1 files changed, 92 insertions, 0 deletions
diff --git a/Source/WebCore/style/IdChangeInvalidation.cpp b/Source/WebCore/style/IdChangeInvalidation.cpp
new file mode 100644
index 000000000..a0d99febf
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+++ b/Source/WebCore/style/IdChangeInvalidation.cpp
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+/*
+ * 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 "IdChangeInvalidation.h"
+
+#include "DocumentRuleSets.h"
+#include "ElementChildIterator.h"
+#include "ShadowRoot.h"
+#include "StyleResolver.h"
+#include "StyleScope.h"
+
+namespace WebCore {
+namespace Style {
+
+static bool mayBeAffectedByHostRules(const Element& element, const AtomicString& changedId)
+{
+    auto* shadowRoot = element.shadowRoot();
+    if (!shadowRoot)
+        return false;
+    auto& shadowRuleSets = shadowRoot->styleScope().resolver().ruleSets();
+    if (shadowRuleSets.authorStyle().hostPseudoClassRules().isEmpty())
+        return false;
+    return shadowRuleSets.features().idsInRules.contains(changedId);
+}
+
+static bool mayBeAffectedBySlottedRules(const Element& element, const AtomicString& changedId)
+{
+    for (auto* shadowRoot : assignedShadowRootsIfSlotted(element)) {
+        auto& ruleSets = shadowRoot->styleScope().resolver().ruleSets();
+        if (ruleSets.authorStyle().slottedPseudoElementRules().isEmpty())
+            continue;
+        if (ruleSets.features().idsInRules.contains(changedId))
+            return true;
+    }
+    return false;
+}
+
+void IdChangeInvalidation::invalidateStyle(const AtomicString& changedId)
+{
+    if (changedId.isEmpty())
+        return;
+
+    auto& ruleSets = m_element.styleResolver().ruleSets();
+
+    bool mayAffectStyle = ruleSets.features().idsInRules.contains(changedId)
+        || mayBeAffectedByHostRules(m_element, changedId)
+        || mayBeAffectedBySlottedRules(m_element, changedId);
+
+    if (!mayAffectStyle)
+        return;
+
+    if (m_element.shadowRoot() && ruleSets.authorStyle().hasShadowPseudoElementRules()) {
+        m_element.invalidateStyleForSubtree();
+        return;
+    }
+
+    m_element.invalidateStyle();
+
+    // This could be easily optimized for fine-grained descendant invalidation similar to ClassChangeInvalidation.
+    // However using ids for dynamic styling is rare and this is probably not worth the memory cost of the required data structures.
+    bool mayAffectDescendantStyle = ruleSets.features().idsMatchingAncestorsInRules.contains(changedId);
+    if (mayAffectDescendantStyle)
+        m_element.invalidateStyleForSubtree();
+    else
+        m_element.invalidateStyle();
+}
+
+}
+}