001/* An attribute that represents a MoML parser.
002
003 Copyright (c) 1998-2018 The Regents of the University of California.
004 All rights reserved.
005 Permission is hereby granted, without written agreement and without
006 license or royalty fees, to use, copy, modify, and distribute this
007 software and its documentation for any purpose, provided that the above
008 copyright notice and the following two paragraphs appear in all copies
009 of this software.
010
011 IN NO EVENT SHALL THE UNIVERSITY OF CALIFORNIA BE LIABLE TO ANY PARTY
012 FOR DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
013 ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN IF
014 THE UNIVERSITY OF CALIFORNIA HAS BEEN ADVISED OF THE POSSIBILITY OF
015 SUCH DAMAGE.
016
017 THE UNIVERSITY OF CALIFORNIA SPECIFICALLY DISCLAIMS ANY WARRANTIES,
018 INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
019 MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE
020 PROVIDED HEREUNDER IS ON AN "AS IS" BASIS, AND THE UNIVERSITY OF
021 CALIFORNIA HAS NO OBLIGATION TO PROVIDE MAINTENANCE, SUPPORT, UPDATES,
022 ENHANCEMENTS, OR MODIFICATIONS.
023
024 PT_COPYRIGHT_VERSION_2
025 COPYRIGHTENDKEY
026
027 */
028package ptolemy.moml;
029
030import java.util.List;
031
032import ptolemy.kernel.util.IllegalActionException;
033import ptolemy.kernel.util.InternalErrorException;
034import ptolemy.kernel.util.KernelException;
035import ptolemy.kernel.util.NameDuplicationException;
036import ptolemy.kernel.util.NamedObj;
037import ptolemy.kernel.util.SingletonAttribute;
038import ptolemy.kernel.util.Workspace;
039
040///////////////////////////////////////////////////////////////////
041//// ParserAttribute
042
043/**
044 This attribute represents a MoML parser.
045 If it is present in an entity that is the context for a MoMLChangeRequest,
046 then that change request will use it to parse the changes.
047 It is not a persistent attribute (exportMoML() writes nothing).
048 It is a singleton, meaning that if it is inserted into a container
049 that already contains a singleton attribute with the same name,
050 then it will replace the previous attribute.
051 <p>
052 By default, this attribute is not persistent, so it will not
053 be present in a MoML representation of its container.
054
055 @see MoMLChangeRequest
056 @author  Edward A. Lee
057 @version $Id$
058 @since Ptolemy II 1.0
059 @Pt.ProposedRating Red (eal)
060 @Pt.AcceptedRating Red (reviewmoderator)
061 */
062public class ParserAttribute extends SingletonAttribute {
063    /** Construct an attribute with the specified container and name.
064     *  @param container The container.
065     *  @param name The name of this attribute.
066     *  @exception IllegalActionException If the attribute is not of an
067     *   acceptable class for the container, or if the name contains a period.
068     *  @exception NameDuplicationException If the name coincides with
069     *   an attribute already in the container.
070     */
071    public ParserAttribute(NamedObj container, String name)
072            throws IllegalActionException, NameDuplicationException {
073        super(container, name);
074        setPersistent(false);
075    }
076
077    ///////////////////////////////////////////////////////////////////
078    ////                         public methods                    ////
079
080    /** Clone the attribute into the specified workspace.  The
081     *  resulting object a null value for the value of the parser.
082
083     *  @param workspace The workspace for the cloned object.
084     *  @return A new attribute.
085     *  @exception CloneNotSupportedException If a derived class contains
086     *   an attribute that cannot be cloned.
087     */
088    @Override
089    public Object clone(Workspace workspace) throws CloneNotSupportedException {
090        ParserAttribute newObject = (ParserAttribute) super.clone(workspace);
091        // If we don't set _parser to null, then the master and the
092        // clone share a MoMLParser, which is not good.
093        newObject._parser = null;
094        return newObject;
095    }
096
097    /** Get the parser.  If none has been set, then return a new one.
098     *  @return A MoML parser.
099     *  @see #setParser(MoMLParser)
100     */
101    public MoMLParser getParser() {
102        if (_parser == null) {
103            _parser = new MoMLParser(workspace());
104        }
105
106        return _parser;
107    }
108
109    /** Get a parser for the specified object. This searches up the
110     *  hierarchy until it finds a container of the specified object
111     *  that contains an instance of ParserAttribute. If none is
112     *  found, then a new ParserAttribute is created at the top level.
113     *  @param object The object for which to find an associated parser.
114     *  @return The parser for the specified object.
115     *  @exception NullPointerException If the argument is null.
116     *  @see #setParser(MoMLParser)
117     */
118    public static MoMLParser getParser(NamedObj object) {
119        NamedObj container = object;
120
121        while (container != null) {
122            // We used to just get the ParserAttribute from the object.
123            // However, this is wrong, we should get it from the
124            // container.
125            // In r51962 the comment was "Bugfix" and the change was
126            // made.
127            // In r51963, the comment was "
128            // "Revert to previous version because the "bugfix" seems
129            // to break some existing editors (such as GT)."
130            //
131            // List attributes = object.attributeList(ParserAttribute.class);
132            List attributes = container.attributeList(ParserAttribute.class);
133
134            if (attributes != null && attributes.size() > 0) {
135                // Found one.
136                ParserAttribute attribute = (ParserAttribute) attributes.get(0);
137                return attribute.getParser();
138            }
139
140            container = container.getContainer();
141        }
142
143        // No parser attribute was found.
144        NamedObj toplevel = object.toplevel();
145
146        try {
147            ParserAttribute attribute = new ParserAttribute(toplevel,
148                    "_parser");
149            return attribute.getParser();
150        } catch (KernelException ex) {
151            // This should not occur.
152            throw new InternalErrorException(ex);
153        }
154    }
155
156    /** Set the parser.
157     *  @param parser The parser.
158     *  @see #getParser()
159     *  @see #getParser(NamedObj)
160     */
161    public void setParser(MoMLParser parser) {
162        _parser = parser;
163    }
164
165    ///////////////////////////////////////////////////////////////////
166    ////                         private variables                 ////
167    // The parser.
168    private MoMLParser _parser;
169}