector,             kStylisticAltOneOffSelector },
      { 'ss02',   kStylisticAlternativesType, kStylisticAltTwoOnSelector,             kStylisticAltTwoOffSelector },
      { 'ss03',   kStylisticAlternativesType, kStylisticAltThreeOnSelector,           kStylisticAltThreeOffSelector },
      { 'ss04',   kStylisticAlternativesType, kStylisticAltFourOnSelector,            kStylisticAltFourOffSelector },
      { 'ss05',   kStylisticAlternativesType, kStylisticAltFiveOnSelector,            kStylisticAltFiveOffSelector },
      { 'ss06',   kStylisticAlternativesType, kStylisticAltSixOnSelector,             kStylisticAltSixOffSelector },
      { 'ss07',   kStylisticAlternativesType, kStylisticAltSevenOnSelector,           kStylisticAltSevenOffSelector },
      { 'ss08',   kStylisticAlternativesType, kStylisticAltEightOnSelector,           kStylisticAltEightOffSelector },
      { 'ss09',   kStylisticAlternativesType, kStylisticAltNineOnSelector,            kStylisticAltNineOffSelector },
      { 'ss10',   kStylisticAlternativesType, kStylisticAltTenOnSelector,             kStylisticAltTenOffSelector },
      { 'ss11',   kStylisticAlternativesType, kStylisticAltElevenOnSelector,          kStylisticAltElevenOffSelector },
      { 'ss12',   kStylisticAlternativesType, kStylisticAltTwelveOnSelector,          kStylisticAltTwelveOffSelector },
      { 'ss13',   kStylisticAlternativesType, kStylisticAltThirteenOnSelector,        kStylisticAltThirteenOffSelector },
      { 'ss14',   kStylisticAlternativesType, kStylisticAltFourteenOnSelector,        kStylisticAltFourteenOffSelector },
      { 'ss15',   kStylisticAlternativesType, kStylisticAltFifteenOnSelector,         kStylisticAltFifteenOffSelector },
      { 'ss16',   kStylisticAlternativesType, kStylisticAltSixteenOnSelector,         kStylisticAltSixteenOffSelector },
      { 'ss17',   kStylisticAlternativesType, kStylisticAltSeventeenOnSelector,       kStylisticAltSeventeenOffSelector },
      { 'ss18',   kStylisticAlternativesType, kStylisticAltEighteenOnSelector,        kStylisticAltEighteenOffSelector },
      { 'ss19',   kStylisticAlternativesType, kStylisticAltNineteenOnSelector,        kStylisticAltNineteenOffSelector },
      { 'ss20',   kStylisticAlternativesType, kStylisticAltTwentyOnSelector,          kStylisticAltTwentyOffSelector },
      { 'subs',   kVerticalPositionType,      kInferiorsSelector,                     kNormalPositionSelector },
      { 'sups',   kVerticalPositionType,      kSuperiorsSelector,                     kNormalPositionSelector },
      { 'swsh',   kContextualAlternatesType,  kSwashAlternatesOnSelector,             kSwashAlternatesOffSelector },
      { 'titl',   kStyleOptionsType,          kTitlingCapsSelector,                   kNoStyleOptionsSelector },
      { 'tnam',   kCharacterShapeType,        kTraditionalNamesCharactersSelector,    16 },
      { 'tnum',   kNumberSpacingType,         kMonospacedNumbersSelector,             4 },
      { 'trad',   kCharacterShapeType,        kTraditionalCharactersSelector,         16 },
      { 'twid',   kTextSpacingType,           kThirdWidthTextSelector,                7 },
      { 'unic',   kLetterCaseType,            14,                                     15 },
      { 'valt',   kTextSpacingType,           kAltProportionalTextSelector,           7 },
      { 'vert',   kVerticalSubstitutionType,  kSubstituteVerticalFormsOnSelector,     kSubstituteVerticalFormsOffSelector },
      { 'vhal',   kTextSpacingType,           kAltHalfWidthTextSelector,              7 },
      { 'vkna',   kAlternateKanaType,         kAlternateVertKanaOnSelector,           kAlternateVertKanaOffSelector },
      { 'vpal',   kTextSpacingType,           kAltProportionalTextSelector,           7 },
      { 'vrt2',   kVerticalSubstitutionType,  kSubstituteVerticalFormsOnSelector,     kSubstituteVerticalFormsOffSelector },
      { 'zero',   kTypographicExtrasType,     kSlashedZeroOnSelector,                 kSlashedZeroOffSelector },
  };
  
  static int
  _hb_feature_mapping_cmp (const void *key_, const void *entry_)
  {
    unsigned int key = * (unsigned int *) key_;
    const feature_mapping_t * entry = (const feature_mapping_t *) entry_;
    return key < entry->otFeatureTag ? -1 :
  	 key > entry->otFeatureTag ? 1 :
  	 0;
  }
  
  hb_bool_t
  _hb_coretext_shape (hb_shape_plan_t    *shape_plan,
  		    hb_font_t          *font,
                      hb_buffer_t        *buffer,
                      const hb_feature_t *features,
                      unsigned int        num_features)
  {
    hb_face_t *face = font->face;
    CGFontRef cg_font = (CGFontRef) HB_SHAPER_DATA_GET (face);
    CTFontRef ct_font = (CTFontRef) HB_SHAPER_DATA_GET (font);
  
