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
015package org.apache.tapestry5.services.meta;
016
017import java.lang.annotation.Annotation;
018
019import org.apache.tapestry5.model.ComponentModel;
020import org.apache.tapestry5.model.MutableComponentModel;
021import 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 */
031public 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}