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107 lines
3.4 KiB
C++
107 lines
3.4 KiB
C++
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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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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#ifndef nsMaybeWeakPtr_h_
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#define nsMaybeWeakPtr_h_
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#include "mozilla/Attributes.h"
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#include "nsCOMPtr.h"
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#include "nsWeakReference.h"
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#include "nsTArray.h"
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#include "nsCycleCollectionNoteChild.h"
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// nsMaybeWeakPtr is a helper object to hold a strong-or-weak reference
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// to the template class. It's pretty minimal, but sufficient.
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class nsMaybeWeakPtr_base
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{
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protected:
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// Returns an addref'd pointer to the requested interface
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void* GetValueAs(const nsIID& iid) const;
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nsCOMPtr<nsISupports> mPtr;
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};
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template<class T>
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class nsMaybeWeakPtr : private nsMaybeWeakPtr_base
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{
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public:
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MOZ_IMPLICIT nsMaybeWeakPtr(nsISupports *ref) { mPtr = ref; }
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MOZ_IMPLICIT nsMaybeWeakPtr(const nsCOMPtr<nsIWeakReference> &ref) { mPtr = ref; }
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MOZ_IMPLICIT nsMaybeWeakPtr(const nsCOMPtr<T> &ref) { mPtr = ref; }
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bool operator==(const nsMaybeWeakPtr<T> &other) const {
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return mPtr == other.mPtr;
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}
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operator const nsCOMPtr<T>() const { return GetValue(); }
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protected:
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const nsCOMPtr<T> GetValue() const {
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return nsCOMPtr<T>(dont_AddRef(static_cast<T*>
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(GetValueAs(NS_GET_TEMPLATE_IID(T)))));
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}
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};
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// nsMaybeWeakPtrArray is an array of MaybeWeakPtr objects, that knows how to
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// grab a weak reference to a given object if requested. It only allows a
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// given object to appear in the array once.
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typedef nsTArray< nsMaybeWeakPtr<nsISupports> > isupports_array_type;
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nsresult NS_AppendWeakElementBase(isupports_array_type *aArray,
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nsISupports *aElement, bool aWeak);
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nsresult NS_RemoveWeakElementBase(isupports_array_type *aArray,
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nsISupports *aElement);
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template<class T>
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class nsMaybeWeakPtrArray : public nsTArray< nsMaybeWeakPtr<T> >
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{
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public:
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nsresult AppendWeakElement(T *aElement, bool aOwnsWeak)
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{
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return NS_AppendWeakElementBase(
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reinterpret_cast<isupports_array_type*>(this), aElement, aOwnsWeak);
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}
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nsresult RemoveWeakElement(T *aElement)
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{
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return NS_RemoveWeakElementBase(
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reinterpret_cast<isupports_array_type*>(this), aElement);
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}
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};
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template <typename T>
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inline void
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ImplCycleCollectionUnlink(nsMaybeWeakPtrArray<T>& aField)
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{
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aField.Clear();
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}
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template <typename E>
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inline void
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ImplCycleCollectionTraverse(nsCycleCollectionTraversalCallback& aCallback,
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nsMaybeWeakPtrArray<E>& aField,
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const char* aName,
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uint32_t aFlags = 0)
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{
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aFlags |= CycleCollectionEdgeNameArrayFlag;
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size_t length = aField.Length();
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for (size_t i = 0; i < length; ++i) {
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CycleCollectionNoteChild(aCallback, aField[i].get(), aName, aFlags);
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}
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}
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// Call a method on each element in the array, but only if the element is
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// non-null.
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#define ENUMERATE_WEAKARRAY(array, type, method) \
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for (uint32_t array_idx = 0; array_idx < array.Length(); ++array_idx) { \
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const nsCOMPtr<type> &e = array.ElementAt(array_idx); \
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if (e) \
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e->method; \
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}
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#endif
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