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140 lines
3.0 KiB
C++
140 lines
3.0 KiB
C++
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* vim: set ts=8 sts=2 et sw=2 tw=80: */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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// nsWeakReference.cpp
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#include "mozilla/Attributes.h"
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#include "nsWeakReference.h"
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#include "nsCOMPtr.h"
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class nsWeakReference MOZ_FINAL : public nsIWeakReference
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{
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public:
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// nsISupports...
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NS_DECL_ISUPPORTS
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// nsIWeakReference...
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NS_DECL_NSIWEAKREFERENCE
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virtual size_t SizeOfOnlyThis(mozilla::MallocSizeOf aMallocSizeOf) const MOZ_OVERRIDE;
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private:
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friend class nsSupportsWeakReference;
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explicit nsWeakReference(nsSupportsWeakReference* aReferent)
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: mReferent(aReferent)
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// ...I can only be constructed by an |nsSupportsWeakReference|
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{
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}
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~nsWeakReference()
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// ...I will only be destroyed by calling |delete| myself.
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{
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if (mReferent) {
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mReferent->NoticeProxyDestruction();
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}
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}
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void
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NoticeReferentDestruction()
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// ...called (only) by an |nsSupportsWeakReference| from _its_ dtor.
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{
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mReferent = 0;
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}
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nsSupportsWeakReference* MOZ_NON_OWNING_REF mReferent;
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};
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nsresult
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nsQueryReferent::operator()(const nsIID& aIID, void** aAnswer) const
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{
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nsresult status;
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if (mWeakPtr) {
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if (NS_FAILED(status = mWeakPtr->QueryReferent(aIID, aAnswer))) {
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*aAnswer = 0;
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}
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} else {
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status = NS_ERROR_NULL_POINTER;
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}
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if (mErrorPtr) {
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*mErrorPtr = status;
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}
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return status;
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}
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nsIWeakReference* // or else |already_AddRefed<nsIWeakReference>|
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NS_GetWeakReference(nsISupports* aInstancePtr, nsresult* aErrorPtr)
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{
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nsresult status;
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nsIWeakReference* result = nullptr;
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if (aInstancePtr) {
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nsCOMPtr<nsISupportsWeakReference> factoryPtr =
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do_QueryInterface(aInstancePtr, &status);
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if (factoryPtr) {
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status = factoryPtr->GetWeakReference(&result);
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}
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// else, |status| has already been set by |do_QueryInterface|
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} else {
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status = NS_ERROR_NULL_POINTER;
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}
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if (aErrorPtr) {
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*aErrorPtr = status;
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}
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return result;
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}
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nsresult
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nsSupportsWeakReference::GetWeakReference(nsIWeakReference** aInstancePtr)
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{
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if (!aInstancePtr) {
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return NS_ERROR_NULL_POINTER;
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}
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if (!mProxy) {
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mProxy = new nsWeakReference(this);
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}
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*aInstancePtr = mProxy;
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nsresult status;
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if (!*aInstancePtr) {
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status = NS_ERROR_OUT_OF_MEMORY;
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} else {
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NS_ADDREF(*aInstancePtr);
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status = NS_OK;
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}
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return status;
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}
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NS_IMPL_ISUPPORTS(nsWeakReference, nsIWeakReference)
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NS_IMETHODIMP
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nsWeakReference::QueryReferent(const nsIID& aIID, void** aInstancePtr)
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{
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return mReferent ? mReferent->QueryInterface(aIID, aInstancePtr) :
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NS_ERROR_NULL_POINTER;
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}
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size_t
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nsWeakReference::SizeOfOnlyThis(mozilla::MallocSizeOf aMallocSizeOf) const
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{
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return aMallocSizeOf(this);
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}
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void
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nsSupportsWeakReference::ClearWeakReferences()
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{
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if (mProxy) {
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mProxy->NoticeReferentDestruction();
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mProxy = 0;
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}
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}
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