001    package org.apache.commons.ognl;
002    
003    /*
004     * Licensed to the Apache Software Foundation (ASF) under one
005     * or more contributor license agreements.  See the NOTICE file
006     * distributed with this work for additional information
007     * regarding copyright ownership.  The ASF licenses this file
008     * to you under the Apache License, Version 2.0 (the
009     * "License"); you may not use this file except in compliance
010     * with the License.  You may obtain a copy of the License at
011     *
012     *   http://www.apache.org/licenses/LICENSE-2.0
013     *
014     * Unless required by applicable law or agreed to in writing,
015     * software distributed under the License is distributed on an
016     * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
017     * KIND, either express or implied.  See the License for the
018     * specific language governing permissions and limitations
019     * under the License.
020     */
021    
022    import java.util.Enumeration;
023    
024    /**
025     * This interface defines a method for getting the "elements" of an object, which means any objects that naturally would
026     * be considered to be contained by the object. So for a collection, you would expect this method to return all the
027     * objects in that collection; while for an ordinary object you would expect this method to return just that object.
028     * <p>
029     * An implementation of this interface will often require that its target objects all be of some particular type. For
030     * example, the MapElementsAccessor class requires that its targets all implement the Map interface.
031     * 
032     * @author Luke Blanshard (blanshlu@netscape.net)
033     * @author Drew Davidson (drew@ognl.org)
034     */
035    public interface ElementsAccessor
036    {
037        /**
038         * Returns an iterator over the elements of the given target object.
039         * 
040         * @param target the object to get the elements of
041         * @return an iterator over the elements of the given object
042         * @exception OgnlException if there is an error getting the given object's elements
043         */
044        Enumeration<?> getElements( Object target ) throws OgnlException;
045    }