gecko-dev/xpcom/glue/nsRefPtrHashtable.h

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/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#ifndef nsRefPtrHashtable_h__
#define nsRefPtrHashtable_h__
#include "nsBaseHashtable.h"
#include "nsHashKeys.h"
#include "nsAutoPtr.h"
/**
* templated hashtable class maps keys to reference pointers.
* See nsBaseHashtable for complete declaration.
* @param KeyClass a wrapper-class for the hashtable key, see nsHashKeys.h
* for a complete specification.
* @param RefPtr the reference-type being wrapped
* @see nsDataHashtable, nsClassHashtable
*/
template<class KeyClass, class RefPtr>
class nsRefPtrHashtable :
public nsBaseHashtable< KeyClass, nsRefPtr<RefPtr> , RefPtr* >
{
public:
typedef typename KeyClass::KeyType KeyType;
typedef RefPtr* UserDataType;
typedef nsBaseHashtable< KeyClass, nsRefPtr<RefPtr> , RefPtr* > base_type;
/**
* @copydoc nsBaseHashtable::Get
* @param pData This is an XPCOM getter, so pData is already_addrefed.
* If the key doesn't exist, pData will be set to nullptr.
*/
bool Get(KeyType aKey, UserDataType* pData) const;
/**
* Gets a weak reference to the hashtable entry.
* @param aFound If not nullptr, will be set to true if the entry is found,
* to false otherwise.
* @return The entry, or nullptr if not found. Do not release this pointer!
*/
RefPtr* GetWeak(KeyType aKey, bool* aFound = nullptr) const;
};
template <typename K, typename T>
inline void
ImplCycleCollectionUnlink(nsRefPtrHashtable<K, T>& aField)
{
aField.Clear();
}
template <typename K, typename T>
inline void
ImplCycleCollectionTraverse(nsCycleCollectionTraversalCallback& aCallback,
nsRefPtrHashtable<K, T>& aField,
const char* aName,
uint32_t aFlags = 0)
{
nsBaseHashtableCCTraversalData userData(aCallback, aName, aFlags);
aField.EnumerateRead(ImplCycleCollectionTraverse_EnumFunc<typename K::KeyType,T*>,
&userData);
}
//
// nsRefPtrHashtable definitions
//
template<class KeyClass, class RefPtr>
bool
nsRefPtrHashtable<KeyClass,RefPtr>::Get
(KeyType aKey, UserDataType* pRefPtr) const
{
typename base_type::EntryType* ent = this->GetEntry(aKey);
if (ent)
{
if (pRefPtr)
{
*pRefPtr = ent->mData;
NS_IF_ADDREF(*pRefPtr);
}
return true;
}
// if the key doesn't exist, set *pRefPtr to null
// so that it is a valid XPCOM getter
if (pRefPtr)
*pRefPtr = nullptr;
return false;
}
template<class KeyClass, class RefPtr>
RefPtr*
nsRefPtrHashtable<KeyClass,RefPtr>::GetWeak
(KeyType aKey, bool* aFound) const
{
typename base_type::EntryType* ent = this->GetEntry(aKey);
if (ent)
{
if (aFound)
*aFound = true;
return ent->mData;
}
// Key does not exist, return nullptr and set aFound to false
if (aFound)
*aFound = false;
return nullptr;
}
#endif // nsRefPtrHashtable_h__