Support slotchange event

third_party/WebKit/Source/core/html/HTMLSlotElement.cpp

 /*
  * Copyright (C) 2015 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.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 14 matching lines @@
  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (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 "core/html/HTMLSlotElement.h"
 
 #include "bindings/core/v8/Microtask.h"
 #include "core/HTMLNames.h"
+#include "core/dom/ElementTraversal.h"
 #include "core/dom/NodeTraversal.h"
 #include "core/dom/StyleChangeReason.h"
+#include "core/dom/StyleEngine.h"
 #include "core/dom/shadow/ElementShadow.h"
 #include "core/dom/shadow/InsertionPoint.h"
 #include "core/events/Event.h"
 #include "core/html/AssignedNodesOptions.h"
 
 namespace blink {
 
 using namespace HTMLNames;
 
 inline HTMLSlotElement::HTMLSlotElement(Document& document)
     : HTMLElement(slotTag, document)
     , m_distributionState(DistributionDone)
+    , m_assignmentState(AssignmentDone)
+    , m_slotchangeEventAdded(false)
 {
     setHasCustomStyleCallbacks();
 }
 
 DEFINE_NODE_FACTORY(HTMLSlotElement);
 
 const HeapVector<Member<Node>> HTMLSlotElement::assignedNodesForBinding(const AssignedNodesOptions& options)
 {
     updateDistribution();
     if (options.hasFlatten() && options.flatten())
@@ skipping 20 matching lines @@
             m_distributedNodes.appendVector(toHTMLSlotElement(child).getDistributedNodes());
         else
             m_distributedNodes.append(&child);
     }
     didUpdateDistribution();
     return m_distributedNodes;
 }
 
 void HTMLSlotElement::appendAssignedNode(Node& node)
 {
-    ASSERT(m_distributionState == DistributionOnGoing);
+    ASSERT(m_assignmentState == AssignmentOnGoing);
     m_assignedNodes.append(&node);
 }
 
 void HTMLSlotElement::appendDistributedNode(Node& node)
 {
     ASSERT(m_distributionState == DistributionOnGoing);
     size_t size = m_distributedNodes.size();
     m_distributedNodes.append(&node);
     m_distributedIndices.set(&node, size);
 }
 
+void HTMLSlotElement::appendFallbackNode(Node& node)
+{
+    ASSERT(m_assignmentState == AssignmentOnGoing);
+    m_fallbackNodes.append(&node);
+}
+
 void HTMLSlotElement::appendDistributedNodesFrom(const HTMLSlotElement& other)
 {
     ASSERT(m_distributionState == DistributionOnGoing);
     size_t index = m_distributedNodes.size();
     m_distributedNodes.appendVector(other.m_distributedNodes);
     for (const auto& node : other.m_distributedNodes)
         m_distributedIndices.set(node.get(), index++);
 }
 
+void HTMLSlotElement::willUpdateAssignment()
+{
+    ASSERT(m_assignmentState != AssignmentOnGoing);
+    m_assignmentState = AssignmentOnGoing;
+    m_oldAssignedNodes.swap(m_assignedNodes);
+    m_assignedNodes.clear();
+}
+
 void HTMLSlotElement::willUpdateDistribution()
 {
     ASSERT(m_distributionState != DistributionOnGoing);
     m_distributionState = DistributionOnGoing;
-    m_assignedNodes.clear();
     m_oldDistributedNodes.swap(m_distributedNodes);
     m_distributedNodes.clear();
     m_distributedIndices.clear();
 }
 
-bool HTMLSlotElement::hasSlotChangeEventListener()
+void HTMLSlotElement::willUpdateFallback()
 {
-    return eventTargetData() && eventTargetData()->eventListenerMap.find(EventTypeNames::slotchange);
+    m_oldFallbackNodes.swap(m_fallbackNodes);
+    m_fallbackNodes.clear();
 }
 
 void HTMLSlotElement::dispatchSlotChangeEvent()
 {
     Event* event = Event::create(EventTypeNames::slotchange);
     event->setTarget(this);
     dispatchScopedEvent(event);
+    m_slotchangeEventAdded = false;
 }
 
