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/*
 * #%L
 * The AIBench Shell Plugin
 * %%
 * Copyright (C) 2006 - 2017 Daniel Glez-Peña and Florentino Fdez-Riverola
 * %%
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation, either version 3 of the
 * License, or (at your option) any later version.
 * 
 * This program is distributed in the hope that it will be useful,
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 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Lesser Public License for more details.
 * 
 * You should have received a copy of the GNU General Lesser Public
 * License along with this program.  If not, see
 * .
 * #L%
 */
/*****************************************************************************
 *                                                                           *
 *  This file is part of the BeanShell Java Scripting distribution.          *
 *  Documentation and updates may be found at http://www.beanshell.org/      *
 *                                                                           *
 *  Sun Public License Notice:                                               *
 *                                                                           *
 *  The contents of this file are subject to the Sun Public License Version  *
 *  1.0 (the "License"); you may not use this file except in compliance with *
 *  the License. A copy of the License is available at http://www.sun.com    * 
 *                                                                           *
 *  The Original Code is BeanShell. The Initial Developer of the Original    *
 *  Code is Pat Niemeyer. Portions created by Pat Niemeyer are Copyright     *
 *  (C) 2000.  All Rights Reserved.                                          *
 *                                                                           *
 *  GNU Public License Notice:                                               *
 *                                                                           *
 *  Alternatively, the contents of this file may be used under the terms of  *
 *  the GNU Lesser General Public License (the "LGPL"), in which case the    *
 *  provisions of LGPL are applicable instead of those above. If you wish to *
 *  allow use of your version of this file only under the  terms of the LGPL *
 *  and not to allow others to use your version of this file under the SPL,  *
 *  indicate your decision by deleting the provisions above and replace      *
 *  them with the notice and other provisions required by the LGPL.  If you  *
 *  do not delete the provisions above, a recipient may use your version of  *
 *  this file under either the SPL or the LGPL.                              *
 *                                                                           *
 *  Patrick Niemeyer ([email protected])                                           *
 *  Author of Learning Java, O'Reilly & Associates                           *
 *  http://www.pat.net/~pat/                                                 *
 *                                                                           *
 *****************************************************************************/

package bsh;

import java.io.FilterReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.Reader;

/**
 * This is a quick hack to turn empty lines entered interactively on the command
 * line into ';\n' empty lines for the interpreter. It's just more pleasant to
 * be able to hit return on an empty line and see the prompt reappear.
 * 
 * This is *not* used when text is sourced from a file non-interactively.
 */
class CommandLineReader extends FilterReader {

        public CommandLineReader(Reader in) {
                super(in);
        }

        static final int normal = 0, lastCharNL = 1, sentSemi = 2;

        int state = lastCharNL;

        public int read() throws IOException {
                int b;

                if (state == sentSemi) {
                        state = lastCharNL;
                        return '\n';
                }

                // skip CR
                while ((b = in.read()) == '\r')
                        ;

                if (b == '\n')
                        if (state == lastCharNL) {
                                b = ';';
                                state = sentSemi;
                        } else
                                state = lastCharNL;
                else
                        state = normal;

                return b;
        }

        /**
         * This is a degenerate implementation. I don't know how to keep this
         * from blocking if we try to read more than one char... There is no
         * available() for Readers ??
         */
        public int read(char buff[], int off, int len) throws IOException {
                int b = read();
                if (b == -1)
                        return -1; // EOF, not zero read apparently
                else {
                        buff[off] = (char) b;
                        return 1;
                }
        }

        // Test it
        public static void main(String[] args) throws Exception {
                Reader in = new CommandLineReader(new InputStreamReader(System.in));
                while (true)
                        System.out.println(in.read());

        }
}