SimpleByteLexer.java

/* $Id$
 *****************************************************************************
 * Copyright (c) 2009 Contributors - see below
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *    thn
 *****************************************************************************
 *
 * Some portions of this file was previously release using the BSD License:
 */

// Copyright (c) 1996-2006 The Regents of the University of California. All
// Rights Reserved. Permission to use, copy, modify, and distribute this
// software and its documentation without fee, and without a written
// agreement is hereby granted, provided that the above copyright notice
// and this paragraph appear in all copies.  This software program and
// documentation are copyrighted by The Regents of the University of
// California. The software program and documentation are supplied "AS
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// does not warrant that the operation of the program will be
// uninterrupted or error-free. The end-user understands that the program
// was developed for research purposes and is advised not to rely
// exclusively on the program for any reason.  IN NO EVENT SHALL THE
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package org.argouml.language.java.reveng.classfile;

import java.io.IOException;
import java.io.InputStream;

import antlr.Token;
import antlr.TokenStream;
import antlr.TokenStreamException;
import antlr.TokenStreamIOException;



/**************************************
 * A simple lexer to scan a bytestream
 * Using a generated scanner results in
 * too much overhead and performance
 * issues.
 **************************************/
public class SimpleByteLexer implements ClassfileTokenTypes, TokenStream {

    //////////////////////
    // Instance variables.

    private InputStream input = null;


    ///////////////
    // Constructors

    /**
     * Create a new bytestream scanner.
     * The constructor.
     *
     * @param in the given inputstream
     */
    public SimpleByteLexer(InputStream in) {
        input = in;
    }


    //////////
    // Methods

    /**
     * Return the next byte as a token.
     *
     * @return The next byte as a token or a EOF token.
     * @throws TokenStreamException if the next byte cannot be read
     * @see antlr.TokenStream#nextToken()
     */
    public final Token nextToken() throws TokenStreamException {
    int nextByte;

    try {
        nextByte = input.read();
    } catch (IOException ie) {
        throw new TokenStreamIOException(ie);
    }

    // System.out.println("Generating token for: " + nextByte);

    return (nextByte == -1)
        ? new ByteToken( Token.EOF_TYPE)
                : new ByteToken( BYTE, (byte) nextByte);
    }
}