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265e672179
# ignore-this-changeset --HG-- extra : amend_source : 4d301d3b0b8711c4692392aa76088ba7fd7d1022
83 lines
3.1 KiB
C++
83 lines
3.1 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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#ifndef mozilla_mscom_Aggregation_h
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#define mozilla_mscom_Aggregation_h
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#include "mozilla/Attributes.h"
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#include <stddef.h>
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#include <unknwn.h>
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namespace mozilla {
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namespace mscom {
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/**
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* This is used for stabilizing a COM object's reference count during
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* construction when that object aggregates other objects. Since the aggregated
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* object(s) may AddRef() or Release(), we need to artifically boost the
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* refcount to prevent premature destruction. Note that we increment/decrement
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* instead of AddRef()/Release() in this class because we want to adjust the
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* refcount without causing any other side effects (like object destruction).
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*/
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template <typename RefCntT>
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class MOZ_RAII StabilizedRefCount {
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public:
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explicit StabilizedRefCount(RefCntT& aRefCnt) : mRefCnt(aRefCnt) {
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++aRefCnt;
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}
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~StabilizedRefCount() { --mRefCnt; }
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StabilizedRefCount(const StabilizedRefCount&) = delete;
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StabilizedRefCount(StabilizedRefCount&&) = delete;
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StabilizedRefCount& operator=(const StabilizedRefCount&) = delete;
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StabilizedRefCount& operator=(StabilizedRefCount&&) = delete;
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private:
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RefCntT& mRefCnt;
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};
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namespace detail {
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template <typename T>
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class InternalUnknown : public IUnknown {
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public:
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STDMETHODIMP QueryInterface(REFIID aIid, void** aOutInterface) override {
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return This()->InternalQueryInterface(aIid, aOutInterface);
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}
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STDMETHODIMP_(ULONG) AddRef() override { return This()->InternalAddRef(); }
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STDMETHODIMP_(ULONG) Release() override { return This()->InternalRelease(); }
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private:
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T* This() {
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return reinterpret_cast<T*>(reinterpret_cast<char*>(this) -
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offsetof(T, mInternalUnknown));
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}
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};
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} // namespace detail
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} // namespace mscom
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} // namespace mozilla
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#define DECLARE_AGGREGATABLE(Type) \
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public: \
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STDMETHODIMP QueryInterface(REFIID riid, void** ppv) override { \
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return mOuter->QueryInterface(riid, ppv); \
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} \
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STDMETHODIMP_(ULONG) AddRef() override { return mOuter->AddRef(); } \
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STDMETHODIMP_(ULONG) Release() override { return mOuter->Release(); } \
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\
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protected: \
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STDMETHODIMP InternalQueryInterface(REFIID riid, void** ppv); \
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STDMETHODIMP_(ULONG) InternalAddRef(); \
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STDMETHODIMP_(ULONG) InternalRelease(); \
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friend class mozilla::mscom::detail::InternalUnknown<Type>; \
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mozilla::mscom::detail::InternalUnknown<Type> mInternalUnknown
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#endif // mozilla_mscom_Aggregation_h
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