package org.drools.xml;
/*
* 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.
*/
import java.util.HashSet;
import java.util.LinkedList;
import java.util.ListIterator;
import org.antlr.runtime.ANTLRStringStream;
import org.antlr.runtime.CharStream;
import org.antlr.runtime.CommonTokenStream;
import org.antlr.runtime.RecognitionException;
import org.antlr.runtime.TokenStream;
import org.drools.lang.DRLLexer;
import org.drools.lang.DRLParser;
import org.drools.lang.descr.BaseDescr;
import org.drools.lang.descr.DeclarativeInvokerDescr;
import org.drools.lang.descr.FromDescr;
import org.xml.sax.Attributes;
import org.xml.sax.SAXException;
import org.xml.sax.SAXParseException;
/**
* @author fernandomeyer
*/
public class ExpressionHandler extends BaseAbstractHandler
implements
Handler {
ExpressionHandler(final XmlPackageReader xmlPackageReader) {
this.xmlPackageReader = xmlPackageReader;
if ( (this.validParents == null) && (this.validPeers == null) ) {
this.validParents = new HashSet();
this.validParents.add( FromHandler.class );
this.validPeers = new HashSet();
this.validPeers.add( null );
this.validPeers.add( BaseDescr.class );
this.allowNesting = true;
}
}
public Class generateNodeFor() {
return BaseDescr.class;
}
public Object start(final String uri,
final String localName,
final Attributes attrs) throws SAXException {
this.xmlPackageReader.startConfiguration( localName,
attrs );
return new BaseDescr();
}
public Object end(final String uri,
final String localName) throws SAXException {
final Configuration config = this.xmlPackageReader.endConfiguration();
final BaseDescr baseDescr = (BaseDescr) this.xmlPackageReader.getCurrent();
final String expression = config.getText();
if ( expression == null || expression.trim().equals( "" ) ) {
throw new SAXParseException( "<" + localName + "> must have some content",
this.xmlPackageReader.getLocator() );
}
final LinkedList parents = this.xmlPackageReader.getParents();
final ListIterator ite = parents.listIterator( parents.size() );
ite.previous();
final Object parent = ite.previous();
final FromDescr fromSource = (FromDescr) parent;
final CharStream charStream = new ANTLRStringStream( expression.trim() );
final DRLLexer lexer = new DRLLexer( charStream );
final TokenStream tokenStream = new CommonTokenStream( lexer );
final DRLParser parser = new DRLParser( tokenStream );
try {
final DeclarativeInvokerDescr declarativeInvoker = parser.from_source( fromSource );
fromSource.setDataSource( declarativeInvoker );
} catch ( final RecognitionException e ) {
throw new SAXParseException( "<" + localName + "> must have a valid expression content ",
this.xmlPackageReader.getLocator() );
}
return null;
}
}