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.lang;
022
023import csheets.core.IllegalValueTypeException;
024import csheets.core.Value;
025import csheets.core.formula.BinaryOperator;
026import csheets.core.formula.Expression;
027
028/**
029 * A relational operator.
030 * @author Einar Pehrson
031 */
032public abstract class RelationalOperator implements BinaryOperator {
033
034        /**
035         * Creates a new relational operator.
036         */
037        public RelationalOperator() {}
038
039        public final Value applyTo(Expression leftOperand, Expression rightOperand) throws IllegalValueTypeException {
040                Value leftValue = leftOperand.evaluate();
041                switch (leftValue.getType()) {
042                        case NUMERIC:
043                                return new Value(compare(leftValue.toDouble(),
044                                        rightOperand.evaluate().toDouble()));
045                        case TEXT:
046                                return new Value(compare(leftValue.toText(),
047                                        rightOperand.evaluate().toText()));
048                        case BOOLEAN:
049                                return new Value(compare(leftValue.toBoolean(),
050                                        rightOperand.evaluate().toBoolean()));
051                        case DATE:
052                                return new Value(compare(leftValue.toDate(),
053                                        rightOperand.evaluate().toDate()));
054                        default:
055                                throw new IllegalValueTypeException(leftValue, Value.Type.NUMERIC);
056                }
057        }
058
059        /**
060         * Applies the operator to the given operands and returns a boolean value.
061         * @param left the value of the left operand
062         * @param right the value of the right operand
063         * @return the result of the comparison
064         */
065        public abstract <T> boolean compare(Comparable<T> left, T right);
066
067        public Value.Type getOperandValueType() {
068                return Value.Type.NUMERIC;
069        }
070
071        public String toString() {
072                return getIdentifier();
073        }
074}