package org.drools.compiler.xml.rules;
/*
* 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 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.antlr.runtime.tree.CommonTreeNodeStream;
import org.antlr.runtime.tree.Tree;
import org.drools.lang.DRLLexer;
import org.drools.lang.DRLParser;
import org.drools.lang.DescrBuilderTree;
import org.drools.lang.DroolsTreeAdaptor;
import org.drools.lang.DescrBuilderTree.from_source_clause_return;
import org.drools.lang.descr.BaseDescr;
import org.drools.lang.descr.FromDescr;
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;
/**
* @author fernandomeyer
*/
public class ExpressionHandler extends BaseAbstractHandler
implements
Handler {
public ExpressionHandler() {
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,
final ExtensibleXmlParser parser) throws SAXException {
parser.startElementBuilder( localName,
attrs );
return new BaseDescr();
}
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();
emptyContentCheck( localName, expression, parser );
FromDescr parent = (FromDescr) parser.getParent();
final CharStream charStream = new ANTLRStringStream( expression.trim() );
final DRLLexer lexer = new DRLLexer( charStream );
final TokenStream tokenStream = new CommonTokenStream( lexer );
final DRLParser drlParser = new DRLParser( tokenStream );
drlParser.setTreeAdaptor(new DroolsTreeAdaptor());
try {
Tree fromSourceTree = (Tree) drlParser.from_source().getTree();
if (!drlParser.hasErrors()){
CommonTreeNodeStream nodes = new CommonTreeNodeStream(fromSourceTree);
nodes.setTokenStream(tokenStream);
DescrBuilderTree walker = new DescrBuilderTree(nodes);
from_source_clause_return fromReturn = walker.from_source_clause();
parent.setDataSource(fromReturn.retAccessorDescr);
parent = fromReturn.fromDescr;
} else {
throw new SAXParseException( "<" + localName + "> must have a valid expression content ",
parser.getLocator() );
}
} catch ( final RecognitionException e ) {
throw new SAXParseException( "<" + localName + "> must have a valid expression content ",
parser.getLocator() );
}
return null;
}
}