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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 */
#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 LocalAccessible;
class DocAccessible;
* This class is used to walk the DOM tree to create accessible tree.
class TreeWalker final {
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,
eScoped = 4
* Used to navigate and create if needed the accessible children.
explicit TreeWalker(LocalAccessible* 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(LocalAccessible* aContext, nsIContent* aAnchorNode,
uint32_t aFlags = eWalkCache);
* Navigates the accessible children within the anchor node subtree.
TreeWalker(DocAccessible* aDocument, nsIContent* aAnchorNode);
* Resets the walker state, and sets the given node as an anchor. Returns a
* first accessible element within the node including the node itself.
LocalAccessible* Scope(nsIContent* aAnchorNode);
* Resets the walker state.
void Reset() {
mPhase = eAtStart;
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.
LocalAccessible* Next();
LocalAccessible* Prev();
LocalAccessible* Context() const { return mContext; }
DocAccessible* Document() const { return mDoc; }
TreeWalker(const TreeWalker&);
TreeWalker& operator=(const TreeWalker&);
* Return an accessible for the given node if any.
LocalAccessible* 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;
LocalAccessible* 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_