Optimize MutableStylePropertySet::findPropertyIndex

Source/core/css/StylePropertySet.cpp

 /*
  * (C) 1999-2003 Lars Knoll (knoll@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2012, 2013 Apple Inc. All rights reserved.
  * Copyright (C) 2011 Research In Motion Limited. All rights reserved.
  * Copyright (C) 2013 Intel Corporation. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
@@ skipping 482 matching lines @@
     // style property set.
     if (m_cssomWrapper) {
         ASSERT(!static_cast<CSSStyleDeclaration*>(m_cssomWrapper.get())->parentRule());
         ASSERT(!m_cssomWrapper->parentElement());
         return m_cssomWrapper.get();
     }
     m_cssomWrapper = adoptPtrWillBeNoop(new PropertySetCSSStyleDeclaration(*this));
     return m_cssomWrapper.get();
 }
 
+
+class CSSPropertyIDComparer {
+public:
+    explicit CSSPropertyIDComparer(CSSPropertyID propertyID)
+        : m_propertyID(static_cast<uint16_t>(propertyID)) { }
+    bool operator()(const CSSProperty& property) const
+    {
+        if (property.metadata().m_propertyID == m_propertyID) {
+            // Only enabled properties should be part of the style.
+            ASSERT(CSSPropertyMetadata::isEnabledProperty(propertyID()));
+            return true;
+        }
+        return false;
+    }
+
+private:
+    CSSPropertyID propertyID() const { return static_cast<CSSPropertyID>(m_propertyID); }
+    uint16_t m_propertyID; // Store as uint16_t to avoid casts while comparing.
+};
+
 int MutableStylePropertySet::findPropertyIndex(CSSPropertyID propertyID) const
 {
-    // Convert here propertyID into an uint16_t to compare it with the metadata's m_propertyID to avoid
-    // the compiler converting it to an int multiple times in the loop.
-    uint16_t id = static_cast<uint16_t>(propertyID);
-    const CSSProperty* properties = m_propertyVector.data();
-    for (int n = m_propertyVector.size() - 1 ; n >= 0; --n) {
-        if (properties[n].metadata().m_propertyID == id) {
-            // Only enabled properties should be part of the style.
-            ASSERT(CSSPropertyMetadata::isEnabledProperty(propertyID));
-            return n;
-        }
-    }
+    const CSSProperty* begin = m_propertyVector.data();
+    const CSSProperty* end = begin + m_propertyVector.size();
+    const CSSProperty* it = std::find_if(begin, end, CSSPropertyIDComparer(propertyID));
 
-    return -1;
+    return (it == end) ? -1 : it - begin;
 }
 
 DEFINE_TRACE_AFTER_DISPATCH(MutableStylePropertySet)
 {
 #if ENABLE(OILPAN)
     visitor->trace(m_cssomWrapper);
     visitor->trace(m_propertyVector);
 #endif
     StylePropertySet::traceAfterDispatch(visitor);
 }
@@ skipping 21 matching lines @@
 {
     return adoptRefWillBeNoop(new MutableStylePropertySet(cssParserMode));
 }
 
 PassRefPtrWillBeRawPtr<MutableStylePropertySet> MutableStylePropertySet::create(const CSSProperty* properties, unsigned count)
 {
     return adoptRefWillBeNoop(new MutableStylePropertySet(properties, count));
 }
 
 } // namespace blink