gecko-dev/toolkit/components/places/nsMaybeWeakPtr.h
Ehsan Akhgari d0800c4d23 Bug 1060974 - Fix more bad implicit constructors in places; r=mak
--HG--
extra : rebase_source : c8d465b4de55d000d1475994827766e33396ff12
2014-09-03 18:25:36 -04:00

107 lines
3.4 KiB
C++

/* -*- Mode: C++; tab-width: 8; 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 nsMaybeWeakPtr_h_
#define nsMaybeWeakPtr_h_
#include "mozilla/Attributes.h"
#include "nsCOMPtr.h"
#include "nsWeakReference.h"
#include "nsTArray.h"
#include "nsCycleCollectionNoteChild.h"
// nsMaybeWeakPtr is a helper object to hold a strong-or-weak reference
// to the template class. It's pretty minimal, but sufficient.
class nsMaybeWeakPtr_base
{
protected:
// Returns an addref'd pointer to the requested interface
void* GetValueAs(const nsIID& iid) const;
nsCOMPtr<nsISupports> mPtr;
};
template<class T>
class nsMaybeWeakPtr : private nsMaybeWeakPtr_base
{
public:
MOZ_IMPLICIT nsMaybeWeakPtr(nsISupports *ref) { mPtr = ref; }
MOZ_IMPLICIT nsMaybeWeakPtr(const nsCOMPtr<nsIWeakReference> &ref) { mPtr = ref; }
MOZ_IMPLICIT nsMaybeWeakPtr(const nsCOMPtr<T> &ref) { mPtr = ref; }
bool operator==(const nsMaybeWeakPtr<T> &other) const {
return mPtr == other.mPtr;
}
operator const nsCOMPtr<T>() const { return GetValue(); }
protected:
const nsCOMPtr<T> GetValue() const {
return nsCOMPtr<T>(dont_AddRef(static_cast<T*>
(GetValueAs(NS_GET_TEMPLATE_IID(T)))));
}
};
// nsMaybeWeakPtrArray is an array of MaybeWeakPtr objects, that knows how to
// grab a weak reference to a given object if requested. It only allows a
// given object to appear in the array once.
typedef nsTArray< nsMaybeWeakPtr<nsISupports> > isupports_array_type;
nsresult NS_AppendWeakElementBase(isupports_array_type *aArray,
nsISupports *aElement, bool aWeak);
nsresult NS_RemoveWeakElementBase(isupports_array_type *aArray,
nsISupports *aElement);
template<class T>
class nsMaybeWeakPtrArray : public nsTArray< nsMaybeWeakPtr<T> >
{
public:
nsresult AppendWeakElement(T *aElement, bool aOwnsWeak)
{
return NS_AppendWeakElementBase(
reinterpret_cast<isupports_array_type*>(this), aElement, aOwnsWeak);
}
nsresult RemoveWeakElement(T *aElement)
{
return NS_RemoveWeakElementBase(
reinterpret_cast<isupports_array_type*>(this), aElement);
}
};
template <typename T>
inline void
ImplCycleCollectionUnlink(nsMaybeWeakPtrArray<T>& aField)
{
aField.Clear();
}
template <typename E>
inline void
ImplCycleCollectionTraverse(nsCycleCollectionTraversalCallback& aCallback,
nsMaybeWeakPtrArray<E>& aField,
const char* aName,
uint32_t aFlags = 0)
{
aFlags |= CycleCollectionEdgeNameArrayFlag;
size_t length = aField.Length();
for (size_t i = 0; i < length; ++i) {
CycleCollectionNoteChild(aCallback, aField[i].get(), aName, aFlags);
}
}
// Call a method on each element in the array, but only if the element is
// non-null.
#define ENUMERATE_WEAKARRAY(array, type, method) \
for (uint32_t array_idx = 0; array_idx < array.Length(); ++array_idx) { \
const nsCOMPtr<type> &e = array.ElementAt(array_idx); \
if (e) \
e->method; \
}
#endif