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HashMap.java

package ca.mcgill.sable.util;

/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
 * SableUtil, a clean room implementation of the Collection API.     *
 * Copyright (C) 1997, 1998, 1999 Raja Vallee-Rai                    *
 * (kor@sable.mcgill.ca).  All rights reserved.                      *
 *                                                                   *
 * This work was done as a project of the Sable Research Group,      *
 * School of Computer Science, McGill University, Canada             *
 * (http://www.sable.mcgill.ca/).  It is understood that any         *
 * modification not identified as such is not covered by the         *
 * preceding statement.                                              *
 *                                                                   *
 * This work is free software; you can redistribute it and/or        *
 * modify it under the terms of the GNU Library General Public       *
 * License as published by the Free Software Foundation; either      *
 * version 2 of the License, or (at your option) any later version.  *
 *                                                                   *
 * This work 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 *
 * Library General Public License for more details.                  *
 *                                                                   *
 * You should have received a copy of the GNU Library 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.                                      *
 *                                                                   *
 * To submit a bug report, send a comment, or get the latest news on *
 * this project and other Sable Research Group projects, please      *
 * visit the web site: http://www.sable.mcgill.ca/                   *
 * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */

/*
 Reference Version
 -----------------
 This is the latest official version on which this file is based.
 The reference version is: $SableUtilVersion: 1.11 $

 Change History
 --------------
 A) Notes:

 Please use the following template.  Most recent changes should
 appear at the top of the list.

 - Modified on [date (March 1, 1900)] by [name]. [(*) if appropriate]
   [description of modification].

 Any Modification flagged with "(*)" was done as a project of the
 Sable Research Group, School of Computer Science,
 McGill University, Canada (http://www.sable.mcgill.ca/).

 You should add your copyright, using the following template, at
 the top of this file, along with other copyrights.

 *                                                                   *
 * Modifications by [name] are                                       *
 * Copyright (C) [year(s)] [your name (or company)].  All rights     *
 * reserved.                                                         *
 *                                                                   *

 B) Changes:

 - Modified on January 20, 1999 by Raja Vallee-Rai (rvalleerai@sable.mcgill.ca). (*)
   Changed the entries implementation to be linear.


 - Modified on July 21, 1998 by Raja Vallee-Rai (kor@sable.mcgill.ca). (*)
   Renamed this class to HashMap to avoid conflicts.

 - Modified on June 15, 1998 by Raja Vallee-Rai (kor@sable.mcgill.ca). (*)
   First release of this file.
*/

public class HashMap extends AbstractMap
{
    java.util.Hashtable table;

    private class HashEntry implements Map.Entry
    {
        private Object key;

        public HashEntry(Object key)
        {
            this.key = key;
        }

        public boolean equals(Object obj)
        {
            if(!(obj instanceof Map.Entry))
                return false;
            else {
                Map.Entry e = (Map.Entry) obj;

                return e.getKey().equals(key) && getValue().equals(e.getValue());
            }
        }

        public Object getKey()
        {
            return key;
        }

        public Object getValue()
        {
            return get(key);
        }

        public Object setValue(Object obj)
        {
            return put(key, obj);
        }

        public int hashCode()
        {
            return (getKey()==null ? 0 : getKey().hashCode()) ^ (getValue()==null ? 0 :
                getValue().hashCode());
        }

        public String toString()
        {
            return key.toString() + " -> " + get(key);
        }
    }

    public HashMap()
    {
        table = new java.util.Hashtable();
    }
    public HashMap(int initialCapacity)
    {
        table = new java.util.Hashtable(initialCapacity);
    }
    public HashMap(int initialCapacity, float loadFactor)
    {
        if(initialCapacity <= 0)
            throw new RuntimeException("initialCapacity is " + initialCapacity);

        if(loadFactor <= 0)
            throw new RuntimeException("loadFactor is " + initialCapacity);


        table = new java.util.Hashtable(initialCapacity, loadFactor);
    }
    public void clear()
    {
        table.clear();
    }
    public boolean contains(Object value)
    {
        return table.contains(value);
    }
    public boolean containsKey(Object key)
    {
        if(key == null)
            throw new RuntimeException("Hey hey!");

        return table.containsKey(key);
    }
    /**
     * This implementation does not correspond exactly to the 1.2 definition.  The collection
     * which is returned is not backed by the def'n.
     */

    public Collection entries()
    {
        java.util.Enumeration entries = table.keys();
        /*Set keySet = new VectorSet();

        while(entries.hasMoreElements())
            keySet.add(new HashEntry(entries.nextElement()));
          */

        List keyList = new ArrayList();

        while(entries.hasMoreElements())
            keyList.add(new HashEntry(entries.nextElement()));

        return keyList;
    }
    public Object get(Object entry)
    {
        return table.get(entry);
    }
    public boolean isEmpty()
    {
        return table.size() == 0;
    }
    public Set keySet()
    {
        java.util.Enumeration keys = table.keys();
        Set keySet = new HashSet();

        while(keys.hasMoreElements())
            keySet.add(keys.nextElement());

        return keySet;
    }
    public Object put(Object key, Object value)
    {
        return table.put(key, value);

    /*
        Object previousEntry = null;

        if(table.containsKey(key))
            previousEntry = table.get(key);

        table.put(key, value);

        return previousEntry; */
    }
    public Object remove(Object obj)
    {
        return table.remove(obj);
    }
    public int size()
    {
        return table.size();
    }
}

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