001/* The base unit of a unit category.
002
003 Copyright (c) 2001-2014 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 */
027package ptolemy.data.unit;
028
029import java.util.Iterator;
030
031import ptolemy.data.ScalarToken;
032import ptolemy.data.Token;
033import ptolemy.data.expr.Parameter;
034import ptolemy.kernel.util.IllegalActionException;
035import ptolemy.kernel.util.NameDuplicationException;
036import ptolemy.kernel.util.NamedObj;
037
038///////////////////////////////////////////////////////////////////
039//// BaseUnit
040
041/**
042 The base unit of a unit category.  The category of a base unit is specified
043 by a unit category property.
044
045 @author Xiaojun Liu
046 @version $Id$
047 @since Ptolemy II 2.0
048 @Pt.ProposedRating Red (liuxj)
049 @Pt.AcceptedRating Red (liuxj)
050 */
051public class BaseUnit extends Parameter {
052    /** Construct a base unit with the given name contained by
053     *  the specified entity. The container argument must not be null, or a
054     *  NullPointerException will be thrown.  This attribute will use the
055     *  workspace of the container for synchronization and version counts.
056     *  If the name argument is null, then the name is set to the empty string.
057     *  Increment the version of the workspace.
058     *  @param container The container.
059     *  @param name The name of this attribute.
060     *  @exception IllegalActionException If the attribute is not of an
061     *   acceptable class for the container, or if the name contains a period.
062     *  @exception NameDuplicationException If the name coincides with
063     *   an attribute already in the container.
064     */
065    public BaseUnit(NamedObj container, String name)
066            throws IllegalActionException, NameDuplicationException {
067        super(container, name);
068    }
069
070    ///////////////////////////////////////////////////////////////////
071    ////                         public methods                    ////
072
073    /** Get the token contained by this base unit.  The token contains
074     *  the unit information specified by the unit category property.
075     *  Calling this method
076     *  will trigger evaluation of the expression, if the value has been
077     *  given by setExpression(). Notice the evaluation of the expression
078     *  can trigger an exception if the expression is not valid, or if the
079     *  result of the expression violates type constraints specified by
080     *  setTypeEquals() or setTypeAtMost(), or if the result of the expression
081     *  is null and there are other variables that depend on this one.
082     *  The returned value will be null if neither an expression nor a
083     *  token has been set, or either has been set to null.
084     *  @return The token contained by this variable converted to the
085     *   type of this variable, or null if there is none.
086     *  @exception IllegalActionException If the expression cannot
087     *   be parsed or cannot be evaluated, or if the result of evaluation
088     *   violates type constraints, or if the result of evaluation is null
089     *   and there are variables that depend on this one.
090     */
091    @Override
092    public Token getToken() throws IllegalActionException {
093        Token token = super.getToken();
094
095        if (token != _token) {
096            Iterator attributes = attributeList(UnitCategory.class).iterator();
097
098            if (attributes.hasNext()) {
099                //UnitCategory category = (UnitCategory) attributes.next();
100                String name = getName();
101                UnitUtilities.registerUnitCategory(name);
102
103                int index = UnitUtilities.getUnitCategoryIndex(name);
104
105                if (index >= 0) {
106                    ((ScalarToken) token).setUnitCategory(index);
107                }
108            }
109
110            _token = token;
111        }
112
113        return _token;
114    }
115
116    ///////////////////////////////////////////////////////////////////
117    ////                         private variables                 ////
118    // The token that has unit exponents set correctly.
119    private Token _token = null;
120}