001/*
002 The contents of this file are subject to the Mozilla Public License Version 1.1
003 (the "License"); you may not use this file except in compliance with the License.
004 You may obtain a copy of the License at http://www.mozilla.org/MPL/
005 Software distributed under the License is distributed on an "AS IS" basis,
006 WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License for the
007 specific language governing rights and limitations under the License.
008
009 The Original Code is "Visitable.java ".  Description:
010 "Callback method for the visitor"
011
012 The Initial Developer of the Original Code is University Health Network. Copyright (C)
013 2013.  All Rights Reserved.
014
015 Contributor(s): ______________________________________.
016
017 Alternatively, the contents of this file may be used under the terms of the
018 GNU General Public License (the "GPL"), in which case the provisions of the GPL are
019 applicable instead of those above.  If you wish to allow use of your version of this
020 file only under the terms of the GPL and not to allow others to use your version
021 of this file under the MPL, indicate your decision by deleting  the provisions above
022 and replace  them with the notice and other provisions required by the GPL License.
023 If you do not delete the provisions above, a recipient may use your version of
024 this file under either the MPL or the GPL.
025 */
026
027package ca.uhn.hl7v2.model;
028
029import ca.uhn.hl7v2.HL7Exception;
030import ca.uhn.hl7v2.Location;
031
032/**
033 * Interface that marks implementing classes as being capable to be visited by a
034 * {@link MessageVisitor}
035 */
036public interface Visitable {
037
038    /**
039     * Callback method for the visitor. This method is supposed to either directly
040     * call one of the visitors methods, passing <code>this</code> as parameter, or
041     * traverse through a hierarchical substructure and call accept(MessageVisitor)
042     * for each visited element.
043     *
044     * @param visitor MessageVisitor instance to be called back
045     * @param currentLocation location of this object
046     * @return <code>true</code> if the visit process shall continue
047     * @throws HL7Exception if a problem occurred during visiting
048     */
049    boolean accept(MessageVisitor visitor, Location currentLocation) throws HL7Exception;
050    
051    /**
052     * Reusing the location of this object's parent, this method returns its own
053     * location within the message.
054     * 
055     * @param parentLocation the parents location
056     * @param index index of this object
057     * @param repetition repetition of this object
058     * @return this objects location
059     */
060    Location provideLocation(Location parentLocation, int index, int repetition);
061
062    /**
063     * Returns true if this Visitable has actual content
064     *
065     * @return true if Visitable is empty
066     * @throws HL7Exception if an error occurred while determining emptiness
067     */
068    boolean isEmpty() throws HL7Exception;
069}