Port ax_dump_tree tool on mac: seamless work with BrowserAccessibilityCocoa and AXUIElement objects

Bug: 1124366
Change-Id: I2dccf90e0de2ef06969630c0d6b890f5e619cf39
AX-Relnotes: n/a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2392848
Commit-Queue: Alexander Surkov <asurkov@igalia.com>
Reviewed-by: Dominic Mazzoni <dmazzoni@chromium.org>
Cr-Commit-Position: refs/heads/master@{#805380}

content/browser/accessibility/accessibility_tree_formatter_mac.mm

@@ -25,8 +25,9 @@ using base::SysNSStringToUTF8;
 using base::SysNSStringToUTF16;
 using base::SysUTF16ToNSString;
 using content::a11y::AttributeInvoker;
-using content::a11y::AXLineIndexer;
-using content::a11y::CocoaLineIndexer;
+using content::a11y::ChildrenOf;
+using content::a11y::IsAXUIElement;
+using content::a11y::IsBrowserAccessibilityCocoa;
 using content::a11y::LineIndexer;
 using content::a11y::OptionalNSObject;
 using std::string;
@@ -150,7 +151,7 @@ AccessibilityTreeFormatterMac::BuildAccessibilityTree(
     BrowserAccessibility* root) {
   DCHECK(root);
   BrowserAccessibilityCocoa* cocoa_root = ToBrowserAccessibilityCocoa(root);
-  CocoaLineIndexer line_indexer(cocoa_root);
+  LineIndexer line_indexer(cocoa_root);
   std::unique_ptr<base::DictionaryValue> dict(new base::DictionaryValue);
   RecursiveBuildAccessibilityTree(cocoa_root, &line_indexer, dict.get());
   return dict;
@@ -160,7 +161,7 @@ std::unique_ptr<base::DictionaryValue>
 AccessibilityTreeFormatterMac::BuildAccessibilityTreeForWindow(
     gfx::AcceleratedWidget widget) {
   AXUIElementRef application = AXUIElementCreateApplication(widget);
-  AXLineIndexer line_indexer(application);
+  LineIndexer line_indexer(static_cast<id>(application));
   std::unique_ptr<base::DictionaryValue> dict(new base::DictionaryValue);
   RecursiveBuildAccessibilityTree(static_cast<id>(application), &line_indexer,
                                   dict.get());
@@ -178,31 +179,22 @@ void AccessibilityTreeFormatterMac::RecursiveBuildAccessibilityTree(
     const id node,
     const LineIndexer* line_indexer,
     base::DictionaryValue* dict) const {
-  NSArray* children = nil;
-  if (CFGetTypeID(node) == AXUIElementGetTypeID()) {
+  if (IsAXUIElement(node)) {
     AddProperties(static_cast<AXUIElementRef>(node), line_indexer, dict);
-    CFTypeRef children_ref;
-    if ((AXUIElementCopyAttributeValue(static_cast<AXUIElementRef>(node),
-                                       kAXChildrenAttribute, &children_ref)) ==
-        kAXErrorSuccess) {
-      children = static_cast<NSArray*>(children_ref);
-    }
-  } else if ([node isKindOfClass:[BrowserAccessibilityCocoa class]]) {
+  } else if (IsBrowserAccessibilityCocoa(node)) {
     AddProperties(static_cast<BrowserAccessibilityCocoa*>(node), line_indexer,
                   dict);
-    children = [node children];
   }
 
-  if (children) {
-    auto child_dict_list = std::make_unique<base::ListValue>();
-    for (id child in children) {
-      std::unique_ptr<base::DictionaryValue> child_dict(
-          new base::DictionaryValue);
-      RecursiveBuildAccessibilityTree(child, line_indexer, child_dict.get());
-      child_dict_list->Append(std::move(child_dict));
-    }
-    dict->Set(kChildrenDictAttr, std::move(child_dict_list));
+  NSArray* children = ChildrenOf(node);
+  auto child_dict_list = std::make_unique<base::ListValue>();
+  for (id child in children) {
+    std::unique_ptr<base::DictionaryValue> child_dict(
+        new base::DictionaryValue);
+    RecursiveBuildAccessibilityTree(child, line_indexer, child_dict.get());
+    child_dict_list->Append(std::move(child_dict));
   }
+  dict->Set(kChildrenDictAttr, std::move(child_dict_list));
 }
 
