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/*
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
 *
 * Copyright (c) 2012 Oracle and/or its affiliates. All rights reserved.
 *
 * The contents of this file are subject to the terms of either the GNU
 * General Public License Version 2 only ("GPL") or the Common Development
 * and Distribution License("CDDL") (collectively, the "License").  You
 * may not use this file except in compliance with the License.  You can
 * obtain a copy of the License at
 * https://glassfish.dev.java.net/public/CDDL+GPL_1_1.html
 * or packager/legal/LICENSE.txt.  See the License for the specific
 * language governing permissions and limitations under the License.
 *
 * When distributing the software, include this License Header Notice in each
 * file and include the License file at packager/legal/LICENSE.txt.
 *
 * GPL Classpath Exception:
 * Oracle designates this particular file as subject to the "Classpath"
 * exception as provided by Oracle in the GPL Version 2 section of the License
 * file that accompanied this code.
 *
 * Modifications:
 * If applicable, add the following below the License Header, with the fields
 * enclosed by brackets [] replaced by your own identifying information:
 * "Portions Copyright [year] [name of copyright owner]"
 *
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 * If you wish your version of this file to be governed by only the CDDL or
 * only the GPL Version 2, indicate your decision by adding "[Contributor]
 * elects to include this software in this distribution under the [CDDL or GPL
 * Version 2] license."  If you don't indicate a single choice of license, a
 * recipient has the option to distribute your version of this file under
 * either the CDDL, the GPL Version 2 or to extend the choice of license to
 * its licensees as provided above.  However, if you add GPL Version 2 code
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 */
package org.jvnet.hk2.internal;

import java.util.Collection;
import java.util.LinkedList;
import java.util.ListIterator;
import java.util.TreeSet;

/**
 * This object contains a list of values.  The list is not always sorted, but will
 * always be returned sorted.
 * 
 * All of the methods on here must be called with lock held.
 * 
 * @author jwells
 *
 */
public class IndexedListData {
    private final static DescriptorComparator UNSORTED_COMPARATOR = new DescriptorComparator();
    
    private LinkedList> unsortedList = new LinkedList>();
    private TreeSet> sortedList = null;
    
    public Collection> getSortedList() {
        if (sortedList != null) return sortedList;
        
        if (unsortedList.size() <= 1) return unsortedList;
        
        sortedList = new TreeSet>(ServiceLocatorImpl.DESCRIPTOR_COMPARATOR);
        sortedList.addAll(unsortedList);
        
        unsortedList.clear();
        unsortedList = null;
        
        return sortedList;
    }
    
    public void addDescriptor(SystemDescriptor descriptor) {
        if (sortedList != null) {  
            sortedList.add(descriptor);
        }
        else {
            unsortedList.add(descriptor);
        }
        
        descriptor.addList(this);
    }
    
    public void removeDescriptor(SystemDescriptor descriptor) {
        if (sortedList != null) {
            sortedList.remove(descriptor);
        }
        else {
            ListIterator> iterator = unsortedList.listIterator();
            while (iterator.hasNext()) {
                SystemDescriptor candidate = iterator.next();
                if (UNSORTED_COMPARATOR.compare(descriptor, candidate) == 0) {
                    iterator.remove();
                    break;
                }
            }
        }
        
        descriptor.removeList(this);
    }
    
    public boolean isEmpty() {
        if (sortedList != null) {
            return sortedList.isEmpty();
        }
        return unsortedList.isEmpty();
    }
    
    /**
     * Called by a SystemDescriptor when its ranking has changed
     */
    public void unSort() {
        if (sortedList != null) {
            unsortedList = new LinkedList>(sortedList);
            
            sortedList.clear();
            sortedList = null;
        }
    }
    
    public void clear() {
        Collection> removeMe;
        if (sortedList != null) {
            removeMe = sortedList;
        }
        else {
            removeMe = unsortedList;
        }
        
        for (SystemDescriptor descriptor : removeMe) {
            descriptor.removeList(this);
        }
        
        if (sortedList != null) {
            sortedList.clear();
            sortedList = null;
            
            unsortedList = new LinkedList>();
        }
        else {
            unsortedList.clear();
        }
    }
}