 Node* HTMLSlotElement::distributedNodeNextTo(const Node& node) const
 {
     const auto& it = m_distributedIndices.find(&node);
     if (it == m_distributedIndices.end())
         return nullptr;
     size_t index = it->value;
     if (index + 1 == m_distributedNodes.size())
         return nullptr;
@@ skipping 32 matching lines @@
         node->lazyReattachIfAttached();
 
     HTMLElement::detach(context);
 }
 
 void HTMLSlotElement::attributeChanged(const QualifiedName& name, const AtomicString& oldValue, const AtomicString& newValue, AttributeModificationReason reason)
 {
     if (name == nameAttr) {
         if (ShadowRoot* root = containingShadowRoot())
             root->owner()->willAffectSelector();
+        document().updateAssignment();
     }
     HTMLElement::attributeChanged(name, oldValue, newValue, reason);
 }
 
 void HTMLSlotElement::childrenChanged(const ChildrenChange& change)
 {
     HTMLElement::childrenChanged(change);
     if (ShadowRoot* root = containingShadowRoot()) {
-        if (ElementShadow* rootOwner = root->owner())
+        if (ElementShadow* rootOwner = root->owner()) {
             rootOwner->setNeedsDistributionRecalc();
+            if (document().shadowCascadeOrder() == ShadowCascadeOrder::ShadowCascadeV1)
+                document().updateAssignment();
+        }
     }
 }
 
 Node::InsertionNotificationRequest HTMLSlotElement::insertedInto(ContainerNode* insertionPoint)
 {
     HTMLElement::insertedInto(insertionPoint);
     if (ShadowRoot* root = containingShadowRoot()) {
         if (ElementShadow* rootOwner = root->owner())
             rootOwner->setNeedsDistributionRecalc();
         if (root == insertionPoint->treeScope().rootNode())
             root->didAddSlot();
     }
 
     // We could have been distributed into in a detached subtree, make sure to
     // clear the distribution when inserted again to avoid cycles.
     clearDistribution();
 
+    if (document().shadowCascadeOrder() == ShadowCascadeOrder::ShadowCascadeV1)
+        document().updateAssignment();
     return InsertionDone;
 }
 
 void HTMLSlotElement::removedFrom(ContainerNode* insertionPoint)
 {
     ShadowRoot* root = containingShadowRoot();
     if (!root)
         root = insertionPoint->containingShadowRoot();
     if (root) {
         if (ElementShadow* rootOwner = root->owner())
             rootOwner->setNeedsDistributionRecalc();
     }
 
     // Since this insertion point is no longer visible from the shadow subtree, it need to clean itself up.
     clearDistribution();
 
     if (root == insertionPoint->treeScope().rootNode())
         root->didRemoveSlot();
-
+    if (document().shadowCascadeOrder() == ShadowCascadeOrder::ShadowCascadeV1) {
+        document().updateAssignment();
+    }
     HTMLElement::removedFrom(insertionPoint);
 }
 
 void HTMLSlotElement::willRecalcStyle(StyleRecalcChange change)
 {
     if (change < Inherit && getStyleChangeType() < SubtreeStyleChange)
         return;
 
     for (auto& node : m_distributedNodes)
         node->setNeedsStyleRecalc(LocalStyleChange, StyleChangeReasonForTracing::create(StyleChangeReason::PropagateInheritChangeToDistributedNodes));
 }
 
-void HTMLSlotElement::updateDistributedNodesWithFallback()
+void HTMLSlotElement::updateFallbackNodes()
 {
-    if (!m_distributedNodes.isEmpty())
+    if (!m_fallbackNodes.isEmpty())
         return;
     for (auto& child : NodeTraversal::childrenOf(*this)) {
         if (!child.isSlotAssignable())
             continue;
         // Insertion points are not supported as slots fallback
         if (isActiveInsertionPoint(child))
             continue;
-        if (isHTMLSlotElement(child))
-            appendDistributedNodesFrom(toHTMLSlotElement(child));
+        appendFallbackNode(child);
+    }
+}
+
+void HTMLSlotElement::updateDistributedNodesWithFallback()
+{
+    if (!m_distributedNodes.isEmpty())
+        return;
+    for (auto node : m_fallbackNodes) {
+        if (isHTMLSlotElement(node))
+            appendDistributedNodesFrom(*toHTMLSlotElement(node));
         else
-            appendDistributedNode(child);
+            appendDistributedNode(*node);
     }
 }
 
