Add AXTreeDelegate and refactor other AXTree classes slightly.

ui/accessibility/ax_serializable_tree.cc

 // Copyright 2013 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.
 
 #include "ui/accessibility/ax_serializable_tree.h"
 
 #include "ui/accessibility/ax_node.h"
 
 namespace ui {
 
 // This class is an implementation of the AXTreeSource interface with
 // AXNode as the node type, that just delegates to an AXTree. The purpose
 // of this is so that AXTreeSerializer only needs to work with the
 // AXTreeSource abstraction and doesn't need to actually know about
 // AXTree directly. Another AXTreeSource is used to abstract the Blink
 // accessibility tree.
-class AX_EXPORT AXTreeSourceAdapter : public AXTreeSource<AXNode> {
+class AX_EXPORT AXTreeSourceAdapter : public AXTreeSource<const AXNode*> {
  public:
   AXTreeSourceAdapter(AXTree* tree) : tree_(tree) {}
   virtual ~AXTreeSourceAdapter() {}
 
   // AXTreeSource implementation.
   virtual AXNode* GetRoot() const OVERRIDE {
     return tree_->GetRoot();
   }
 
   virtual AXNode* GetFromId(int32 id) const OVERRIDE {
     return tree_->GetFromId(id);
   }
 
   virtual int32 GetId(const AXNode* node) const OVERRIDE {
     return node->id();
   }
 
-  virtual int GetChildCount(const AXNode* node) const OVERRIDE {
-    return node->child_count();
-  }
-
-  virtual AXNode* GetChildAtIndex(const AXNode* node, int index)
-      const OVERRIDE {
-    return node->ChildAtIndex(index);
+  virtual void GetChildren(
+      const AXNode* node,
+      std::vector<const AXNode*>* out_children) const OVERRIDE {
+    for (int i = 0; i < node->child_count(); ++i)
+      out_children->push_back(node->ChildAtIndex(i));
   }
 
   virtual AXNode* GetParent(const AXNode* node) const OVERRIDE {
     return node->parent();
   }
 
+  virtual bool IsValid(const AXNode* node) const OVERRIDE {
+    return node != NULL;
+  }
+
+  virtual bool IsEqual(const AXNode* node1,
+                       const AXNode* node2) const OVERRIDE {
+    return node1 == node2;
+  }
+
+  virtual const AXNode* GetNull() const OVERRIDE {

[David Tseng, 2014/02/21 00:33:23]

Is there ever an instance where GetNull wouldn't return NULL?

[dmazzoni, 2014/02/21 06:44:59]

Yes - I had to add this so I can make AXTreeSource<WebAXObject>, because
WebAXObject is just a ref-counted wrapper class, not a pointer - it's never null
itself, you have to call isNull() on it to see if doesn't point to anything.

+    return NULL;
+  }
+
   virtual void SerializeNode(
       const AXNode* node, AXNodeData* out_data) const OVERRIDE {
     *out_data = node->data();
   }
 
  private:
   AXTree* tree_;
 };
 
 AXSerializableTree::AXSerializableTree()
     : AXTree() {}
 
 AXSerializableTree::AXSerializableTree(const AXTreeUpdate& initial_state)
     : AXTree(initial_state) {
 }
 
 AXSerializableTree::~AXSerializableTree() {
 }
 
-AXTreeSource<AXNode>* AXSerializableTree::CreateTreeSource() {
+AXTreeSource<const AXNode*>* AXSerializableTree::CreateTreeSource() {
   return new AXTreeSourceAdapter(this);
 }
 
 }  // namespace ui