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    
026    /**
027     * A unary operator in a formula.
028     * @author Einar Pehrson
029     */
030    public interface UnaryOperator extends Operator {
031    
032            /**
033             * Applies the operator to the given operand and returns the result.
034             * @return the result of the operation
035             * @throws IllegalValueTypeException if the value of the operand is not of the expected type
036             */
037            public Value applyTo(Expression operand) throws IllegalValueTypeException;
038    
039            /**
040             * Returns whether the operator is a prefix operator, i.e. it appears
041             * before its operand.
042             * @return true for prefix operators, false for postfix operators
043             */
044            public boolean isPrefix();
045    }