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.lang;
022
023 import csheets.core.IllegalValueTypeException;
024 import csheets.core.Value;
025 import csheets.core.formula.BinaryOperator;
026 import csheets.core.formula.Expression;
027
028 /**
029 * A relational operator.
030 * @author Einar Pehrson
031 */
032 public 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 }