Support the essential part of Shadow DOM v1

third_party/WebKit/Source/core/dom/shadow/ComposedTreeTraversal.cpp

 /*
  * Copyright (C) 2012 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Neither the name of Google Inc. nor the names of its
@@ skipping 12 matching lines @@
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 #include "config.h"
 #include "core/dom/shadow/ComposedTreeTraversal.h"
 
 #include "core/dom/Element.h"
 #include "core/dom/shadow/ElementShadow.h"
 #include "core/html/HTMLShadowElement.h"
+#include "core/html/HTMLSlotElement.h"
 
 namespace blink {
 
 static inline ElementShadow* shadowFor(const Node& node)
 {
     return node.isElementNode() ? toElement(node).shadow() : nullptr;
 }
 
 Node* ComposedTreeTraversal::traverseChild(const Node& node, TraversalDirection direction)
 {
     ElementShadow* shadow = shadowFor(node);
     if (shadow) {
         ShadowRoot& shadowRoot = shadow->youngestShadowRoot();
         return resolveDistributionStartingAt(direction == TraversalDirectionForward ? shadowRoot.firstChild() : shadowRoot.lastChild(), direction);
     }
     return resolveDistributionStartingAt(direction == TraversalDirectionForward ? node.firstChild() : node.lastChild(), direction);
 }
 
 Node* ComposedTreeTraversal::resolveDistributionStartingAt(const Node* node, TraversalDirection direction)
 {
-    for (const Node* sibling = node; sibling; sibling = (direction == TraversalDirectionForward ? sibling->nextSibling() : sibling->previousSibling())) {
+    if (!node)
+        return nullptr;
+    if (node->isInShadowTree() && node->containingShadowRoot()->isV1())
+        return v1ResolveDistributionStartingAt(*node, direction);
+    return v0ResolveDistributionStartingAt(*node, direction);
+}
+
+Node* ComposedTreeTraversal::v0ResolveDistributionStartingAt(const Node& node, TraversalDirection direction)
+{
+    for (const Node* sibling = &node; sibling; sibling = (direction == TraversalDirectionForward ? sibling->nextSibling() : sibling->previousSibling())) {
         if (!isActiveInsertionPoint(*sibling))
             return const_cast<Node*>(sibling);
         const InsertionPoint& insertionPoint = toInsertionPoint(*sibling);
         if (Node* found = (direction == TraversalDirectionForward ? insertionPoint.firstDistributedNode() : insertionPoint.lastDistributedNode()))
             return found;
         ASSERT(isHTMLShadowElement(insertionPoint) || (isHTMLContentElement(insertionPoint) && !insertionPoint.hasChildren()));
     }
     return nullptr;
 }
 
+Node* ComposedTreeTraversal::v1ResolveDistributionStartingAt(const Node& node, TraversalDirection direction)
+{
+    for (const Node* sibling = &node; sibling; sibling = (direction == TraversalDirectionForward ? sibling->nextSibling() : sibling->previousSibling())) {
+        if (!isHTMLSlotElement(*sibling))
+            return const_cast<Node*>(sibling);
+        const HTMLSlotElement& slot = toHTMLSlotElement(*sibling);
+        if (Node* found = (direction == TraversalDirectionForward ? slot.firstDistributedNode() : slot.lastDistributedNode()))
+            return found;
+    }
+    return nullptr;
+}
+
+static HTMLSlotElement* finalDestinationSlotFor(const Node& node)
+{
+    HTMLSlotElement* slot = node.assignedSlot();
+    if (!slot)
+        return nullptr;
+    for (HTMLSlotElement* next = slot->assignedSlot(); next; next = next->assignedSlot()) {
+        slot = next;
+    }
+    return slot;
+}
+
+Node* ComposedTreeTraversal::traverseSiblings(const Node& node, TraversalDirection direction)
+{
+    Node* parent = node.parentNode();
+    if (!parent)
+        return nullptr;
+    if (parent->isElementNode()) {
+        if (ElementShadow* shadow = toElement(parent)->shadow()) {
+            if (shadow->isV1()) {
+                return v1TraverseSiblings(node, direction);
+            }
+        }
+    }
+    return v0TraverseSiblings(node, direction);
+}
+
 // TODO(hayato): This may return a wrong result for a node which is not in a
 // document composed tree.  See ComposedTreeTraversalTest's redistribution test for details.
-Node* ComposedTreeTraversal::traverseSiblings(const Node& node, TraversalDirection direction)
+// TODO(hayato): Fix for v1

[kochi, 2015/12/09 12:02:27]

Could you be more specific about what to be fixed?

[hayato, 2015/12/10 02:17:31]

Done. I've removed this.

