AOO410/main/vbahelper/inc/vbahelper/weakreference.hxx

/**************************************************************
 * 
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 * 
 *   http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 * 
 *************************************************************/



#ifndef VBAHELPER_WEAKREFERENCE_HXX
#define VBAHELPER_WEAKREFERENCE_HXX

#include <cppuhelper/weakref.hxx>
#include <rtl/ref.hxx>

namespace vbahelper {

// ============================================================================

/** A weak reference holding any UNO implementation object.

    The held object must implement the ::com::sun::star::uno::XWeak interface.
    
    In difference to the ::com::sun::star::uno::WeakReference<> implementation
    from cppuhelper/weakref.hxx, the class type of this weak reference is not
    restricted to UNO interface types, but can be used for any C++ class type
    implementing the XWeak interface somehow (e.g. ::cppu::WeakImplHelperN<>,
    ::cppu::ImplInheritanceHelperN<>, etc.).
 */
template< typename ObjectType >
class WeakReference
{
public:
    /** Default constructor. Creates an empty weak reference.
     */
    inline explicit WeakReference() SAL_THROW( () ) : mpObject( 0 ) {}

    /** Initializes this weak reference with the passed reference to an object.
     */
    inline explicit WeakReference( const ::rtl::Reference< ObjectType >& rxObject ) SAL_THROW( () ) :
        mxWeakRef( rxObject.get() ), mpObject( rxObject.get() ) {}

    /** Releases this weak reference and takes over the passed reference.
     */
    inline WeakReference& SAL_CALL operator=( const ::rtl::Reference< ObjectType >& rxObject ) SAL_THROW( () )
    {
        mxWeakRef = ::com::sun::star::uno::Reference< ::com::sun::star::uno::XWeak >( rxObject.get() );
        mpObject = rxObject.get();
        return *this;
    }

    /** Gets an RTL reference to the referenced object.

        @return  Reference or null, if the weakly referenced object is gone.
     */
    inline SAL_CALL operator ::rtl::Reference< ObjectType >() SAL_THROW( () )
    {
        ::com::sun::star::uno::Reference< ::com::sun::star::uno::XWeak > xRef = mxWeakRef;
        ::rtl::Reference< ObjectType > xObject;
        if( xRef.is() )
            xObject = mpObject;
        else
            mpObject = 0;
        return xObject;
    }

private:
    ::com::sun::star::uno::WeakReference< ::com::sun::star::uno::XWeak > mxWeakRef;
    ObjectType* mpObject;
};

// ============================================================================

} // namespace vbahelper

#endif