a11y: Move CreateTextMarker[Range] to TextMarkerHelperMac.

content/browser/accessibility/browser_accessibility_cocoa.mm

Index: content/browser/accessibility/browser_accessibility_cocoa.mm
diff --git a/content/browser/accessibility/browser_accessibility_cocoa.mm b/content/browser/accessibility/browser_accessibility_cocoa.mm
index bf5b5e2821bf9caeba7286cfb6972a1b00ea3d41..6ac825d1b12dfa5000e0fa1efac5d464272ff728 100644
--- a/content/browser/accessibility/browser_accessibility_cocoa.mm
+++ b/content/browser/accessibility/browser_accessibility_cocoa.mm
@@ -28,14 +28,11 @@
 #include "third_party/skia/include/core/SkColor.h"
 #include "ui/accessibility/ax_range.h"
 #import "ui/accessibility/platform/ax_platform_node_mac.h"
+#import "ui/accessibility/platform/text_marker_helper_mac.h"
 
-using AXAbstractPositionInstance =
-    content::AXPlatformPosition::AXPositionInstance;
 using AXPlatformPositionInstance =
     content::AXPlatformPosition::ConcreteInstance;
 using AXPlatformRange = ui::AXRange<AXPlatformPositionInstance::element_type>;
-using AXTextMarkerRangeRef = CFTypeRef;
-using AXTextMarkerRef = CFTypeRef;
 using StringAttribute = ui::AXStringAttribute;
 using content::AXPlatformPosition;
 using content::AccessibilityMatchPredicate;
@@ -113,63 +110,30 @@ NSDictionary* attributeToMethodNameMap = nil;
 // VoiceOver uses -1 to mean "no limit" for AXResultsLimit.
 const int kAXResultsLimitNoLimit = -1;
 
-extern "C" {
-
-// The following are private accessibility APIs required for cursor navigation
-// and text selection. VoiceOver started relying on them in Mac OS X 10.11.
-#if !defined(MAC_OS_X_VERSION_10_11) || \
-    MAC_OS_X_VERSION_MIN_REQUIRED < MAC_OS_X_VERSION_10_11
-
-AXTextMarkerRef AXTextMarkerCreate(CFAllocatorRef allocator,
-                                   const UInt8* bytes,
-                                   CFIndex length);
-
-const UInt8* AXTextMarkerGetBytePtr(AXTextMarkerRef text_marker);
-
-size_t AXTextMarkerGetLength(AXTextMarkerRef text_marker);
-
-AXTextMarkerRangeRef AXTextMarkerRangeCreate(CFAllocatorRef allocator,
-                                             AXTextMarkerRef start_marker,
-                                             AXTextMarkerRef end_marker);
-
-AXTextMarkerRef AXTextMarkerRangeCopyStartMarker(
-    AXTextMarkerRangeRef text_marker_range);
+static_assert(sizeof(AXPlatformPosition) == sizeof(ui::AXPositionBase),
+              "AXPosition size mismatch");
+constexpr size_t kAXPositionSize = sizeof(ui::AXPositionBase);
 
-AXTextMarkerRef AXTextMarkerRangeCopyEndMarker(
-    AXTextMarkerRangeRef text_marker_range);
+class BrowserPositionFactory : public ui::PositionFactory {
+ public:
+  explicit BrowserPositionFactory(
+      content::BrowserAccessibility* browser_accessibility)
+      : browser_accessibility_(browser_accessibility) {}
 
-#endif  // MAC_OS_X_VERSION_10_11
+  std::unique_ptr<ui::AXPositionBase> GetRoot() const override;
+  std::unique_ptr<ui::AXAbstractRange> GetSelection() const override;
+  std::unique_ptr<ui::AXPositionBase> ExtractFromMarker(
+      AXTextMarkerRef marker) const override;
 
-}  // extern "C"
+ private:
+  bool IsActive() const {
+    return browser_accessibility_ && browser_accessibility_->instance_active();
+  }
 
