/*  PositionImpl - A class to implement the functionality of the position                  of one piece of a chess game.  Copyright (C) 2003 The Java-Chess team <info@java-chess.de>  This program 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 2  of the License, or (at your option) any later version.  This program 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 this program; if not, write to the Free Software  Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.*/ package de.java_chess.javaChess.position;/** * This class implements the functionality to store the position * of a chess piece. */public class PositionImpl implements Position {    // Instance variables    /**     * The index of the chessboard square.     */    private int _squareIndex;    // Constructors    /**     * Create a position from a given square index.     *     * @param squareIndex The index of the square (0..63).     */    public PositionImpl( int squareIndex) {	setSquareIndex( squareIndex);    }    /**     * Create a position from a given square name (i.e. 'd4').     *     * @param squareName The name of the square.     *     * @throws IllegalPositionException If the argument is not a valid square name.     */    public PositionImpl( String squareName) throws IllegalPositionException {		// -1 indicates an error here.	int squareIndex = -1;	// Trim and convert the name to lower case.	squareName = squareName.trim().toLowerCase();		// Check if the name has no extra characters	if( squareName.length() != 2) {	    throw new IllegalPositionException();	} else {	    // Get the line.	    char lineLetter = squareName.charAt(0);	    if( ( lineLetter < 'a') || ( lineLetter > 'h')) {		throw new IllegalPositionException();	    } else {		// Compute the index of the line.		int lineIndex = lineLetter - 'a';		// Get the name of the row.		char rowLetter = squareName.charAt(1);		if( ( rowLetter < '1') || ( rowLetter > '8')) {		    throw new IllegalPositionException();		} else {		    int rowIndex = rowLetter - '1';		    		    // The square index is 8 * row + line.		    squareIndex = ( rowIndex << 3) + lineIndex;		}	    }	}		// Set the computed square index.	setSquareIndex( squareIndex);    }    // Methods    /**     * Get the square index of this position (0-63).     *     * @return The square index of this position.     */    public final int getSquareIndex() {	return _squareIndex;    }    /**     * Set the square index of this position.     *     * @param squareIndex The new square index of this position.     */    public final void setSquareIndex( int squareIndex) {	_squareIndex = squareIndex;    }    /**     * Get the row index of this position (0-7).     *     * @return The row index of this position.     */    public final int getRowIndex() {	return _squareIndex >> 3;    }    /**     * Get the line index of this postion (0-7).     *     * @return The line index of this position.     */    public final int getLineIndex() {	return _squareIndex & 7;    }    /**     * Convert this position to a square name (like 'a4').     *     * @return The suare name of this position.     */    public final String toSquareName() {	byte [] byteRepresentation = new byte[2];	byteRepresentation[0] = (byte)((int)'a' + getLineIndex());	byteRepresentation[1] = (byte)((int)'1' + getRowIndex());	return new String( byteRepresentation);    }    /**     * Test if 2 positions are equal.     *     * @param Another position.     *     * @return true, if the positions are equal, false otherwise.     */    public final boolean equals( Position pos) {	return pos.getSquareIndex() == getSquareIndex();    }}