/* Copyright (C) 2002 Univ. of Massachusetts Amherst, Computer Science Dept.
 This file is part of "MALLET" (MAchine Learning for LanguagE Toolkit).
 http://www.cs.umass.edu/~mccallum/mallet
 This software is provided under the terms of the Common Public License,
 version 1.0, as published by http://www.opensource.org.  For further
 information, see the file `LICENSE' included with this distribution. */
/**
 * @author Andrew McCallum <a
 * href="mailto:mccallum@cs.umass.edu">mccallum@cs.umass.edu</a>
 */
package mstparser;

import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;

public class Alphabet implements Serializable {

    gnu.trove.TObjectIntHashMap map;
    int numEntries;
    boolean growthStopped = false;

    public Alphabet(int capacity) {
        this.map = new gnu.trove.TObjectIntHashMap(capacity);
        //this.map.setDefaultValue(-1);

        numEntries = 0;
    }

    public Alphabet() {
        this(10000);
    }

    /**
     * Return -1 if entry isn't present.
     */
    public int lookupIndex(Object entry) {
        if (entry == null) {
            throw new IllegalArgumentException("Can't lookup \"null\" in an Alphabet.");
        }

        int ret = map.get(entry);

        if (ret == -1 && !growthStopped) {
            ret = numEntries;
            map.put(entry, ret);
            numEntries++;
        }

        return ret;
    }

    public Object[] toArray() {
        return map.keys();
    }

    public boolean contains(Object entry) {
        return map.contains(entry);
    }

    public int size() {
        return numEntries;
    }

    public void stopGrowth() {
        growthStopped = true;
        map.compact();
    }

    public void allowGrowth() {
        growthStopped = false;
    }

    public boolean growthStopped() {
        return growthStopped;
    }
    
    // Serialization 
    private static final long serialVersionUID = 1;
    private static final int CURRENT_SERIAL_VERSION = 0;

    private void writeObject(ObjectOutputStream out) throws IOException {
        out.writeInt(CURRENT_SERIAL_VERSION);
        out.writeInt(numEntries);
        out.writeObject(map);
        out.writeBoolean(growthStopped);
    }

    private void readObject(ObjectInputStream in) throws IOException, ClassNotFoundException {
        int version = in.readInt();
        numEntries = in.readInt();
        map = (gnu.trove.TObjectIntHashMap) in.readObject();
        growthStopped = in.readBoolean();
    }
}