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      1 /*
      2  * Copyright (C) 2014 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 V8PersistentValueMap_h
     32 #define V8PersistentValueMap_h
     33 
     34 #include "wtf/HashMap.h"
     35 #include <v8-util.h>
     36 #include <v8.h>
     37 
     38 namespace WebCore {
     39 
     40 /**
     41  * A Traits class for v8::PersistentValueMap that uses wtf/HashMap as a
     42  * backing store.
     43  *
     44  * The parameter is_weak will determine whether the references are 'weak'.
     45  * If so, entries will be removed from the map as the weak references are
     46  * collected.
     47  */
     48 template<class KeyType, class ValueType, bool is_weak>
     49 class V8PersistentValueMapTraits {
     50 public:
     51     // Map traits:
     52     typedef HashMap<KeyType, v8::PersistentContainerValue> Impl;
     53     typedef typename Impl::iterator Iterator;
     54     static size_t Size(const Impl* impl) { return impl->size(); }
     55     static bool Empty(Impl* impl) { return impl->isEmpty(); }
     56     static void Swap(Impl& impl, Impl& other) { impl.swap(other); }
     57     static Iterator Begin(Impl* impl) { return impl->begin(); }
     58     static Iterator End(Impl* impl) { return impl->end(); }
     59     static v8::PersistentContainerValue Value(Iterator& iter)
     60     {
     61         return iter->value;
     62     }
     63     static KeyType Key(Iterator& iter) { return iter->key; }
     64     static v8::PersistentContainerValue Set(
     65         Impl* impl, KeyType key, v8::PersistentContainerValue value)
     66     {
     67         v8::PersistentContainerValue oldValue = Get(impl, key);
     68         impl->set(key, value);
     69         return oldValue;
     70     }
     71     static v8::PersistentContainerValue Get(const Impl* impl, KeyType key)
     72     {
     73         return impl->get(key);
     74     }
     75 
     76     static v8::PersistentContainerValue Remove(Impl* impl, KeyType key)
     77     {
     78         return impl->take(key);
     79     }
     80 
     81     // Weak traits:
     82     static const v8::PersistentContainerCallbackType kCallbackType = is_weak ? v8::kWeak : v8::kNotWeak;
     83     typedef v8::PersistentValueMap<KeyType, ValueType, V8PersistentValueMapTraits<KeyType, ValueType, is_weak> > MapType;
     84 
     85     typedef void WeakCallbackDataType;
     86 
     87     static WeakCallbackDataType* WeakCallbackParameter(MapType* map, KeyType key, const v8::Local<ValueType>& value)
     88     {
     89         return 0;
     90     }
     91 
     92     static void DisposeCallbackData(WeakCallbackDataType* callbackData)
     93     {
     94     }
     95 
     96     static MapType* MapFromWeakCallbackData(
     97         const v8::WeakCallbackData<ValueType, WeakCallbackDataType>& data)
     98     {
     99         return 0;
    100     }
    101 
    102     static KeyType KeyFromWeakCallbackData(
    103         const v8::WeakCallbackData<ValueType, WeakCallbackDataType>& data)
    104     {
    105         return KeyType();
    106     }
    107 
    108     // Dispose traits:
    109     static void Dispose(v8::Isolate* isolate, v8::UniquePersistent<ValueType> value, KeyType key) { }
    110 };
    111 
    112 /**
    113  * A map for safely storing persistent V8 values, based on
    114  * v8::PersistentValueMap.
    115  *
    116  * If is_weak is set, values will be held weakly and map entries will be
    117  * removed as their values are being collected.
    118  */
    119 template<class KeyType, class ValueType, bool is_weak = true>
    120 class V8PersistentValueMap : public v8::PersistentValueMap<KeyType, ValueType, V8PersistentValueMapTraits<KeyType, ValueType, is_weak> > {
    121 public:
    122     typedef V8PersistentValueMapTraits<KeyType, ValueType, is_weak> Traits;
    123     explicit V8PersistentValueMap(v8::Isolate* isolate) : v8::PersistentValueMap<KeyType, ValueType, Traits>(isolate) { }
    124 };
    125 
    126 } // namespace WebCore
    127 
    128 #endif // V8PersistentValueMap_h
    129