import FIREFOX_52_6_0esr_RELEASE from mozilla-esr52 hg repo

dom/base/ChildIterator.cpp

@@ -0,0 +1,616 @@
+/* -*- 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/XBLChildrenElement.h"
+#include "mozilla/dom/HTMLContentElement.h"
+#include "mozilla/dom/HTMLShadowElement.h"
+#include "mozilla/dom/ShadowRoot.h"
+#include "nsIAnonymousContentCreator.h"
+#include "nsIFrame.h"
+#include "nsCSSAnonBoxes.h"
+
+namespace mozilla {
+namespace dom {
+
+class MatchedNodes {
+public:
+  explicit MatchedNodes(HTMLContentElement* aInsertionPoint)
+    : mIsContentElement(true), mContentElement(aInsertionPoint) {}
+
+  explicit MatchedNodes(XBLChildrenElement* aInsertionPoint)
+    : mIsContentElement(false), mChildrenElement(aInsertionPoint) {}
+
+  uint32_t Length() const
+  {
+    return mIsContentElement ? mContentElement->MatchedNodes().Length()
+                             : mChildrenElement->InsertedChildrenLength();
+  }
+
+  nsIContent* operator[](int32_t aIndex) const
+  {
+    return mIsContentElement ? mContentElement->MatchedNodes()[aIndex]
+                             : mChildrenElement->InsertedChild(aIndex);
+  }
+
+  bool IsEmpty() const
+  {
+    return mIsContentElement ? mContentElement->MatchedNodes().IsEmpty()
+                             : !mChildrenElement->HasInsertedChildren();
+  }
+protected:
+  bool mIsContentElement;
+  union {
+    HTMLContentElement* mContentElement;
+    XBLChildrenElement* mChildrenElement;
+  };
+};
+
+static inline MatchedNodes
+GetMatchedNodesForPoint(nsIContent* aContent)
+{
+  if (aContent->NodeInfo()->Equals(nsGkAtoms::children, kNameSpaceID_XBL)) {
+    // XBL case
+    return MatchedNodes(static_cast<XBLChildrenElement*>(aContent));
+  }
+
+  // Web components case
+  MOZ_ASSERT(aContent->IsHTMLElement(nsGkAtoms::content));
+  return MatchedNodes(HTMLContentElement::FromContent(aContent));
+}
+
+nsIContent*
+ExplicitChildIterator::GetNextChild()
+{
+  // If we're already in the inserted-children array, look there first
+  if (mIndexInInserted) {
+    MOZ_ASSERT(mChild);
+    MOZ_ASSERT(nsContentUtils::IsContentInsertionPoint(mChild));
+    MOZ_ASSERT(!mDefaultChild);
+
+    MatchedNodes assignedChildren = GetMatchedNodesForPoint(mChild);
+    if (mIndexInInserted < assignedChildren.Length()) {
+      return assignedChildren[mIndexInInserted++];
+    }
+    mIndexInInserted = 0;
+    mChild = mChild->GetNextSibling();
+  } else if (mShadowIterator) {
+    // If we're inside of a <shadow> element, look through the
+    // explicit children of the projected ShadowRoot via
+    // the mShadowIterator.
+    nsIContent* nextChild = mShadowIterator->GetNextChild();
+    if (nextChild) {
+      return nextChild;
+    }
+
+    mShadowIterator = nullptr;
+    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(nsContentUtils::IsContentInsertionPoint(mChild));
+
+    mDefaultChild = mDefaultChild->GetNextSibling();
+    if (mDefaultChild) {
+      return mDefaultChild;
+    }
+
+    mChild = mChild->GetNextSibling();
+  } else if (mIsFirst) {  // at the beginning of the child list
+    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 the current child being iterated is a shadow insertion point then
+    // the iterator needs to go into the projected ShadowRoot.
+    if (ShadowRoot::IsShadowInsertionPoint(mChild)) {
+      // Look for the next child in the projected ShadowRoot for the <shadow>
+      // element.
+      HTMLShadowElement* shadowElem = HTMLShadowElement::FromContent(mChild);
+      ShadowRoot* projectedShadow = shadowElem->GetOlderShadowRoot();
+      if (projectedShadow) {
+        mShadowIterator = new ExplicitChildIterator(projectedShadow);
+        nsIContent* nextChild = mShadowIterator->GetNextChild();
+        if (nextChild) {
+          return nextChild;
+        }
+        mShadowIterator = nullptr;
+      }
+      mChild = mChild->GetNextSibling();
+    } else if (nsContentUtils::IsContentInsertionPoint(mChild)) {
+      // 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.
