001    // Copyright 2010 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.services.meta;
016    
017    import java.lang.annotation.Annotation;
018    
019    import org.apache.tapestry5.model.ComponentModel;
020    import org.apache.tapestry5.model.MutableComponentModel;
021    import org.apache.tapestry5.services.MetaDataLocator;
022    
023    /**
024     * Used to extract a {@linkplain ComponentModel#getMeta(String) meta data value} from a component annotation. Instances
025     * of this interface are contributed into the MetaWorker service.
026     * 
027     * @since 5.2.0
028     * @see MetaWorker
029     * @see MetaDataLocator
030     */
031    public interface MetaDataExtractor<T extends Annotation>
032    {
033        /**
034         * Invoked on the extractor to extract the appropriate value for the annotation and
035         * {@linkplain MutableComponentModel#setMeta(String, String) set the meta data on the model}.
036         * 
037         * @param model
038         *            on which to set meta data
039         * @param annotation
040         *            class annotation, from whose attributes specific data may be extracted
041         */
042        void extractMetaData(MutableComponentModel model, T annotation);
043    }