001 //$HeadURL: https://svn.wald.intevation.org/svn/deegree/base/branches/2.3_testing/src/org/deegree/model/filterencoding/ArithmeticExpression.java $
002 /*----------------------------------------------------------------------------
003 This file is part of deegree, http://deegree.org/
004 Copyright (C) 2001-2009 by:
005 Department of Geography, University of Bonn
006 and
007 lat/lon GmbH
008
009 This library is free software; you can redistribute it and/or modify it under
010 the terms of the GNU Lesser General Public License as published by the Free
011 Software Foundation; either version 2.1 of the License, or (at your option)
012 any later version.
013 This library is distributed in the hope that it will be useful, but WITHOUT
014 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
015 FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more
016 details.
017 You should have received a copy of the GNU Lesser General Public License
018 along with this library; if not, write to the Free Software Foundation, Inc.,
019 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
020
021 Contact information:
022
023 lat/lon GmbH
024 Aennchenstr. 19, 53177 Bonn
025 Germany
026 http://lat-lon.de/
027
028 Department of Geography, University of Bonn
029 Prof. Dr. Klaus Greve
030 Postfach 1147, 53001 Bonn
031 Germany
032 http://www.geographie.uni-bonn.de/deegree/
033
034 e-mail: info@deegree.org
035 ----------------------------------------------------------------------------*/
036 package org.deegree.model.filterencoding;
037
038 import org.deegree.framework.xml.ElementList;
039 import org.deegree.framework.xml.XMLTools;
040 import org.deegree.model.feature.Feature;
041 import org.w3c.dom.Element;
042
043 /**
044 * Encapsulates the information of a <Add> / <Sub>/ <Mul> or <DIV> element
045 * as defined in the Expression DTD.
046 *
047 * @author <a href="mailto:schneider@lat-lon.de">Markus Schneider</a>
048 * @author last edited by: $Author: mschneider $
049 *
050 * @version $Revision: 18195 $, $Date: 2009-06-18 17:55:39 +0200 (Do, 18. Jun 2009) $
051 */
052 public class ArithmeticExpression extends Expression {
053
054 /**
055 * The first operand.
056 *
057 */
058 Expression expr1;
059
060 /**
061 * The second operand.
062 *
063 */
064 Expression expr2;
065
066 /**
067 * Constructs a new ArithmeticExpression.
068 *
069 * @param id
070 * @param expr1
071 * @param expr2
072 */
073 public ArithmeticExpression( int id, Expression expr1, Expression expr2 ) {
074 this.id = id;
075 this.expr1 = expr1;
076 this.expr2 = expr2;
077 }
078
079 /**
080 * Given a DOM-fragment, a corresponding Expression-object is built. This method recursively
081 * calls other buildFromDOM () - methods to validate the structure of the DOM-fragment.
082 *
083 * @param element
084 * @return the new instance
085 *
086 * @throws FilterConstructionException
087 * if the structure of the DOM-fragment is invalid
088 */
089 public static Expression buildFromDOM( Element element )
090 throws FilterConstructionException {
091
092 // check if root element's name is 'Add' / 'Sub' / 'Mul' or 'Div'
093 String name = element.getLocalName();
094 int id = ExpressionDefines.getIdByName( name );
095 switch ( id ) {
096 case ExpressionDefines.ADD:
097 case ExpressionDefines.SUB:
098 case ExpressionDefines.MUL:
099 case ExpressionDefines.DIV: {
100 break;
101 }
102 default: {
103 throw new FilterConstructionException( "Element's name does not match 'Add' / 'Sub' / 'Mul' or 'Div'!" );
104 }
105 }
106
107 // determine the arguments
108 ElementList children = XMLTools.getChildElements( element );
109 if ( children.getLength() != 2 )
110 throw new FilterConstructionException( "'" + name + "' requires exactly 2 elements!" );
111
112 Expression expr1 = Expression.buildFromDOM( children.item( 0 ) );
113 Expression expr2 = Expression.buildFromDOM( children.item( 1 ) );
114
115 return new ArithmeticExpression( id, expr1, expr2 );
116 }
117
118 /**
119 * Produces an indented XML representation of this object.
120 *
121 * @return XML representation of this object.
122 */
123 @Override
124 public StringBuffer toXML() {
125 StringBuffer sb = new StringBuffer();
126
127 sb.append( "<ogc:" ).append( getExpressionName() ).append( ">" );
128 sb.append( expr1.toXML() );
129 sb.append( expr2.toXML() );
130 sb.append( "</ogc:" ).append( getExpressionName() ).append( ">" );
131 return sb;
132 }
133
134 /**
135 * Returns this <tt>ArithmeticExpression/tt>'s value (to be used in the
136 * evaluation of complex <tt>Expression</tt>s).
137 * TODO: Improve datatype handling.
138 * @param feature that determines the concrete values of
139 * <tt>PropertyNames</tt> in the expression
140 * @return the resulting value (as <tt>Double</tt>)
141 * @throws FilterEvaluationException if the expressions are not numerical
142 */
143 @Override
144 public Object evaluate( Feature feature )
145 throws FilterEvaluationException {
146
147 Object o1 = expr1.evaluate( feature );
148 Object o2 = expr2.evaluate( feature );
149
150 if ( !( o1 instanceof Number && o2 instanceof Number ) ) {
151 throw new FilterEvaluationException( "ADD/SUB/DIV/MUL may only be applied to numerical expressions." );
152 }
153 double d1 = ( (Number) o1 ).doubleValue();
154 double d2 = ( (Number) o2 ).doubleValue();
155 switch ( id ) {
156 case ExpressionDefines.ADD:
157 return new Double( d1 + d2 );
158 case ExpressionDefines.SUB:
159 return new Double( d1 - d2 );
160 case ExpressionDefines.MUL:
161 return new Double( d1 * d2 );
162 case ExpressionDefines.DIV:
163 return new Double( d1 / d2 );
164 default: {
165 throw new FilterEvaluationException( "Unknown ArithmeticExpression: '" + getExpressionName() + "'!" );
166 }
167 }
168 }
169
170 /**
171 * returns the first expression
172 *
173 * @return the first expression
174 */
175 public Expression getFirstExpression() {
176 return expr1;
177 }
178
179 /**
180 * returns the second expression
181 *
182 * @return the second expression
183 */
184 public Expression getSecondExpression() {
185 return expr2;
186 }
187 }