FreezableList.java

/*
 * Copyright (c) 2000, 2003, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code 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
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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package org.jboss.com.sun.corba.se.impl.ior;

import java.util.AbstractList;
import java.util.Iterator;
import java.util.List;

import org.jboss.com.sun.corba.se.spi.ior.MakeImmutable;

/**
 * Simple class that delegates all List operations to another list. It also can be frozen, which means that a number of
 * operations can be performed on the list, and then the list can be made immutable, so that no further changes are
 * possible. A FreezableList is frozen using the makeImmutable method.
 */
public class FreezableList extends AbstractList<Object>
{
    private List<Object> delegate = null;

    private boolean immutable = false;

    public boolean equals(Object obj)
    {
        if (obj == null)
            return false;

        if (!(obj instanceof FreezableList))
            return false;

        FreezableList other = (FreezableList) obj;

        return delegate.equals(other.delegate) && (immutable == other.immutable);
    }

    public int hashCode()
    {
        return delegate.hashCode();
    }

    public FreezableList(List<Object> delegate, boolean immutable)
    {
        this.delegate = delegate;
        this.immutable = immutable;
    }

    public FreezableList(List<Object> delegate)
    {
        this(delegate, false);
    }

    public void makeImmutable()
    {
        immutable = true;
    }

    public boolean isImmutable()
    {
        return immutable;
    }

    public void makeElementsImmutable()
    {
        Iterator<Object> iter = iterator();
        while (iter.hasNext())
        {
            Object obj = iter.next();
            if (obj instanceof MakeImmutable)
            {
                MakeImmutable element = (MakeImmutable) obj;
                element.makeImmutable();
            }
        }
    }

    // Methods overridden from AbstractList

    public int size()
    {
        return delegate.size();
    }

    public Object get(int index)
    {
        return delegate.get(index);
    }

    public Object set(int index, Object element)
    {
        if (immutable)
            throw new UnsupportedOperationException();

        return delegate.set(index, element);
    }

    public void add(int index, Object element)
    {
        if (immutable)
            throw new UnsupportedOperationException();

        delegate.add(index, element);
    }

    public Object remove(int index)
    {
        if (immutable)
            throw new UnsupportedOperationException();

        return delegate.remove(index);
    }

    // We also override subList so that the result is a FreezableList.
    public List<Object> subList(int fromIndex, int toIndex)
    {
        List<Object> list = delegate.subList(fromIndex, toIndex);
        List<Object> result = new FreezableList(list, immutable);
        return result;
    }
}