    CGFloat ct_font_size = CTFontGetSize (ct_font);
    CGFloat x_mult = (CGFloat) font->x_scale / ct_font_size;
    CGFloat y_mult = (CGFloat) font->y_scale / ct_font_size;
  
    /* Attach marks to their bases, to match the 'ot' shaper.
     * Adapted from hb-ot-shape:hb_form_clusters().
     * Note that this only makes us be closer to the 'ot' shaper,
     * but by no means the same.  For example, if there's
     * B1 M1 B2 M2, and B1-B2 form a ligature, M2's cluster will
     * continue pointing to B2 even though B2 was merged into B1's
     * cluster... */
    if (buffer->cluster_level == HB_BUFFER_CLUSTER_LEVEL_MONOTONE_GRAPHEMES)
    {
      hb_unicode_funcs_t *unicode = buffer->unicode;
      unsigned int count = buffer->len;
      hb_glyph_info_t *info = buffer->info;
      for (unsigned int i = 1; i < count; i++)
        if (HB_UNICODE_GENERAL_CATEGORY_IS_MARK (unicode->general_category (info[i].codepoint)))
  	buffer->merge_clusters (i - 1, i + 1);
    }
  
    hb_auto_array_t<feature_record_t> feature_records;
    hb_auto_array_t<range_record_t> range_records;
  
    /*
     * Set up features.
     * (copied + modified from code from hb-uniscribe.cc)
     */
    if (num_features)
    {
      /* Sort features by start/end events. */
      hb_auto_array_t<feature_event_t> feature_events;
      for (unsigned int i = 0; i < num_features; i++)
      {
        const feature_mapping_t * mapping = (const feature_mapping_t *) bsearch (&features[i].tag,
  									       feature_mappings,
  									       ARRAY_LENGTH (feature_mappings),
  									       sizeof (feature_mappings[0]),
  									       _hb_feature_mapping_cmp);
        if (!mapping)
          continue;
  
        active_feature_t feature;
        feature.rec.feature = mapping->aatFeatureType;
        feature.rec.setting = features[i].value ? mapping->selectorToEnable : mapping->selectorToDisable;
        feature.order = i;
  
        feature_event_t *event;
  
        event = feature_events.push ();
        if (unlikely (!event))
  	goto fail_features;
        event->index = features[i].start;
        event->start = true;
        event->feature = feature;
  
        event = feature_events.push ();
        if (unlikely (!event))
  	goto fail_features;
        event->index = features[i].end;
        event->start = false;
        event->feature = feature;
      }
      feature_events.qsort ();
      /* Add a strategic final event. */
      {
        active_feature_t feature;
        feature.rec.feature = HB_TAG_NONE;
        feature.rec.setting = 0;
        feature.order = num_features + 1;
  
        feature_event_t *event = feature_events.push ();
        if (unlikely (!event))
  	goto fail_features;
        event->index = 0; /* This value does magic. */
        event->start = false;
        event->feature = feature;
      }
  
      /* Scan events and save features for each range. */
      hb_auto_array_t<active_feature_t> active_features;
      unsigned int last_index = 0;
      for (unsigned int i = 0; i < feature_events.len; i++)
      {
        feature_event_t *event = &feature_events[i];
  
        if (event->index != last_index)
        {
          /* Save a snapshot of active features and the range. */
  	range_record_t *range = range_records.push ();
  	if (unlikely (!range))
  	  goto fail_features;
  
  	if (active_features.len)
  	{
  	  CFMutableArrayRef features_array = CFArrayCreateMutable(kCFAllocatorDefault, 0, &kCFTypeArrayCallBacks);
  
