001 /*
002 * Copyright (C) 2012 eXo Platform SAS.
003 *
004 * This is free software; you can redistribute it and/or modify it
005 * under the terms of the GNU Lesser General Public License as
006 * published by the Free Software Foundation; either version 2.1 of
007 * the License, or (at your option) any later version.
008 *
009 * This software is distributed in the hope that it will be useful,
010 * but WITHOUT ANY WARRANTY; without even the implied warranty of
011 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
012 * Lesser General Public License for more details.
013 *
014 * You should have received a copy of the GNU Lesser General Public
015 * License along with this software; if not, write to the Free
016 * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
017 * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
018 */
019
020 package org.crsh.cli.type;
021
022 import java.util.Collections;
023 import java.util.Iterator;
024 import java.util.LinkedHashSet;
025 import java.util.ServiceConfigurationError;
026 import java.util.ServiceLoader;
027 import java.util.logging.Level;
028 import java.util.logging.Logger;
029
030 /**
031 * A factory for value types.
032 */
033 public class ValueTypeFactory {
034
035 /** A value type factory instance that provides a predefined set of value types. */
036 public static final ValueTypeFactory DEFAULT = new ValueTypeFactory();
037
038 /** The known types. */
039 private final ValueType<?>[] types;
040
041 private ValueTypeFactory() {
042 this.types = new ValueType<?>[]{ ValueType.STRING, ValueType.INTEGER, ValueType.BOOLEAN,
043 ValueType.ENUM, ValueType.PROPERTIES, ValueType.OBJECT_NAME, ValueType.THREAD};
044 }
045
046 /**
047 * Create a value type factory for the the default value types and the value types that the specified
048 * classloader will load.
049 *
050 * @param loader the loader
051 * @throws NullPointerException if the loader is null
052 */
053 public ValueTypeFactory(ClassLoader loader) throws NullPointerException {
054 if (loader == null) {
055 throw new NullPointerException("No null loader accepted");
056 }
057
058 //
059 LinkedHashSet<ValueType> types = new LinkedHashSet<ValueType>();
060 Collections.addAll(types, DEFAULT.types);
061 Iterator<ValueType> sl = ServiceLoader.load(ValueType.class, loader).iterator();
062 while (sl.hasNext()) {
063 try {
064 ValueType type = sl.next();
065 types.add(type);
066 }
067 catch (ServiceConfigurationError e) {
068 // Log it
069 Logger logger = Logger.getLogger(ValueTypeFactory.class.getName());
070 logger.log(Level.WARNING, "Could not load value type factory", e);
071 }
072 }
073
074 //
075 this.types = types.toArray(new ValueType[types.size()]);
076 }
077
078 public <T, S extends T> ValueType<T> get(Class<S> clazz) {
079 ValueType<?> bestType = null;
080 int bestDegree = Integer.MAX_VALUE;
081 for (ValueType<?> type : types) {
082 int degree = type.getDistance(clazz);
083 if (degree != -1 && degree < bestDegree) {
084 bestType = type;
085 bestDegree = degree;
086 }
087 }
088 return (ValueType<T>)bestType;
089 }
090 }