gecko-dev/accessible/base/TreeWalker.cpp

111 lines
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/. */
#include "TreeWalker.h"
#include "Accessible.h"
#include "nsAccessibilityService.h"
#include "DocAccessible.h"
#include "mozilla/dom/ChildIterator.h"
#include "mozilla/dom/Element.h"
using namespace mozilla;
using namespace mozilla::a11y;
////////////////////////////////////////////////////////////////////////////////
// TreeWalker
////////////////////////////////////////////////////////////////////////////////
TreeWalker::
TreeWalker(Accessible* aContext, nsIContent* aContent, uint32_t aFlags) :
mDoc(aContext->Document()), mContext(aContext), mAnchorNode(aContent),
mFlags(aFlags)
{
NS_ASSERTION(aContent, "No node for the accessible tree walker!");
mChildFilter = mContext->CanHaveAnonChildren() ?
nsIContent::eAllChildren : nsIContent::eAllButXBL;
mChildFilter |= nsIContent::eSkipPlaceholderContent;
if (aContent)
PushState(aContent);
MOZ_COUNT_CTOR(TreeWalker);
}
TreeWalker::~TreeWalker()
{
MOZ_COUNT_DTOR(TreeWalker);
}
////////////////////////////////////////////////////////////////////////////////
// TreeWalker: private
Accessible*
TreeWalker::NextChild()
{
if (mStateStack.IsEmpty())
return nullptr;
dom::AllChildrenIterator* top = &mStateStack[mStateStack.Length() - 1];
while (top) {
while (nsIContent* childNode = top->GetNextChild()) {
bool isSubtreeHidden = false;
Accessible* accessible = mFlags & eWalkCache ?
mDoc->GetAccessible(childNode) :
GetAccService()->GetOrCreateAccessible(childNode, mContext,
&isSubtreeHidden);
if (accessible)
return accessible;
// Walk down into subtree to find accessibles.
if (!isSubtreeHidden && childNode->IsElement())
top = PushState(childNode);
}
top = PopState();
}
// If we traversed the whole subtree of the anchor node. Move to next node
// relative anchor node within the context subtree if possible.
if (mFlags != eWalkContextTree)
return nullptr;
nsINode* contextNode = mContext->GetNode();
while (mAnchorNode != contextNode) {
nsINode* parentNode = mAnchorNode->GetFlattenedTreeParent();
if (!parentNode || !parentNode->IsElement())
return nullptr;
nsIContent* parent = parentNode->AsElement();
top = mStateStack.AppendElement(dom::AllChildrenIterator(parent,
mChildFilter));
while (nsIContent* childNode = top->GetNextChild()) {
if (childNode == mAnchorNode) {
mAnchorNode = parent;
return NextChild();
}
}
// XXX We really should never get here, it means we're trying to find an
// accessible for a dom node where iterating over its parent's children
// doesn't return it. However this sometimes happens when we're asked for
// the nearest accessible to place holder content which we ignore.
mAnchorNode = parent;
}
return nullptr;
}
dom::AllChildrenIterator*
TreeWalker::PopState()
{
size_t length = mStateStack.Length();
mStateStack.RemoveElementAt(length - 1);
return mStateStack.IsEmpty() ? nullptr : &mStateStack[mStateStack.Length() - 1];
}