/*
* 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.exoplatform.services.jcr.impl.core.query;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.HashSet;
import java.util.List;
import java.util.Set;
import javax.jcr.query.InvalidQueryException;
/**
* Implements a central access to QueryTreeBuilder instances.
*/
public class QueryTreeBuilderRegistry
{
/**
* Logger instance for this class.
*/
private static final Logger log = LoggerFactory.getLogger("exo.jcr.component.core.QueryTreeBuilderRegistry");
/**
* List of <code>QueryTreeBuilder</code> instances known to the classloader.
*/
private static final List<QueryTreeBuilder> BUILDERS = new ArrayList<QueryTreeBuilder>();
/**
* Set of languages known to the registered builders.
*/
private static final Set<String> LANGUAGES;
static
{
Set<String> languages = new HashSet<String>();
BUILDERS.add(new org.exoplatform.services.jcr.impl.core.query.sql.QueryBuilder());
BUILDERS.add(new org.exoplatform.services.jcr.impl.core.query.xpath.QueryBuilder());
for (QueryTreeBuilder builder : BUILDERS)
{
languages.addAll(Arrays.asList(builder.getSupportedLanguages()));
}
if (BUILDERS.size() < 1)
log.warn("No builders found");
LANGUAGES = Collections.unmodifiableSet(languages);
}
/**
* Returns the <code>QueryTreeBuilder</code> for <code>language</code>.
*
* @param language the language of the query statement.
* @return the <code>QueryTreeBuilder</code> for <code>language</code>.
* @throws InvalidQueryException if there is no query tree builder for
* <code>language</code>.
*/
public static QueryTreeBuilder getQueryTreeBuilder(String language) throws InvalidQueryException
{
for (int i = 0; i < BUILDERS.size(); i++)
{
QueryTreeBuilder builder = (QueryTreeBuilder)BUILDERS.get(i);
if (builder.canHandle(language))
{
return builder;
}
}
throw new InvalidQueryException("Unsupported language: " + language);
}
/**
* Returns the set of query languages supported by all registered
* {@link QueryTreeBuilder} implementations.
*
* @return String array containing the names of the supported languages.
*/
public static String[] getSupportedLanguages()
{
return (String[])LANGUAGES.toArray(new String[LANGUAGES.size()]);
}
}