    001    // Copyright 2008 The Apache Software Foundation
    002    //
    003    // Licensed under the Apache License, Version 2.0 (the "License");
    004    // you may not use this file except in compliance with the License.
    005    // You may obtain a copy of the License at
    006    //
    007    //     http://www.apache.org/licenses/LICENSE-2.0
    008    //
    009    // Unless required by applicable law or agreed to in writing, software
    010    // distributed under the License is distributed on an "AS IS" BASIS,
    011    // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    012    // See the License for the specific language governing permissions and
    013    // limitations under the License.
    014
    015    package org.apache.tapestry5.ioc.internal.services;
    016
    017    import org.apache.tapestry5.ioc.AnnotationProvider;
    018
    019    import java.lang.annotation.Annotation;
    020    import java.util.List;
    021
    022    /**
    023     * Chain of command for {@link org.apache.tapestry5.ioc.AnnotationProvider}.
    024     */
    025    public class AnnotationProviderChain implements AnnotationProvider
    026    {
    027        private final AnnotationProvider[] providers;
    028
    029        public AnnotationProviderChain(AnnotationProvider[] providers)
    030        {
    031            this.providers = providers;
    032        }
    033
    034        /**
    035         * Creates an AnnotationProvider from the list of providers.  Returns either an {@link AnnotationProviderChain} or
    036         * the sole element in the list.
    037         */
    038        public static AnnotationProvider create(List<AnnotationProvider> providers)
    039        {
    040            int size = providers.size();
    041
    042            if (size == 1) return providers.get(0);
    043
    044            return new AnnotationProviderChain(providers.toArray(new AnnotationProvider[providers.size()]));
    045        }
    046
    047        public <T extends Annotation> T getAnnotation(Class<T> annotationClass)
    048        {
    049            for (AnnotationProvider p : providers)
    050            {
    051                T result = p.getAnnotation(annotationClass);
    052
    053                if (result != null) return result;
    054            }
    055
    056            return null;
    057        }
    058    }