  	  /* TODO sort and resolve conflicting features? */
  	  /* active_features.qsort (); */
  	  for (unsigned int j = 0; j < active_features.len; j++)
  	  {
  	    CFStringRef keys[] = {
  	      kCTFontFeatureTypeIdentifierKey,
  	      kCTFontFeatureSelectorIdentifierKey
  	    };
  	    CFNumberRef values[] = {
  	      CFNumberCreate (kCFAllocatorDefault, kCFNumberIntType, &active_features[j].rec.feature),
  	      CFNumberCreate (kCFAllocatorDefault, kCFNumberIntType, &active_features[j].rec.setting)
  	    };
  	    static_assert ((ARRAY_LENGTH_CONST (keys) == ARRAY_LENGTH_CONST (values)), "");
  	    CFDictionaryRef dict = CFDictionaryCreate (kCFAllocatorDefault,
  						       (const void **) keys,
  						       (const void **) values,
  						       ARRAY_LENGTH (keys),
  						       &kCFTypeDictionaryKeyCallBacks,
  						       &kCFTypeDictionaryValueCallBacks);
  	    for (unsigned int i = 0; i < ARRAY_LENGTH (values); i++)
  	      CFRelease (values[i]);
  
  	    CFArrayAppendValue (features_array, dict);
  	    CFRelease (dict);
  
  	  }
  
  	  CFDictionaryRef attributes = CFDictionaryCreate (kCFAllocatorDefault,
  							   (const void **) &kCTFontFeatureSettingsAttribute,
  							   (const void **) &features_array,
  							   1,
  							   &kCFTypeDictionaryKeyCallBacks,
  							   &kCFTypeDictionaryValueCallBacks);
  	  CFRelease (features_array);
  
  	  CTFontDescriptorRef font_desc = CTFontDescriptorCreateWithAttributes (attributes);
  	  CFRelease (attributes);
  
  	  range->font = CTFontCreateCopyWithAttributes (ct_font, 0.0, nullptr, font_desc);
  	  CFRelease (font_desc);
  	}
  	else
  	{
  	  range->font = nullptr;
  	}
  
  	range->index_first = last_index;
  	range->index_last  = event->index - 1;
  
  	last_index = event->index;
        }
  
        if (event->start) {
          active_feature_t *feature = active_features.push ();
  	if (unlikely (!feature))
  	  goto fail_features;
  	*feature = event->feature;
        } else {
          active_feature_t *feature = active_features.find (&event->feature);
  	if (feature)
  	  active_features.remove (feature - active_features.array);
        }
      }
    }
    else
    {
    fail_features:
      num_features = 0;
    }
  
    unsigned int scratch_size;
    hb_buffer_t::scratch_buffer_t *scratch = buffer->get_scratch_buffer (&scratch_size);
  
  #define ALLOCATE_ARRAY(Type, name, len, on_no_room) \
    Type *name = (Type *) scratch; \
    { \
      unsigned int _consumed = DIV_CEIL ((len) * sizeof (Type), sizeof (*scratch)); \
      if (unlikely (_consumed > scratch_size)) \
      { \
        on_no_room; \
        assert (0); \
      } \
      scratch += _consumed; \
      scratch_size -= _consumed; \
    }
  
    ALLOCATE_ARRAY (UniChar, pchars, buffer->len * 2, /*nothing*/);
    unsigned int chars_len = 0;
    for (unsigned int i = 0; i < buffer->len; i++) {
      hb_codepoint_t c = buffer->info[i].codepoint;
      if (likely (c <= 0xFFFFu))
        pchars[chars_len++] = c;
      else if (unlikely (c > 0x10FFFFu))
        pchars[chars_len++] = 0xFFFDu;
      else {
        pchars[chars_len++] = 0xD800u + ((c - 0x10000u) >> 10);
        pchars[chars_len++] = 0xDC00u + ((c - 0x10000u) & ((1u << 10) - 1));
      }
    }
  
    ALLOCATE_ARRAY (unsigned int, log_clusters, chars_len, /*nothing*/);
    chars_len = 0;
    for (unsigned int i = 0; i < buffer->len; i++)
    {
      hb_codepoint_t c = buffer->info[i].codepoint;
      unsigned int cluster = buffer->info[i].cluster;
      log_clusters[chars_len++] = cluster;
      if (hb_in_range (c, 0x10000u, 0x10FFFFu))
        log_clusters[chars_len++] = cluster; /* Surrogates. */
    }
  
  #define FAIL(...) \
    HB_STMT_START { \
      DEBUG_MSG (CORETEXT, nullptr, __VA_ARGS__); \
      ret = false; \
      goto fail; \
    } HB_STMT_END;
  
    bool ret = true;
    CFStringRef string_ref = nullptr;
    CTLineRef line = nullptr;
  
    if (0)
    {
  resize_and_retry:
      DEBUG_MSG (CORETEXT, buffer, "Buffer resize");
      /* string_ref uses the scratch-buffer for backing store, and line references
       * string_ref (via attr_string).  We must release those before resizing buffer. */
      assert (string_ref);
      assert (line);
      CFRelease (string_ref);
      CFRelease (line);
      string_ref = nullptr;
      line = nullptr;
  
