diff -r 000000000000 -r 6474c204b198 accessible/src/base/AccCollector.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/accessible/src/base/AccCollector.h	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,95 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_a11y_AccCollector_h__
+#define mozilla_a11y_AccCollector_h__
+
+#include "Filters.h"
+
+#include "nsTArray.h"
+
+namespace mozilla {
+namespace a11y {
+
+class Accessible;
+
+/**
+ * Collect accessible children complying with filter function. Provides quick
+ * access to accessible by index.
+ */
+class AccCollector
+{
+public:
+  AccCollector(Accessible* aRoot, filters::FilterFuncPtr aFilterFunc);
+  virtual ~AccCollector();
+
+  /**
+   * Return accessible count within the collection.
+   */
+  uint32_t Count();
+
+  /**
+   * Return an accessible from the collection at the given index.
+   */
+  Accessible* GetAccessibleAt(uint32_t aIndex);
+
+  /**
+   * Return index of the given accessible within the collection.
+   */
+  virtual int32_t GetIndexAt(Accessible* aAccessible);
+
+protected:
+  /**
+   * Ensure accessible at the given index is stored and return it.
+   */
+  Accessible* EnsureNGetObject(uint32_t aIndex);
+
+  /**
+   * Ensure index for the given accessible is stored and return it.
+   */
+  int32_t EnsureNGetIndex(Accessible* aAccessible);
+
+  /**
+   * Append the object to collection.
+   */
+  virtual void AppendObject(Accessible* aAccessible);
+
+  filters::FilterFuncPtr mFilterFunc;
+  Accessible* mRoot;
+  uint32_t mRootChildIdx;
+
+  nsTArray<Accessible*> mObjects;
+
+private:
+  AccCollector();
+  AccCollector(const AccCollector&);
+  AccCollector& operator =(const AccCollector&);
+};
+
+/**
+ * Collect embedded objects. Provide quick access to accessible by index and
+ * vice versa.
+ */
+class EmbeddedObjCollector : public AccCollector
+{
+public:
+  virtual ~EmbeddedObjCollector() { }
+
+public:
+  virtual int32_t GetIndexAt(Accessible* aAccessible);
+
+protected:
+  // Make sure it's used by Accessible class only.
+  EmbeddedObjCollector(Accessible* aRoot) :
+    AccCollector(aRoot, filters::GetEmbeddedObject) { }
+
+  virtual void AppendObject(Accessible* aAccessible);
+
+  friend class Accessible;
+};
+
+} // namespace a11y
+} // namespace mozilla
+
+#endif