Move attributes-related methods from ElementData to AttributeCollection

Source/core/dom/ElementData.h

 /*
  * Copyright (C) 2013 Google Inc. All rights reserved.
  * Copyright (C) 2014 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
@@ skipping 26 matching lines @@
 #include "platform/heap/Handle.h"
 #include "wtf/text/AtomicString.h"
 
 namespace WebCore {
 
 class Attr;
 class ShareableElementData;
 class StylePropertySet;
 class UniqueElementData;
 
 class AttributeCollection {

[Inactive, 2014/06/26 22:16:40]

Ok, I'll move this to a separate file since it is getting bigger.

 public:
     typedef const Attribute* const_iterator;
 
     AttributeCollection(const Attribute* array, unsigned size)
         : m_array(array)
         , m_size(size)
     { }
 
+    const Attribute& operator[](unsigned index) const { return at(index); }
+    const Attribute& at(unsigned index) const
+    {
+        RELEASE_ASSERT(index < m_size);
+        return m_array[index];
+    }
+
+    const Attribute* get(const QualifiedName&) const;
+    const Attribute* get(const AtomicString& name, bool shouldIgnoreCase) const;
+    size_t find(const QualifiedName&, bool shouldIgnoreCase = false) const;
+    size_t find(const AtomicString& name, bool shouldIgnoreCase) const;
+    size_t find(Attr*) const;

[esprehn, 2014/06/26 22:03:58]

We're going to have to be really careful here, originally it was called
findByName because get() does a linear search and get() methods are usually
assumed to be cheap while find() implies more work. We can see how this shakes
out though.

[Inactive, 2014/06/26 22:16:40]

To be fair, they were called getAttributeItem() / getAttributeItemIndex() before
I renamed them to find*ByName() a couple of week ago :)

However, I totally agree. I did not think about this but the name should
definitely reflect that the implementation is actually doing work (linear search
in this case). I'll propose a better naming.

+
     const_iterator begin() const { return m_array; }
     const_iterator end() const { return m_array + m_size; }
 
     unsigned size() const { return m_size; }
+    bool isEmpty() const { return !m_size; }
 
 private:
+    size_t findSlowCase(const AtomicString& name, bool shouldIgnoreAttributeCase) const;
+
     const Attribute* m_array;
     unsigned m_size;
 };
 
 // ElementData represents very common, but not necessarily unique to an element,
 // data such as attributes, inline style, and parsed class names and ids.
 class ElementData : public RefCountedWillBeGarbageCollectedFinalized<ElementData> {
     WTF_MAKE_FAST_ALLOCATED_WILL_BE_REMOVED;
 public:
 #if ENABLE(OILPAN)
@@ skipping 10 matching lines @@
     void setClass(const AtomicString& className, bool shouldFoldCase) const { m_classNames.set(className, shouldFoldCase); }
     const SpaceSplitString& classNames() const { return m_classNames; }
 
     const AtomicString& idForStyleResolution() const { return m_idForStyleResolution; }
     void setIdForStyleResolution(const AtomicString& newId) const { m_idForStyleResolution = newId; }
 
     const StylePropertySet* inlineStyle() const { return m_inlineStyle.get(); }
 
     const StylePropertySet* presentationAttributeStyle() const;
 
-    // This is not a trivial getter and its return value should be cached for performance.
-    size_t attributeCount() const;
-    bool hasAttributes() const { return !!attributeCount(); }
-
     AttributeCollection attributes() const;
 
-    const Attribute& attributeAt(unsigned index) const;
-    const Attribute* findAttributeByName(const QualifiedName&) const;
-    size_t findAttributeIndexByName(const QualifiedName&, bool shouldIgnoreCase = false) const;
-    size_t findAttributeIndexByName(const AtomicString& name, bool shouldIgnoreAttributeCase) const;
-    size_t findAttrNodeIndex(Attr*) const;
-
     bool hasID() const { return !m_idForStyleResolution.isNull(); }
     bool hasClass() const { return !m_classNames.isNull(); }
 
     bool isEquivalent(const ElementData* other) const;
 
     bool isUnique() const { return m_isUnique; }
 
     void traceAfterDispatch(Visitor*);
     void trace(Visitor*);
 
@@ skipping 16 matching lines @@
 private:
     friend class Element;
     friend class ShareableElementData;
     friend class UniqueElementData;
     friend class SVGElement;
 