+      MatchedNodes assignedChildren = GetMatchedNodesForPoint(mChild);
+      if (!assignedChildren.IsEmpty()) {
+        // Iterate through elements projected on insertion point.
+        mIndexInInserted = 1;
+        return assignedChildren[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) {
+    return;
+  }
+
+  nsXBLBinding* binding =
+    mParent->OwnerDoc()->BindingManager()->GetBindingWithContent(mParent);
+
+  if (binding) {
+    nsIContent* anon = binding->GetAnonymousContent();
+    if (anon) {
+      mParent = anon;
+      mXBLInvolved = true;
+    }
+  }
+
+  // We set mXBLInvolved to true if either:
+  // - The node we're iterating has a binding with content attached to it.
+  // - The node is generated XBL content and has an <xbl:children> child.
+  if (!mXBLInvolved && mParent->GetBindingParent()) {
+    for (nsIContent* child = mParent->GetFirstChild();
+         child;
+         child = child->GetNextSibling()) {
+      if (child->NodeInfo()->Equals(nsGkAtoms::children, kNameSpaceID_XBL)) {
+        MOZ_ASSERT(child->GetBindingParent());
+        mXBLInvolved = true;
+        break;
+      }
+    }
+  }
+}
+
+bool
+ExplicitChildIterator::Seek(nsIContent* aChildToFind)
+{
+  if (aChildToFind->GetParent() == mParent &&
+      !aChildToFind->IsRootOfAnonymousSubtree()) {
+    // Fast path: just point ourselves to aChildToFind, which is a
+    // normal DOM child of ours.
+    MOZ_ASSERT(!ShadowRoot::IsShadowInsertionPoint(aChildToFind));
+    MOZ_ASSERT(!nsContentUtils::IsContentInsertionPoint(aChildToFind));
+    mChild = aChildToFind;
+    mIndexInInserted = 0;
+    mShadowIterator = nullptr;
+    mDefaultChild = nullptr;
+    mIsFirst = false;
+    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);
+
+  if (mIndexInInserted) {
+    MatchedNodes assignedChildren = GetMatchedNodesForPoint(mChild);
+    return assignedChildren[mIndexInInserted - 1];
+  } else if (mShadowIterator)  {
+    return mShadowIterator->Get();
+  }
+  return mDefaultChild ? mDefaultChild : mChild;
+}
+
+nsIContent*
+ExplicitChildIterator::GetPreviousChild()
+{
+  // If we're already in the inserted-children array, look there first
+  if (mIndexInInserted) {
+    // NB: mIndexInInserted points one past the last returned child so we need
+    // to look *two* indices back in order to return the previous child.
+    MatchedNodes assignedChildren = GetMatchedNodesForPoint(mChild);
+    if (--mIndexInInserted) {
+      return assignedChildren[mIndexInInserted - 1];
+    }
+    mChild = mChild->GetPreviousSibling();
+  } else if (mShadowIterator) {
+    nsIContent* previousChild = mShadowIterator->GetPreviousChild();
+    if (previousChild) {
+      return previousChild;
+    }
+    mShadowIterator = nullptr;
+    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
+    mChild = mParent->GetLastChild();
+  }
+
+  // Iterate until we find a non-insertion point, or an insertion point with
+  // content.
+  while (mChild) {
+    if (ShadowRoot::IsShadowInsertionPoint(mChild)) {
+      // If the current child being iterated is a shadow insertion point then
+      // the iterator needs to go into the projected ShadowRoot.
+      HTMLShadowElement* shadowElem = HTMLShadowElement::FromContent(mChild);
+      ShadowRoot* projectedShadow = shadowElem->GetOlderShadowRoot();
+      if (projectedShadow) {
+        // Create a ExplicitChildIterator that begins iterating from the end.
+        mShadowIterator = new ExplicitChildIterator(projectedShadow, false);
+        nsIContent* previousChild = mShadowIterator->GetPreviousChild();
+        if (previousChild) {
+          return previousChild;
+        }
+        mShadowIterator = nullptr;
+      }
+      mChild = mChild->GetPreviousSibling();
+    } else if (nsContentUtils::IsContentInsertionPoint(mChild)) {
+      // 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.
