Sibling invalidation sets

Source/core/css/invalidation/InvalidationData.cpp

Index: Source/core/css/invalidation/InvalidationData.cpp
diff --git a/Source/core/css/invalidation/InvalidationData.cpp b/Source/core/css/invalidation/InvalidationData.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..7ef4fb95e42313455d16f0aa0c3ae5c2206a5896
--- /dev/null
+++ b/Source/core/css/invalidation/InvalidationData.cpp
@@ -0,0 +1,35 @@
+// 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/css/invalidation/InvalidationData.h"
+
+namespace blink {
+
+InvalidationSet& InvalidationData::ensureInvalidationSet(InvalidationType type)
+{
+    RefPtrWillBeMember<InvalidationSet>& invalidationSet = (type == InvalidateDescendants) ? m_descendants : m_siblings;
+
+    if (!invalidationSet)
+        invalidationSet = InvalidationSet::create();
+
+    return *invalidationSet;
+}
+
+void InvalidationData::combine(const InvalidationData& other)
+{
+    if (other.descendants())
+        ensureInvalidationSet(InvalidateDescendants).combine(*other.descendants());
+
+    if (other.siblings())
+        ensureInvalidationSet(InvalidateSiblings).combine(*other.siblings());
+}
+
+DEFINE_TRACE(InvalidationData)
+{
+    visitor->trace(m_descendants);
+    visitor->trace(m_siblings);
+}
+
+} // namespace blink