      /* Get previous start-of-scratch-area, that we use later for readjusting
       * our existing scratch arrays. */
      unsigned int old_scratch_used;
      hb_buffer_t::scratch_buffer_t *old_scratch;
      old_scratch = buffer->get_scratch_buffer (&old_scratch_used);
      old_scratch_used = scratch - old_scratch;
  
      if (unlikely (!buffer->ensure (buffer->allocated * 2)))
        FAIL ("Buffer resize failed");
  
      /* Adjust scratch, pchars, and log_cluster arrays.  This is ugly, but really the
       * cleanest way to do without completely restructuring the rest of this shaper. */
      scratch = buffer->get_scratch_buffer (&scratch_size);
      pchars = reinterpret_cast<UniChar *> (((char *) scratch + ((char *) pchars - (char *) old_scratch)));
      log_clusters = reinterpret_cast<unsigned int *> (((char *) scratch + ((char *) log_clusters - (char *) old_scratch)));
      scratch += old_scratch_used;
      scratch_size -= old_scratch_used;
    }
    {
      string_ref = CFStringCreateWithCharactersNoCopy (nullptr,
  						     pchars, chars_len,
  						     kCFAllocatorNull);
      if (unlikely (!string_ref))
        FAIL ("CFStringCreateWithCharactersNoCopy failed");
  
      /* Create an attributed string, populate it, and create a line from it, then release attributed string. */
      {
        CFMutableAttributedStringRef attr_string = CFAttributedStringCreateMutable (kCFAllocatorDefault,
  										  chars_len);
        if (unlikely (!attr_string))
  	FAIL ("CFAttributedStringCreateMutable failed");
        CFAttributedStringReplaceString (attr_string, CFRangeMake (0, 0), string_ref);
        if (HB_DIRECTION_IS_VERTICAL (buffer->props.direction))
        {
  	CFAttributedStringSetAttribute (attr_string, CFRangeMake (0, chars_len),
  					kCTVerticalFormsAttributeName, kCFBooleanTrue);
        }
  
        if (buffer->props.language)
        {
  /* What's the iOS equivalent of this check?
   * The symbols was introduced in iOS 7.0.
   * At any rate, our fallback is safe and works fine. */
  #if MAC_OS_X_VERSION_MIN_REQUIRED < 1090
  #  define kCTLanguageAttributeName CFSTR ("NSLanguage")
  #endif
          CFStringRef lang = CFStringCreateWithCStringNoCopy (kCFAllocatorDefault,
  							    hb_language_to_string (buffer->props.language),
  							    kCFStringEncodingUTF8,
  							    kCFAllocatorNull);
  	if (unlikely (!lang))
  	  FAIL ("CFStringCreateWithCStringNoCopy failed");
  	CFAttributedStringSetAttribute (attr_string, CFRangeMake (0, chars_len),
  					kCTLanguageAttributeName, lang);
  	CFRelease (lang);
        }
        CFAttributedStringSetAttribute (attr_string, CFRangeMake (0, chars_len),
  				      kCTFontAttributeName, ct_font);
  
        if (num_features && range_records.len)
        {
  	unsigned int start = 0;
  	range_record_t *last_range = &range_records[0];
  	for (unsigned int k = 0; k < chars_len; k++)
  	{
  	  range_record_t *range = last_range;
  	  while (log_clusters[k] < range->index_first)
  	    range--;
  	  while (log_clusters[k] > range->index_last)
  	    range++;
  	  if (range != last_range)
  	  {
  	    if (last_range->font)
  	      CFAttributedStringSetAttribute (attr_string, CFRangeMake (start, k - start),
  					      kCTFontAttributeName, last_range->font);
  
  	    start = k;
  	  }
  
  	  last_range = range;
  	}
  	if (start != chars_len && last_range->font)
  	  CFAttributedStringSetAttribute (attr_string, CFRangeMake (start, chars_len - start),
  					  kCTFontAttributeName, last_range->font);
        }
        /* Enable/disable kern if requested.
         *
         * Note: once kern is disabled, reenabling it doesn't currently seem to work in CoreText.
         */
        if (num_features)
        {
  	unsigned int zeroint = 0;
  	CFNumberRef zero = CFNumberCreate (kCFAllocatorDefault, kCFNumberIntType, &zeroint);
  	for (unsigned int i = 0; i < num_features; i++)
  	{
  	  const hb_feature_t &feature = features[i];
  	  if (feature.tag == HB_TAG('k','e','r','n') &&
  	      feature.start < chars_len && feature.start < feature.end)
  	  {
  	    CFRange feature_range = CFRangeMake (feature.start,
  	                                         MIN (feature.end, chars_len) - feature.start);
  	    if (feature.value)
  	      CFAttributedStringRemoveAttribute (attr_string, feature_range, kCTKernAttributeName);
  	    else
  	      CFAttributedStringSetAttribute (attr_string, feature_range, kCTKernAttributeName, zero);
  	  }
  	}
  	CFRelease (zero);
        }
  
