gecko-dev/dom/base/ChildIterator.cpp

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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* 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 "ChildIterator.h"
#include "nsContentUtils.h"
#include "mozilla/dom/HTMLSlotElement.h"
#include "mozilla/dom/XBLChildrenElement.h"
#include "mozilla/dom/ShadowRoot.h"
#include "nsIAnonymousContentCreator.h"
#include "nsIFrame.h"
#include "nsCSSAnonBoxes.h"
#include "nsDocument.h"
namespace mozilla {
namespace dom {
ExplicitChildIterator::ExplicitChildIterator(const nsIContent* aParent,
bool aStartAtBeginning)
: mParent(aParent),
mChild(nullptr),
mDefaultChild(nullptr),
mIsFirst(aStartAtBeginning),
mIndexInInserted(0)
{
mParentAsSlot = nsDocument::IsShadowDOMEnabled(mParent) ?
HTMLSlotElement::FromNode(mParent) : nullptr;
}
nsIContent*
ExplicitChildIterator::GetNextChild()
{
// If we're already in the inserted-children array, look there first
if (mIndexInInserted) {
MOZ_ASSERT(mChild);
MOZ_ASSERT(!mDefaultChild);
if (mParentAsSlot) {
const nsTArray<RefPtr<nsINode>>& assignedNodes =
mParentAsSlot->AssignedNodes();
mChild = (mIndexInInserted < assignedNodes.Length()) ?
assignedNodes[mIndexInInserted++]->AsContent() : nullptr;
return mChild;
}
MOZ_ASSERT(mChild->IsActiveChildrenElement());
auto* childrenElement =
static_cast<XBLChildrenElement*>(mChild);
if (mIndexInInserted < childrenElement->InsertedChildrenLength()) {
return childrenElement->InsertedChild(mIndexInInserted++);
}
mIndexInInserted = 0;
mChild = mChild->GetNextSibling();
} else if (mDefaultChild) {
// If we're already in default content, check if there are more nodes there
MOZ_ASSERT(mChild);
MOZ_ASSERT(mChild->IsActiveChildrenElement());
mDefaultChild = mDefaultChild->GetNextSibling();
if (mDefaultChild) {
return mDefaultChild;
}
mChild = mChild->GetNextSibling();
} else if (mIsFirst) { // at the beginning of the child list
// For slot parent, iterate over assigned nodes if not empty, otherwise
// fall through and iterate over direct children (fallback content).
if (mParentAsSlot) {
const nsTArray<RefPtr<nsINode>>& assignedNodes =
mParentAsSlot->AssignedNodes();
if (!assignedNodes.IsEmpty()) {
mIndexInInserted = 1;
mChild = assignedNodes[0]->AsContent();
mIsFirst = false;
return mChild;
}
}
mChild = mParent->GetFirstChild();
mIsFirst = false;
} else if (mChild) { // in the middle of the child list
mChild = mChild->GetNextSibling();
}
// Iterate until we find a non-insertion point, or an insertion point with
// content.
while (mChild) {
if (mChild->IsActiveChildrenElement()) {
// If the current child being iterated is a content insertion point
// then the iterator needs to return the nodes distributed into
// the content insertion point.
auto* childrenElement =
static_cast<XBLChildrenElement*>(mChild);
if (childrenElement->HasInsertedChildren()) {
// Iterate through elements projected on insertion point.
mIndexInInserted = 1;
return childrenElement->InsertedChild(0);
}
// Insertion points inside fallback/default content
// are considered inactive and do not get assigned nodes.
mDefaultChild = mChild->GetFirstChild();
if (mDefaultChild) {
return mDefaultChild;
}
// If we have an insertion point with no assigned nodes and
// no default content, move on to the next node.
mChild = mChild->GetNextSibling();
} else {
// mChild is not an insertion point, thus it is the next node to
// return from this iterator.
break;
}
}
return mChild;
}
void
FlattenedChildIterator::Init(bool aIgnoreXBL)
{
if (aIgnoreXBL) {
mXBLInvolved = Some(false);
return;
}
// TODO(emilio): I think it probably makes sense to only allow constructing
// FlattenedChildIterators with Element.
if (mParent->IsElement()) {
if (ShadowRoot* shadow = mParent->AsElement()->GetShadowRoot()) {
mParent = shadow;
mXBLInvolved = Some(true);
return;
}
}
nsXBLBinding* binding =
mParent->OwnerDoc()->BindingManager()->GetBindingWithContent(mParent);
if (binding) {
MOZ_ASSERT(binding->GetAnonymousContent());
mParent = binding->GetAnonymousContent();
mXBLInvolved = Some(true);
}
}
bool
FlattenedChildIterator::ComputeWhetherXBLIsInvolved() const
{
MOZ_ASSERT(mXBLInvolved.isNothing());
// We set mXBLInvolved to true if either the node we're iterating has a
// binding with content attached to it (in which case it is handled in Init),
// or the node is generated XBL content and has an <xbl:children> child.