+bool HTMLSlotElement::assignmentChanged()
+{
+    ASSERT(m_assignmentState != AssignmentOnGoing);
+    if (m_assignmentState == AssignmentDone)
+        m_assignmentState = m_oldAssignedNodes == m_assignedNodes ? AssignmentUnchanged : AssignmentChanged;
+    return m_assignmentState == AssignmentChanged;
+}
+
 bool HTMLSlotElement::distributionChanged()
 {
     ASSERT(m_distributionState != DistributionOnGoing);
     if (m_distributionState == DistributionDone)
         m_distributionState = m_oldDistributedNodes == m_distributedNodes ? DistributionUnchanged : DistributionChanged;
     return m_distributionState == DistributionChanged;
 }
 
+bool HTMLSlotElement::fallbackChanged()
+{
+    return m_oldFallbackNodes == m_fallbackNodes;
+}
+
+void HTMLSlotElement::didUpdateAssignment()
+{
+    ASSERT(m_assignmentState == AssignmentOnGoing);
+    m_assignmentState = AssignmentDone;
+    if ((assignmentChanged() || fallbackChanged()) && !m_slotchangeEventAdded)
+        fireSlotChangeEvent();
+}
+
 void HTMLSlotElement::didUpdateDistribution()
 {
     ASSERT(m_distributionState == DistributionOnGoing);
     m_distributionState = DistributionDone;
     if (isChildOfV1ShadowHost()) {
         ElementShadow* shadow = parentElementShadow();
         ASSERT(shadow);
         if (!shadow->needsDistributionRecalc() && distributionChanged())
             shadow->setNeedsDistributionRecalc();
     }
-    if (hasSlotChangeEventListener() && distributionChanged()) {
-        // TODO(hayato): Do not enqueue a slotchange event for the same slot twice in the microtask queue
-        Microtask::enqueueMicrotask(WTF::bind(&HTMLSlotElement::dispatchSlotChangeEvent, this));
+}
+
+void HTMLSlotElement::fireSlotChangeEvent()
+{
+    ASSERT(!m_slotchangeEventAdded);
+    Microtask::enqueueMicrotask(WTF::bind(&HTMLSlotElement::dispatchSlotChangeEvent, this));
+    m_slotchangeEventAdded = true;
+
+    Element* shadowHost = isShadowHost(parentElement()) ? parentElement() : nullptr;
+    ShadowRoot* shadowRoot = shadowRootIfV1();
+    if (shadowHost && shadowRoot) {
+        // If this slot is assigned to another slot, fire slot change event of that slot too.
+        const AtomicString& assignedSlot = normalizeSlotName(fastGetAttribute(HTMLNames::slotAttr));
+        if (assignedSlot != emptyAtom) {
+            const HeapVector<Member<HTMLSlotElement>>& slots = shadowRoot->descendantSlots();
+            for (Member<HTMLSlotElement> slot : slots) {
+                if (slot->name() == assignedSlot && !slot->hasSlotChangeEventInMicrotask()) {
+                    slot->fireSlotChangeEvent();
+                    break;
+                }
+            }
+        }
     }
 }
 
 void HTMLSlotElement::clearDistribution()
 {
     willUpdateDistribution();
     didUpdateDistribution();
 }
 
 short HTMLSlotElement::tabIndex() const
 {
     return Element::tabIndex();
 }
 
 DEFINE_TRACE(HTMLSlotElement)
 {
     visitor->trace(m_assignedNodes);
     visitor->trace(m_distributedNodes);
+    visitor->trace(m_fallbackNodes);
     visitor->trace(m_distributedIndices);
+    visitor->trace(m_oldAssignedNodes);
     visitor->trace(m_oldDistributedNodes);
+    visitor->trace(m_oldFallbackNodes);
     HTMLElement::trace(visitor);
 }
 
 } // namespace blink