ZsciiString.java

/*
 * $Id: ZsciiString.java 536 2008-02-19 06:03:27Z weiju $
 * 
 * Created on 2006/02/01
 * 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;

/**
 * This class represents ZSCII strings. These are especially important to the
 * input system since the dictionaries store their entries in ZSCII and the
 * input will be converted into this encoding.
 *
 * ZSCII strings are represented as a sequence of 16-bit characters.
 *
 * @author Wei-ju Wu
 * @version 1.0
 */
public class ZsciiString {

    /**
     * The encoding object.
     */
    private static ZsciiEncoding encoding;

    /**
     * The string data.
     */
    private char[] data;

    /**
     * Global initialization method.
     *
     * @param encoding the encoding
     */
    public static void initialize(final ZsciiEncoding encoding) {

        ZsciiString.encoding = encoding;
    }

    /**
     * Constructor.
     *
     * @param data the source array
     */
    public ZsciiString(final char[] data) {

        super();
        this.data = data;
    }

    /**
     * Creates a ZSCII string from a string.
     *
     * @param str the string
     */
    public ZsciiString(final String str) {

        super();
        this.data = encoding.convertToZscii(str);
    }

    /**
     * Returns the ZSCII character at the specified position.
     *
     * @param pos the position
     * @return the character
     */
    public char charAt(final int pos) {

        return data[pos];
    }

    /**
     * Returns the length of this string.
     *
     * @return the length
     */
    public int length() {

        return data.length;
    }

    /**
     * Returns the index of the first occurrence of the specified sub string.
     *
     * @param str the string
     * @param startIndex the start index
     * @return the first index
     */
    public int indexOf(final ZsciiString str, final int startIndex) {

        int current = startIndex;
        final int length = length();
        final int n = str.length();

        while (current < length) {

            if (charAt(current) == str.charAt(0)) {

                // Compare all characters of str from the index on
                int i = 1;
                for (; i < n; i++) {

                    if (charAt(current + i) != str.charAt(i)) {
                        break;
                    }
                }
                if (i == n) {
                    return current;
                }
            }
            current++;
        }
        return -1;
    }

    /**
     * Returns a new string that is a substring of this string. The substring
     * begins at the specified startindex and extends to the character at index
     * endindex - 1. Thus the length of the substring is endindex-startindex.
     *
     * @param startindex start index
     * @param endindex end index
     * @return the sub string
     */
    public ZsciiString substring(final int startindex, final int endindex) {

        final int n = endindex - startindex;
        final char[] dat = new char[n];
        for (int i = 0; i < n; i++) {

            dat[i] = charAt(startindex + i);
        }
        return new ZsciiString(dat);
    }

    /**
     * {@inheritDoc}
     */
    public int hashCode() {

        int hashvalue = 0;
        for (int i = 0; i < data.length; i++) {

            hashvalue = 31 * hashvalue + data[i];
        }
        return hashvalue;
    }

    /**
     * {@inheritDoc}
     */
    public boolean equals(final Object o) {

        if (o == this) {
            return true;
        }
        if (o instanceof ZsciiString) {

            final char[] data2 = ((ZsciiString) o).data;
            if (data.length == data2.length) {

                for (int i = 0; i < data.length; i++) {

                    if (data[i] != data2[i]) {
                        return false;
                    }
                }
                return true;
            }
        }
        return false;
    }

    /**
     * {@inheritDoc}
     */
    public String toString() {

        final StringBuilder builder = new StringBuilder();
        for (int i = 0; i < data.length; i++) {

            builder.append(encoding.getUnicodeChar(data[i]));
        }
        return builder.toString();
    }
}