a11y: Move CreateTextMarker[Range] to TextMarkerHelperMac.

ui/accessibility/platform/text_marker_helper_mac.mm

Index: ui/accessibility/platform/text_marker_helper_mac.mm
diff --git a/ui/accessibility/platform/text_marker_helper_mac.mm b/ui/accessibility/platform/text_marker_helper_mac.mm
new file mode 100644
index 0000000000000000000000000000000000000000..96f10ef1b85d4cc5d73b8082c82f4b44f8bf3c48
--- /dev/null
+++ b/ui/accessibility/platform/text_marker_helper_mac.mm
@@ -0,0 +1,255 @@
+// Copyright 2017 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#import "ui/accessibility/platform/text_marker_helper_mac.h"
+
+#import <Cocoa/Cocoa.h>
+
+#import "base/mac/foundation_util.h"
+#include "base/mac/scoped_cftyperef.h"
+#include "ui/accessibility/ax_position.h"
+#include "ui/accessibility/ax_range.h"
+
+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.
+AXTextMarkerRef AXTextMarkerCreate(CFAllocatorRef allocator,
+                                   const UInt8* bytes,
+                                   CFIndex length);
+
+AXTextMarkerRangeRef AXTextMarkerRangeCreate(CFAllocatorRef allocator,
+                                             AXTextMarkerRef start_marker,
+                                             AXTextMarkerRef end_marker);
+
+}  // extern "C"
+
+namespace {
+
+// to call |release| on it to transfer ownership of the position to the text
+// marker object.
+id CreateTextMarker(std::unique_ptr<ui::AXPositionBase> position) {
+  AXTextMarkerRef text_marker = AXTextMarkerCreate(
+      kCFAllocatorDefault, reinterpret_cast<const UInt8*>(position.release()),
+      sizeof(ui::AXPositionBase));
+  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()),
+      sizeof(ui::AXPositionBase));
+  AXTextMarkerRef end_marker = AXTextMarkerCreate(
+      kCFAllocatorDefault, reinterpret_cast<const UInt8*>(range.focus()),
+      sizeof(ui::AXPositionBase));
+  AXTextMarkerRangeRef marker_range =
+      AXTextMarkerRangeCreate(kCFAllocatorDefault, start_marker, end_marker);
+  return static_cast<id>(
+      base::mac::CFTypeRefToNSObjectAutorelease(marker_range));
+}
+
+}  // namespace
+
+@interface TextMarkerHelperMac ()
+- (std::unique_ptr<ui::AXPositionBase>)extractFrom:(id)parameter;
+@end
+
+@implementation TextMarkerHelperMac {
+  std::unique_ptr<ui::PositionFactory> factory_;
+}
+
+- (instancetype)initWithFactory:(std::unique_ptr<ui::PositionFactory>)factory {
+  if ((self = [super init])) {
+    factory_ = std::move(factory);
+  }
+  return self;
+}
+
+- (id)startTextMarker {
+  std::unique_ptr<ui::AXPositionBase> root = factory_->GetRoot();
+  return root ? CreateTextMarker(root->CreatePositionAtStartOfAnchor()) : nil;
+}
+
+- (id)endTextMarker {
+  std::unique_ptr<ui::AXPositionBase> root = factory_->GetRoot();
+  return root ? CreateTextMarker(root->CreatePositionAtEndOfAnchor()) : nil;
+}
+
+- (id)selectedTextMarkerRange {
+  std::unique_ptr<ui::AXAbstractRange> selection = factory_->GetSelection();
+  return selection ? CreateTextMarkerRange(std::move(*selection)) : nil;
+}
+
+- (std::unique_ptr<ui::AXPositionBase>)extractFrom:(id)parameter {
+  AXTextMarkerRef marker = base::mac::CFCastStrict<AXTextMarkerRef>(parameter);
+  return factory_->ExtractFromMarker(marker);
+}
+
+- (id)AXTextMarkerRangeForUIElement:(id)parameter {
+  std::unique_ptr<ui::AXPositionBase> startPosition = factory_->GetRoot();
+  std::unique_ptr<ui::AXPositionBase> endPosition =
+      startPosition->CreatePositionAtEndOfAnchor();
+  ui::AXAbstractRange range =
+      ui::AXAbstractRange(std::move(startPosition), std::move(endPosition));
+  return CreateTextMarkerRange(std::move(range));
+}
+
+- (id)AXNextTextMarkerForTextMarker:(id)parameter {
+  std::unique_ptr<ui::AXPositionBase> position = [self extractFrom:parameter];
+  if (position->IsNullPosition())
+    return nil;
+  return CreateTextMarker(position->CreateNextCharacterPosition());
+}
+
+- (id)AXPreviousTextMarkerForTextMarker:(id)parameter {
+  std::unique_ptr<ui::AXPositionBase> position = [self extractFrom:parameter];
+  if (position->IsNullPosition())
+    return nil;
+  return CreateTextMarker(position->CreatePreviousCharacterPosition());
+}
+
+- (id)AXLeftWordTextMarkerRangeForTextMarker:(id)parameter {
+  std::unique_ptr<ui::AXPositionBase> endPosition =
+      [self extractFrom:parameter];
+  if (endPosition->IsNullPosition())
+    return nil;
+
+  std::unique_ptr<ui::AXPositionBase> startWordPosition =
+      endPosition->CreatePreviousWordStartPosition();
+  std::unique_ptr<ui::AXPositionBase> endWordPosition =
+      endPosition->CreatePreviousWordEndPosition();
+  std::unique_ptr<ui::AXPositionBase> startPosition =
+      *startWordPosition <= *endWordPosition ? std::move(endWordPosition)
+                                             : std::move(startWordPosition);
+  ui::AXAbstractRange range(std::move(startPosition), std::move(endPosition));