+      MatchedNodes assignedChildren = GetMatchedNodesForPoint(mChild);
+      if (!assignedChildren.IsEmpty()) {
+        mIndexInInserted = assignedChildren.Length();
+        return assignedChildren[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: {
+      nsIFrame* frame = mOriginalContent->GetPrimaryFrame();
+      MOZ_ASSERT(frame, "No frame at eAtBeforeKid phase");
+      nsIFrame* beforeFrame = nsLayoutUtils::GetBeforeFrame(frame);
+      MOZ_ASSERT(beforeFrame, "No content before frame at eAtBeforeKid phase");
+      return beforeFrame->GetContent();
+    }
+
+    case eAtExplicitKids:
+      return ExplicitChildIterator::Get();
+
+    case eAtAnonKids:
+      return mAnonKids[mAnonKidsIdx];
+
+    case eAtAfterKid: {
+      nsIFrame* frame = mOriginalContent->GetPrimaryFrame();
+      MOZ_ASSERT(frame, "No frame at eAtAfterKid phase");
+      nsIFrame* afterFrame = nsLayoutUtils::GetAfterFrame(frame);
+      MOZ_ASSERT(afterFrame, "No content before frame at eAtBeforeKid phase");
+      return afterFrame->GetContent();
+    }
+
+    default:
+      return nullptr;
+  }
+}
+
+
+bool
+AllChildrenIterator::Seek(nsIContent* aChildToFind)
+{
+  if (mPhase == eAtBegin || mPhase == eAtBeforeKid) {
+    mPhase = eAtExplicitKids;
+    nsIFrame* frame = mOriginalContent->GetPrimaryFrame();
+    if (frame) {
+      nsIFrame* beforeFrame = nsLayoutUtils::GetBeforeFrame(frame);
+      if (beforeFrame) {
+        if (beforeFrame->GetContent() == 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()
+{
+  AppendNativeAnonymousChildrenFromFrame(mOriginalContent->GetPrimaryFrame());
+
+  // The root scroll frame is not the primary frame of the root element.
+  // Detect and handle this case.
+  if (mOriginalContent == mOriginalContent->OwnerDoc()->GetRootElement()) {
+    nsIPresShell* presShell = mOriginalContent->OwnerDoc()->GetShell();
+    nsIFrame* scrollFrame = presShell ? presShell->GetRootScrollFrame() : nullptr;
+    if (scrollFrame) {
+      AppendNativeAnonymousChildrenFromFrame(scrollFrame);
+    }
+  }
+}
+
+void
+AllChildrenIterator::AppendNativeAnonymousChildrenFromFrame(nsIFrame* aFrame)
+{
+  nsIAnonymousContentCreator* ac = do_QueryFrame(aFrame);
+  if (ac) {
+    ac->AppendAnonymousContentTo(mAnonKids, mFlags);
+  }
+}
+
+nsIContent*
+AllChildrenIterator::GetNextChild()
+{
+  if (mPhase == eAtBegin) {
+    mPhase = eAtExplicitKids;
+    nsIFrame* frame = mOriginalContent->GetPrimaryFrame();
+    if (frame) {
+      nsIFrame* beforeFrame = nsLayoutUtils::GetBeforeFrame(frame);
+      if (beforeFrame) {
+        mPhase = eAtBeforeKid;
+        return beforeFrame->GetContent();
+      }
+    }
+  }
+
+  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];
+    }
+
+    nsIFrame* frame = mOriginalContent->GetPrimaryFrame();
+    if (frame) {
+      nsIFrame* afterFrame = nsLayoutUtils::GetAfterFrame(frame);
+      if (afterFrame) {
+        mPhase = eAtAfterKid;
+        return afterFrame->GetContent();
+      }
+    }
+  }
+
+  mPhase = eAtEnd;
+  return nullptr;
+}
+
+nsIContent*
+AllChildrenIterator::GetPreviousChild()
+{
+  if (mPhase == eAtEnd) {
+    MOZ_ASSERT(mAnonKidsIdx == mAnonKids.Length());
+    mPhase = eAtAnonKids;
+    nsIFrame* frame = mOriginalContent->GetPrimaryFrame();
+    if (frame) {
+      nsIFrame* afterFrame = nsLayoutUtils::GetAfterFrame(frame);
+      if (afterFrame) {
+        mPhase = eAtAfterKid;
+        return afterFrame->GetContent();
+      }
+    }
+  }
+
+  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;
+    }
+
+    nsIFrame* frame = mOriginalContent->GetPrimaryFrame();
+    if (frame) {
+      nsIFrame* beforeFrame = nsLayoutUtils::GetBeforeFrame(frame);
+      if (beforeFrame) {
+        mPhase = eAtBeforeKid;
+        return beforeFrame->GetContent();
+      }
+    }
+  }
+
+  mPhase = eAtBegin;
+  return nullptr;
+}
+
+static bool
+IsNativeAnonymousImplementationOfPseudoElement(nsIContent* aContent)
+{
+  // First, we need a frame. This leads to the tricky issue of what we can
+  // infer if the frame is null.
