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;
022
023import csheets.core.IllegalValueTypeException;
024import csheets.core.Value;
025import csheets.core.formula.util.ExpressionVisitor;
026
027/**
028 * A unary operation in a formula.
029 * @author Einar Pehrson
030 */
031public class UnaryOperation extends Operation<UnaryOperator> {
032
033        /** The unique version identifier used for serialization */
034        private static final long serialVersionUID = -1630292510063782201L;
035
036        /** The operand */
037        private Expression operand;
038
039        /**
040         * Creates a new unary operation.
041         * @param operator the unary operator
042         * @param operand the operand
043         */
044        public UnaryOperation(UnaryOperator operator, Expression operand) {
045                super(operator);
046                this.operand = operand;
047        }
048
049        public Value evaluate() throws IllegalValueTypeException {
050                return operator.applyTo(operand);
051        }
052
053        /** 
054         * Returns the operand.
055         * @return an expression tree representing the operand
056         */
057        public Expression getOperand() {
058                return operand;
059        }
060
061        public Object accept(ExpressionVisitor visitor) {
062                return visitor.visitUnaryOperation(this);
063        }
064
065        public String toString() {
066                if (operator.isPrefix())
067                        return operator + operand.toString();
068                else
069                        return operand + operator.toString();
070        }
071}