Add hb-coretext for Mac host builds.

Change-Id: Ibfacfb5839ebbacf36c213ea087d337130fb3fe8
diff --git a/BUILD.gn b/BUILD.gn
index 5b3b387..64b7770 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -45,7 +45,6 @@
     "src/hb-face-private.hh",
     "src/hb-face.cc",
     "src/hb-face.h",
-    "src/hb-fallback-shape.cc",
     "src/hb-font-private.hh",
     "src/hb-font.cc",
     "src/hb-font.h",
@@ -148,6 +147,14 @@
     "HB_NO_MT",
   ]
 
+  if (is_mac) {
+    sources += [
+      "src/hb-coretext.cc",
+      "src/hb-coretext.h",
+    ]
+    defines += [ "HAVE_CORETEXT" ]
+  }
+
   configs += [ ":harfbuzz_warnings" ]
   public_configs = [ ":harfbuzz_config" ]
 
diff --git a/src/hb-coretext.cc b/src/hb-coretext.cc
new file mode 100644
index 0000000..ba96d39
--- /dev/null
+++ b/src/hb-coretext.cc
@@ -0,0 +1,1342 @@
+/*
+ * 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-shaper-impl-private.hh"
+
+#include "hb-coretext.h"
+
+
+#ifndef HB_DEBUG_CORETEXT
+#define HB_DEBUG_CORETEXT (HB_DEBUG+0)
+#endif
+
+
+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 NULL;
+
+  const char *data = reinterpret_cast<const char*> (CFDataGetBytePtr (cf_data));
+  const size_t length = CFDataGetLength (cf_data);
+  if (!data || !length)
+    return NULL;
+
+  return hb_blob_create (data, length, HB_MEMORY_MODE_READONLY,
+			 reinterpret_cast<void *> (const_cast<__CFData *> (cf_data)),
+			 release_table_data);
+}
+
+hb_face_t *
+hb_coretext_face_create (CGFontRef cg_font)
+{
+  return hb_face_create_for_tables (reference_table, CGFontRetain (cg_font), (hb_destroy_func_t) CGFontRelease);
+}
+
+
+HB_SHAPER_DATA_ENSURE_DEFINE(coretext, face)
+HB_SHAPER_DATA_ENSURE_DEFINE(coretext, font)
+
+
+/*
+ * shaper face data
+ */
+
+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, NULL) == data);
+
+  hb_blob_destroy ((hb_blob_t *) info);
+}
+
+static CGFontRef
+create_cg_font (hb_face_t *face)
+{
+  CGFontRef cg_font = NULL;
+  if (face->destroy == (hb_destroy_func_t) CGFontRelease)
+  {
+    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 = CTFontCreateWithGraphicsFont (cg_font, font_size, NULL, NULL);
+  if (unlikely (!ct_font)) {
+    DEBUG_MSG (CORETEXT, cg_font, "Font CTFontCreateWithGraphicsFont() failed");
+    return NULL;
+  }
+
+  /* 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 != NULL && 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, NULL, 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;
+}
+
+struct hb_coretext_shaper_face_data_t {
+  CGFontRef cg_font;
+  CTFontRef ct_font;
+};
+
+hb_coretext_shaper_face_data_t *
+_hb_coretext_shaper_face_data_create (hb_face_t *face)
+{
+  hb_coretext_shaper_face_data_t *data = (hb_coretext_shaper_face_data_t *) calloc (1, sizeof (hb_coretext_shaper_face_data_t));
+  if (unlikely (!data))
+    return NULL;
+
+  data->cg_font = create_cg_font (face);
+  if (unlikely (!data->cg_font))
+  {
+    DEBUG_MSG (CORETEXT, face, "CGFont creation failed..");
+    free (data);
+    return NULL;
+  }
+
+  /* We use 36pt size instead of UPEM, because CoreText implements the 'trak' table,
+   * which can make the font too tight at large sizes.  36pt should be a good semi-neutral
+   * size.
+   *
+   * Since we always create CTFont at a fixed size, our CTFont lives in face_data
+   * instead of font_data.  Which is good, because when people change scale on
+   * hb_font_t, we won't need to update our CTFont. */
+  data->ct_font = create_ct_font (data->cg_font, 36.);
+  if (unlikely (!data->ct_font))
+  {
+    DEBUG_MSG (CORETEXT, face, "CTFont creation failed.");
+    CFRelease (data->cg_font);
+    free (data);
+    return NULL;
+  }
+
+  return data;
+}
+
+void
+_hb_coretext_shaper_face_data_destroy (hb_coretext_shaper_face_data_t *data)
+{
+  CFRelease (data->ct_font);
+  CFRelease (data->cg_font);
+  free (data);
+}
+
+/*
+ * 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 NULL;
+  hb_coretext_shaper_face_data_t *face_data = HB_SHAPER_DATA_GET (face);
+  return face_data->cg_font;
+}
+
+
+/*
+ * shaper font data
+ */
+
+struct hb_coretext_shaper_font_data_t {};
+
+hb_coretext_shaper_font_data_t *
+_hb_coretext_shaper_font_data_create (hb_font_t *font HB_UNUSED)
+{