-static_assert(sizeof(AXPlatformPosition) == sizeof(ui::AXPositionBase),
-              "AXPosition size mismatch");
-constexpr size_t kAXPositionSize = sizeof(ui::AXPositionBase);
+  content::BrowserAccessibility* browser_accessibility_;
 
-// to call |release| on it to transfer ownership of the position to the text
-// marker object.
-id CreateTextMarker(AXAbstractPositionInstance position) {
-  AXTextMarkerRef text_marker = AXTextMarkerCreate(
-      kCFAllocatorDefault, reinterpret_cast<const UInt8*>(position.release()),
-      kAXPositionSize);
-  return static_cast<id>(
-      base::mac::CFTypeRefToNSObjectAutorelease(text_marker));
-}
-
-// |range| is destructed at the end of this method and ownership of its |anchor|
-// and |focus| are transfered to the marker range object.
-id CreateTextMarkerRange(const ui::AXAbstractRange range) {
-  AXTextMarkerRef start_marker = AXTextMarkerCreate(
-      kCFAllocatorDefault, reinterpret_cast<const UInt8*>(range.anchor()),
-      kAXPositionSize);
-  AXTextMarkerRef end_marker = AXTextMarkerCreate(
-      kCFAllocatorDefault, reinterpret_cast<const UInt8*>(range.focus()),
-      kAXPositionSize);
-  AXTextMarkerRangeRef marker_range =
-      AXTextMarkerRangeCreate(kCFAllocatorDefault, start_marker, end_marker);
-  return static_cast<id>(
-      base::mac::CFTypeRefToNSObjectAutorelease(marker_range));
-}
+  DISALLOW_COPY_AND_ASSIGN(BrowserPositionFactory);
+};
 
 AXPlatformPositionInstance CreateConcretePositionFromTextMarker(
     AXTextMarkerRef text_marker) {
@@ -189,12 +153,6 @@ AXPlatformPositionInstance CreateConcretePositionFromTextMarker(
   return position;
 }
 
-AXAbstractPositionInstance CreatePositionFromTextMarker(
-    AXTextMarkerRef text_marker) {
-  return base::WrapUnique(
-      CreateConcretePositionFromTextMarker(text_marker).release());
-}
-
 AXPlatformRange CreateRangeFromTextMarkerRange(
     AXTextMarkerRangeRef marker_range) {
   DCHECK(marker_range);
@@ -536,7 +494,16 @@ NSString* const NSAccessibilityRequiredAttribute = @"AXRequired";
 }
 #endif  // MAC_OS_X_VERSION_10_12
 
-@implementation BrowserAccessibilityCocoa
+@interface BrowserAccessibilityCocoa ()
+
+// Lazily creates a TextMarkerHelper and returns it.
+- (TextMarkerHelperMac*)textMarkerHelper;
+
+@end
+
+@implementation BrowserAccessibilityCocoa {
+  base::scoped_nsobject<TextMarkerHelperMac> textMarkerHelper_;
+}
 
 + (void)initialize {
   const struct {
@@ -979,16 +946,12 @@ NSString* const NSAccessibilityRequiredAttribute = @"AXRequired";
       !GetState(browserAccessibility_, ui::AX_STATE_DISABLED)];
 }
 
-// Returns a text marker that points to the last character in the document that
-// can be selected with VoiceOver.
 - (id)endTextMarker {
-  const BrowserAccessibility* root =
-      browserAccessibility_->manager()->GetRoot();
-  if (!root)
-    return nil;
+  return [[self textMarkerHelper] endTextMarker];
+}
 
-  AXAbstractPositionInstance position = root->CreatePositionAt(0);
-  return CreateTextMarker(position->CreatePositionAtEndOfAnchor());
+- (id)startTextMarker {

[tapted, 2017/06/19 11:44:30]

(self review: swap order with endTextMarker)

+  return [[self textMarkerHelper] startTextMarker];
 }
 
 - (NSNumber*)expanded {
@@ -1682,35 +1645,7 @@ NSString* const NSAccessibilityRequiredAttribute = @"AXRequired";
 }
 