        int level = HB_DIRECTION_IS_FORWARD (buffer->props.direction) ? 0 : 1;
        CFNumberRef level_number = CFNumberCreate (kCFAllocatorDefault, kCFNumberIntType, &level);
        CFDictionaryRef options = CFDictionaryCreate (kCFAllocatorDefault,
  						    (const void **) &kCTTypesetterOptionForcedEmbeddingLevel,
  						    (const void **) &level_number,
  						    1,
  						    &kCFTypeDictionaryKeyCallBacks,
  						    &kCFTypeDictionaryValueCallBacks);
        CFRelease (level_number);
        if (unlikely (!options))
          FAIL ("CFDictionaryCreate failed");
  
        CTTypesetterRef typesetter = CTTypesetterCreateWithAttributedStringAndOptions (attr_string, options);
        CFRelease (options);
        CFRelease (attr_string);
        if (unlikely (!typesetter))
  	FAIL ("CTTypesetterCreateWithAttributedStringAndOptions failed");
  
        line = CTTypesetterCreateLine (typesetter, CFRangeMake(0, 0));
        CFRelease (typesetter);
        if (unlikely (!line))
  	FAIL ("CTTypesetterCreateLine failed");
      }
  
      CFArrayRef glyph_runs = CTLineGetGlyphRuns (line);
      unsigned int num_runs = CFArrayGetCount (glyph_runs);
      DEBUG_MSG (CORETEXT, nullptr, "Num runs: %d", num_runs);
  
      buffer->len = 0;
      uint32_t status_and = ~0, status_or = 0;
      double advances_so_far = 0;
      /* For right-to-left runs, CoreText returns the glyphs positioned such that
       * any trailing whitespace is to the left of (0,0).  Adjust coordinate system
       * to fix for that.  Test with any RTL string with trailing spaces.
       * https://code.google.com/p/chromium/issues/detail?id=469028
       */
      if (HB_DIRECTION_IS_BACKWARD (buffer->props.direction))
      {
        advances_so_far -= CTLineGetTrailingWhitespaceWidth (line);
        if (HB_DIRECTION_IS_VERTICAL (buffer->props.direction))
  	  advances_so_far = -advances_so_far;
      }
  
      const CFRange range_all = CFRangeMake (0, 0);
  
      for (unsigned int i = 0; i < num_runs; i++)
      {
        CTRunRef run = static_cast<CTRunRef>(CFArrayGetValueAtIndex (glyph_runs, i));
        CTRunStatus run_status = CTRunGetStatus (run);
        status_or  |= run_status;
        status_and &= run_status;
        DEBUG_MSG (CORETEXT, run, "CTRunStatus: %x", run_status);
        double run_advance = CTRunGetTypographicBounds (run, range_all, nullptr, nullptr, nullptr);
        if (HB_DIRECTION_IS_VERTICAL (buffer->props.direction))
  	  run_advance = -run_advance;
        DEBUG_MSG (CORETEXT, run, "Run advance: %g", run_advance);
  
        /* CoreText does automatic font fallback (AKA "cascading") for  characters
         * not supported by the requested font, and provides no way to turn it off,
         * so we must detect if the returned run uses a font other than the requested
         * one and fill in the buffer with .notdef glyphs instead of random glyph
         * indices from a different font.
         */
        CFDictionaryRef attributes = CTRunGetAttributes (run);
        CTFontRef run_ct_font = static_cast<CTFontRef>(CFDictionaryGetValue (attributes, kCTFontAttributeName));
        if (!CFEqual (run_ct_font, ct_font))
        {
  	/* The run doesn't use our main font instance.  We have to figure out
  	 * whether font fallback happened, or this is just CoreText giving us
  	 * another CTFont using the same underlying CGFont.  CoreText seems
  	 * to do that in a variety of situations, one of which being vertical
  	 * text, but also perhaps for caching reasons.
  	 *
  	 * First, see if it uses any of our subfonts created to set font features...
  	 *
  	 * Next, compare the CGFont to the one we used to create our fonts.
  	 * Even this doesn't work all the time.
  	 *
  	 * Finally, we compare PS names, which I don't think are unique...
  	 *
  	 * Looks like if we really want to be sure here we have to modify the
  	 * font to change the name table, similar to what we do in the uniscribe
  	 * backend.
  	 *
  	 * However, even that wouldn't work if we were passed in the CGFont to
  	 * construct a hb_face to begin with.
  	 *
  	 * See: http://github.com/harfbuzz/harfbuzz/pull/36
  	 *
  	 * Also see: https://bugs.chromium.org/p/chromium/issues/detail?id=597098
  	 */
  	bool matched = false;
  	for (unsigned int i = 0; i < range_records.len; i++)
  	  if (range_records[i].font && CFEqual (run_ct_font, range_records[i].font))
  	  {
  	    matched = true;
  	    break;
  	  }
  	if (!matched)
  	{
  	  CGFontRef run_cg_font = CTFontCopyGraphicsFont (run_ct_font, 0);
  	  if (run_cg_font)
  	  {
  	    matched = CFEqual (run_cg_font, cg_font);
  	    CFRelease (run_cg_font);
  	  }
  	}
  	if (!matched)
  	{
  	  CFStringRef font_ps_name = CTFontCopyName (ct_font, kCTFontPostScriptNameKey);
  	  CFStringRef run_ps_name = CTFontCopyName (run_ct_font, kCTFontPostScriptNameKey);
  	  CFComparisonResult result = CFStringCompare (run_ps_name, font_ps_name, 0);
  	  CFRelease (run_ps_name);
  	  CFRelease (font_ps_name);
  	  if (result == kCFCompareEqualTo)
  	    matched = true;
  	}
  	if (!matched)
  	{
  	  CFRange range = CTRunGetStringRange (run);
            DEBUG_MSG (CORETEXT, run, "Run used fallback font: %ld..%ld",
  		     range.location, range.location + range.length);
  	  if (!buffer->ensure_inplace (buffer->len + range.length))
  	    goto resize_and_retry;
  	  hb_glyph_info_t *info = buffer->info + buffer->len;
  
