tapestry/tapestry-contrib/src/java/org/apache/tapestry/contrib/table/model/common/AbstractTableDataModel.java

// Copyright 2004, 2005 The Apache Software Foundation
//
// Licensed 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.

package org.apache.tapestry.contrib.table.model.common;

import java.lang.ref.WeakReference;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;

import org.apache.tapestry.contrib.table.model.CTableDataModelEvent;
import org.apache.tapestry.contrib.table.model.ITableDataModel;
import org.apache.tapestry.contrib.table.model.ITableDataModelListener;

/**
 * An implementation of the listener support in the ITableDataModel interface.
 * 
 * @author mindbridge
 */
public abstract class AbstractTableDataModel implements ITableDataModel
{

    private List m_arrListeners;

    public AbstractTableDataModel()
    {
        m_arrListeners = new ArrayList();
    }

    /**
     * Method fireTableDataModelEvent. Fires a change event to all listeners.
     * 
     * @param objEvent
     *            the event to pass to the listeners
     */
    protected void fireTableDataModelEvent(CTableDataModelEvent objEvent)
    {
        synchronized(m_arrListeners)
        {
            List arrEmptyReferences = null;

            for(Iterator it = m_arrListeners.iterator(); it.hasNext();)
            {
                WeakReference objRef = (WeakReference) it.next();
                ITableDataModelListener objListener = (ITableDataModelListener) objRef
                        .get();
                if (objListener != null)
                    objListener.tableDataChanged(objEvent);
                else
                {
                    if (arrEmptyReferences == null)
                        arrEmptyReferences = new ArrayList();
                    arrEmptyReferences.add(objRef);
                }
            }

            if (arrEmptyReferences != null)
                m_arrListeners.removeAll(arrEmptyReferences);
        }
    }

    /**
     * @see org.apache.tapestry.contrib.table.model.ITableDataModel#addTableDataModelListener(ITableDataModelListener) .
     */
    public void addTableDataModelListener(ITableDataModelListener objListener)
    {
        synchronized(m_arrListeners)
        {
            m_arrListeners.add(new WeakReference(objListener));
        }
    }

    /**
     * @see org.apache.tapestry.contrib.table.model.ITableDataModel#removeTableDataModelListener(ITableDataModelListener) .
     */
    public void removeTableDataModelListener(ITableDataModelListener objListener)
    {
        synchronized(m_arrListeners)
        {
            List arrEmptyReferences = null;

            for(Iterator it = m_arrListeners.iterator(); it.hasNext();)
            {
                WeakReference objRef = (WeakReference) it.next();
                ITableDataModelListener objStoredListener = (ITableDataModelListener) objRef
                        .get();
                if (objListener == objStoredListener
                        || objStoredListener == null)
                {
                    if (arrEmptyReferences == null)
                        arrEmptyReferences = new ArrayList();
                    arrEmptyReferences.add(objRef);
                }
            }

            if (arrEmptyReferences != null)
                m_arrListeners.removeAll(arrEmptyReferences);
        }
    }

}