if (!mParent->GetBindingParent()) {
return false;
}
for (nsIContent* child = mParent->GetFirstChild();
child;
child = child->GetNextSibling()) {
if (child->NodeInfo()->Equals(nsGkAtoms::children, kNameSpaceID_XBL)) {
MOZ_ASSERT(child->GetBindingParent());
return true;
}
}
return false;
}
bool
ExplicitChildIterator::Seek(const nsIContent* aChildToFind)
{
if (aChildToFind->GetParent() == mParent &&
!aChildToFind->IsRootOfAnonymousSubtree()) {
// Fast path: just point ourselves to aChildToFind, which is a
// normal DOM child of ours.
mChild = const_cast<nsIContent*>(aChildToFind);
mIndexInInserted = 0;
mDefaultChild = nullptr;
mIsFirst = false;
MOZ_ASSERT(!mChild->IsActiveChildrenElement());
return true;
}
// Can we add more fast paths here based on whether the parent of aChildToFind
// is a shadow insertion point or content insertion point?
// Slow path: just walk all our kids.
return Seek(aChildToFind, nullptr);
}
nsIContent*
ExplicitChildIterator::Get() const
{
MOZ_ASSERT(!mIsFirst);
// When mParentAsSlot is set, mChild is always set to the current child. It
// does not matter whether mChild is an assigned node or a fallback content.
if (mParentAsSlot) {
return mChild;
}
if (mIndexInInserted) {
MOZ_ASSERT(mChild->IsActiveChildrenElement());
auto* childrenElement = static_cast<XBLChildrenElement*>(mChild);
return childrenElement->InsertedChild(mIndexInInserted - 1);
}
return mDefaultChild ? mDefaultChild : mChild;
}
nsIContent*
ExplicitChildIterator::GetPreviousChild()
{
// If we're already in the inserted-children array, look there first
if (mIndexInInserted) {
if (mParentAsSlot) {
const nsTArray<RefPtr<nsINode>>& assignedNodes =
mParentAsSlot->AssignedNodes();
mChild = (--mIndexInInserted) ?
assignedNodes[mIndexInInserted - 1]->AsContent() : nullptr;
if (!mChild) {
mIsFirst = true;
}
return mChild;
}
// NB: mIndexInInserted points one past the last returned child so we need
// to look *two* indices back in order to return the previous child.
MOZ_ASSERT(mChild->IsActiveChildrenElement());
auto* childrenElement = static_cast<XBLChildrenElement*>(mChild);
if (--mIndexInInserted) {
return childrenElement->InsertedChild(mIndexInInserted - 1);
}
mChild = mChild->GetPreviousSibling();
} else if (mDefaultChild) {
// If we're already in default content, check if there are more nodes there
mDefaultChild = mDefaultChild->GetPreviousSibling();
if (mDefaultChild) {
return mDefaultChild;
}
mChild = mChild->GetPreviousSibling();
} else if (mIsFirst) { // at the beginning of the child list
return nullptr;
} else if (mChild) { // in the middle of the child list
mChild = mChild->GetPreviousSibling();
} else { // at the end of the child list
// For slot parent, iterate over assigned nodes if not empty, otherwise
// fall through and iterate over direct children (fallback content).
if (mParentAsSlot) {
const nsTArray<RefPtr<nsINode>>& assignedNodes =
mParentAsSlot->AssignedNodes();
if (!assignedNodes.IsEmpty()) {
mIndexInInserted = assignedNodes.Length();
mChild = assignedNodes[mIndexInInserted - 1]->AsContent();
return mChild;
}
}
mChild = mParent->GetLastChild();
}
// Iterate until we find a non-insertion point, or an insertion point with
// content.
while (mChild) {
if (mChild->IsActiveChildrenElement()) {
// If the current child being iterated is a content insertion point
// then the iterator needs to return the nodes distributed into
// the content insertion point.
auto* childrenElement = static_cast<XBLChildrenElement*>(mChild);
if (childrenElement->HasInsertedChildren()) {
mIndexInInserted = childrenElement->InsertedChildrenLength();
return childrenElement->InsertedChild(mIndexInInserted - 1);
}
mDefaultChild = mChild->GetLastChild();
if (mDefaultChild) {
return mDefaultChild;
}
mChild = mChild->GetPreviousSibling();
} else {
// mChild is not an insertion point, thus it is the next node to
// return from this iterator.
