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 csheets.core.IllegalValueTypeException;
024    import csheets.core.Value;
025    import csheets.core.formula.util.ExpressionVisitor;
026    
027    /**
028     * A unary operation in a formula.
029     * @author Einar Pehrson
030     */
031    public 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    }