/* An attribute that represents a MoML parser.

 Copyright (c) 1998-2014 The Regents of the University of California.
 All rights reserved.
 Permission is hereby granted, without written agreement and without
 license or royalty fees, to use, copy, modify, and distribute this
 software and its documentation for any purpose, provided that the above
 copyright notice and the following two paragraphs appear in all copies
 of this software.

 IN NO EVENT SHALL THE UNIVERSITY OF CALIFORNIA BE LIABLE TO ANY PARTY
 FOR DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
 ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN IF
 THE UNIVERSITY OF CALIFORNIA HAS BEEN ADVISED OF THE POSSIBILITY OF
 SUCH DAMAGE.

 THE UNIVERSITY OF CALIFORNIA SPECIFICALLY DISCLAIMS ANY WARRANTIES,
 INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
 MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE
 PROVIDED HEREUNDER IS ON AN "AS IS" BASIS, AND THE UNIVERSITY OF
 CALIFORNIA HAS NO OBLIGATION TO PROVIDE MAINTENANCE, SUPPORT, UPDATES,
 ENHANCEMENTS, OR MODIFICATIONS.

 PT_COPYRIGHT_VERSION_2
 COPYRIGHTENDKEY

 */
package ptolemy.moml;

import java.util.List;

import ptolemy.kernel.util.IllegalActionException;
import ptolemy.kernel.util.InternalErrorException;
import ptolemy.kernel.util.KernelException;
import ptolemy.kernel.util.NameDuplicationException;
import ptolemy.kernel.util.NamedObj;
import ptolemy.kernel.util.SingletonAttribute;
import ptolemy.kernel.util.Workspace;

///////////////////////////////////////////////////////////////////
//// ParserAttribute

/**
 This attribute represents a MoML parser.
 If it is present in an entity that is the context for a MoMLChangeRequest,
 then that change request will use it to parse the changes.
 It is not a persistent attribute (exportMoML() writes nothing).
 It is a singleton, meaning that if it is inserted into a container
 that already contains a singleton attribute with the same name,
 then it will replace the previous attribute.
 <p>
 By default, this attribute is not persistent, so it will not
 be present in a MoML representation of its container.

 @see MoMLChangeRequest
 @author  Edward A. Lee
 @version $Id: ParserAttribute.java 70398 2014-10-22 23:44:32Z cxh $
 @since Ptolemy II 1.0
 @Pt.ProposedRating Red (eal)
 @Pt.AcceptedRating Red (reviewmoderator)
 */
public class ParserAttribute extends SingletonAttribute {
    /** Construct an attribute with the specified container and name.
     *  @param container The container.
     *  @param name The name of this attribute.
     *  @exception IllegalActionException If the attribute is not of an
     *   acceptable class for the container, or if the name contains a period.
     *  @exception NameDuplicationException If the name coincides with
     *   an attribute already in the container.
     */
    public ParserAttribute(NamedObj container, String name)
            throws IllegalActionException, NameDuplicationException {
        super(container, name);
        setPersistent(false);
    }

    ///////////////////////////////////////////////////////////////////
    ////                         public methods                    ////

    /** Clone the attribute into the specified workspace.  The
     *  resulting object a null value for the value of the parser.

     *  @param workspace The workspace for the cloned object.
     *  @return A new attribute.
     *  @exception CloneNotSupportedException If a derived class contains
     *   an attribute that cannot be cloned.
     */
    @Override
    public Object clone(Workspace workspace) throws CloneNotSupportedException {
        ParserAttribute newObject = (ParserAttribute) super.clone(workspace);
        // If we don't set _parser to null, then the master and the
        // clone share a MoMLParser, which is not good.
        newObject._parser = null;
        return newObject;
    }

    /** Get the parser.  If none has been set, then return a new one.
     *  @return A MoML parser.
     *  @see #setParser(MoMLParser)
     */
    public MoMLParser getParser() {
        if (_parser == null) {
            _parser = new MoMLParser(workspace());
        }

        return _parser;
    }

    /** Get a parser for the specified object. This searches up the
     *  hierarchy until it finds a container of the specified object
     *  that contains an instance of ParserAttribute. If none is
     *  found, then a new ParserAttribute is created at the top level.
     *  @param object The object for which to find an associated parser.
     *  @return The parser for the specified object.
     *  @exception NullPointerException If the argument is null.
     *  @see #setParser(MoMLParser)
     */
    public static MoMLParser getParser(NamedObj object) {
        NamedObj container = object;

        while (container != null) {
            // We used to just get the ParserAttribute from the object.
            // However, this is wrong, we should get it from the
            // container.
            // In r51962 the comment was "Bugfix" and the change was
            // made.
            // In r51963, the comment was "
            // "Revert to previous version because the "bugfix" seems
            // to break some existing editors (such as GT)."
            //
            // List attributes = object.attributeList(ParserAttribute.class);
            List attributes = container.attributeList(ParserAttribute.class);

            if (attributes != null && attributes.size() > 0) {
                // Found one.
                ParserAttribute attribute = (ParserAttribute) attributes.get(0);
                return attribute.getParser();
            }

            container = container.getContainer();
        }

        // No parser attribute was found.
        NamedObj toplevel = object.toplevel();

        try {
            ParserAttribute attribute = new ParserAttribute(toplevel, "_parser");
            return attribute.getParser();
        } catch (KernelException ex) {
            // This should not occur.
            throw new InternalErrorException(ex);
        }
    }

    /** Set the parser.
     *  @param parser The parser.
     *  @see #getParser()
     *  @see #getParser(NamedObj)
     */
    public void setParser(MoMLParser parser) {
        _parser = parser;
    }

    ///////////////////////////////////////////////////////////////////
    ////                         private variables                 ////
    // The parser.
    private MoMLParser _parser;
}