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265e672179
# ignore-this-changeset --HG-- extra : amend_source : 4d301d3b0b8711c4692392aa76088ba7fd7d1022
108 lines
2.9 KiB
C++
108 lines
2.9 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_AgileReference_h
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#define mozilla_mscom_AgileReference_h
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#include "mozilla/RefPtr.h"
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#include <objidl.h>
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namespace mozilla {
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namespace mscom {
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/**
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* This class encapsulates an "agile reference." These are references that
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* allow you to pass COM interfaces between apartments. When you have an
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* interface that you would like to pass between apartments, you wrap that
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* interface in an AgileReference and pass the agile reference instead. Then
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* you unwrap the interface by calling AgileReference::Resolve.
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*
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* Sample usage:
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*
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* // In the multithreaded apartment, foo is an IFoo*
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* auto myAgileRef = MakeUnique<AgileReference>(IID_IFoo, foo);
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*
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* // myAgileRef is passed to our main thread, which runs in a single-threaded
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* // apartment:
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*
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* RefPtr<IFoo> foo;
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* HRESULT hr = myAgileRef->Resolve(IID_IFoo, getter_AddRefs(foo));
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* // Now foo may be called from the main thread
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*/
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class AgileReference final {
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public:
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AgileReference();
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template <typename InterfaceT>
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explicit AgileReference(RefPtr<InterfaceT>& aObject)
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: AgileReference(__uuidof(InterfaceT), aObject) {}
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AgileReference(REFIID aIid, IUnknown* aObject);
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AgileReference(AgileReference&& aOther);
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~AgileReference();
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explicit operator bool() const { return mAgileRef || mGitCookie; }
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template <typename T>
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void Assign(const RefPtr<T>& aOther) {
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Assign(__uuidof(T), aOther);
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}
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template <typename T>
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AgileReference& operator=(const RefPtr<T>& aOther) {
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Assign(aOther);
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return *this;
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}
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HRESULT Resolve(REFIID aIid, void** aOutInterface) const;
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AgileReference(const AgileReference& aOther) = delete;
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AgileReference& operator=(const AgileReference& aOther) = delete;
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AgileReference& operator=(AgileReference&& aOther);
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AgileReference& operator=(decltype(nullptr)) {
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Clear();
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return *this;
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}
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void Clear();
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private:
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void Assign(REFIID aIid, IUnknown* aObject);
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void AssignInternal(IUnknown* aObject);
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static IGlobalInterfaceTable* ObtainGit();
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private:
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IID mIid;
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RefPtr<IAgileReference> mAgileRef;
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DWORD mGitCookie;
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};
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} // namespace mscom
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} // namespace mozilla
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template <typename T>
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RefPtr<T>::RefPtr(const mozilla::mscom::AgileReference& aAgileRef)
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: mRawPtr(nullptr) {
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(*this) = aAgileRef;
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}
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template <typename T>
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RefPtr<T>& RefPtr<T>::operator=(
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const mozilla::mscom::AgileReference& aAgileRef) {
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void* newRawPtr;
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if (FAILED(aAgileRef.Resolve(__uuidof(T), &newRawPtr))) {
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newRawPtr = nullptr;
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}
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assign_assuming_AddRef(static_cast<T*>(newRawPtr));
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return *this;
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}
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#endif // mozilla_mscom_AgileReference_h
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