Reuse executeForTraverseRoot to avoid a manual loop in SelectorQuery::findTraverseRootsAndExecute.

third_party/WebKit/Source/core/dom/SelectorQuery.cpp

 /*
  * Copyright (C) 2011, 2013 Apple Inc. All rights reserved.
  * Copyright (C) 2014 Samsung Electronics. 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.
@@ skipping 241 matching lines @@
       DCHECK(!isRightmostSelector);
       Element* element =
           rootNode.containingTreeScope().getElementById(selector->value());
       if (!element)
         return;
       ContainerNode* start = &rootNode;
       if (element->isDescendantOf(&rootNode))
         start = element;
       if (startFromParent)
         start = start->parentNode();
-      executeForTraverseRoot<SelectorQueryTrait>(start, rootNode, output);
+      if (!start)
+        return;
+      executeForTraverseRoot<SelectorQueryTrait>(*start, rootNode, output);
       return;
     }
 
     // If we have both CSSSelector::Id and CSSSelector::Class at the same time,
     // we should use Id to find traverse root.
     if (!SelectorQueryTrait::shouldOnlyMatchFirstElement && !startFromParent &&
         selector->match() == CSSSelector::Class) {
       if (isRightmostSelector) {
         ClassElementList<AllElements> traverseRoots(rootNode,
                                                     selector->value());
         while (!traverseRoots.isEmpty()) {
           Element& element = *traverseRoots.next();
           if (selectorMatches(*m_selectors[0], element, rootNode))
             SelectorQueryTrait::appendElement(output, element);
         }
         return;
       }
       // Since there exists some ancestor element which has the class name, we
       // need to see all children of rootNode.
       if (ancestorHasClassName(rootNode, selector->value()))
         break;
 
       ClassElementList<OnlyRoots> traverseRoots(rootNode, selector->value());
       while (!traverseRoots.isEmpty()) {
-        for (Element& element :
-             ElementTraversal::descendantsOf(*traverseRoots.next())) {
-          if (selectorMatches(*m_selectors[0], element, rootNode))
-            SelectorQueryTrait::appendElement(output, element);
-        }
+        executeForTraverseRoot<SelectorQueryTrait>(*traverseRoots.next(),
+                                                   rootNode, output);
       }
       return;
     }
 
     if (selector->relation() == CSSSelector::SubSelector)
       continue;
     isRightmostSelector = false;
     if (selector->relation() == CSSSelector::DirectAdjacent ||
         selector->relation() == CSSSelector::IndirectAdjacent)
       startFromParent = true;
     else
       startFromParent = false;
   }
 
-  executeForTraverseRoot<SelectorQueryTrait>(&rootNode, rootNode, output);
+  executeForTraverseRoot<SelectorQueryTrait>(rootNode, rootNode, output);
 }
 
 template <typename SelectorQueryTrait>
 void SelectorQuery::executeForTraverseRoot(
-    ContainerNode* traverseRoot,
+    ContainerNode& traverseRoot,
     ContainerNode& rootNode,
     typename SelectorQueryTrait::OutputType& output) const {
   DCHECK_EQ(m_selectors.size(), 1u);
 
-  if (!traverseRoot)
-    return;
   const CSSSelector& selector = *m_selectors[0];
 
-  for (Element& element : ElementTraversal::descendantsOf(*traverseRoot)) {
+  for (Element& element : ElementTraversal::descendantsOf(traverseRoot)) {
     if (selectorMatches(selector, element, rootNode)) {
       SelectorQueryTrait::appendElement(output, element);
       if (SelectorQueryTrait::shouldOnlyMatchFirstElement)
         return;
     }
   }
 }
 
 template <typename SelectorQueryTrait>
 bool SelectorQuery::selectorListMatches(
@@ skipping 229 matching lines @@
   return m_entries
       .insert(selectors, SelectorQuery::adopt(std::move(selectorList)))
       .storedValue->value.get();
 }
 
 void SelectorQueryCache::invalidate() {
   m_entries.clear();
 }
 
 }  // namespace blink