deep-c-rsc/JCGO/jtrsrc/com/ivmaisoft/jcgo/OrderedMap.java

/*
 * @(#) $(JCGO)/jtrsrc/com/ivmaisoft/jcgo/OrderedMap.java --
 * a part of JCGO translator.
 **
 * Project: JCGO (http://www.ivmaisoft.com/jcgo/)
 * Copyright (C) 2001-2012 Ivan Maidanski <ivmai@mail.ru>
 * All rights reserved.
 */

/*
 * This is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2, or (at your option)
 * any later version.
 **
 * This software 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 (GPL) for more details.
 **
 * Linking this library statically or dynamically with other modules is
 * making a combined work based on this library. Thus, the terms and
 * conditions of the GNU General Public License cover the whole
 * combination.
 **
 * As a special exception, the copyright holders of this library give you
 * permission to link this library with independent modules to produce an
 * executable, regardless of the license terms of these independent
 * modules, and to copy and distribute the resulting executable under
 * terms of your choice, provided that you also meet, for each linked
 * independent module, the terms and conditions of the license of that
 * module. An independent module is a module which is not derived from
 * or based on this library. If you modify this library, you may extend
 * this exception to your version of the library, but you are not
 * obligated to do so. If you do not wish to do so, delete this
 * exception statement from your version.
 */

package com.ivmaisoft.jcgo;

import java.util.Enumeration;

/**
 * An ordered hashtable (FIFO).
 */

final class OrderedMap {

    private final ObjHashtable map = new ObjHashtable();

    private final ObjVector orderedKeys = new ObjVector();

    OrderedMap() {
    }

    Object put(Object key, Object value) {
        Object oldValue = map.put(key, value);
        if (oldValue == null) {
            orderedKeys.addElement(key);
        }
        return oldValue;
    }

    Object remove(Object key) {
        Object oldValue = map.remove(key);
        if (oldValue != null) {
            orderedKeys.removeElementAt(orderedKeys.indexOf(key));
        }
        return oldValue;
    }

    Object get(Object key) {
        return map.get(key);
    }

    int size() {
        return orderedKeys.size();
    }

    Object keyAt(int index) {
        return orderedKeys.elementAt(index);
    }

    Enumeration keys() {
        return orderedKeys.elements();
    }

    Enumeration unorderedElements() {
        return map.elements();
    }

    void copyKeysInto(Object[] anArray) {
        orderedKeys.copyInto(anArray);
    }
}