Cache element indices for :nth-child and :nth-last-child selectors.

Source/core/dom/Document.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  *           (C) 2006 Alexey Proskuryakov (ap@webkit.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2011, 2012 Apple Inc. All rights reserved.
  * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  * Copyright (C) 2008, 2009, 2011, 2012 Google Inc. All rights reserved.
  * Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies)
  * Copyright (C) Research In Motion Limited 2010-2011. All rights reserved.
@@ skipping 68 matching lines @@
 #include "core/dom/Microtask.h"
 #include "core/dom/MutationObserver.h"
 #include "core/dom/NodeChildRemovalTracker.h"
 #include "core/dom/NodeFilter.h"
 #include "core/dom/NodeIterator.h"
 #include "core/dom/NodeLayoutStyle.h"
 #include "core/dom/NodeRareData.h"
 #include "core/dom/NodeRenderingTraversal.h"
 #include "core/dom/NodeTraversal.h"
 #include "core/dom/NodeWithIndex.h"
+#include "core/dom/NthIndexCache.h"
 #include "core/dom/ProcessingInstruction.h"
 #include "core/dom/RequestAnimationFrameCallback.h"
 #include "core/dom/ScriptRunner.h"
 #include "core/dom/ScriptedAnimationController.h"
 #include "core/dom/SelectorQuery.h"
 #include "core/dom/StaticNodeList.h"
 #include "core/dom/StyleEngine.h"
 #include "core/dom/TouchList.h"
 #include "core/dom/TransformSource.h"
 #include "core/dom/TreeWalker.h"
@@ skipping 368 matching lines @@
     , m_writeRecursionDepth(0)
     , m_taskRunner(MainThreadTaskRunner::create(this))
     , m_registrationContext(initializer.registrationContext(this))
     , m_elementDataCacheClearTimer(this, &Document::elementDataCacheClearTimerFired)
     , m_timeline(AnimationTimeline::create(this))
     , m_templateDocumentHost(nullptr)
     , m_didAssociateFormControlsTimer(this, &Document::didAssociateFormControlsTimerFired)
     , m_hasViewportUnits(false)
     , m_styleRecalcElementCounter(0)
     , m_parserSyncPolicy(AllowAsynchronousParsing)
+    , m_useNthIndexCache(false)
 {
     if (m_frame) {
         ASSERT(m_frame->page());
         provideContextFeaturesToDocumentFrom(*this, *m_frame->page());
 
         m_fetcher = m_frame->loader().documentLoader()->fetcher();
     }
 
     if (!m_fetcher)
         m_fetcher = FrameFetchContext::createContextAndFetcher(nullptr);
@@ skipping 162 matching lines @@
 }
 #endif
 
 SelectorQueryCache& Document::selectorQueryCache()
 {
     if (!m_selectorQueryCache)
         m_selectorQueryCache = adoptPtr(new SelectorQueryCache());
     return *m_selectorQueryCache;
 }
 
+NthIndexCache* Document::nthIndexCache()
+{
+    if (!m_useNthIndexCache)
+        return nullptr;
+    if (!m_nthIndexCache)
+        m_nthIndexCache = NthIndexCache::create(*this);
+    return m_nthIndexCache.get();
+}
+
+void Document::setUseNthIndexCache(bool use)
+{
+    m_useNthIndexCache = use;
+    if (!use && m_nthIndexCache)
+        m_nthIndexCache->clear();
+}
+
 MediaQueryMatcher& Document::mediaQueryMatcher()
 {
     if (!m_mediaQueryMatcher)
         m_mediaQueryMatcher = MediaQueryMatcher::create(*this);
     return *m_mediaQueryMatcher;
 }
 
 void Document::mediaQueryAffectingValueChanged()
 {
     m_evaluateMediaQueriesOnStyleRecalc = true;
@@ skipping 1097 matching lines @@
     InspectorInstrumentation::didRecalculateStyle(cookie, m_styleRecalcElementCounter);
 }
 
 void Document::updateStyle(StyleRecalcChange change)
 {
     TRACE_EVENT0("blink", "Document::updateStyle");
 
     HTMLFrameOwnerElement::UpdateSuspendScope suspendWidgetHierarchyUpdates;
     m_lifecycle.advanceTo(DocumentLifecycle::InStyleRecalc);
 
+    UseNthIndexCacheScope nthIndexScope(*this);
+
     if (styleChangeType() >= SubtreeStyleChange)
         change = Force;
 
     // FIXME: Cannot access the ensureStyleResolver() before calling styleForDocument below because
     // apparently the StyleResolver's constructor has side effects. We should fix it.
     // See printing/setPrinting.html, printing/width-overflow.html though they only fail on
     // mac when accessing the resolver by what appears to be a viewport size difference.
 
     if (change == Force) {
         m_hasNodesWithPlaceholderStyle = false;
@@ skipping 3921 matching lines @@
     visitor->trace(m_elementDataCache);
     visitor->trace(m_associatedFormControls);
     visitor->trace(m_useElementsNeedingUpdate);
     visitor->trace(m_layerUpdateSVGFilterElements);
     visitor->trace(m_timers);
     visitor->trace(m_templateDocument);
     visitor->trace(m_templateDocumentHost);
     visitor->trace(m_visibilityObservers);
     visitor->trace(m_userActionElements);
     visitor->trace(m_svgExtensions);
+    visitor->trace(m_nthIndexCache);
     visitor->trace(m_timeline);
     visitor->trace(m_compositorPendingAnimations);
     visitor->trace(m_contextDocument);
     visitor->template registerWeakMembers<Document, &Document::clearWeakMembers>(this);
     DocumentSupplementable::trace(visitor);
 #endif
     TreeScope::trace(visitor);
     ContainerNode::trace(visitor);
     ExecutionContext::trace(visitor);
     DocumentLifecycleNotifier::trace(visitor);
 }
 
 } // namespace blink
 
 #ifndef NDEBUG
 using namespace blink;
 void showLiveDocumentInstances()
 {
     WeakDocumentSet& set = liveDocumentSet();
     fprintf(stderr, "There are %u documents currently alive:\n", set.size());
     for (Document* document : set)
         fprintf(stderr, "- Document %p URL: %s\n", document, document->url().string().utf8().data());
 }
 #endif