gecko-dev/accessible/base/TreeWalker.h

130 строки
3.4 KiB
C++

/* -*- 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();
/**
* Clears the tree walker state and resets it to the given child 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(nsIContent* aStopNode = nullptr);
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_