/*

  * 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.apache.commons.classscan.util;

 import java.util.ArrayList;

 import java.util.Collection;

 import java.util.Collections;

 import java.util.Iterator;

 /**

  * A cache of service providers.

  *

  * @param <T> The interface of the service provider

  */

 public class FactoryCache<T> implements Iterable<T>  {

         final private Collection<T> readOnly;

         /**

          * Find service providers available to the given classLoader

          * 

          * @param serviceProvider The interface of the service provider

          * @param classLoader The ClassLoader to load the service provider instances

          */

         public FactoryCache(Class<T> serviceProvider, ClassLoader classLoader) {

                 final ArrayList<T> instances = new ArrayList<T>();

                 new ServiceVisitor<T>() {

                         @Override

                         protected boolean visit(T factory) {

                             instances.add(factory);

                             return true;

                         }

                 }.visitProviders(serviceProvider, classLoader);

                 instances.trimToSize();

             readOnly = Collections.unmodifiableCollection(instances);

         }

         @Override

         public Iterator<T> iterator() {

                 return readOnly.iterator();

         }

 }