 - (id)selectedTextMarkerRange {
-  if (![self instanceActive])
-    return nil;
-
-  BrowserAccessibilityManager* manager = browserAccessibility_->manager();
-  if (!manager)
-    return nil;
-
-  int32_t anchorId = manager->GetTreeData().sel_anchor_object_id;
-  const BrowserAccessibility* anchorObject = manager->GetFromID(anchorId);
-  if (!anchorObject)
-    return nil;
-
-  int32_t focusId = manager->GetTreeData().sel_focus_object_id;
-  const BrowserAccessibility* focusObject = manager->GetFromID(focusId);
-  if (!focusObject)
-    return nil;
-
-  int anchorOffset = manager->GetTreeData().sel_anchor_offset;
-  int focusOffset = manager->GetTreeData().sel_focus_offset;
-  if (anchorOffset < 0 || focusOffset < 0)
-    return nil;
-
-  ui::AXTextAffinity anchorAffinity =
-        manager->GetTreeData().sel_anchor_affinity;
-  ui::AXTextAffinity focusAffinity = manager->GetTreeData().sel_focus_affinity;
-
-  return CreateTextMarkerRange(CreateTextRange(*anchorObject, anchorOffset,
-                                               anchorAffinity, *focusObject,
-                                               focusOffset, focusAffinity));
+  return [[self textMarkerHelper] selectedTextMarkerRange];
 }
 
 - (NSValue*)size {
@@ -1744,18 +1679,6 @@ NSString* const NSAccessibilityRequiredAttribute = @"AXRequired";
   return nil;
 }
 
-// Returns a text marker that points to the first character in the document that
-// can be selected with VoiceOver.
-- (id)startTextMarker {
-  const BrowserAccessibility* root =
-      browserAccessibility_->manager()->GetRoot();
-  if (!root)
-    return nil;
-
-  AXAbstractPositionInstance position = root->CreatePositionAt(0);
-  return CreateTextMarker(position->CreatePositionAtStartOfAnchor());
-}
-
 // Returns a subrole based upon the role.
 - (NSString*) subrole {
   if (![self instanceActive])
@@ -2026,6 +1949,15 @@ NSString* const NSAccessibilityRequiredAttribute = @"AXRequired";
   return [attributedValue attributedSubstringFromRange:range];
 }
 
+- (TextMarkerHelperMac*)textMarkerHelper {
+  if (!textMarkerHelper_) {
+    textMarkerHelper_.reset([[TextMarkerHelperMac alloc]
+        initWithFactory:base::MakeUnique<BrowserPositionFactory>(
+                            browserAccessibility_)]);
+  }
+  return textMarkerHelper_;
+}
+
 // Returns the accessibility value for the given attribute.  If the value isn't
 // supported this will return nil.
 - (id)accessibilityAttributeValue:(NSString*)attribute {
@@ -2142,165 +2074,35 @@ NSString* const NSAccessibilityRequiredAttribute = @"AXRequired";
     return nil;
   }
 
+  SEL selector = NSSelectorFromString(attribute);

[tapted, 2017/06/19 11:44:30]

(self review: this needs a colon appended to the string it (or a static map
string -> @selector(..) or TextMarkerHelper)

+  DCHECK(selector);
+  if ([TextMarkerHelperMac instancesRespondToSelector:selector]) {
+    return
+        [[self textMarkerHelper] performSelector:selector withObject:parameter];
+  }
+
   if ([attribute isEqualToString:@"AXUIElementForTextMarker"]) {
-    AXPlatformPositionInstance position =
-        CreateConcretePositionFromTextMarker(parameter);
+    AXPlatformPositionInstance position = CreateConcretePositionFromTextMarker(
+        base::mac::CFCastStrict<AXTextMarkerRef>(parameter));
     if (!position->IsNullPosition())
       return ToBrowserAccessibilityCocoa(position->GetAnchor());
 
     return nil;
   }
 
-  if ([attribute isEqualToString:@"AXTextMarkerRangeForUIElement"]) {
-    AXAbstractPositionInstance startPosition =
-        browserAccessibility_->CreatePositionAt(0);
-    AXAbstractPositionInstance endPosition =
-        startPosition->CreatePositionAtEndOfAnchor();
-    ui::AXAbstractRange range =
-        ui::AXAbstractRange(std::move(startPosition), std::move(endPosition));
-    return CreateTextMarkerRange(std::move(range));
+  if ([attribute isEqualToString:@"AXStringForTextMarkerRange"]) {
+    return GetTextForTextMarkerRange(
+        base::mac::CFCastStrict<AXTextMarkerRangeRef>(parameter));
   }
 
