| /****************************************************************************** |
| * Copyright (c) 2005 BEA Systems, Inc. |
| * All rights reserved. This program and the accompanying materials |
| * are made available under the terms of the Eclipse Public License v1.0 |
| * which accompanies this distribution, and is available at |
| * http://www.eclipse.org/legal/epl-v10.html |
| * |
| * Contributors: |
| * Konstantin Komissarchik - initial API and implementation |
| ******************************************************************************/ |
| |
| package org.eclipse.wst.common.project.facet.core.internal; |
| |
| import java.util.AbstractSet; |
| import java.util.Collection; |
| import java.util.Collections; |
| import java.util.HashSet; |
| import java.util.Iterator; |
| import java.util.Set; |
| |
| /** |
| * @author <a href="mailto:kosta@bea.com">Konstantin Komissarchik</a> |
| */ |
| |
| public final class CopyOnWriteSet |
| |
| extends AbstractSet |
| |
| { |
| private Set base; |
| private Set baseReadOnly; |
| |
| public CopyOnWriteSet() |
| { |
| this.base = new HashSet(); |
| this.baseReadOnly = null; |
| } |
| |
| public boolean add( final Object obj ) |
| { |
| copy(); |
| return this.base.add( obj ); |
| } |
| |
| public boolean addAll( final Collection collection ) |
| { |
| copy(); |
| return this.base.addAll( collection ); |
| } |
| |
| public boolean remove( final Object obj ) |
| { |
| copy(); |
| return this.base.remove( obj ); |
| } |
| |
| public boolean removeAll( final Collection collection ) |
| { |
| copy(); |
| return this.base.removeAll( collection ); |
| } |
| |
| public boolean retainAll( final Collection collection ) |
| { |
| copy(); |
| return this.base.retainAll( collection ); |
| } |
| |
| public void clear() |
| { |
| if( this.baseReadOnly != null ) |
| { |
| this.base = new HashSet(); |
| this.baseReadOnly = null; |
| } |
| else |
| { |
| this.base.clear(); |
| } |
| } |
| |
| public int size() |
| { |
| return this.base.size(); |
| } |
| |
| public Iterator iterator() |
| { |
| return new CopyOnWriteIterator( this.base.iterator() ); |
| } |
| |
| public Set getReadOnlySet() |
| { |
| if( this.baseReadOnly == null ) |
| { |
| this.baseReadOnly = Collections.unmodifiableSet( this.base ); |
| } |
| |
| return this.baseReadOnly; |
| } |
| |
| private boolean copy() |
| { |
| if( this.baseReadOnly != null ) |
| { |
| this.base = new HashSet( this.base ); |
| this.baseReadOnly = null; |
| return true; |
| } |
| else |
| { |
| return false; |
| } |
| } |
| |
| private final class CopyOnWriteIterator |
| |
| implements Iterator |
| |
| { |
| private final Iterator itr; |
| private Object current; |
| |
| public CopyOnWriteIterator( final Iterator itr ) |
| { |
| this.itr = itr; |
| this.current = null; |
| } |
| |
| public void remove() |
| { |
| if( copy() ) |
| { |
| CopyOnWriteSet.this.base.remove( this.current ); |
| } |
| else |
| { |
| this.itr.remove(); |
| } |
| } |
| |
| public boolean hasNext() |
| { |
| return this.itr.hasNext(); |
| } |
| |
| public Object next() |
| { |
| this.current = this.itr.next(); |
| return this.current; |
| } |
| } |
| |
| } |