 #if !ENABLE(OILPAN)
     void destroy();
 #endif
 
-    const Attribute* attributeBase() const;
-    const Attribute* findAttributeByName(const AtomicString& name, bool shouldIgnoreAttributeCase) const;
-    size_t findAttributeIndexByNameSlowCase(const AtomicString& name, bool shouldIgnoreAttributeCase) const;
-
     PassRefPtrWillBeRawPtr<UniqueElementData> makeUniqueCopy() const;
 };
 
 #if COMPILER(MSVC)
 #pragma warning(push)
 #pragma warning(disable: 4200) // Disable "zero-sized array in struct/union" warning
 #endif
 
 // SharableElementData is managed by ElementDataCache and is produced by
 // the parser during page load for elements that have identical attributes. This
@@ skipping 12 matching lines @@
     // Add support for placement new as ShareableElementData is not allocated
     // with a fixed size. Instead the allocated memory size is computed based on
     // the number of attributes. This requires us to use Heap::allocate directly
     // with the computed size and subsequently call placement new with the
     // allocated memory address.
     void* operator new(std::size_t, void* location)
     {
         return location;
     }
 
+    AttributeCollection attributes() const;
+
     Attribute m_attributeArray[0];
 };
 
 #if COMPILER(MSVC)
 #pragma warning(pop)
 #endif
 
 // UniqueElementData is created when an element needs to mutate its attributes
 // or gains presentation attribute style (ex. width="10"). It does not need to
 // be created to fill in values in the ElementData that are derived from
 // attributes. For example populating the m_inlineStyle from the style attribute
 // doesn't require a UniqueElementData as all elements with the same style
 // attribute will have the same inline style.
 class UniqueElementData FINAL : public ElementData {
 public:
     static PassRefPtrWillBeRawPtr<UniqueElementData> create();
     PassRefPtrWillBeRawPtr<ShareableElementData> makeShareableCopy() const;
 
     // These functions do no error/duplicate checking.
     void appendAttribute(const QualifiedName&, const AtomicString&);
     void removeAttributeAt(size_t index);
 
+    AttributeCollection attributes() const;
+
     Attribute& attributeAt(unsigned index);
     Attribute* findAttributeByName(const QualifiedName&);
 
     UniqueElementData();
     explicit UniqueElementData(const ShareableElementData&);
     explicit UniqueElementData(const UniqueElementData&);
 
     void traceAfterDispatch(Visitor*);
 
     // FIXME: We might want to support sharing element data for elements with
     // presentation attribute style. Lots of table cells likely have the same
     // attributes. Most modern pages don't use presentation attributes though
     // so this might not make sense.
     mutable RefPtrWillBeMember<StylePropertySet> m_presentationAttributeStyle;
     Vector<Attribute, 4> m_attributeVector;
 };
 
 #if !ENABLE(OILPAN)
 inline void ElementData::deref()
 {
     if (!derefBase())
         return;
     destroy();
 }
 #endif
 
-inline size_t ElementData::attributeCount() const
-{
-    if (isUnique())
-        return static_cast<const UniqueElementData*>(this)->m_attributeVector.size();
-    return m_arraySize;
-}
-
 inline const StylePropertySet* ElementData::presentationAttributeStyle() const
 {
     if (!m_isUnique)
         return 0;
     return static_cast<const UniqueElementData*>(this)->m_presentationAttributeStyle.get();
 }
 
-inline const Attribute* ElementData::findAttributeByName(const AtomicString& name, bool shouldIgnoreAttributeCase) const
+inline const Attribute* AttributeCollection::get(const AtomicString& name, bool shouldIgnoreCase) const
 {
-    size_t index = findAttributeIndexByName(name, shouldIgnoreAttributeCase);
-    if (index != kNotFound)
-        return &attributeAt(index);
-    return 0;
+    size_t index = find(name, shouldIgnoreCase);
+    return index != kNotFound ? &at(index) : 0;
 }
 