-  if ([attribute isEqualToString:@"AXStringForTextMarkerRange"])
-    return GetTextForTextMarkerRange(parameter);
-
-  if ([attribute isEqualToString:@"AXAttributedStringForTextMarkerRange"])
-    return GetAttributedTextForTextMarkerRange(parameter);
-
-  if ([attribute isEqualToString:@"AXNextTextMarkerForTextMarker"]) {
-    AXAbstractPositionInstance position =
-        CreatePositionFromTextMarker(parameter);
-    if (position->IsNullPosition())
-      return nil;
-    return CreateTextMarker(position->CreateNextCharacterPosition());
-  }
-
-  if ([attribute isEqualToString:@"AXPreviousTextMarkerForTextMarker"]) {
-    AXAbstractPositionInstance position =
-        CreatePositionFromTextMarker(parameter);
-    if (position->IsNullPosition())
-      return nil;
-    return CreateTextMarker(position->CreatePreviousCharacterPosition());
-  }
-
-  if ([attribute isEqualToString:@"AXLeftWordTextMarkerRangeForTextMarker"]) {
-    AXAbstractPositionInstance endPosition =
-        CreatePositionFromTextMarker(parameter);
-    if (endPosition->IsNullPosition())
-      return nil;
-
-    AXAbstractPositionInstance startWordPosition =
-        endPosition->CreatePreviousWordStartPosition();
-    AXAbstractPositionInstance endWordPosition =
-        endPosition->CreatePreviousWordEndPosition();
-    AXAbstractPositionInstance startPosition =
-        *startWordPosition <= *endWordPosition ? std::move(endWordPosition)
-                                               : std::move(startWordPosition);
-    ui::AXAbstractRange range(std::move(startPosition), std::move(endPosition));
-    return CreateTextMarkerRange(std::move(range));
-  }
-
-  if ([attribute isEqualToString:@"AXRightWordTextMarkerRangeForTextMarker"]) {
-    AXAbstractPositionInstance startPosition =
-        CreatePositionFromTextMarker(parameter);
-    if (startPosition->IsNullPosition())
-      return nil;
-
-    AXAbstractPositionInstance endWordPosition =
-        startPosition->CreateNextWordEndPosition();
-    AXAbstractPositionInstance startWordPosition =
-        startPosition->CreateNextWordStartPosition();
-    AXAbstractPositionInstance endPosition =
-        *startWordPosition <= *endWordPosition ? std::move(startWordPosition)
-                                               : std::move(endWordPosition);
-    ui::AXAbstractRange range(std::move(startPosition), std::move(endPosition));
-    return CreateTextMarkerRange(std::move(range));
-  }
-
-  if ([attribute isEqualToString:@"AXNextWordEndTextMarkerForTextMarker"]) {
-    AXAbstractPositionInstance position =
-        CreatePositionFromTextMarker(parameter);
-    if (position->IsNullPosition())
-      return nil;
-    return CreateTextMarker(position->CreateNextWordEndPosition());
-  }
-
-  if ([attribute
-          isEqualToString:@"AXPreviousWordStartTextMarkerForTextMarker"]) {
-    AXAbstractPositionInstance position =
-        CreatePositionFromTextMarker(parameter);
-    if (position->IsNullPosition())
-      return nil;
-    return CreateTextMarker(position->CreatePreviousWordStartPosition());
-  }
-
-  if ([attribute isEqualToString:@"AXTextMarkerRangeForLine"]) {
-    AXAbstractPositionInstance position =
-        CreatePositionFromTextMarker(parameter);
-    if (position->IsNullPosition())
-      return nil;
-
-    AXAbstractPositionInstance startPosition =
-        position->CreatePreviousLineStartPosition();
-    AXAbstractPositionInstance endPosition =
-        position->CreateNextLineEndPosition();
-    ui::AXAbstractRange range(std::move(startPosition), std::move(endPosition));
-    return CreateTextMarkerRange(std::move(range));
-  }
-
-  if ([attribute isEqualToString:@"AXLeftLineTextMarkerRangeForTextMarker"]) {
-    AXAbstractPositionInstance endPosition =
-        CreatePositionFromTextMarker(parameter);
-    if (endPosition->IsNullPosition())
-      return nil;
-
-    AXAbstractPositionInstance startLinePosition =
-        endPosition->CreatePreviousLineStartPosition();
-    AXAbstractPositionInstance endLinePosition =
-        endPosition->CreatePreviousLineEndPosition();
-    AXAbstractPositionInstance startPosition =
-        *startLinePosition <= *endLinePosition ? std::move(endLinePosition)
-                                               : std::move(startLinePosition);
-    ui::AXAbstractRange range(std::move(startPosition), std::move(endPosition));
-    return CreateTextMarkerRange(std::move(range));
-  }
-
-  if ([attribute isEqualToString:@"AXRightLineTextMarkerRangeForTextMarker"]) {
-    AXAbstractPositionInstance startPosition =
-        CreatePositionFromTextMarker(parameter);
-    if (startPosition->IsNullPosition())
-      return nil;
-
-    AXAbstractPositionInstance startLinePosition =
-        startPosition->CreateNextLineStartPosition();
-    AXAbstractPositionInstance endLinePosition =
-        startPosition->CreateNextLineEndPosition();
-    AXAbstractPositionInstance endPosition =
-        *startLinePosition <= *endLinePosition ? std::move(startLinePosition)
-                                               : std::move(endLinePosition);
-    ui::AXAbstractRange range(std::move(startPosition), std::move(endPosition));
-    return CreateTextMarkerRange(std::move(range));
-  }
-
-  if ([attribute isEqualToString:@"AXNextLineEndTextMarkerForTextMarker"]) {
-    AXAbstractPositionInstance position =
-        CreatePositionFromTextMarker(parameter);
-    if (position->IsNullPosition())
-      return nil;
-    return CreateTextMarker(position->CreateNextLineEndPosition());
-  }
-
-  if ([attribute
-          isEqualToString:@"AXPreviousLineStartTextMarkerForTextMarker"]) {
-    AXAbstractPositionInstance position =
-        CreatePositionFromTextMarker(parameter);
-    if (position->IsNullPosition())
-      return nil;
-    return CreateTextMarker(position->CreatePreviousLineStartPosition());
+  if ([attribute isEqualToString:@"AXAttributedStringForTextMarkerRange"]) {
+    return GetAttributedTextForTextMarkerRange(
+        base::mac::CFCastStrict<AXTextMarkerRangeRef>(parameter));
   }
 
