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//
// $Id: OidList.java 6426 2011-01-10 22:47:09Z tim $
//
// Narya library - tools for developing networked games
// Copyright (C) 2002-2011 Three Rings Design, Inc., All Rights Reserved
// http://code.google.com/p/narya/
//
// This library is free software; you can redistribute it and/or modify it
// under the terms of the GNU Lesser General Public License as published
// by the Free Software Foundation; either version 2.1 of the License, or
// (at your option) any later version.
//
// This library 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
// Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public
// License along with this library; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA

package com.threerings.presents.dobj;

import java.util.Iterator;
import java.util.NoSuchElementException;

import com.threerings.io.Streamable;

/**
 * An oid list is used to store lists of object ids. The list will not
 * allow duplicate ids. This class is not synchronized, with the
 * expectation that all modifications of instances will take place on the
 * dobjmgr thread.
 *
 * 
 *  Do not use an OidList to store a set of ints. OidList has special meaning inside
 * of the dobj system, namely:
 * 
 When an object is destroyed, its oid is automagically removed from any OidLists.
 * 
 */
public class OidList
    implements Streamable, Iterable
{
    /**
     * Creates an empty oid list.
     */
    public OidList ()
    {
        this(DEFAULT_SIZE);
    }

    /**
     * Creates an empty oid list with space for at least
     * initialSize object ids before it will need to expand.
     */
    public OidList (int initialSize)
    {
        // ensure that we have at least two slots or the expansion code
        // won't work
        _oids = new int[Math.max(initialSize, 2)];
    }

    /**
     * Returns the number of object ids in the list.
     */
    public int size ()
    {
        return _size;
    }

    /**
     * Adds the specified object id to the list if it is not already
     * there.
     *
     * @return true if the object was added, false if it was already in
     * the list.
     */
    public boolean add (int oid)
    {
        // check for existence
        for (int ii = 0; ii < _size; ii++) {
            if (_oids[ii] == oid) {
                return false;
            }
        }

        // make room if necessary
        if (_size+1 >= _oids.length) {
            expand();
        }

        // add the oid
        _oids[_size++] = oid;
        return true;
    }

    /**
     * Removes the specified oid from the list.
     *
     * @return true if the oid was in the list and was removed, false
     * otherwise.
     */
    public boolean remove (int oid)
    {
        // scan for the oid in question
        for (int ii = 0; ii < _size; ii++) {
            if (_oids[ii] == oid) {
                // shift the rest of the list back one
                System.arraycopy(_oids, ii+1, _oids, ii, --_size-ii);
                return true;
            }
        }

        return false;
    }

    /**
     * Returns true if the specified oid is in the list, false if not.
     */
    public boolean contains (int oid)
    {
        for (int ii = 0; ii < _size; ii++) {
            if (_oids[ii] == oid) {
                return true;
            }
        }

        return false;
    }

    /**
     * Returns the object id at the specified index. This does no boundary
     * checking.
     */
    public int get (int index)
    {
        return _oids[index];
    }

    @Override
    public String toString ()
    {
        StringBuilder buf = new StringBuilder();
        buf.append("{");
        for (int ii = 0; ii < _size; ii++) {
            if (ii > 0) {
                buf.append(", ");
            }
            buf.append(_oids[ii]);
        }
        buf.append("}");
        return buf.toString();
    }

    public Iterator iterator ()
    {
        return new OidIterator();
    }

    private void expand ()
    {
        int[] oids = new int[_oids.length*2];
        System.arraycopy(_oids, 0, oids, 0, _oids.length);
        _oids = oids;
    }

    protected class OidIterator
        implements Iterator
    {
        public boolean hasNext ()
        {
            return _index < size();
        }

        public Integer next ()
        {
            if (!hasNext()) {
                throw new NoSuchElementException();
            }
            return get(_index++);
        }

        public void remove ()
        {
            throw new UnsupportedOperationException();
        }

        protected int _index = 0;
    }

    private int[] _oids;
    private int _size;

    protected static final int DEFAULT_SIZE = 4;
}