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      1 /*
      2  * Copyright (C) 2009 Google Inc. All rights reserved.
      3  *
      4  * Redistribution and use in source and binary forms, with or without
      5  * modification, are permitted provided that the following conditions are
      6  * met:
      7  *
      8  *     * Redistributions of source code must retain the above copyright
      9  * notice, this list of conditions and the following disclaimer.
     10  *     * Redistributions in binary form must reproduce the above
     11  * copyright notice, this list of conditions and the following disclaimer
     12  * in the documentation and/or other materials provided with the
     13  * distribution.
     14  *     * Neither the name of Google Inc. nor the names of its
     15  * contributors may be used to endorse or promote products derived from
     16  * this software without specific prior written permission.
     17  *
     18  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
     19  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
     20  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
     21  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
     22  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
     23  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
     24  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
     25  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
     26  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     27  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
     28  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     29  */
     30 
     31 #ifndef V8DOMMap_h
     32 #define V8DOMMap_h
     33 
     34 #include <wtf/HashMap.h>
     35 #include <wtf/OwnPtr.h>
     36 #include <v8.h>
     37 
     38 namespace WebCore {
     39     class DOMDataStore;
     40     class Node;
     41 #if ENABLE(SVG)
     42     class SVGElementInstance;
     43 #endif
     44 
     45     template <class KeyType, class ValueType> class AbstractWeakReferenceMap {
     46     public:
     47         AbstractWeakReferenceMap(v8::WeakReferenceCallback callback) : m_weakReferenceCallback(callback) { }
     48         virtual ~AbstractWeakReferenceMap() { }
     49 
     50         class Visitor {
     51         public:
     52             virtual void startMap() { }
     53             virtual void endMap() { }
     54             virtual void visitDOMWrapper(DOMDataStore* store, KeyType* key, v8::Persistent<ValueType> object) = 0;
     55         protected:
     56             virtual ~Visitor() { }
     57         };
     58 
     59         virtual v8::Persistent<ValueType> get(KeyType* obj) = 0;
     60         virtual void set(KeyType* obj, v8::Persistent<ValueType> wrapper) = 0;
     61         virtual bool contains(KeyType* obj) = 0;
     62         virtual void visit(DOMDataStore* store, Visitor* visitor) = 0;
     63         virtual bool removeIfPresent(KeyType*, v8::Persistent<ValueType>) = 0;
     64         virtual void clear() = 0;
     65 
     66         v8::WeakReferenceCallback weakReferenceCallback() { return m_weakReferenceCallback; }
     67     private:
     68         v8::WeakReferenceCallback m_weakReferenceCallback;
     69     };
     70 
     71     typedef AbstractWeakReferenceMap<Node, v8::Object> DOMNodeMapping;
     72 
     73     // A table of wrappers with weak pointers.
     74     // This table allows us to avoid track wrapped objects for debugging
     75     // and for ensuring that we don't double wrap the same object.
     76     template<class KeyType, class ValueType> class WeakReferenceMap : public AbstractWeakReferenceMap<KeyType, ValueType> {
     77     public:
     78         typedef AbstractWeakReferenceMap<KeyType, ValueType> Parent;
     79         WeakReferenceMap(v8::WeakReferenceCallback callback) : Parent(callback) { }
     80         virtual ~WeakReferenceMap() { }
     81 
     82         // Get the JS wrapper object of an object.
     83         virtual v8::Persistent<ValueType> get(KeyType* obj)
     84         {
     85             ValueType* wrapper = m_map.get(obj);
     86             return wrapper ? v8::Persistent<ValueType>(wrapper) : v8::Persistent<ValueType>();
     87         }
     88 
     89         virtual void set(KeyType* obj, v8::Persistent<ValueType> wrapper)
     90         {
     91             ASSERT(!m_map.contains(obj));
     92             wrapper.MakeWeak(obj, Parent::weakReferenceCallback());
     93             m_map.set(obj, *wrapper);
     94         }
     95 
     96         virtual void forget(KeyType* obj)
     97         {
     98             ASSERT(obj);
     99             ValueType* wrapper = m_map.take(obj);
    100             if (!wrapper)
    101                 return;
    102 
    103             v8::Persistent<ValueType> handle(wrapper);
    104             handle.Dispose();
    105             handle.Clear();
    106         }
    107 
    108         bool removeIfPresent(KeyType* key, v8::Persistent<ValueType> value)
    109         {
    110             typename HashMap<KeyType*, ValueType*>::iterator it = m_map.find(key);
    111             if (it == m_map.end() || it->second != *value)
    112                 return false;
    113 
    114             m_map.remove(it);
    115             value.Dispose();
    116             return true;
    117         }
    118 
    119         void clear()
    120         {
    121             m_map.clear();
    122         }
    123 
    124         bool contains(KeyType* obj) { return m_map.contains(obj); }
    125 
    126         virtual void visit(DOMDataStore* store, typename Parent::Visitor* visitor)
    127         {
    128             visitor->startMap();
    129             typename HashMap<KeyType*, ValueType*>::iterator it = m_map.begin();
    130             for (; it != m_map.end(); ++it)
    131                 visitor->visitDOMWrapper(store, it->first, v8::Persistent<ValueType>(it->second));
    132             visitor->endMap();
    133         }
    134 
    135     protected:
    136         HashMap<KeyType*, ValueType*> m_map;
    137     };
    138 
    139     template <class KeyType> class DOMWrapperMap : public WeakReferenceMap<KeyType, v8::Object> {
    140     public:
    141         DOMWrapperMap(v8::WeakReferenceCallback callback) : WeakReferenceMap<KeyType, v8::Object>(callback) { }
    142     };
    143 
    144     // An opaque class that represents a set of DOM wrappers.
    145     class DOMDataStore;
    146 
    147     // A utility class to manage the lifetime of set of DOM wrappers.
    148     class DOMDataStoreHandle {
    149     public:
    150         DOMDataStoreHandle();
    151         ~DOMDataStoreHandle();
    152 
    153         DOMDataStore* getStore() const { return m_store.get(); }
    154 
    155     private:
    156         OwnPtr<DOMDataStore> m_store;
    157     };
    158 
    159     // A map from DOM node to its JS wrapper.
    160     DOMNodeMapping& getDOMNodeMap();
    161     void visitDOMNodesInCurrentThread(DOMWrapperMap<Node>::Visitor*);
    162 
    163     // A map from a DOM object (non-node) to its JS wrapper. This map does not contain the DOM objects which can have pending activity (active dom objects).
    164     DOMWrapperMap<void>& getDOMObjectMap();
    165     void visitDOMObjectsInCurrentThread(DOMWrapperMap<void>::Visitor*);
    166 
    167     // A map from a DOM object to its JS wrapper for DOM objects which can have pending activity.
    168     DOMWrapperMap<void>& getActiveDOMObjectMap();
    169     void visitActiveDOMObjectsInCurrentThread(DOMWrapperMap<void>::Visitor*);
    170 
    171     // This should be called to remove all DOM objects associated with the current thread when it is tearing down.
    172     void removeAllDOMObjectsInCurrentThread();
    173 
    174 #if ENABLE(SVG)
    175     // A map for SVGElementInstances to its JS wrapper.
    176     DOMWrapperMap<SVGElementInstance>& getDOMSVGElementInstanceMap();
    177     void visitSVGElementInstancesInCurrentThread(DOMWrapperMap<SVGElementInstance>::Visitor*);
    178 #endif
    179 
    180     void enableFasterDOMStoreAccess();
    181 } // namespace WebCore
    182 
    183 #endif // V8DOMMap_h
    184