import java.io.*;
import java.util.*;

/**
 * class for reading files and returning one word
 * from the file at a time using the Iterator idiom
 * 
 * Usage:
 * <XMP>
 *        Iterator it = new WordIterator("filename.txt");
 *        while (it.hasNext())
 *             Process((String) it.next());
 * </XMP>
 *
 * @author  $Author: ola $
 * @version $Id: WordIterator.java,v 1.1 1999/10/13 06:18:06 ola Exp ola $
 * @see Enumeration
 *
 * $Date: 1999/10/13 06:18:06 $
 */
 
public class WordIterator implements Iterator
{
    /**
     * opens file, readies for reading, re-throws failure to open
     *
     * @param filename the name of the file to get words from
     *
     */

    public WordIterator(String filename) throws FileNotFoundException
    {
	this(new FileReader(filename));
    }

    /**
      * read one word-at-a-time from a reader
      * @param r is reader bound to WordIterator
      *
      */
    public WordIterator(Reader r)
    {
	myInput = new BufferedReader(r);
	myLineNumber = 0;
	getNextLine();
    }

    private void getNextLine()
    {
	try
	{
	    myWord = null;   // default
	    while ((myLine = myInput.readLine()) != null)
	    {
		myLineNumber++;
		myTokenizer = new StringTokenizer(myLine, " \t\n\r");
		if (myTokenizer.hasMoreTokens())
		{
		    myWord = myTokenizer.nextToken();
		    break;
		}
	    }
	}
	catch (IOException e)
	{
	    // what to do with an IOException??
	    myWord = null;
	}
    }

    /**
     * @return true if more words to be read, else false
     *
     */
    public boolean hasNext()
    { 
        return myWord != null;
    }

    /**
     *
     * @return next word (String) from input 
     *
     * Note: user casts return type to string
     */
    
    public Object next()
    {
	String word = myWord;
	if (myWord == null)
	{
	    throw new
		NoSuchElementException("next() in WordIterator");
	}
	
	if (! myTokenizer.hasMoreTokens())
	{
	    getNextLine();
	}
	else
	{
	    myWord = myTokenizer.nextToken();
	}	
	return word;
    }

    public void remove()
    {
	throw new UnsupportedOperationException("WordIterator does not remove");
    }

    public static void main(String args[])
    {
	if (args.length != 1)
	{
	    System.out.println("usage: test <filename>");
	}
	else
	{
	    WordIterator wit = null;
	    try{
		wit = new WordIterator(args[0]);		
	    }
	    catch (FileNotFoundException fnf){
		System.out.println(fnf + " **ERROR opening " + args[0]);
	    }

	    while (wit.hasNext())
	    {
	      System.out.println(wit.next());
	    }	    	    
	}
    }

    /**
     * @return current line number in file
     *
     */
    public int getLineNumber()
    {
	return myLineNumber;
    }
    
    private BufferedReader  myInput;
    private StringTokenizer myTokenizer;
    private String myWord;  
    private String myLine;
    private int myLineNumber;
}