+  //
+  // Unlike regular nodes, native anonymous content (NAC) gets created during
+  // frame construction, which happens after the main style traversal. This
+  // means that we have to manually resolve style for those nodes shortly after
+  // they're created, either by (a) invoking ResolvePseudoElementStyle (for PE
+  // NAC), or (b) handing the subtree off to Servo for a mini-traversal (for
+  // non-PE NAC). We have assertions in nsCSSFrameConstructor that we don't do
+  // both.
+  //
+  // Once that happens, the NAC has a frame. So if we have no frame here,
+  // we're either not NAC, or in the process of doing (b). Either way, this
+  // isn't a PE.
+  nsIFrame* f = aContent->GetPrimaryFrame();
+  if (!f) {
+    return false;
+  }
+
+  // Get the pseudo type.
+  CSSPseudoElementType pseudoType = f->StyleContext()->GetPseudoType();
+
+  // In general nodes never get anonymous box style. However, there are a few
+  // special cases:
+  //
+  // * We somewhat-confusingly give text nodes a style context tagged with
+  //   ":-moz-text", so we need to check for the anonymous box case here.
+  // * The primary frame for table elements is an anonymous box that inherits
+  //   from the table's style.
+  if (pseudoType == CSSPseudoElementType::AnonBox) {
+    MOZ_ASSERT(f->StyleContext()->GetPseudo() == nsCSSAnonBoxes::mozText ||
+               f->StyleContext()->GetPseudo() == nsCSSAnonBoxes::tableWrapper);
+    return false;
+  }
+
+  // Finally check the actual pseudo type.
+  bool isImpl = pseudoType != CSSPseudoElementType::NotPseudo;
+  MOZ_ASSERT_IF(isImpl, aContent->IsRootOfNativeAnonymousSubtree());
+  return isImpl;
+}
+
+/* static */ bool
+StyleChildrenIterator::IsNeeded(const Element* aElement)
+{
+  // If the node is in an anonymous subtree, we conservatively return true to
+  // handle insertion points.
+  if (aElement->IsInAnonymousSubtree()) {
+    return true;
+  }
+
+  // If the node has an XBL binding with anonymous content return true.
+  if (aElement->HasFlag(NODE_MAY_BE_IN_BINDING_MNGR)) {
+    nsBindingManager* manager = aElement->OwnerDoc()->BindingManager();
+    nsXBLBinding* binding = manager->GetBindingWithContent(aElement);
+    if (binding && binding->GetAnonymousContent()) {
+      return true;
+    }
+  }
+
+  // If the node has native anonymous content, return true.
+  nsIAnonymousContentCreator* ac = do_QueryFrame(aElement->GetPrimaryFrame());
+  if (ac) {
+    return true;
+  }
+
+  // The root element has a scroll frame that is not the primary frame, so we
+  // need to do special checking for that case.
+  if (aElement == aElement->OwnerDoc()->GetRootElement()) {
+    return true;
+  }
+
+  return false;
+}
+
+
+nsIContent*
+StyleChildrenIterator::GetNextChild()
+{
+  while (nsIContent* child = AllChildrenIterator::GetNextChild()) {
+    if (IsNativeAnonymousImplementationOfPseudoElement(child)) {
+      // Skip any native-anonymous children that are used to implement pseudo-
+      // elements. These match pseudo-element selectors instead of being
+      // considered a child of their host, and thus the style system needs to
+      // handle them separately.
+    } else {
+      return child;
+    }
+  }
+
+  return nullptr;
+}
+
+} // namespace dom
+} // namespace mozilla