DefaultAlphabetTable.java

/*
 * $Id: DefaultAlphabetTable.java 536 2008-02-19 06:03:27Z weiju $
 * 
 * Created on 2006/01/12
 * Copyright 2005-2008 by Wei-ju Wu
 * This file is part of The Z-machine Preservation Project (ZMPP).
 *
 * ZMPP is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * ZMPP 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with ZMPP.  If not, see <http://www.gnu.org/licenses/>.
 */
package org.zmpp.encoding;

/**
 * The default alphabet table implementation.
 *
 * @author Wei-ju Wu
 */
public class DefaultAlphabetTable implements AlphabetTable {

    private static final String A0CHARS = "abcdefghijklmnopqrstuvwxyz";
    private static final String A1CHARS = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
    private static final String A2CHARS = " \n0123456789.,!?_#'\"/\\-:()";

    /**
     * {@inheritDoc}
     */
    public char getA0Char(final byte zchar) {

        if (zchar == 0) {
            return ' ';
        }
        return A0CHARS.charAt(zchar - ALPHABET_START);
    }

    /**
     * {@inheritDoc}
     */
    public char getA1Char(final byte zchar) {

        if (zchar == 0) {
            return ' ';
        }
        return A1CHARS.charAt(zchar - ALPHABET_START);
    }

    /**
     * {@inheritDoc}
     */
    public char getA2Char(final byte zchar) {

        if (zchar == 0) {
            return ' ';
        }
        return A2CHARS.charAt(zchar - ALPHABET_START);
    }

    /**
     * {@inheritDoc}
     */
    public final byte getA0CharCode(final char zsciiChar) {

        return getCharCodeFor(A0CHARS, zsciiChar);
    }

    /**
     * {@inheritDoc}
     */
    public final byte getA1CharCode(final char zsciiChar) {

        return getCharCodeFor(A1CHARS, zsciiChar);
    }

    /**
     * {@inheritDoc}
     */
    public byte getA2CharCode(final char zsciiChar) {

        return getCharCodeFor(A2CHARS, zsciiChar);
    }

    protected static byte getCharCodeFor(final String chars,
            final char zsciiChar) {

        int index = chars.indexOf(zsciiChar);
        if (index >= 0) {

            index += ALPHABET_START;
        }
        return (byte) index;
    }

    /**
     * {@inheritDoc}
     */
    public boolean isShift1(final char zchar) {

        return zchar == SHIFT_4;
    }

    /**
     * {@inheritDoc}
     */
    public boolean isShift2(final char zchar) {

        return zchar == SHIFT_5;
    }

    /**
     * {@inheritDoc}
     */
    public boolean isShift(final char zchar) {

        return isShift1(zchar) || isShift2(zchar);
    }

    /**
     * {@inheritDoc}
     */
    public boolean isShiftLock(final char zchar) {

        return false;
    }

    /**
     * {@inheritDoc}
     */
    public boolean isAbbreviation(final char zchar) {

        return 1 <= zchar && zchar <= 3;
    }
}