1 files changed, 158 insertions, 0 deletions
diff --git a/Source/WebCore/style/ClassChangeInvalidation.cpp b/Source/WebCore/style/ClassChangeInvalidation.cpp
new file mode 100644
index 000000000..e25fc49b4
--- /dev/null
+++ b/Source/WebCore/style/ClassChangeInvalidation.cpp
@@ -0,0 +1,158 @@
+/*
+ * Copyright (C) 2016 Apple 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:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
+ * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
+ * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 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 "config.h"
+#include "ClassChangeInvalidation.h"
+
+#include "DocumentRuleSets.h"
+#include "ElementChildIterator.h"
+#include "ShadowRoot.h"
+#include "SpaceSplitString.h"
+#include "StyleInvalidationAnalysis.h"
+#include "StyleResolver.h"
+#include "StyleScope.h"
+#include <wtf/BitVector.h>
+
+namespace WebCore {
+namespace Style {
+
+using ClassChangeVector = Vector<AtomicStringImpl*, 4>;
+
+static ClassChangeVector collectClasses(const SpaceSplitString& classes)
+{
+    ClassChangeVector result;
+    result.reserveCapacity(classes.size());
+    for (unsigned i = 0; i < classes.size(); ++i)
+        result.uncheckedAppend(classes[i].impl());
+    return result;
+}
+
+static ClassChangeVector computeClassChange(const SpaceSplitString& oldClasses, const SpaceSplitString& newClasses)
+{
+    unsigned oldSize = oldClasses.size();
+    unsigned newSize = newClasses.size();
+
+    if (!oldSize)
+        return collectClasses(newClasses);
+    if (!newSize)
+        return collectClasses(oldClasses);
+
+    ClassChangeVector changedClasses;
+
+    BitVector remainingClassBits;
+    remainingClassBits.ensureSize(oldSize);
+    // Class vectors tend to be very short. This is faster than using a hash table.
+    for (unsigned i = 0; i < newSize; ++i) {
+        bool foundFromBoth = false;
+        for (unsigned j = 0; j < oldSize; ++j) {
+            if (newClasses[i] == oldClasses[j]) {
+                remainingClassBits.quickSet(j);
+                foundFromBoth = true;
+            }
+        }
+        if (foundFromBoth)
+            continue;
+        changedClasses.append(newClasses[i].impl());
+    }
+    for (unsigned i = 0; i < oldSize; ++i) {
+        // If the bit is not set the the corresponding class has been removed.
+        if (remainingClassBits.quickGet(i))
+            continue;
+        changedClasses.append(oldClasses[i].impl());
+    }
+
+    return changedClasses;
+}
+
+static bool mayBeAffectedByHostRules(ShadowRoot* shadowRoot, AtomicStringImpl* changedClass)
+{
+    if (!shadowRoot)
+        return false;
+    auto& shadowRuleSets = shadowRoot->styleScope().resolver().ruleSets();
+    if (shadowRuleSets.authorStyle().hostPseudoClassRules().isEmpty())
+        return false;
+    return shadowRuleSets.features().classesInRules.contains(changedClass);
+}
+
+static bool mayBeAffectedBySlottedRules(const Vector<ShadowRoot*>& assignedShadowRoots, AtomicStringImpl* changedClass)
+{
+    for (auto& assignedShadowRoot : assignedShadowRoots) {
+        auto& ruleSets = assignedShadowRoot->styleScope().resolver().ruleSets();
+        if (ruleSets.authorStyle().slottedPseudoElementRules().isEmpty())
+            continue;
+        if (ruleSets.features().classesInRules.contains(changedClass))
+            return true;
+    }
+    return false;
+}
+
+void ClassChangeInvalidation::invalidateStyle(const SpaceSplitString& oldClasses, const SpaceSplitString& newClasses)
+{
+    auto changedClasses = computeClassChange(oldClasses, newClasses);
+
+    auto& ruleSets = m_element.styleResolver().ruleSets();
+    auto* shadowRoot = m_element.shadowRoot();
+    auto assignedShadowRoots = assignedShadowRootsIfSlotted(m_element);
+
+    ClassChangeVector changedClassesAffectingStyle;
+    for (auto* changedClass : changedClasses) {
+        bool mayAffectStyle = ruleSets.features().classesInRules.contains(changedClass)
+            || mayBeAffectedByHostRules(shadowRoot, changedClass)
+            || mayBeAffectedBySlottedRules(assignedShadowRoots, changedClass);
+        if (mayAffectStyle)
+            changedClassesAffectingStyle.append(changedClass);
+    };
+
+    if (changedClassesAffectingStyle.isEmpty())
+        return;
+
+    if (shadowRoot && ruleSets.authorStyle().hasShadowPseudoElementRules()) {
+        m_element.invalidateStyleForSubtree();
+        return;
+    }
+
+    m_element.invalidateStyle();
+
+    if (!childrenOfType<Element>(m_element).first())
+        return;
+
+    for (auto* changedClass : changedClassesAffectingStyle) {
+        auto* ancestorClassRules = ruleSets.ancestorClassRules(changedClass);
+        if (!ancestorClassRules)
+            continue;
+        m_descendantInvalidationRuleSets.append(ancestorClassRules);
+    }
+}
+
+void ClassChangeInvalidation::invalidateDescendantStyle()
+{
+    for (auto* ancestorClassRules : m_descendantInvalidationRuleSets) {
+        StyleInvalidationAnalysis invalidationAnalysis(*ancestorClassRules);
+        invalidationAnalysis.invalidateStyle(m_element);
+    }
+}
+
+}
+}