/**
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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.apache.oodt.xmlps.queryparser;
//JDK imports
import org.apache.oodt.xmlps.mapping.Mapping;
import org.apache.oodt.xmlps.mapping.MappingField;
import java.util.List;
import java.util.Stack;
//OODT imports
import org.apache.oodt.xmlquery.QueryElement;
import org.apache.oodt.xmlquery.XMLQuery;
/**
*
* Parsers the {@link XMLQuery} and its @link XMLQuery#getWhereElementSet()}
* into an {@link Expression} tree.
*/
public class HandlerQueryParser implements ParseConstants {
/**
* Calls {@link #parse(Stack, Mapping)} with a null mapping.
*
* @param queryStack The {@link XMLQuery#getWhereElementSet()}.
* @return The parsed {@link Expression} tree.
*/
public static Expression parse(Stack<QueryElement> queryStack) {
return parse(queryStack, null);
}
/**
*
* Parses the {@link XMLQuery#getWhereElementSet()} using the provided
* <param>map</param>.
*
* @param queryStack The {@link XMLQuery#getWhereElementSet()}
* @param map The provided ontological mapping.
* @return The parsed {@link Expression} tree.
*/
public static Expression parse(Stack<QueryElement> queryStack, Mapping map) {
QueryElement qe = null;
if (!queryStack.empty()) {
qe = (QueryElement) queryStack.pop();
} else
return null;
if (qe.getRole().equalsIgnoreCase(XMLQUERY_LOGOP)) {
String logOpType = qe.getValue();
if (logOpType.equalsIgnoreCase(XMLQUERY_AND)) {
return new AndExpression(parse(queryStack), parse(queryStack, map));
} else if (logOpType.equalsIgnoreCase(XMLQUERY_OR)) {
return new OrExpression(parse(queryStack), parse(queryStack, map));
} else
return null;
} else if (qe.getRole().equalsIgnoreCase(XMLQUERY_RELOP)) {
String relOpType = qe.getValue();
QueryElement rhsQE = (QueryElement) queryStack.pop();
QueryElement lhsQE = (QueryElement) queryStack.pop();
String rhsVal = (String) rhsQE.getValue();
String lhsVal = (String) lhsQE.getValue();
if (map != null) {
// convert the right hand side, using
// the local name
MappingField fld = map.getFieldByLocalName(lhsVal);
if (fld != null) {
if (fld.isString()) {
rhsVal = "'" + rhsVal + "'";
}
}
}
if (relOpType.equalsIgnoreCase(XMLQUERY_EQUAL)) {
return new EqualsExpression(lhsVal, new Literal(rhsVal));
} else if (relOpType.equalsIgnoreCase(XMLQUERY_LIKE)) {
return new ContainsExpression(lhsVal, new WildcardLiteral(rhsVal));
} else if (relOpType.equalsIgnoreCase(XMLQUERY_GREATER_THAN)) {
return new GreaterThanExpression(lhsVal, new Literal(rhsVal));
} else if (relOpType.equalsIgnoreCase(XMLQUERY_GREATER_THAN_OR_EQUAL_TO)) {
return new GreaterThanEqualsExpression(lhsVal, new Literal(rhsVal));
} else if (relOpType.equalsIgnoreCase(XMLQUERY_LESS_THAN)) {
return new LessThanExpression(lhsVal, new Literal(rhsVal));
} else if (relOpType.equalsIgnoreCase(XMLQUERY_LESS_THAN_OR_EQUAL_TO)) {
return new LessThanEqualsExpression(lhsVal, new Literal(rhsVal));
} else
return null;
} else if (qe.getRole().equalsIgnoreCase(XMLQUERY_LITERAL)) {
return new Literal(qe.getValue());
} else
return null;
}
public static Stack<QueryElement> createQueryStack(List<QueryElement> l) {
Stack<QueryElement> ret = new Stack<QueryElement>();
for (int i = 0; i < l.size(); i++) {
ret.push(l.get(i));
}
return ret;
}
}