Support the essential part of Shadow DOM v1

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

+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "config.h"
+#include "core/dom/shadow/SlotAssignment.h"
+
+#include "core/HTMLNames.h"
+#include "core/dom/ElementTraversal.h"
+#include "core/dom/NodeTraversal.h"
+#include "core/dom/shadow/InsertionPoint.h"
+#include "core/dom/shadow/ShadowRoot.h"
+#include "core/html/HTMLSlotElement.h"
+
+namespace blink {
+
+HTMLSlotElement* SlotAssignment::assignedSlotFor(const Node& node) const
+{
+    return m_assignment.get(const_cast<Node*>(&node));
+}
+
+static void detachNotAssignedNode(Node& node)
+{
+    if (node.layoutObject())
+        node.lazyReattachIfAttached();
+}
+
+void SlotAssignment::resolveAssignment(const ShadowRoot& shadowRoot)
+{
+    m_assignment.clear();
+
+    using Name2Slot = HashMap<AtomicString, HTMLSlotElement*>;
+    Name2Slot name2slot;
+    HTMLSlotElement* defaultSlot = nullptr;
+
+    // TODO(hayato): Cache slots elements so that we do not have to travese the shadow tree. See ShadowRoot::descendantInsertionPoints()
+    for (HTMLSlotElement& slot : Traversal<HTMLSlotElement>::descendantsOf(shadowRoot)) {
+        slot.clearDistribution();
+
+        AtomicString name = slot.fastGetAttribute(HTMLNames::nameAttr);
+        if (name.isNull() || name.isEmpty()) {
+            if (!defaultSlot)
+                defaultSlot = &slot;
+        } else {
+            name2slot.add(name, &slot);
+        }
+    }
+
+    for (Node& child : NodeTraversal::childrenOf(*shadowRoot.host())) {
+        if (child.isElementNode()) {
+            if (isActiveInsertionPoint(child)) {
+                // TODO(hayato): Support re-distribution across v0 and v1 shadow trees
+                detachNotAssignedNode(child);
+                continue;
+            }
+            AtomicString slotName = toElement(child).fastGetAttribute(HTMLNames::slotAttr);
+            if (slotName.isNull() || slotName.isEmpty()) {
+                if (defaultSlot)
+                    assign(child, *defaultSlot);
+                else
+                    detachNotAssignedNode(child);
+            } else {
+                HTMLSlotElement* slot = name2slot.get(slotName);
+                if (slot)
+                    assign(child, *slot);
+                else
+                    detachNotAssignedNode(child);
+            }
+        } else if (defaultSlot) {
+            assign(child, *defaultSlot);
+        } else {
+            detachNotAssignedNode(child);
+        }
+    }
+}
+
+void SlotAssignment::assign(Node& hostChild, HTMLSlotElement& slot)
+{
+    m_assignment.add(&hostChild, &slot);
+    slot.appendAssignedNode(hostChild);
+    if (isHTMLSlotElement(hostChild))
+        slot.appendDistributedNodes(toHTMLSlotElement(hostChild).getDistributedNodes());
+    else
+        slot.appendDistributedNode(hostChild);
+}
+
+DEFINE_TRACE(SlotAssignment)
+{
+#if ENABLE(OILPAN)
+    visitor->trace(m_assignment);
+#endif
+}
+
+} // namespace blink