-inline const Attribute* ElementData::attributeBase() const
+inline size_t AttributeCollection::find(const QualifiedName& name, bool shouldIgnoreCase) const
 {
-    if (m_isUnique)
-        return static_cast<const UniqueElementData*>(this)->m_attributeVector.begin();
-    return static_cast<const ShareableElementData*>(this)->m_attributeArray;
-}
-
-inline size_t ElementData::findAttributeIndexByName(const QualifiedName& name, bool shouldIgnoreCase) const
-{
-    AttributeCollection attributes = this->attributes();
-    AttributeCollection::const_iterator end = attributes.end();
+    const_iterator end = this->end();
     unsigned index = 0;
-    for (AttributeCollection::const_iterator it = attributes.begin(); it != end; ++it, ++index) {
+    for (const_iterator it = begin(); it != end; ++it, ++index) {
         if (it->name().matchesPossiblyIgnoringCase(name, shouldIgnoreCase))
             return index;
     }
     return kNotFound;
 }
 
 // We use a boolean parameter instead of calling shouldIgnoreAttributeCase so that the caller
 // can tune the behavior (hasAttribute is case sensitive whereas getAttribute is not).
-inline size_t ElementData::findAttributeIndexByName(const AtomicString& name, bool shouldIgnoreAttributeCase) const
+inline size_t AttributeCollection::find(const AtomicString& name, bool shouldIgnoreCase) const
 {
-    bool doSlowCheck = shouldIgnoreAttributeCase;
+    bool doSlowCheck = shouldIgnoreCase;
 
     // Optimize for the case where the attribute exists and its name exactly matches.
-    AttributeCollection attributes = this->attributes();
-    AttributeCollection::const_iterator end = attributes.end();
+    const_iterator end = this->end();
     unsigned index = 0;
-    for (AttributeCollection::const_iterator it = attributes.begin(); it != end; ++it, ++index) {
+    for (const_iterator it = begin(); it != end; ++it, ++index) {
         // FIXME: Why check the prefix? Namespaces should be all that matter.
         // Most attributes (all of HTML and CSS) have no namespace.
         if (!it->name().hasPrefix()) {
             if (name == it->localName())
                 return index;
         } else {
             doSlowCheck = true;
         }
     }
 
     if (doSlowCheck)
-        return findAttributeIndexByNameSlowCase(name, shouldIgnoreAttributeCase);
+        return findSlowCase(name, shouldIgnoreCase);
     return kNotFound;
 }
 
 inline AttributeCollection ElementData::attributes() const
 {
-    if (isUnique()) {
-        const Vector<Attribute, 4>& attributeVector = static_cast<const UniqueElementData*>(this)->m_attributeVector;
-        return AttributeCollection(attributeVector.data(), attributeVector.size());
-    }
-    return AttributeCollection(static_cast<const ShareableElementData*>(this)->m_attributeArray, m_arraySize);
+    if (isUnique())
+        return static_cast<const UniqueElementData*>(this)->attributes();
+    return static_cast<const ShareableElementData*>(this)->attributes();
 }
 
-inline const Attribute* ElementData::findAttributeByName(const QualifiedName& name) const
+inline AttributeCollection ShareableElementData::attributes() const
 {
-    AttributeCollection attributes = this->attributes();
-    AttributeCollection::const_iterator end = attributes.end();
-    for (AttributeCollection::const_iterator it = attributes.begin(); it != end; ++it) {
+    return AttributeCollection(m_attributeArray, m_arraySize);
+}
+
+inline AttributeCollection UniqueElementData::attributes() const
+{
+    return AttributeCollection(m_attributeVector.data(), m_attributeVector.size());
+}
+
+inline const Attribute* AttributeCollection::get(const QualifiedName& name) const
+{
+    const_iterator end = this->end();
+    for (const_iterator it = begin(); it != end; ++it) {
         if (it->name().matches(name))
             return it;
     }
     return 0;
 }
 
-inline const Attribute& ElementData::attributeAt(unsigned index) const
-{
-    RELEASE_ASSERT(index < attributeCount());
-    ASSERT(attributeBase() + index);
-    return *(attributeBase() + index);
-}
-
 inline void UniqueElementData::appendAttribute(const QualifiedName& attributeName, const AtomicString& value)
 {
     m_attributeVector.append(Attribute(attributeName, value));
 }
 
 inline void UniqueElementData::removeAttributeAt(size_t index)
 {
     m_attributeVector.remove(index);
 }
 
 inline Attribute& UniqueElementData::attributeAt(unsigned index)
 {
     return m_attributeVector.at(index);
 }
 
 } // namespace WebCore
 
 #endif // ElementData_h