  	  hb_codepoint_t notdef = 0;
  	  hb_direction_t dir = buffer->props.direction;
  	  hb_position_t x_advance, y_advance, x_offset, y_offset;
  	  hb_font_get_glyph_advance_for_direction (font, notdef, dir, &x_advance, &y_advance);
  	  hb_font_get_glyph_origin_for_direction (font, notdef, dir, &x_offset, &y_offset);
  	  hb_position_t advance = x_advance + y_advance;
  	  x_offset = -x_offset;
  	  y_offset = -y_offset;
  
  	  unsigned int old_len = buffer->len;
  	  for (CFIndex j = range.location; j < range.location + range.length; j++)
  	  {
  	      UniChar ch = CFStringGetCharacterAtIndex (string_ref, j);
  	      if (hb_in_range<UniChar> (ch, 0xDC00u, 0xDFFFu) && range.location < j)
  	      {
  		ch = CFStringGetCharacterAtIndex (string_ref, j - 1);
  		if (hb_in_range<UniChar> (ch, 0xD800u, 0xDBFFu))
  		  /* This is the second of a surrogate pair.  Don't need .notdef
  		   * for this one. */
  		  continue;
  	      }
  	      if (buffer->unicode->is_default_ignorable (ch))
  	        continue;
  
  	      info->codepoint = notdef;
  	      info->cluster = log_clusters[j];
  
  	      info->mask = advance;
  	      info->var1.i32 = x_offset;
  	      info->var2.i32 = y_offset;
  
  	      info++;
  	      buffer->len++;
  	  }
  	  if (HB_DIRECTION_IS_BACKWARD (buffer->props.direction))
  	    buffer->reverse_range (old_len, buffer->len);
  	  advances_so_far += run_advance;
  	  continue;
  	}
        }
  
        unsigned int num_glyphs = CTRunGetGlyphCount (run);
        if (num_glyphs == 0)
  	continue;
  
        if (!buffer->ensure_inplace (buffer->len + num_glyphs))
  	goto resize_and_retry;
  
        hb_glyph_info_t *run_info = buffer->info + buffer->len;
  
        /* Testing used to indicate that CTRunGetGlyphsPtr, etc (almost?) always
         * succeed, and so copying data to our own buffer will be rare.  Reports
         * have it that this changed in OS X 10.10 Yosemite, and nullptr is returned
         * frequently.  At any rate, we can test that codepath by setting USE_PTR
         * to false. */
  
  #define USE_PTR true
  
  #define SCRATCH_SAVE() \
    unsigned int scratch_size_saved = scratch_size; \
    hb_buffer_t::scratch_buffer_t *scratch_saved = scratch
  
  #define SCRATCH_RESTORE() \
    scratch_size = scratch_size_saved; \
    scratch = scratch_saved;
  
