org.drools.compiler.xml.rules.PredicateHandler Maven / Gradle / Ivy

Go to download
Show more of this group Show more artifacts with this name
Show all versions of drools-compiler Show documentation
There is a newer version: 10.0.0
/*
 * Copyright 2005 JBoss Inc
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.drools.compiler.xml.rules;

import java.util.HashSet;

import org.drools.lang.descr.BindingDescr;
import org.drools.lang.descr.ExprConstraintDescr;
import org.drools.lang.descr.FieldConstraintDescr;
import org.drools.lang.descr.PatternDescr;
import org.drools.lang.descr.PredicateDescr;
import org.drools.xml.BaseAbstractHandler;
import org.drools.xml.ExtensibleXmlParser;
import org.drools.xml.Handler;
import org.w3c.dom.Element;
import org.xml.sax.Attributes;
import org.xml.sax.SAXException;
import org.xml.sax.SAXParseException;

/**
 *
 * TODO To change the template for this generated type comment go to Window -
 * Preferences - Java - Code Style - Code Templates
 */
public class PredicateHandler extends BaseAbstractHandler
    implements
    Handler {
    public PredicateHandler() {
    }

    public Object start(final String uri,
                        final String localName,
                        final Attributes attrs,
                        final ExtensibleXmlParser parser) throws SAXException {
        parser.startElementBuilder( localName,
                                    attrs );
        return ""; // need to return something, otherwise it'll pop the parent
    }

    public Object end(final String uri,
                      final String localName,
                      final ExtensibleXmlParser parser) throws SAXException {
        final Element element = parser.endElementBuilder();

        final String expression =((org.w3c.dom.Text)element.getChildNodes().item( 0 )).getWholeText();

        if ( expression == null || expression.trim().equals( "" ) ) {
            throw new SAXParseException( " must have some content",
                                         parser.getLocator() );
        }

        final PatternDescr patternDescr = (PatternDescr) parser.getParent();
        
        ExprConstraintDescr expr = new ExprConstraintDescr("eval(" + expression + ")");

        patternDescr.addConstraint( expr );

        return expr;
    }

    public Class generateNodeFor() {
        return PredicateDescr.class;
    }
}