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.Expression;
025import csheets.core.formula.FunctionCall;
026import csheets.core.formula.Literal;
027import csheets.core.formula.Reference;
028import csheets.core.formula.UnaryOperation;
029
030/**
031 * A default implementation of an expression visitor, that simply visits all
032 * the nodes in the tree. All methods return the expression that was visited.
033 * @author Einar Pehrson
034 */
035public abstract class AbstractExpressionVisitor implements ExpressionVisitor {
036
037        /**
038         * Creates a new expression visitor.
039         */
040        public AbstractExpressionVisitor() {}
041
042        public Object visitLiteral(Literal literal) {
043                return literal;
044        }
045
046        public Object visitUnaryOperation(UnaryOperation operation) {
047                operation.getOperand().accept(this);
048                return operation;
049        }
050
051        public Object visitBinaryOperation(BinaryOperation operation) {
052                operation.getLeftOperand().accept(this);
053                operation.getRightOperand().accept(this);
054                return operation;
055        }
056
057        public Object visitReference(Reference reference) {
058                return reference;
059        }
060
061        public Object visitFunctionCall(FunctionCall call) {
062                for (Expression argument : call.getArguments())
063                        argument.accept(this);
064                return call;
065        }
066}