001: //$HeadURL: https://svn.wald.intevation.org/svn/deegree/base/trunk/src/org/deegree/model/filterencoding/Expression.java $
002: /*---------------- FILE HEADER ------------------------------------------
003:
004: This file is part of deegree.
005: Copyright (C) 2001-2008 by:
006: EXSE, Department of Geography, University of Bonn
007: http://www.giub.uni-bonn.de/deegree/
008: lat/lon GmbH
009: http://www.lat-lon.de
010:
011: This library is free software; you can redistribute it and/or
012: modify it under the terms of the GNU Lesser General Public
013: License as published by the Free Software Foundation; either
014: version 2.1 of the License, or (at your option) any later version.
015:
016: This library is distributed in the hope that it will be useful,
017: but WITHOUT ANY WARRANTY; without even the implied warranty of
018: MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
019: Lesser General Public License for more details.
020:
021: You should have received a copy of the GNU Lesser General Public
022: License along with this library; if not, write to the Free Software
023: Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
024:
025: Contact:
026:
027: Andreas Poth
028: lat/lon GmbH
029: Aennchenstr. 19
030: 53115 Bonn
031: Germany
032: E-Mail: poth@lat-lon.de
033:
034: Prof. Dr. Klaus Greve
035: Department of Geography
036: University of Bonn
037: Meckenheimer Allee 166
038: 53115 Bonn
039: Germany
040: E-Mail: greve@giub.uni-bonn.de
041:
042:
043: ---------------------------------------------------------------------------*/
044: package org.deegree.model.filterencoding;
045:
046: import org.deegree.model.feature.Feature;
047: import org.w3c.dom.Element;
048:
049: /**
050: * Abstract superclass representing expr-entities (as defined in the Expression DTD).
051: *
052: * @author Markus Schneider
053: * @version 06.08.2002
054: */
055: abstract public class Expression {
056:
057: /**
058: * The underlying expression's id.
059: *
060: * @see ExpressionDefines
061: */
062: protected int id;
063:
064: /**
065: * Given a DOM-fragment, a corresponding Expression-object is built. This method recursively
066: * calls other buildFromDOM () - methods to validate the structure of the DOM-fragment.
067: *
068: * @param element
069: * @param useVersion_1_0_0
070: * if the filterencoding 1.0.0 should be used.
071: * @return the Bean of the DOM
072: *
073: * @throws FilterConstructionException
074: * if the structure of the DOM-fragment is invalid
075: */
076: public static Expression buildFromDOM(Element element)
077: throws FilterConstructionException {
078:
079: // check if root element's name is a known expression
080: String name = element.getLocalName();
081: int id = ExpressionDefines.getIdByName(name);
082: Expression expression = null;
083:
084: switch (id) {
085: case ExpressionDefines.EXPRESSION: {
086: break;
087: }
088: case ExpressionDefines.PROPERTYNAME: {
089: expression = PropertyName.buildFromDOM(element);
090: break;
091: }
092: case ExpressionDefines.LITERAL: {
093: expression = Literal.buildFromDOM(element);
094: break;
095: }
096: case ExpressionDefines.FUNCTION: {
097: expression = Function.buildFromDOM(element);
098: break;
099: }
100: case ExpressionDefines.ADD:
101: case ExpressionDefines.SUB:
102: case ExpressionDefines.MUL:
103: case ExpressionDefines.DIV: {
104: expression = ArithmeticExpression.buildFromDOM(element);
105: break;
106: }
107: default: {
108: throw new FilterConstructionException(
109: "Unknown expression '" + name + "'!");
110: }
111: }
112: return expression;
113: }
114:
115: /** @return the name of the expression. */
116: public String getExpressionName() {
117: return ExpressionDefines.getNameById(id);
118: }
119:
120: /**
121: * @return the expression's id.
122: *
123: * @see ExpressionDefines
124: */
125: public int getExpressionId() {
126: return this .id;
127: }
128:
129: /**
130: * Calculates the <tt>Expression</tt>'s value based on the certain property values of the
131: * given feature.
132: * <p>
133: *
134: * @param feature
135: * that determines the values of <tt>PropertyNames</tt> in the expression
136: * @return the resulting Object
137: * @throws FilterEvaluationException
138: * if the evaluation fails
139: */
140: public abstract Object evaluate(Feature feature)
141: throws FilterEvaluationException;
142:
143: /**
144: * Produces an indented XML representation of this object.
145: *
146: * @return XML representation of this object
147: */
148: public abstract StringBuffer toXML();
149: }
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