001    /*
002     * Copyright (c) 2005 Einar Pehrson <einar@pehrson.nu>.
003     *
004     * This file is part of
005     * CleanSheets - a spreadsheet application for the Java platform.
006     *
007     * CleanSheets is free software; you can redistribute it and/or modify
008     * it under the terms of the GNU General Public License as published by
009     * the Free Software Foundation; either version 2 of the License, or
010     * (at your option) any later version.
011     *
012     * CleanSheets is distributed in the hope that it will be useful,
013     * but WITHOUT ANY WARRANTY; without even the implied warranty of
014     * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
015     * GNU General Public License for more details.
016     *
017     * You should have received a copy of the GNU General Public License
018     * along with CleanSheets; if not, write to the Free Software
019     * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
020     */
021    package csheets.core.formula.util;
022    
023    import csheets.core.formula.Formula;
024    
025    /**
026     * An exception that is thrown if a formula contains a reference (directly or
027     * indirectly) to the cell in which it is contained.
028     * @author Einar Pehrson
029     */
030    public class CircularReferenceException extends ExpressionVisitorException {
031    
032            /** The serialVersionUID of the CircularReferenceException.java */
033            private static final long serialVersionUID = 4204972508404909370L;
034    
035            /** The formula in which the circularity exists */
036            private Formula formula;
037    
038            /**
039             * Creates a new circular reference exception.
040             * @param formula the formula that caused the exception
041             */
042            public CircularReferenceException(Formula formula) {
043                    super("A circular reference was encountered in the formula " + formula + ".");
044                    this.formula = formula;
045            }
046    
047            /**
048             * Returns the formula in which the circularity exists.
049             * @return the formula in which the circularity exists
050             */
051            public Formula getFormula() {
052                    return formula;
053            }
054    
055            /**
056             * Returns a string representation of the exception.
057             * @return a string representation of the exception
058             */
059            public String toString() {
060                    return "#CIRCLE!";
061            }
062    
063            /**
064             * Returns whether the other object is an identical value .
065             * @param other the object to check for equality
066             * @return true if the objects are equal
067             */
068            public boolean equals(Object other) {
069                    if (!(other instanceof CircularReferenceException) || other == null)
070                            return false;
071                    CircularReferenceException e = (CircularReferenceException)other;
072                    return formula.getCell().equals(e.formula.getCell());
073            }
074    }