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// Copyright 2008, Google Inc.
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
// * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
// ClassFactory<class>
// is a simple class factory object for the parameterized class.
//
#ifndef _CLASSFACTORY_H_
#define _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
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