+Node* ComposedTreeTraversal::v0TraverseSiblings(const Node& node, TraversalDirection direction)
 {
     if (!shadowWhereNodeCanBeDistributed(node))
         return traverseSiblingsOrShadowInsertionPointSiblings(node, direction);
 
     const InsertionPoint* finalDestination = resolveReprojection(&node);
     if (!finalDestination)
         return nullptr;
     if (Node* found = (direction == TraversalDirectionForward ? finalDestination->distributedNodeNextTo(&node) : finalDestination->distributedNodePreviousTo(&node)))
         return found;
     return traverseSiblings(*finalDestination, direction);
 }
 
+Node* ComposedTreeTraversal::v1TraverseSiblings(const Node& node, TraversalDirection direction)
+{
+    HTMLSlotElement* slot = finalDestinationSlotFor(node);
+    if (!slot)
+        return resolveDistributionStartingAt(direction == TraversalDirectionForward ? node.nextSibling() : node.previousSibling(), direction);
+    if (Node* siblingInDistributedNodes = (direction == TraversalDirectionForward ? slot->distributedNodeNextTo(node) : slot->distributedNodePreviousTo(node)))
+        return siblingInDistributedNodes;
+    return v1TraverseSiblings(*slot, direction);
+}
+
 Node* ComposedTreeTraversal::traverseSiblingsOrShadowInsertionPointSiblings(const Node& node, TraversalDirection direction)
 {
     if (Node* found = resolveDistributionStartingAt(direction == TraversalDirectionForward ? node.nextSibling() : node.previousSibling(), direction))
         return found;
 
     if (node.parentNode() && node.parentNode()->isShadowRoot()) {
         ShadowRoot* parentShadowRoot = toShadowRoot(node.parentNode());
         if (!parentShadowRoot->isYoungest()) {
             HTMLShadowElement* assignedInsertionPoint = parentShadowRoot->shadowInsertionPointOfYoungerShadowRoot();
             ASSERT(assignedInsertionPoint);
             return traverseSiblingsOrShadowInsertionPointSiblings(*assignedInsertionPoint, direction);
         }
     }
     return nullptr;
 }
 
-// FIXME: Use an iterative algorithm so that it can be inlined.
-// https://bugs.webkit.org/show_bug.cgi?id=90415
+static ElementShadow* parentElementShadow(const Node& node)

[kochi, 2015/12/09 12:02:27]

nit: this function looks a part of Node::assignedSlot().
Can this be moved to some header file (ElementShadow.h?)?

[hayato, 2015/12/10 02:17:31]

This function is too specific to the file. Let me keep this function as a file
scope static function unless we want to use this function in other places.

+{
+    Node* parent = node.parentNode();
+    if (!parent)
+        return nullptr;
+    if (parent->isElementNode())
+        return toElement(parent)->shadow();
+    return nullptr;
+}
+
 ContainerNode* ComposedTreeTraversal::traverseParent(const Node& node, ParentTraversalDetails* details)
 {
     // TODO(hayato): Stop this hack for a pseudo element because a pseudo element is not a child of its parentOrShadowHostNode() in a composed tree.
     if (node.isPseudoElement())
         return node.parentOrShadowHostNode();
 
-    if (shadowWhereNodeCanBeDistributed(node)) {
-        if (const InsertionPoint* insertionPoint = resolveReprojection(&node)) {
-            if (details)
-                details->didTraverseInsertionPoint(insertionPoint);
-            // The node is distributed. But the distribution was stopped at this insertion point.
-            if (shadowWhereNodeCanBeDistributed(*insertionPoint))
-                return nullptr;
-            return traverseParentOrHost(*insertionPoint);
-        }
+    ElementShadow* shadow = parentElementShadow(node);
+    if (shadow && shadow->isV1())
+        return v1TraverseParent(node);
+    if (shadowWhereNodeCanBeDistributed(node))
+        return v0TraverseParent(node, details);
+    return traverseParentOrHost(node);
+}
+
+ContainerNode* ComposedTreeTraversal::v1TraverseParent(const Node& node)
+{
+    HTMLSlotElement* slot = finalDestinationSlotFor(node);
+    if (!slot)
+        return nullptr;
+    if (parentElementShadow(*slot)) {
+        // The node is distributed to the |slot|, however, |slot|, which is a
+        // child of a shadow host, is not assigned to any slots.
         return nullptr;
     }
-    return traverseParentOrHost(node);
+    return traverseParentOrHost(*slot);
+}
+
+ContainerNode* ComposedTreeTraversal::v0TraverseParent(const Node& node, ParentTraversalDetails* details)
+{
+    if (const InsertionPoint* insertionPoint = resolveReprojection(&node)) {
+        if (details)
+            details->didTraverseInsertionPoint(insertionPoint);
+        // The node is distributed. But the distribution was stopped at this insertion point.
+        if (shadowWhereNodeCanBeDistributed(*insertionPoint))
+            return nullptr;
+        return traverseParentOrHost(*insertionPoint);
+    }
+    return nullptr;
 }
 
 inline ContainerNode* ComposedTreeTraversal::traverseParentOrHost(const Node& node)
 {
+    // TODO(hayato): Support fallback contents of slots. The parent can be a slot.
     ContainerNode* parent = node.parentNode();
     if (!parent)
         return nullptr;
     if (!parent->isShadowRoot())
         return parent;
     ShadowRoot* shadowRoot = toShadowRoot(parent);
     ASSERT(!shadowRoot->shadowInsertionPointOfYoungerShadowRoot());
     if (!shadowRoot->isYoungest())
         return nullptr;
     Element* host = shadowRoot->host();
@@ skipping 148 matching lines @@
 Node& ComposedTreeTraversal::lastWithinOrSelf(const Node& node)
 {
     assertPrecondition(node);
     Node* lastDescendant = lastWithin(node);
     Node& result = lastDescendant ? *lastDescendant : const_cast<Node&>(node);
     assertPostcondition(&result);
     return result;
 }
 
 } // namespace