/*
 * An attribute for token property.
 * 
 * Below is the copyright agreement for the Ptolemy II system.
 * 
 * Copyright (c) 2007-2009 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.
 */
package ptolemy.data.properties.token;

import ptolemy.data.Token;
import ptolemy.data.expr.ASTPtRootNode;
import ptolemy.data.expr.ParseTreeEvaluator;
import ptolemy.data.expr.PtParser;
import ptolemy.data.properties.PropertyAttribute;
import ptolemy.data.properties.PropertySolverBase;
import ptolemy.kernel.util.IllegalActionException;
import ptolemy.kernel.util.NameDuplicationException;
import ptolemy.kernel.util.NamedObj;

/**
 * An attribute for token property. The PropertyTokenSolver uses this to
 * annotate the model.
 * 
 * @author Man-Kit Leung
 * @version $Id$
 * @since Ptolemy II 7.1
 * @Pt.ProposedRating Red (mankit)
 * @Pt.AcceptedRating Red (mankit)
 */
public class PropertyTokenAttribute extends PropertyAttribute {

    /**
     * Construct a PropertyTokenAttribute with the specified container and name.
     * @param container The specified container for this attribute.
     * @param name The specified name.
     * @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 PropertyTokenAttribute(NamedObj container, String name)
            throws IllegalActionException, NameDuplicationException {
        super(container, name);
    }

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

    /**
     * Set the expression. This method takes the descriptive form and determines
     * the internal form (by parsing the descriptive form) and stores it.
     * @param expression A String that is the descriptive form of either a Unit
     * or a UnitEquation.
     * @see ptolemy.kernel.util.Settable#setExpression(java.lang.String)
     */
    public void setExpression(String expression) throws IllegalActionException {
        if (expression.length() > 0) {

            // Get the shared parser.
            PtParser parser = PropertySolverBase.getParser();
            ASTPtRootNode root = parser.generateParseTree(expression);

            ParseTreeEvaluator evaluator = new ParseTreeEvaluator();

            // FIXME: we may need scoping for evaluating variables
            // in the expression.
            Token token = evaluator.evaluateParseTree(root);

            _property = new PropertyToken(token);
        }
        super.setExpression(expression);
    }
}