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;
022
023 import java.io.Serializable;
024
025 import csheets.core.IllegalValueTypeException;
026 import csheets.core.Value;
027 import csheets.core.formula.util.ExpressionVisitor;
028
029 /**
030 * An expression in a formula, that can be evaluated and visited.
031 * @author Einar Pehrson
032 */
033 public interface Expression extends Serializable {
034
035 /**
036 * Evaluates the expression and returns the result.
037 * @return the result of the evaluation
038 * @throws IllegalValueTypeException if a value of an unexpected type was
039 * encountered when evaluating the expression
040 */
041 public Value evaluate() throws IllegalValueTypeException;
042
043 /**
044 * Accepts to visit the given expression visitor.
045 * @param visitor the visitor
046 */
047 public Object accept(ExpressionVisitor visitor);
048 }