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package org.openide.options;

import java.beans.PropertyChangeEvent;
import java.beans.PropertyVetoException;
import java.beans.VetoableChangeListener;

import java.util.*;


/** Extends the functionality of <CODE>SystemOption</CODE>
* by providing support for veto listeners.
*
* @author Jaroslav Tulach
* @version 0.11 Dec 6, 1997
*/
public abstract class VetoSystemOption extends SystemOption {
    /** generated Serialized Version UID */
    static final long serialVersionUID = -614731095908156413L;

    /** vetoable listener property */
    private static final String PROP_VETO_SUPPORT = "vetoSupport"; // NOI18N

    /** Default constructor. */
    public VetoSystemOption() {
    }

    /** Lazy getter for veto hashtable.
    * @return the hashtable
    */
    private HashSet getVeto() {
        HashSet set = (HashSet) getProperty(PROP_VETO_SUPPORT);

        if (set == null) {
            set = new HashSet();
            putProperty(PROP_VETO_SUPPORT, set);
        }

        return set;
    }

    /** Add a new veto listener to all instances of this exact class.
    * @param list the listener to add
    */
    public final void addVetoableChangeListener(VetoableChangeListener list) {
        synchronized (getLock()) {
            getVeto().add(list);
        }
    }

    /** Remove a veto listener from all instances of this exact class.
    * @param list the listener to remove
    */
    public final void removeVetoableChangeListener(VetoableChangeListener list) {
        synchronized (getLock()) {
            getVeto().remove(list);
        }
    }

    /** Fire a property change event.
    * @param name the name of the property
    * @param oldValue the old value
    * @param newValue the new value
    * @exception PropertyVetoException if the change is vetoed
    */
    public final void fireVetoableChange(String name, Object oldValue, Object newValue)
    throws PropertyVetoException {
        PropertyChangeEvent ev = new PropertyChangeEvent(this, name, oldValue, newValue);

        Iterator en;

        synchronized (getLock()) {
            en = ((HashSet) getVeto().clone()).iterator();
        }

        while (en.hasNext()) {
            ((VetoableChangeListener) en.next()).vetoableChange(ev);
        }
    }
}