   if ([attribute isEqualToString:@"AXLengthForTextMarkerRange"]) {
-    NSString* text = GetTextForTextMarkerRange(parameter);
+    NSString* text = GetTextForTextMarkerRange(
+        base::mac::CFCastStrict<AXTextMarkerRangeRef>(parameter));
     return [NSNumber numberWithInt:[text length]];
   }
 
@@ -2340,24 +2142,14 @@ NSString* const NSAccessibilityRequiredAttribute = @"AXRequired";
     return nil;
   }
 
-  if ([attribute isEqualToString:
-           NSAccessibilityLineTextMarkerRangeForTextMarkerParameterizedAttribute]) {
-    AXAbstractPositionInstance position =
-        CreatePositionFromTextMarker(parameter);
-    if (position->IsNullPosition())
-      return nil;
-
-    ui::AXAbstractRange range(position->CreatePreviousLineStartPosition(),
-                              position->CreateNextLineEndPosition());
-    return CreateTextMarkerRange(std::move(range));
-  }
-
+  // TODO(tapted): Move this to TextMarkerHelper.
   if ([attribute isEqualToString:
            NSAccessibilityBoundsForTextMarkerRangeParameterizedAttribute]) {
     BrowserAccessibility* startObject;
     BrowserAccessibility* endObject;
     int startOffset, endOffset;
-    AXPlatformRange range = CreateRangeFromTextMarkerRange(parameter);
+    AXPlatformRange range = CreateRangeFromTextMarkerRange(
+        base::mac::CFCastStrict<AXTextMarkerRangeRef>(parameter));
     if (range.IsNull())
       return nil;
 
