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 */
021package csheets.core.formula.util;
022
023import csheets.core.formula.BinaryOperation;
024import csheets.core.formula.FunctionCall;
025import csheets.core.formula.Literal;
026import csheets.core.formula.Reference;
027import csheets.core.formula.UnaryOperation;
028
029/**
030 * An interface for using the Visitor pattern for traversing expressions.
031 * @author Einar Pehrson
032 */
033public interface ExpressionVisitor {
034
035        /**
036         * Visits the given literal.
037         * @param literal the literal to visit
038         * @return an arbitrary object
039         */
040        public Object visitLiteral(Literal literal);
041
042        /**
043         * Visits the given unary expression.
044         * @param operation the operation to visit
045         * @return an arbitrary object
046         */
047        public Object visitUnaryOperation(UnaryOperation operation);
048
049        /**
050         * Visits the given binary expression.
051         * @param operation the operation to visit
052         * @return an arbitrary object
053         */
054        public Object visitBinaryOperation(BinaryOperation operation);
055
056        /**
057         * Visits the given cell reference.
058         * @param reference the reference to visit
059         * @return an arbitrary object
060         */
061        public Object visitReference(Reference reference);
062
063        /**
064         * Visits the given function call.
065         * @param call the function call to visit
066         * @return an arbitrary object
067         */
068        public Object visitFunctionCall(FunctionCall call);
069}