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// Copyright (c) 2006-2008 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
// ClassFactory<class>
// is a simple class factory object for the parameterized class.
//
#ifndef CHROME_COMMON_CLASSFACTORY_H_
#define CHROME_COMMON_CLASSFACTORY_H_
#include <unknwn.h>
// GenericClassFactory
// provides the basic COM plumbing to implement IClassFactory, and
// maintains a static count on the number of these objects in existence.
// It remains for subclasses to implement CreateInstance.
class GenericClassFactory : public IClassFactory {
public:
GenericClassFactory();
~GenericClassFactory();
// IUnknown methods
STDMETHOD(QueryInterface)(REFIID iid, LPVOID* ppvObject);
STDMETHOD_(ULONG, AddRef)();
STDMETHOD_(ULONG, Release)();
// IClassFactory methods
STDMETHOD(CreateInstance)(LPUNKNOWN pUnkOuter, REFIID riid,
LPVOID* ppvObject) = 0;
STDMETHOD(LockServer)(BOOL fLock);
// generally handy for DllUnloadNow -- count of existing descendant objects
static LONG GetObjectCount() { return object_count_; }
protected:
LONG reference_count_; // mind the reference counting for this object
static LONG object_count_; // count of all these objects
};
// OneClassFactory<T>
// Knows how to be a factory for T's
template <class T>
class OneClassFactory : public GenericClassFactory {
public:
// IClassFactory methods
STDMETHOD(CreateInstance)(LPUNKNOWN pUnkOuter, REFIID riid, void** ppvObject);
};
template <class T>
STDMETHODIMP OneClassFactory<T>::CreateInstance(LPUNKNOWN pUnkOuter,
REFIID riid, void** result) {
*result = NULL;
if (pUnkOuter != NULL)
return CLASS_E_NOAGGREGATION;
T* const obj = new T();
if (!obj)
return E_OUTOFMEMORY;
obj->AddRef();
HRESULT const hr = obj->QueryInterface(riid, result);
obj->Release();
return hr;
}
#endif // CHROME_COMMON_CLASSFACTORY_H_
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