 void AccessibilityTreeFormatterMac::AddProperties(

content/browser/accessibility/accessibility_tree_formatter_utils_mac.h

@@ -11,48 +11,40 @@
 namespace content {
 namespace a11y {
 
+/**
+ * Return true if the given object is internal BrowserAccessibilityCocoa.
+ */
+bool IsBrowserAccessibilityCocoa(const id node);
+
+/**
+ * Returns true if the given object is AXUIElement.
+ */
+bool IsAXUIElement(const id node);
+
+/**
+ * Returns children of an accessible object, either AXUIElement or
+ * BrowserAccessibilityCocoa.
+ */
+NSArray* ChildrenOf(const id node);
+
 /**
  * Converts accessible node object to a line index in the formatted
  * accessibility tree, the node is placed at, and vice versa.
  */
-class LineIndexer {
+class LineIndexer final {
  public:
-  LineIndexer();
+  LineIndexer(const gfx::NativeViewAccessible node);
   virtual ~LineIndexer();
 
   std::string IndexBy(const gfx::NativeViewAccessible node) const;
   gfx::NativeViewAccessible NodeBy(const std::string& index) const;
 
- protected:
-  virtual NSArray* Children(const gfx::NativeViewAccessible node) const = 0;
+ private:
   void Build(const gfx::NativeViewAccessible node, int* counter);
 
- private:
   std::map<const gfx::NativeViewAccessible, std::string> map;
 };
 
-/**
- * Line indexer for internal BrowserAccessibilityCocoa trees.
- */
-class CocoaLineIndexer final : public LineIndexer {
- public:
-  CocoaLineIndexer(const BrowserAccessibilityCocoa* node);
-
- protected:
-  NSArray* Children(const gfx::NativeViewAccessible node) const override;
-};
-
-/**
- * Line indexer for external AXUIElement trees.
- */
-class AXLineIndexer final : public LineIndexer {
- public:
-  AXLineIndexer(const AXUIElementRef node);
-
- protected:
-  NSArray* Children(const gfx::NativeViewAccessible node) const override;
-};
-
 // Implements stateful id values. Can be either id or be in
 // error or not applciable state. Similar to base::Optional, but tri-state
 // allowing nullable values.

content/browser/accessibility/accessibility_tree_formatter_utils_mac.mm

@@ -49,9 +49,40 @@ namespace {
 
 }  // namespace
 
+bool IsBrowserAccessibilityCocoa(const id node) {
+  return [node isKindOfClass:[BrowserAccessibilityCocoa class]];
+}
+
+bool IsAXUIElement(const id node) {
+  return CFGetTypeID(node) == AXUIElementGetTypeID();
+}
+
+NSArray* ChildrenOf(const id node) {
+  if (IsBrowserAccessibilityCocoa(node)) {
+    return [node children];
+  }
+
+  if (IsAXUIElement(node)) {
+    CFTypeRef children_ref;
+    if ((AXUIElementCopyAttributeValue(static_cast<AXUIElementRef>(node),
+                                       kAXChildrenAttribute, &children_ref)) ==
+        kAXErrorSuccess) {
+      return static_cast<NSArray*>(children_ref);
+    }
+    return nil;
+  }
+
+  NOTREACHED();
+  return nil;
+}
+
 // Line indexers
 
-LineIndexer::LineIndexer() {}
+LineIndexer::LineIndexer(const gfx::NativeViewAccessible node) {
+  int counter = 0;
+  Build(node, &counter);
+}
+
 LineIndexer::~LineIndexer() {}
 
 std::string LineIndexer::IndexBy(const gfx::NativeViewAccessible node) const {
@@ -76,36 +107,12 @@ void LineIndexer::Build(const gfx::NativeViewAccessible node, int* counter) {
   const std::string line_index =
       std::string(1, ':') + base::NumberToString(++(*counter));
   map.insert({node, line_index});
-  NSArray* children = Children(node);
+  NSArray* children = ChildrenOf(node);
   for (gfx::NativeViewAccessible child in children) {
     Build(child, counter);
   }
 }
 
-CocoaLineIndexer::CocoaLineIndexer(const BrowserAccessibilityCocoa* node) {
-  int counter = 0;
-  Build(node, &counter);
-}
-
-NSArray* CocoaLineIndexer::Children(gfx::NativeViewAccessible node) const {
-  return [node children];
-}
-
-AXLineIndexer::AXLineIndexer(const AXUIElementRef node) {
-  int counter = 0;
-  Build(static_cast<id>(node), &counter);
-}
-
-NSArray* AXLineIndexer::Children(gfx::NativeViewAccessible node) const {
-  CFTypeRef children_ref;
-  if ((AXUIElementCopyAttributeValue(static_cast<AXUIElementRef>(node),
-                                     kAXChildrenAttribute, &children_ref)) ==
-      kAXErrorSuccess) {
-    return static_cast<NSArray*>(children_ref);
-  }
-  return nil;
-}
-
 // AttributeInvoker
 
 AttributeInvoker::AttributeInvoker(const BrowserAccessibilityCocoa* cocoa_node,