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Unified Diff: Source/core/dom/NthIndexCache.cpp

Issue 1023393002: Cache element indices for :nth-child and :nth-last-child selectors. (Closed) Base URL: https://chromium.googlesource.com/chromium/blink.git@master
Patch Set: Moved nth-index-cache scope to updateStyle Created 5 years, 9 months ago
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Index: Source/core/dom/NthIndexCache.cpp
diff --git a/Source/core/dom/NthIndexCache.cpp b/Source/core/dom/NthIndexCache.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..1cb353d9d7d62ee8467a06048501c12a5e37ace9
--- /dev/null
+++ b/Source/core/dom/NthIndexCache.cpp
@@ -0,0 +1,62 @@
+// 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/NthIndexCache.h"
+
+#include "core/dom/Document.h"
+
+namespace blink {
+
+void NthIndexCache::clear()
+{
+ if (m_parentMap)
+ m_parentMap->clear();
+}
+
+NthIndexCache::NthIndexData& NthIndexCache::ensureNthIndexDataFor(Node& parent)
+{
+ if (!m_parentMap)
+ m_parentMap = adoptPtrWillBeNoop(new ParentMap());
+
+ ParentMap::AddResult addResult = m_parentMap->add(&parent, nullptr);
+ if (addResult.isNewEntry)
+ addResult.storedValue->value = adoptPtrWillBeNoop(new NthIndexData());
+
+ ASSERT(addResult.storedValue->value);
+ return *addResult.storedValue->value;
+}
+
+unsigned NthIndexCache::NthIndexData::cacheNthIndices(Element& element)
+{
+ unsigned index = 0;
+ const unsigned spread = 3;
+ unsigned count = 0;
+ for (Element* sibling = ElementTraversal::firstChild(*element.parentNode()); sibling; sibling = ElementTraversal::nextSibling(*sibling)) {
+ if (!(++count % spread))
+ m_elementIndexMap.add(sibling, count);
+ if (sibling == &element)
+ index = count;
+ }
+ ASSERT(count && index);
+ m_count = count;
+ return index;
+}
+
+DEFINE_TRACE(NthIndexCache)
+{
+#if ENABLE(OILPAN)
+ visitor->trace(m_parentMap);
+ visitor->trace(m_document);
+#endif
+}
+
+DEFINE_TRACE(NthIndexCache::NthIndexData)
+{
+#if ENABLE(OILPAN)
+ visitor->trace(m_elementIndexMap);
+#endif
+}
+
+} // namespace blink

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