code: //==============================================================================
  //	
  //	Copyright (c) 2002-
  //	Authors:
  //	* Andrew Hinton <ug60axh@cs.bham.ac.uk> (University of Birmingham)
  //	* Dave Parker <david.parker@comlab.ox.ac.uk> (University of Oxford, formerly University of Birmingham)
  //	
  //------------------------------------------------------------------------------
  //	
  //	This file is part of PRISM.
  //	
  //	PRISM is free software; you can redistribute it and/or modify
  //	it under the terms of the GNU General Public License as published by
  //	the Free Software Foundation; either version 2 of the License, or
  //	(at your option) any later version.
  //	
  //	PRISM is distributed in the hope that it will be useful,
  //	but WITHOUT ANY WARRANTY; without even the implied warranty of
  //	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  //	GNU General Public License for more details.
  //	
  //	You should have received a copy of the GNU General Public License
  //	along with PRISM; if not, write to the Free Software Foundation,
  //	Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  //	
  //==============================================================================
  
  package userinterface.util;
  
  import java.util.ArrayList;
  import java.util.*;
  
  /**
   * Handles the selection of PropertyOwners
   */
  public abstract class SelectionModel extends Observable
  {
  
  	private ArrayList<SelectionListener> listeners;
  	private ArrayList<PropertyOwner> currentSelection;
  
  	public SelectionModel()
  	{
  		listeners = new ArrayList<SelectionListener>();
  		currentSelection = new ArrayList<PropertyOwner>();
  	}
  
  	public void addSelectionListener(SelectionListener s)
  	{
  		listeners.add(s);
  	}
  
  	public void removeSelectionListener(SelectionListener s)
  	{
  		listeners.remove(s);
  	}
  
  	public void fireSelectionChanged()
  	{
  		SelectionEvent event = new SelectionEvent(getCurrentSelection());
  		SelectionListener sl;
  
  		for (int i = 0; i < listeners.size(); i++) {
  			sl = listeners.get(i);
  			sl.selectionPerformed(event);
  		}
  	}
  
  	public ArrayList<PropertyOwner> getCurrentSelection()
  	{
  		return currentSelection;
  	}
  
  	public PropertyOwner getSelectedItem(int i)
  	{
  		return currentSelection.get(i);
  	}
  
  	public int getSelectionSize()
  	{
  		return currentSelection.size();
  	}
  
  	protected void addToSelection(PropertyOwner owner, boolean fireEvent)
  	{
  		if (!currentSelection.contains(owner))
  			currentSelection.add(owner);
  
  		if (fireEvent)
  			fireSelectionChanged();
  	}
  
  	protected void removeFromSelection(PropertyOwner owner, boolean fireEvent)
  	{
  		if (currentSelection.contains(owner))
  			currentSelection.remove(owner);
  
  		if (fireEvent)
  			fireSelectionChanged();
  	}
  
  	protected void clearSelection(boolean fireEvent)
  	{
  		currentSelection.clear();
  
  		if (fireEvent)
  			fireSelectionChanged();
  	}
  
  	protected void setSelection(ArrayList<PropertyOwner> a, boolean fireEvent)
  	{
  		currentSelection = a;
  
  		if (fireEvent)
  			fireSelectionChanged();
  	}
  }
  