86 lines
2.6 KiB
C++
86 lines
2.6 KiB
C++
//+-------------------------------------------------------------------------
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//
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// Microsoft Windows
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//
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// Copyright (C) Microsoft Corporation, 1999 - 1999
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//
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// File: observer.h
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//
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//--------------------------------------------------------------------------
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#ifndef _OBSERVER_H_
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#define _OBSERVER_H_
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#include <vector>
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// Event source interface template
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// Defines event source class for specific observer class
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template <class Observer>
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class EventSource
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{
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public:
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STDMETHOD(Advise)(Observer* pObserver, LONG_PTR* pCookie) = 0;
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STDMETHOD(Unadvise)(LONG_PTR Cookie) = 0;
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};
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// Event source implementation template
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// Defines implementation of event source for a specific observer class
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// maintains a vector of the active observers of this event source
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template <class Observer>
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class ATL_NO_VTABLE EventSourceImpl : EventSource<Observer>
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{
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typedef std::list<Observer*> ObserverList;
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typedef std::list<Observer*>::iterator ObserverIter;
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public:
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STDMETHOD(Advise)(Observer* pObserver, LONG_PTR* plCookie);
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STDMETHOD(Unadvise)(LONG_PTR lCookie);
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protected:
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~EventSourceImpl()
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{
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// verify there are no obervers when going away
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ASSERT(m_Observers.empty());
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}
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ObserverList m_Observers;
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};
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template <class Observer>
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STDMETHODIMP EventSourceImpl<Observer>::Advise(Observer* pObserver, LONG_PTR* plCookie)
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{
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ASSERT(pObserver != NULL);
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ASSERT(plCookie != NULL);
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ObserverIter iter = m_Observers.insert(m_Observers.end(), pObserver);
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// can't cast iterator to LONG_PTR so check size before cheating
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ASSERT(sizeof(ObserverIter) == sizeof(LONG_PTR));
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*(ObserverIter*)plCookie = iter;
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return S_OK;
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}
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template <class Observer>
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STDMETHODIMP EventSourceImpl<Observer>::Unadvise(LONG_PTR lCookie)
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{
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// Can't cast LONG_PTR to iterator, so have to cheat
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// see Advise method for size check
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ObserverIter iter;
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*(LONG_PTR*)&iter = lCookie;
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m_Observers.erase(iter);
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return S_OK;
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}
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// Observer enumerator helper
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// Provides for-loop header for iterating over observers of a specified observer class
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#define FOR_EACH_OBSERVER(ObserverClass, ObserverIter) \
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for ( \
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std::list<ObserverClass*>::iterator ObserverIter = EventSourceImpl<ObserverClass>::m_Observers.begin(); \
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ObserverIter != EventSourceImpl<ObserverClass>::m_Observers.end(); \
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++ObserverIter \
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)
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#endif // _OBSERVER_H_
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