org.apache.jackrabbit.commons.query.QueryObjectModelBuilderRegistry Maven / Gradle / Ivy
/*
* 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.commons.query;
import java.util.List;
import java.util.ServiceLoader;
import java.util.ArrayList;
import java.util.Set;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Arrays;
import java.util.Collections;
import javax.jcr.query.InvalidQueryException;
/**
* Implements a central access to QueryObjectModelBuilder instances.
*/
public class QueryObjectModelBuilderRegistry {
/**
* List of QueryObjectModelBuilder instances known to the classloader.
*/
private static final List BUILDERS = new ArrayList();
/**
* Set of languages known to the registered builders.
*/
private static final Set LANGUAGES;
static {
Set languages = new HashSet();
Iterator it = ServiceLoader.load(QueryObjectModelBuilder.class,
QueryObjectModelBuilder.class.getClassLoader()).iterator();
while (it.hasNext()) {
QueryObjectModelBuilder builder = it.next();
BUILDERS.add(builder);
languages.addAll(Arrays.asList(builder.getSupportedLanguages()));
}
LANGUAGES = Collections.unmodifiableSet(languages);
}
/**
* Returns the QueryObjectModelBuilder for
* language.
*
* @param language the language of the query statement.
* @return the QueryObjectModelBuilder for
* language.
* @throws InvalidQueryException if there is no query object model builder
* for language.
*/
public static QueryObjectModelBuilder getQueryObjectModelBuilder(String language)
throws InvalidQueryException {
for (QueryObjectModelBuilder builder : BUILDERS) {
if (builder.canHandle(language)) {
return builder;
}
}
throw new InvalidQueryException("Unsupported language: " + language);
}
/**
* Returns the set of query languages supported by all registered
* {@link QueryObjectModelBuilder} implementations.
*
* @return String array containing the names of the supported languages.
*/
public static String[] getSupportedLanguages() {
return LANGUAGES.toArray(new String[LANGUAGES.size()]);
}
}