/*
* 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.jackrabbit.oak.query;
import java.text.ParseException;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import org.apache.jackrabbit.mk.api.MicroKernel;
import org.apache.jackrabbit.oak.api.CoreValue;
import org.apache.jackrabbit.oak.api.CoreValueFactory;
import org.apache.jackrabbit.oak.api.QueryEngine;
import org.apache.jackrabbit.oak.query.index.FilterImpl;
import org.apache.jackrabbit.oak.query.index.TraversingIndex;
import org.apache.jackrabbit.oak.spi.QueryIndex;
import org.apache.jackrabbit.oak.spi.QueryIndexProvider;
import org.apache.jackrabbit.oak.spi.state.NodeStore;
public class QueryEngineImpl implements QueryEngine {
static final String SQL2 = "JCR-SQL2";
private static final String XPATH = "xpath";
private final MicroKernel mk;
private final CoreValueFactory vf;
private final SQL2Parser parserSQL2;
private final QueryIndexProvider indexProvider;
public QueryEngineImpl(NodeStore store, MicroKernel mk, QueryIndexProvider indexProvider) {
this.mk = mk;
this.vf = store.getValueFactory();
this.indexProvider = indexProvider;
parserSQL2 = new SQL2Parser(vf);
}
@Override
public void init() {
// TODO the list of index providers should be configurable as well
indexProvider.init();
}
/**
* Parse the query (check if it's valid) and get the list of bind variable names.
*
* @param statement
* @param language
* @return the list of bind variable names
* @throws ParseException
*/
@Override
public List<String> getBindVariableNames(String statement, String language) throws ParseException {
Query q = parseQuery(statement, language);
return q.getBindVariableNames();
}
private Query parseQuery(String statement, String language) throws ParseException {
Query q;
if (SQL2.equals(language)) {
q = parserSQL2.parse(statement);
} else if (XPATH.equals(language)) {
XPathToSQL2Converter converter = new XPathToSQL2Converter();
String sql2 = converter.convert(statement);
q = parserSQL2.parse(sql2);
} else {
throw new ParseException("Unsupported language: " + language, 0);
}
return q;
}
@Override
public ResultImpl executeQuery(String statement, String language, Map<String, CoreValue> bindings) throws ParseException {
Query q = parseQuery(statement, language);
q.setMicroKernel(mk);
if (bindings != null) {
for (Entry<String, CoreValue> e : bindings.entrySet()) {
q.bindValue(e.getKey(), e.getValue());
}
}
q.setQueryEngine(this);
q.prepare();
return q.executeQuery(mk.getHeadRevision());
}
public QueryIndex getBestIndex(FilterImpl filter) {
QueryIndex best = null;
double bestCost = Double.MAX_VALUE;
for (QueryIndex index : getIndexes()) {
double cost = index.getCost(filter);
if (cost < bestCost) {
best = index;
}
}
if (best == null) {
best = new TraversingIndex(mk);
}
return best;
}
private List<QueryIndex> getIndexes() {
return indexProvider.getQueryIndexes(mk);
}
}