+  return (hb_coretext_shaper_font_data_t *) HB_SHAPER_DATA_SUCCEEDED;
+}
+
+void
+_hb_coretext_shaper_font_data_destroy (hb_coretext_shaper_font_data_t *data)
+{
+}
+
+
+/*
+ * 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)
+{
+}
+
+CTFontRef
+hb_coretext_font_get_ct_font (hb_font_t *font)
+{
+  hb_face_t *face = font->face;
+  if (unlikely (!hb_coretext_shaper_face_data_ensure (face))) return NULL;
+  hb_coretext_shaper_face_data_t *face_data = HB_SHAPER_DATA_GET (face);
+  return face_data->ct_font;
+}
+
+
+/*
+ * 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 active_feature_t *a, const active_feature_t *b) {
+    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 feature_event_t *a, const feature_event_t *b) {
+    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;
+  hb_coretext_shaper_face_data_t *face_data = HB_SHAPER_DATA_GET (face);
+
+  CGFloat ct_font_size = CTFontGetSize (face_data->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)
+	    };
+	    ASSERT_STATIC (ARRAY_LENGTH (keys) == ARRAY_LENGTH (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 (face_data->ct_font, 0.0, NULL, font_desc);
+	  CFRelease (font_desc);
+	}
+	else
+	{
+	  range->font = NULL;
+	}
+
+	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, NULL, __VA_ARGS__); \
+    ret = false; \
+    goto fail; \
+  } HB_STMT_END;
+
+  bool ret = true;
+  CFStringRef string_ref = NULL;
+  CTLineRef line = NULL;
+
+  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 = NULL;
+    line = NULL;
+
+    /* 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 (NULL,
+						     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, face_data->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, NULL, "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, NULL, NULL, NULL);
+      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, face_data->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/behdad/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, face_data->cg_font);
+	    CFRelease (run_cg_font);
+	  }
+	}
+	if (!matched)
+	{
+	  CFStringRef font_ps_name = CTFontCopyName (face_data->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 NULL 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) : NULL;
+	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) : NULL;
+	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) : NULL;
+	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;
+	}
+      }
+    }
+  }
+
+#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)
+{
+  hb_blob_t *mort_blob = face->reference_table (HB_CORETEXT_TAG_MORT);
+  /* Umm, we just reference the table to check whether it exists.
+   * Maybe add better API for this? */
+  if (!hb_blob_get_length (mort_blob))
+  {
+    hb_blob_destroy (mort_blob);
+    mort_blob = face->reference_table (HB_CORETEXT_TAG_MORX);
+    if (!hb_blob_get_length (mort_blob))
+    {
+      hb_blob_destroy (mort_blob);
+      return NULL;
+    }
+  }
+  hb_blob_destroy (mort_blob);
+
+  return hb_coretext_shaper_face_data_ensure (face) ? (hb_coretext_aat_shaper_face_data_t *) HB_SHAPER_DATA_SUCCEEDED : NULL;
+}
+
+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 : NULL;
+}
+
+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);
+}
diff --git a/src/hb-coretext.h b/src/hb-coretext.h
new file mode 100644
index 0000000..82066e4
--- /dev/null
+++ b/src/hb-coretext.h
@@ -0,0 +1,60 @@
+/*
+ * Copyright © 2012  Mozilla Foundation.
+ *
+ *  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
+ */
+
+#ifndef HB_CORETEXT_H
+#define HB_CORETEXT_H
+
+#include "hb.h"
+
+#include <TargetConditionals.h>
+#if TARGET_OS_IPHONE
+#  include <CoreText/CoreText.h>
+#  include <CoreGraphics/CoreGraphics.h>
+#else
+#  include <ApplicationServices/ApplicationServices.h>
+#endif
+
+HB_BEGIN_DECLS
+
+
+#define HB_CORETEXT_TAG_MORT HB_TAG('m','o','r','t')
+#define HB_CORETEXT_TAG_MORX HB_TAG('m','o','r','x')
+
+
+HB_EXTERN hb_face_t *
+hb_coretext_face_create (CGFontRef cg_font);
+
+
+HB_EXTERN CGFontRef
+hb_coretext_face_get_cg_font (hb_face_t *face);
+
+HB_EXTERN CTFontRef
+hb_coretext_font_get_ct_font (hb_font_t *font);
+
+
+HB_END_DECLS
+
+#endif /* HB_CORETEXT_H */