pjs/xpcom/proxy/public/nsProxiedService.h

/* -*- Mode: C++; tab-width: 3; indent-tabs-mode: nil; c-basic-offset: 3 -*-
 *
 * The contents of this file are subject to the Netscape Public License
 * Version 1.0 (the "NPL"); you may not use this file except in
 * compliance with the NPL.  You may obtain a copy of the NPL at
 * http://www.mozilla.org/NPL/
 *
 * Software distributed under the NPL is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the NPL
 * for the specific language governing rights and limitations under the
 * NPL.
 *
 * The Initial Developer of this code under the NPL is Netscape
 * Communications Corporation.  Portions created by Netscape are
 * Copyright (C) 1998 Netscape Communications Corporation.  All Rights
 * Reserved.
 */

#ifndef __nsProxiedServiceManager_h_
#define __nsProxiedServiceManager_h_

#include "nsIServiceManager.h"
#include "nsProxyObjectManager.h"

////////////////////////////////////////////////////////////////////////////////
// NS_WITH_PROXIED_SERVICE: macro to make using services that need to be proxied
//                                   before using them easier. 
// Now you can replace this:
// {
//      nsresult rv;
//      NS_WITH_SERVICE(nsIMyService, pIMyService, kMyServiceCID, &rv);
//      if(NS_FAILED(rv))
//          return;
//      NS_WITH_SERVICE(nsIProxyObjectManager, pIProxyObjectManager, kProxyObjectManagerCID, &rv);
//      if(NS_FAILED(rv))
//          return;
//      nsIMyService pIProxiedObject = NULL;
//      rv = pIProxyObjectManager->GetProxyObject(pIProxyQueue, 
//                                                              nsIMyService::GetIID(), 
//                                                              pIMyService, PROXY_SYNC,
//                                                              (void**)&pIProxiedObject);
//      pIProxiedObject->DoIt(...);  // Executed on same thread as pIProxyQueue
//      ...
//      pIProxiedObject->Release();  // Must be done as not managed for you.
//      }
//  with this:
//      {
//      nsresult rv;
//      NS_WITH_PROXIED_SERVICE(nsIMyService, pIMyService, kMyServiceCID, 
//                                      pIProxyQueue, &rv);
//      if(NS_FAILED(rv))
//          return;
//      pIMyService->DoIt(...);  // Executed on the same thread as pIProxyQueue
//      }
// and the automatic destructor will take care of releasing the service and
// the proxied object for you. 
// 
// Note that this macro requires you to link with the xpcom DLL to pick up the
// static member functions from nsServiceManager.

#define NS_WITH_PROXIED_SERVICE(T, var, cid, Q, rvAddr)     \
    nsProxiedService _serv##var(cid, T::GetIID(), Q, rvAddr);           \
    T* var = (T*)(nsISupports*)_serv##var;

////////////////////////////////////////////////////////////////////////////////
// nsProxiedService
////////////////////////////////////////////////////////////////////////////////

class nsProxiedService : public nsService
{
protected:
    nsISupports* mProxiedService;
public:
  nsProxiedService(const nsCID &aClass, const nsIID &aIID, 
            nsIEventQueue* pIProxyQueue, nsresult*rv): nsService(aClass, aIID, rv),
            mProxiedService(nsnull)
    {
    static NS_DEFINE_IID(kProxyObjectManagerCID, NS_PROXYEVENT_MANAGER_CID);

    if(NS_FAILED(*rv))
        return;
    NS_WITH_SERVICE(nsIProxyObjectManager, pIProxyObjectManager, 
                        kProxyObjectManagerCID, rv);
    if(NS_FAILED(*rv))
        {
        nsServiceManager::ReleaseService(mCID, mService);
        mService = nsnull;
        return;
        }

    *rv = pIProxyObjectManager->GetProxyObject(pIProxyQueue,
                                                            aIID,
                                                            mService,
                                                            PROXY_SYNC,
                                                            (void**)&mProxiedService);
    if(NS_FAILED(*rv))
        {
        nsServiceManager::ReleaseService(mCID, mService);
        mService = nsnull;
        return;
        }
    }
    
    ~nsProxiedService()
        {
        if(mProxiedService)
            NS_RELEASE(mProxiedService);
        // Base class will free mService
        }

    nsISupports* operator->() const
        {
        NS_PRECONDITION(mProxiedService != 0, "Your code should test the error result from the constructor.");
        return mProxiedService;
        }

    PRBool operator==(const nsISupports* other)
        {
        return ((mProxiedService == other) || (mService == other));
        }

    operator nsISupports*() const
        {
        return mProxiedService;
        }
};


#endif //__nsProxiedServiceManager_h_