+  return CreateTextMarkerRange(std::move(range));
+}
+
+- (id)AXRightWordTextMarkerRangeForTextMarker:(id)parameter {
+  std::unique_ptr<ui::AXPositionBase> startPosition =
+      [self extractFrom:parameter];
+  if (startPosition->IsNullPosition())
+    return nil;
+
+  std::unique_ptr<ui::AXPositionBase> endWordPosition =
+      startPosition->CreateNextWordEndPosition();
+  std::unique_ptr<ui::AXPositionBase> startWordPosition =
+      startPosition->CreateNextWordStartPosition();
+  std::unique_ptr<ui::AXPositionBase> endPosition =
+      *startWordPosition <= *endWordPosition ? std::move(startWordPosition)
+                                             : std::move(endWordPosition);
+  ui::AXAbstractRange range(std::move(startPosition), std::move(endPosition));
+  return CreateTextMarkerRange(std::move(range));
+}
+
+- (id)AXNextWordEndTextMarkerForTextMarker:(id)parameter {
+  std::unique_ptr<ui::AXPositionBase> position = [self extractFrom:parameter];
+  if (position->IsNullPosition())
+    return nil;
+  return CreateTextMarker(position->CreateNextWordEndPosition());
+}
+
+- (id)AXPreviousWordStartTextMarkerForTextMarker:(id)parameter {
+  std::unique_ptr<ui::AXPositionBase> position = [self extractFrom:parameter];
+  if (position->IsNullPosition())
+    return nil;
+  return CreateTextMarker(position->CreatePreviousWordStartPosition());
+}
+
+- (id)AXTextMarkerRangeForLine:(id)parameter {
+  std::unique_ptr<ui::AXPositionBase> position = [self extractFrom:parameter];
+  if (position->IsNullPosition())
+    return nil;
+
+  std::unique_ptr<ui::AXPositionBase> startPosition =
+      position->CreatePreviousLineStartPosition();
+  std::unique_ptr<ui::AXPositionBase> endPosition =
+      position->CreateNextLineEndPosition();
+  ui::AXAbstractRange range(std::move(startPosition), std::move(endPosition));
+  return CreateTextMarkerRange(std::move(range));
+}
+
+- (id)AXLeftLineTextMarkerRangeForTextMarker:(id)parameter {
+  std::unique_ptr<ui::AXPositionBase> endPosition =
+      [self extractFrom:parameter];
+  if (endPosition->IsNullPosition())
+    return nil;
+
+  std::unique_ptr<ui::AXPositionBase> startLinePosition =
+      endPosition->CreatePreviousLineStartPosition();
+  std::unique_ptr<ui::AXPositionBase> endLinePosition =
+      endPosition->CreatePreviousLineEndPosition();
+  std::unique_ptr<ui::AXPositionBase> startPosition =
+      *startLinePosition <= *endLinePosition ? std::move(endLinePosition)
+                                             : std::move(startLinePosition);
+  ui::AXAbstractRange range(std::move(startPosition), std::move(endPosition));
+  return CreateTextMarkerRange(std::move(range));
+}
+
+- (id)AXRightLineTextMarkerRangeForTextMarker:(id)parameter {
+  std::unique_ptr<ui::AXPositionBase> startPosition =
+      [self extractFrom:parameter];
+  if (startPosition->IsNullPosition())
+    return nil;
+
+  std::unique_ptr<ui::AXPositionBase> startLinePosition =
+      startPosition->CreateNextLineStartPosition();
+  std::unique_ptr<ui::AXPositionBase> endLinePosition =
+      startPosition->CreateNextLineEndPosition();
+  std::unique_ptr<ui::AXPositionBase> endPosition =
+      *startLinePosition <= *endLinePosition ? std::move(startLinePosition)
+                                             : std::move(endLinePosition);
+  ui::AXAbstractRange range(std::move(startPosition), std::move(endPosition));
+  return CreateTextMarkerRange(std::move(range));
+}
+
+- (id)AXNextLineEndTextMarkerForTextMarker:(id)parameter {
+  std::unique_ptr<ui::AXPositionBase> position = [self extractFrom:parameter];
+  if (position->IsNullPosition())
+    return nil;
+  return CreateTextMarker(position->CreateNextLineEndPosition());
+}
+
+- (id)AXPreviousLineStartTextMarkerForTextMarker:(id)parameter {
+  std::unique_ptr<ui::AXPositionBase> position = [self extractFrom:parameter];
+  if (position->IsNullPosition())
+    return nil;
+  return CreateTextMarker(position->CreatePreviousLineStartPosition());
+}
+
+- (id)AXLineTextMarkerRangeForTextMarker:(id)parameter {
+  std::unique_ptr<ui::AXPositionBase> position = [self extractFrom:parameter];
+  if (position->IsNullPosition())
+    return nil;
+
+  ui::AXAbstractRange range(position->CreatePreviousLineStartPosition(),
+                            position->CreateNextLineEndPosition());
+  return CreateTextMarkerRange(std::move(range));
+}
+
+- (id)AXTextMarkerRangeForUnorderedTextMarkers:(id)parameter {
+  if (![parameter isKindOfClass:[NSArray class]])
+    return nil;
+
+  NSArray* text_marker_array = parameter;
+  if ([text_marker_array count] != 2)
+    return nil;
+
+  std::unique_ptr<ui::AXPositionBase> startPosition =
+      [self extractFrom:[text_marker_array objectAtIndex:0]];
+  std::unique_ptr<ui::AXPositionBase> endPosition =
+      [self extractFrom:[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)));
+  }
+}
+
+@end