break;
}
}
if (!mChild) {
mIsFirst = true;
}
return mChild;
}
nsIContent*
AllChildrenIterator::Get() const
{
switch (mPhase) {
case eAtBeforeKid: {
Element* before = nsLayoutUtils::GetBeforePseudo(mOriginalContent);
MOZ_ASSERT(before, "No content before frame at eAtBeforeKid phase");
return before;
}
case eAtExplicitKids:
return ExplicitChildIterator::Get();
case eAtAnonKids:
return mAnonKids[mAnonKidsIdx];
case eAtAfterKid: {
Element* after = nsLayoutUtils::GetAfterPseudo(mOriginalContent);
MOZ_ASSERT(after, "No content after frame at eAtAfterKid phase");
return after;
}
default:
return nullptr;
}
}
bool
AllChildrenIterator::Seek(const nsIContent* aChildToFind)
{
if (mPhase == eAtBegin || mPhase == eAtBeforeKid) {
mPhase = eAtExplicitKids;
Element* beforePseudo = nsLayoutUtils::GetBeforePseudo(mOriginalContent);
if (beforePseudo && beforePseudo == aChildToFind) {
mPhase = eAtBeforeKid;
return true;
}
}
if (mPhase == eAtExplicitKids) {
if (ExplicitChildIterator::Seek(aChildToFind)) {
return true;
}
mPhase = eAtAnonKids;
}
nsIContent* child = nullptr;
do {
child = GetNextChild();
} while (child && child != aChildToFind);
return child == aChildToFind;
}
void
AllChildrenIterator::AppendNativeAnonymousChildren()
{
nsContentUtils::AppendNativeAnonymousChildren(
mOriginalContent, mAnonKids, mFlags);
}
nsIContent*
AllChildrenIterator::GetNextChild()
{
if (mPhase == eAtBegin) {
mPhase = eAtExplicitKids;
Element* beforeContent = nsLayoutUtils::GetBeforePseudo(mOriginalContent);
if (beforeContent) {
mPhase = eAtBeforeKid;
return beforeContent;
}
}
if (mPhase == eAtBeforeKid) {
// Advance into our explicit kids.
mPhase = eAtExplicitKids;
}
if (mPhase == eAtExplicitKids) {
nsIContent* kid = ExplicitChildIterator::GetNextChild();
if (kid) {
return kid;
}
mPhase = eAtAnonKids;
}
if (mPhase == eAtAnonKids) {
if (mAnonKids.IsEmpty()) {
MOZ_ASSERT(mAnonKidsIdx == UINT32_MAX);
AppendNativeAnonymousChildren();
mAnonKidsIdx = 0;
}
else {
if (mAnonKidsIdx == UINT32_MAX) {
mAnonKidsIdx = 0;
}
else {
mAnonKidsIdx++;
}
}
if (mAnonKidsIdx < mAnonKids.Length()) {
return mAnonKids[mAnonKidsIdx];
}
Element* afterContent = nsLayoutUtils::GetAfterPseudo(mOriginalContent);
if (afterContent) {
mPhase = eAtAfterKid;
return afterContent;
}
}
mPhase = eAtEnd;
return nullptr;
}
nsIContent*
AllChildrenIterator::GetPreviousChild()
{
if (mPhase == eAtEnd) {
MOZ_ASSERT(mAnonKidsIdx == mAnonKids.Length());
mPhase = eAtAnonKids;
Element* afterContent = nsLayoutUtils::GetAfterPseudo(mOriginalContent);
if (afterContent) {
mPhase = eAtAfterKid;
return afterContent;
}
}
if (mPhase == eAtAfterKid) {
mPhase = eAtAnonKids;
}
if (mPhase == eAtAnonKids) {
if (mAnonKids.IsEmpty()) {
AppendNativeAnonymousChildren();
mAnonKidsIdx = mAnonKids.Length();
}
// If 0 then it turns into UINT32_MAX, which indicates the iterator is
// before the anonymous children.
--mAnonKidsIdx;
if (mAnonKidsIdx < mAnonKids.Length()) {
return mAnonKids[mAnonKidsIdx];
}
mPhase = eAtExplicitKids;
}
if (mPhase == eAtExplicitKids) {
nsIContent* kid = ExplicitChildIterator::GetPreviousChild();
if (kid) {
return kid;
}
Element* beforeContent = nsLayoutUtils::GetBeforePseudo(mOriginalContent);
if (beforeContent) {
mPhase = eAtBeforeKid;
return beforeContent;
}
}
mPhase = eAtBegin;
return nullptr;
}
nsIContent*
StyleChildrenIterator::GetNextChild()
{
return AllChildrenIterator::GetNextChild();
}
} // namespace dom
} // namespace mozilla