/*
* JBoss, Home of Professional Open Source
* Copyright 2010, Red Hat, Inc. and/or its affiliates, and individual contributors
* by the @authors tag. See the copyright.txt in the distribution for a
* full listing of individual contributors.
*
* 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.
*/
package org.hibernate.validator.util.scriptengine;
import java.lang.ref.Reference;
import java.lang.ref.SoftReference;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;
import javax.script.ScriptEngine;
import javax.script.ScriptEngineManager;
import javax.script.ScriptException;
/**
* Factory responsible for the creation of {@link ScriptEvaluator}s. This
* class is thread-safe.
*
* @author Gunnar Morling
* @author Kevin Pollet - SERLI - (kevin.pollet@serli.com)
*/
public class ScriptEvaluatorFactory {
/**
* A reference with an instance of this factory. Allows the factory to be reused several times, but can be GC'ed if required.
*/
private static Reference<ScriptEvaluatorFactory> INSTANCE = new SoftReference<ScriptEvaluatorFactory>( new ScriptEvaluatorFactory() );
/**
* A cache of script executors (keyed by language name).
*/
private ConcurrentMap<String, ScriptEvaluator> scriptExecutorCache = new ConcurrentHashMap<String, ScriptEvaluator>();
private ScriptEvaluatorFactory() {
}
/**
* Retrieves an instance of this factory.
*
* @return A script evaluator factory. Never null.
*/
public static synchronized ScriptEvaluatorFactory getInstance() {
ScriptEvaluatorFactory theValue = INSTANCE.get();
if ( theValue == null ) {
theValue = new ScriptEvaluatorFactory();
INSTANCE = new SoftReference<ScriptEvaluatorFactory>( theValue );
}
return theValue;
}
/**
* Retrieves a script executor for the given language.
*
* @param languageName The name of a scripting language as expected by {@link ScriptEngineManager#getEngineByName(String)}.
*
* @return A script executor for the given language. Never null.
*
* @throws ScriptException In case no JSR 223 compatible engine for the given language could be found.
*/
public ScriptEvaluator getScriptEvaluatorByLanguageName(String languageName) throws ScriptException {
if ( !scriptExecutorCache.containsKey( languageName ) ) {
ScriptEvaluator scriptExecutor = createNewScriptEvaluator( languageName );
scriptExecutorCache.putIfAbsent( languageName, scriptExecutor );
}
return scriptExecutorCache.get( languageName );
}
/**
* Creates a new script executor for the given language.
*
* @param languageName A JSR 223 language name.
*
* @return A newly created script executor for the given language.
*
* @throws ScriptException In case no JSR 223 compatible engine for the given language could be found.
*/
private ScriptEvaluator createNewScriptEvaluator(String languageName) throws ScriptException {
ScriptEngine engine = new ScriptEngineManager().getEngineByName( languageName );
if ( engine == null ) {
throw new ScriptException( "No JSR 223 script engine found for language \"" + languageName + "\"." );
}
return new ScriptEvaluator( engine );
}
}