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/*
* Copyright (C) 2009 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:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
* THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
* THE POSSIBILITY OF SUCH DAMAGE.
*/
#ifndef WeakGCMap_h
#define WeakGCMap_h
#include "Handle.h"
#include "JSGlobalData.h"
#include <wtf/HashMap.h>
namespace JSC {
// A HashMap for GC'd values that removes entries when the associated value
// dies.
template <typename KeyType, typename MappedType> struct DefaultWeakGCMapFinalizerCallback {
static void* finalizerContextFor(KeyType key)
{
return reinterpret_cast<void*>(key);
}
static KeyType keyForFinalizer(void* context, typename HandleTypes<MappedType>::ExternalType)
{
return reinterpret_cast<KeyType>(context);
}
};
template<typename KeyType, typename MappedType, typename FinalizerCallback = DefaultWeakGCMapFinalizerCallback<KeyType, MappedType>, typename HashArg = typename DefaultHash<KeyType>::Hash, typename KeyTraitsArg = HashTraits<KeyType> >
class WeakGCMap : private WeakHandleOwner {
WTF_MAKE_FAST_ALLOCATED;
WTF_MAKE_NONCOPYABLE(WeakGCMap);
typedef HashMap<KeyType, HandleSlot, HashArg, KeyTraitsArg> MapType;
typedef typename HandleTypes<MappedType>::ExternalType ExternalType;
typedef typename MapType::iterator map_iterator;
public:
struct iterator {
friend class WeakGCMap;
iterator(map_iterator iter)
: m_iterator(iter)
{
}
std::pair<KeyType, ExternalType> get() const { return std::make_pair(m_iterator->first, HandleTypes<MappedType>::getFromSlot(m_iterator->second)); }
std::pair<KeyType, HandleSlot> getSlot() const { return *m_iterator; }
iterator& operator++() { ++m_iterator; return *this; }
// postfix ++ intentionally omitted
// Comparison.
bool operator==(const iterator& other) const { return m_iterator == other.m_iterator; }
bool operator!=(const iterator& other) const { return m_iterator != other.m_iterator; }
private:
map_iterator m_iterator;
};
WeakGCMap()
{
}
bool isEmpty() { return m_map.isEmpty(); }
void clear()
{
map_iterator end = m_map.end();
for (map_iterator ptr = m_map.begin(); ptr != end; ++ptr)
HandleHeap::heapFor(ptr->second)->deallocate(ptr->second);
m_map.clear();
}
bool contains(const KeyType& key) const
{
return m_map.contains(key);
}
iterator find(const KeyType& key)
{
return m_map.find(key);
}
void remove(iterator iter)
{
ASSERT(iter.m_iterator != m_map.end());
HandleSlot slot = iter.m_iterator->second;
ASSERT(slot);
HandleHeap::heapFor(slot)->deallocate(slot);
m_map.remove(iter.m_iterator);
}
ExternalType get(const KeyType& key) const
{
return HandleTypes<MappedType>::getFromSlot(m_map.get(key));
}
HandleSlot getSlot(const KeyType& key) const
{
return m_map.get(key);
}
pair<iterator, bool> add(JSGlobalData& globalData, const KeyType& key, ExternalType value)
{
pair<typename MapType::iterator, bool> iter = m_map.add(key, 0);
if (iter.second) {
HandleSlot slot = globalData.allocateGlobalHandle();
iter.first->second = slot;
HandleHeap::heapFor(slot)->makeWeak(slot, this, FinalizerCallback::finalizerContextFor(key));
HandleHeap::heapFor(slot)->writeBarrier(slot, value);
*slot = value;
}
return iter;
}
void set(iterator iter, ExternalType value)
{
HandleSlot slot = iter.m_iterator->second;
ASSERT(slot);
HandleHeap::heapFor(slot)->writeBarrier(slot, value);
*slot = value;
}
void set(JSGlobalData& globalData, const KeyType& key, ExternalType value)
{
pair<typename MapType::iterator, bool> iter = m_map.add(key, 0);
HandleSlot slot = iter.first->second;
if (iter.second) {
slot = globalData.allocateGlobalHandle();
HandleHeap::heapFor(slot)->makeWeak(slot, this, key);
iter.first->second = slot;
}
HandleHeap::heapFor(slot)->writeBarrier(slot, value);
*slot = value;
}
ExternalType take(const KeyType& key)
{
HandleSlot slot = m_map.take(key);
if (!slot)
return HashTraits<ExternalType>::emptyValue();
ExternalType result = HandleTypes<MappedType>::getFromSlot(slot);
HandleHeap::heapFor(slot)->deallocate(slot);
return result;
}
size_t size() { return m_map.size(); }
iterator begin() { return iterator(m_map.begin()); }
iterator end() { return iterator(m_map.end()); }
~WeakGCMap()
{
clear();
}
private:
virtual void finalize(Handle<Unknown> handle, void* context)
{
HandleSlot slot = m_map.take(FinalizerCallback::keyForFinalizer(context, HandleTypes<MappedType>::getFromSlot(handle.slot())));
ASSERT(slot);
HandleHeap::heapFor(slot)->deallocate(slot);
}
MapType m_map;
};
} // namespace JSC
#endif // WeakGCMap_h
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