@@ -2380,28 +2172,6 @@ NSString* const NSAccessibilityRequiredAttribute = @"AXRequired";
   }
 
   if ([attribute isEqualToString:
-           NSAccessibilityTextMarkerRangeForUnorderedTextMarkersParameterizedAttribute]) {
-    if (![parameter isKindOfClass:[NSArray class]])
-      return nil;
-
-    NSArray* text_marker_array = parameter;
-    if ([text_marker_array count] != 2)
-      return nil;
-
-    AXAbstractPositionInstance startPosition =
-        CreatePositionFromTextMarker([text_marker_array objectAtIndex:0]);
-    AXAbstractPositionInstance endPosition =
-        CreatePositionFromTextMarker([text_marker_array objectAtIndex:1]);
-    if (*startPosition <= *endPosition) {
-      return CreateTextMarkerRange(ui::AXAbstractRange(std::move(startPosition),
-                                                       std::move(endPosition)));
-    } else {
-      return CreateTextMarkerRange(ui::AXAbstractRange(
-          std::move(endPosition), std::move(startPosition)));
-    }
-  }
-
-  if ([attribute isEqualToString:
            NSAccessibilityIndexForChildUIElementParameterizedAttribute]) {
     if (![parameter isKindOfClass:[BrowserAccessibilityCocoa class]])
       return nil;
@@ -2898,3 +2668,51 @@ NSString* const NSAccessibilityRequiredAttribute = @"AXRequired";
 }
 
 @end
+
+std::unique_ptr<ui::AXPositionBase> BrowserPositionFactory::GetRoot() const {
+  const BrowserAccessibility* root =
+      browser_accessibility_->manager()->GetRoot();
+  if (!root)
+    return nullptr;
+
+  return root->CreatePositionAt(0);
+}
+
+std::unique_ptr<ui::AXAbstractRange> BrowserPositionFactory::GetSelection()
+    const {
+  if (!IsActive())
+    return nullptr;
+
+  BrowserAccessibilityManager* manager = browser_accessibility_->manager();
+  if (!manager)
+    return nullptr;
+
+  int32_t anchorId = manager->GetTreeData().sel_anchor_object_id;

[tapted, 2017/06/19 11:44:30]

(self review: convert to hacker_case)

+  const BrowserAccessibility* anchorObject = manager->GetFromID(anchorId);
+  if (!anchorObject)
+    return nullptr;
+
+  int32_t focusId = manager->GetTreeData().sel_focus_object_id;
+  const BrowserAccessibility* focusObject = manager->GetFromID(focusId);
+  if (!focusObject)
+    return nullptr;
+
+  int anchorOffset = manager->GetTreeData().sel_anchor_offset;
+  int focusOffset = manager->GetTreeData().sel_focus_offset;
+  if (anchorOffset < 0 || focusOffset < 0)
+    return nullptr;
+
+  ui::AXTextAffinity anchorAffinity =
+      manager->GetTreeData().sel_anchor_affinity;
+  ui::AXTextAffinity focusAffinity = manager->GetTreeData().sel_focus_affinity;
+
+  return base::MakeUnique<ui::AXAbstractRange>(
+      CreateTextRange(*anchorObject, anchorOffset, anchorAffinity, *focusObject,
+                      focusOffset, focusAffinity));
+}
+
+std::unique_ptr<ui::AXPositionBase> BrowserPositionFactory::ExtractFromMarker(
+    AXTextMarkerRef marker) const {
+  return base::WrapUnique(
+      CreateConcretePositionFromTextMarker(marker).release());
+}