        { /* Setup glyphs */
          SCRATCH_SAVE();
  	const CGGlyph* glyphs = USE_PTR ? CTRunGetGlyphsPtr (run) : nullptr;
  	if (!glyphs) {
  	  ALLOCATE_ARRAY (CGGlyph, glyph_buf, num_glyphs, goto resize_and_retry);
  	  CTRunGetGlyphs (run, range_all, glyph_buf);
  	  glyphs = glyph_buf;
  	}
  	const CFIndex* string_indices = USE_PTR ? CTRunGetStringIndicesPtr (run) : nullptr;
  	if (!string_indices) {
  	  ALLOCATE_ARRAY (CFIndex, index_buf, num_glyphs, goto resize_and_retry);
  	  CTRunGetStringIndices (run, range_all, index_buf);
  	  string_indices = index_buf;
  	}
  	hb_glyph_info_t *info = run_info;
  	for (unsigned int j = 0; j < num_glyphs; j++)
  	{
  	  info->codepoint = glyphs[j];
  	  info->cluster = log_clusters[string_indices[j]];
  	  info++;
  	}
  	SCRATCH_RESTORE();
        }
        {
          /* Setup positions.
  	 * Note that CoreText does not return advances for glyphs.  As such,
  	 * for all but last glyph, we use the delta position to next glyph as
  	 * advance (in the advance direction only), and for last glyph we set
  	 * whatever is needed to make the whole run's advance add up. */
          SCRATCH_SAVE();
  	const CGPoint* positions = USE_PTR ? CTRunGetPositionsPtr (run) : nullptr;
  	if (!positions) {
  	  ALLOCATE_ARRAY (CGPoint, position_buf, num_glyphs, goto resize_and_retry);
  	  CTRunGetPositions (run, range_all, position_buf);
  	  positions = position_buf;
  	}
  	hb_glyph_info_t *info = run_info;
  	if (HB_DIRECTION_IS_HORIZONTAL (buffer->props.direction))
  	{
  	  hb_position_t x_offset = (positions[0].x - advances_so_far) * x_mult;
  	  for (unsigned int j = 0; j < num_glyphs; j++)
  	  {
  	    double advance;
  	    if (likely (j + 1 < num_glyphs))
  	      advance = positions[j + 1].x - positions[j].x;
  	    else /* last glyph */
  	      advance = run_advance - (positions[j].x - positions[0].x);
  	    info->mask = advance * x_mult;
  	    info->var1.i32 = x_offset;
  	    info->var2.i32 = positions[j].y * y_mult;
  	    info++;
  	  }
  	}
  	else
  	{
  	  hb_position_t y_offset = (positions[0].y - advances_so_far) * y_mult;
  	  for (unsigned int j = 0; j < num_glyphs; j++)
  	  {
  	    double advance;
  	    if (likely (j + 1 < num_glyphs))
  	      advance = positions[j + 1].y - positions[j].y;
  	    else /* last glyph */
  	      advance = run_advance - (positions[j].y - positions[0].y);
  	    info->mask = advance * y_mult;
  	    info->var1.i32 = positions[j].x * x_mult;
  	    info->var2.i32 = y_offset;
  	    info++;
  	  }
  	}
  	SCRATCH_RESTORE();
  	advances_so_far += run_advance;
        }
  #undef SCRATCH_RESTORE
  #undef SCRATCH_SAVE
  #undef USE_PTR
  #undef ALLOCATE_ARRAY
  
        buffer->len += num_glyphs;
      }
  
      /* Mac OS 10.6 doesn't have kCTTypesetterOptionForcedEmbeddingLevel,
       * or if it does, it doesn't resepct it.  So we get runs with wrong
       * directions.  As such, disable the assert...  It wouldn't crash, but
       * cursoring will be off...
       *
       * http://crbug.com/419769
       */
      if (0)
      {
        /* Make sure all runs had the expected direction. */
        bool backward = HB_DIRECTION_IS_BACKWARD (buffer->props.direction);
        assert (bool (status_and & kCTRunStatusRightToLeft) == backward);
        assert (bool (status_or  & kCTRunStatusRightToLeft) == backward);
      }
  
      buffer->clear_positions ();
  
      unsigned int count = buffer->len;
      hb_glyph_info_t *info = buffer->info;
      hb_glyph_position_t *pos = buffer->pos;
      if (HB_DIRECTION_IS_HORIZONTAL (buffer->props.direction))
        for (unsigned int i = 0; i < count; i++)
        {
  	pos->x_advance = info->mask;
  	pos->x_offset = info->var1.i32;
  	pos->y_offset = info->var2.i32;
  
  	info->mask = HB_GLYPH_FLAG_UNSAFE_TO_BREAK;
  
  	info++, pos++;
        }
      else
        for (unsigned int i = 0; i < count; i++)
        {
  	pos->y_advance = info->mask;
  	pos->x_offset = info->var1.i32;
  	pos->y_offset = info->var2.i32;
  
  	info->mask = HB_GLYPH_FLAG_UNSAFE_TO_BREAK;
  
