/*---------------- FILE HEADER ------------------------------------------
This file is part of deegree.
Copyright (C) 2001-2006 by:
EXSE, Department of Geography, University of Bonn
http://www.giub.uni-bonn.de/deegree/
lat/lon GmbH
http://www.lat-lon.de
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
Contact:
Andreas Poth
lat/lon GmbH
Aennchenstr. 19
53115 Bonn
Germany
E-Mail: poth@lat-lon.de
Prof. Dr. Klaus Greve
Department of Geography
University of Bonn
Meckenheimer Allee 166
53115 Bonn
Germany
E-Mail: greve@giub.uni-bonn.de
---------------------------------------------------------------------------*/
package org.deegree.model.filterencoding;
import org.deegree.model.feature.Feature;
import org.w3c.dom.Element;
/**
* Abstract superclass representing expr-entities (as defined in the Expression DTD).
*
* @author Markus Schneider
* @version 06.08.2002
*/
abstract public class Expression {
/**
* The underlying expression's id.
*
* @see ExpressionDefines
*/
protected int id;
/**
* Given a DOM-fragment, a corresponding Expression-object is built. This method recursively
* calls other buildFromDOM () - methods to validate the structure of the DOM-fragment.
*
* @throws FilterConstructionException
* if the structure of the DOM-fragment is invalid
*/
public static Expression buildFromDOM( Element element ) throws FilterConstructionException {
// check if root element's name is a known expression
String name = element.getLocalName();
int id = ExpressionDefines.getIdByName( name );
Expression expression = null;
switch (id) {
case ExpressionDefines.EXPRESSION: {
break;
}
case ExpressionDefines.PROPERTYNAME: {
expression = PropertyName.buildFromDOM( element );
break;
}
case ExpressionDefines.LITERAL: {
expression = Literal.buildFromDOM( element );
break;
}
case ExpressionDefines.FUNCTION: {
expression = Function.buildFromDOM( element );
break;
}
case ExpressionDefines.ADD:
case ExpressionDefines.SUB:
case ExpressionDefines.MUL:
case ExpressionDefines.DIV: {
expression = ArithmeticExpression.buildFromDOM( element );
break;
}
default: {
throw new FilterConstructionException( "Unknown expression '"
+ name + "'!" );
}
}
return expression;
}
/** Returns the name of the expression. */
public String getExpressionName() {
return ExpressionDefines.getNameById( id );
}
/**
* Returns the expression's id.
*
* @see ExpressionDefines
*/
public int getExpressionId() {
return this.id;
}
/**
* Calculates the <tt>Expression</tt>'s value based on the certain property values of the
* given feature.
* <p>
*
* @param feature
* that determines the values of <tt>PropertyNames</tt> in the expression
* @return the resulting Object
* @throws FilterEvaluationException
* if the evaluation fails
*/
public abstract Object evaluate( Feature feature ) throws FilterEvaluationException;
/** Produces an indented XML representation of this object. */
public abstract StringBuffer toXML();
}/* ********************************************************************
Changes to this class. What the people have been up to:
$Log: Expression.java,v $
Revision 1.6 2006/07/12 14:46:14 poth
comment footer added
********************************************************************** */