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+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* 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_TreeWalker_h_
+#define mozilla_a11y_TreeWalker_h_
+
+#include "mozilla/Attributes.h"
+#include <stdint.h>
+#include "mozilla/dom/ChildIterator.h"
+#include "nsCOMPtr.h"
+
+class nsIContent;
+
+namespace mozilla {
+namespace a11y {
+
+class Accessible;
+class DocAccessible;
+
+/**
+ * This class is used to walk the DOM tree to create accessible tree.
+ */
+class TreeWalker final
+{
+public:
+ enum {
+ // used to walk the existing tree of the given node
+ eWalkCache = 1,
+ // used to walk the context tree starting from given node
+ eWalkContextTree = 2 | eWalkCache
+ };
+
+ /**
+ * Used to navigate and create if needed the accessible children.
+ */
+ explicit TreeWalker(Accessible* aContext);
+
+ /**
+ * Used to navigate the accessible children relative to the anchor.
+ *
+ * @param aContext [in] container accessible for the given node, used to
+ * define accessible context
+ * @param aAnchorNode [in] the node the search will be prepared relative to
+ * @param aFlags [in] flags (see enum above)
+ */
+ TreeWalker(Accessible* aContext, nsIContent* aAnchorNode, uint32_t aFlags = eWalkCache);
+
+ ~TreeWalker();
+
+ /**
+ * Resets the walker state, and sets the given node as an anchor. Returns a
+ * first accessible element within the node including the node itself.
+ */
+ Accessible* Scope(nsIContent* aAnchorNode);
+
+ /**
+ * Resets the walker state.
+ */
+ void Reset()
+ {
+ mPhase = eAtStart;
+ mStateStack.Clear();
+ mARIAOwnsIdx = 0;
+ }
+
+ /**
+ * Sets the walker state to the given child node if it's within the anchor.
+ */
+ bool Seek(nsIContent* aChildNode);
+
+ /**
+ * Return the next/prev accessible.
+ *
+ * @note Returned accessible is bound to the document, if the accessible is
+ * rejected during tree creation then the caller should be unbind it
+ * from the document.
+ */
+ Accessible* Next();
+ Accessible* Prev();
+
+ Accessible* Context() const { return mContext; }
+ DocAccessible* Document() const { return mDoc; }
+
+private:
+ TreeWalker();
+ TreeWalker(const TreeWalker&);
+ TreeWalker& operator =(const TreeWalker&);
+
+ /**
+ * Return an accessible for the given node if any.
+ */
+ Accessible* AccessibleFor(nsIContent* aNode, uint32_t aFlags,
+ bool* aSkipSubtree);
+
+ /**
+ * Create new state for the given node and push it on top of stack / at bottom
+ * of stack.
+ *
+ * @note State stack is used to navigate up/down the DOM subtree during
+ * accessible children search.
+ */
+ dom::AllChildrenIterator* PushState(nsIContent* aContent,
+ bool aStartAtBeginning)
+ {
+ return mStateStack.AppendElement(
+ dom::AllChildrenIterator(aContent, mChildFilter, aStartAtBeginning));
+ }
+ dom::AllChildrenIterator* PrependState(nsIContent* aContent,
+ bool aStartAtBeginning)
+ {
+ return mStateStack.InsertElementAt(0,
+ dom::AllChildrenIterator(aContent, mChildFilter, aStartAtBeginning));
+ }
+
+ /**
+ * Pop state from stack.
+ */
+ dom::AllChildrenIterator* PopState();
+
+ DocAccessible* mDoc;
+ Accessible* mContext;
+ nsIContent* mAnchorNode;
+
+ AutoTArray<dom::AllChildrenIterator, 20> mStateStack;
+ uint32_t mARIAOwnsIdx;
+
+ int32_t mChildFilter;
+ uint32_t mFlags;
+
+ enum Phase {
+ eAtStart,
+ eAtDOM,
+ eAtARIAOwns,
+ eAtEnd
+ };
+ Phase mPhase;
+};
+
+} // namespace a11y
+} // namespace mozilla
+
+#endif // mozilla_a11y_TreeWalker_h_