  	info++, pos++;
        }
  
      /* Fix up clusters so that we never return out-of-order indices;
       * if core text has reordered glyphs, we'll merge them to the
       * beginning of the reordered cluster.  CoreText is nice enough
       * to tell us whenever it has produced nonmonotonic results...
       * Note that we assume the input clusters were nonmonotonic to
       * begin with.
       *
       * This does *not* mean we'll form the same clusters as Uniscribe
       * or the native OT backend, only that the cluster indices will be
       * monotonic in the output buffer. */
      if (count > 1 && (status_or & kCTRunStatusNonMonotonic))
      {
        hb_glyph_info_t *info = buffer->info;
        if (HB_DIRECTION_IS_FORWARD (buffer->props.direction))
        {
  	unsigned int cluster = info[count - 1].cluster;
  	for (unsigned int i = count - 1; i > 0; i--)
  	{
  	  cluster = MIN (cluster, info[i - 1].cluster);
  	  info[i - 1].cluster = cluster;
  	}
        }
        else
        {
  	unsigned int cluster = info[0].cluster;
  	for (unsigned int i = 1; i < count; i++)
  	{
  	  cluster = MIN (cluster, info[i].cluster);
  	  info[i].cluster = cluster;
  	}
        }
      }
    }
  
    buffer->unsafe_to_break_all ();
  
  #undef FAIL
  
  fail:
    if (string_ref)
      CFRelease (string_ref);
    if (line)
      CFRelease (line);
  
    for (unsigned int i = 0; i < range_records.len; i++)
      if (range_records[i].font)
        CFRelease (range_records[i].font);
  
    return ret;
  }
  
  
  /*
   * AAT shaper
   */
  
  HB_SHAPER_DATA_ENSURE_DEFINE(coretext_aat, face)
  HB_SHAPER_DATA_ENSURE_DEFINE(coretext_aat, font)
  
  /*
   * shaper face data
   */
  
  struct hb_coretext_aat_shaper_face_data_t {};
  
  hb_coretext_aat_shaper_face_data_t *
  _hb_coretext_aat_shaper_face_data_create (hb_face_t *face)
  {
    static const hb_tag_t tags[] = {HB_CORETEXT_TAG_MORX, HB_CORETEXT_TAG_MORT, HB_CORETEXT_TAG_KERX};
  
    for (unsigned int i = 0; i < ARRAY_LENGTH (tags); i++)
    {
      hb_blob_t *blob = face->reference_table (tags[i]);
      if (hb_blob_get_length (blob))
      {
        hb_blob_destroy (blob);
        return hb_coretext_shaper_face_data_ensure (face) ? (hb_coretext_aat_shaper_face_data_t *) HB_SHAPER_DATA_SUCCEEDED : nullptr;
      }
      hb_blob_destroy (blob);
    }
  
    return nullptr;
  }
  
  void
  _hb_coretext_aat_shaper_face_data_destroy (hb_coretext_aat_shaper_face_data_t *data HB_UNUSED)
  {
  }
  
  
  /*
   * shaper font data
   */
  
  struct hb_coretext_aat_shaper_font_data_t {};
  
  hb_coretext_aat_shaper_font_data_t *
  _hb_coretext_aat_shaper_font_data_create (hb_font_t *font)
  {
    return hb_coretext_shaper_font_data_ensure (font) ? (hb_coretext_aat_shaper_font_data_t *) HB_SHAPER_DATA_SUCCEEDED : nullptr;
  }
  
  void
  _hb_coretext_aat_shaper_font_data_destroy (hb_coretext_aat_shaper_font_data_t *data HB_UNUSED)
  {
  }
  
  
  /*
   * shaper shape_plan data
   */
  
  struct hb_coretext_aat_shaper_shape_plan_data_t {};
  
  hb_coretext_aat_shaper_shape_plan_data_t *
  _hb_coretext_aat_shaper_shape_plan_data_create (hb_shape_plan_t    *shape_plan HB_UNUSED,
  					     const hb_feature_t *user_features HB_UNUSED,
  					     unsigned int        num_user_features HB_UNUSED,
  					     const int          *coords HB_UNUSED,
  					     unsigned int        num_coords HB_UNUSED)
  {
    return (hb_coretext_aat_shaper_shape_plan_data_t *) HB_SHAPER_DATA_SUCCEEDED;
  }
  
  void
  _hb_coretext_aat_shaper_shape_plan_data_destroy (hb_coretext_aat_shaper_shape_plan_data_t *data HB_UNUSED)
  {
  }
  
  
  /*
   * shaper
   */
  
  hb_bool_t
  _hb_coretext_aat_shape (hb_shape_plan_t    *shape_plan,
  			hb_font_t          *font,
  			hb_buffer_t        *buffer,
  			const hb_feature_t *features,
  			unsigned int        num_features)
  {
    return _hb_coretext_shape (shape_plan, font, buffer, features, num_features);
  }
  