001/* A logical equals operator.
002
003 Copyright (c) 1997-2014 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
027 */
028package ptolemy.actor.lib.logic;
029
030import ptolemy.actor.lib.Transformer;
031import ptolemy.data.BooleanToken;
032import ptolemy.data.Token;
033import ptolemy.data.type.BaseType;
034import ptolemy.kernel.CompositeEntity;
035import ptolemy.kernel.util.IllegalActionException;
036import ptolemy.kernel.util.NameDuplicationException;
037
038///////////////////////////////////////////////////////////////////
039//// Equals
040
041/**
042 A logical equals operator.  This operator has one input
043 multiport and one output port that is not a multiport. It will consume
044 at most one token from each input channel, and compare the tokens
045 using the isEqualTo() method of the Token class.  If all observed
046 input tokens are equal, then the output will be a true-valued boolean
047 token.  If there is not at least one token on the input channels,
048 then no output is produced.
049 The type of the input port is undeclared and will be resolved by the type
050 resolution mechanism.  Note that all input channels must resolve to the
051 same type.  The type of the output port is boolean.
052
053 @see Token#isEqualTo(Token)
054 @author John Li and Edward A. Lee
055 @version $Id$
056 @since Ptolemy II 0.4
057 @Pt.ProposedRating Green (eal)
058 @Pt.AcceptedRating Green (johnli)
059 */
060public class Equals extends Transformer {
061    /** Construct an actor in the specified container with the specified
062     *  name.
063     *  @param container The container.
064     *  @param name The name of this actor within the container.
065     *  @exception IllegalActionException If the actor cannot be contained
066     *   by the proposed container.
067     *  @exception NameDuplicationException If the name coincides with
068     *   an actor already in the container.
069     */
070    public Equals(CompositeEntity container, String name)
071            throws IllegalActionException, NameDuplicationException {
072        super(container, name);
073        input.setMultiport(true);
074        output.setTypeEquals(BaseType.BOOLEAN);
075
076        _attachText("_iconDescription",
077                "<svg>\n" + "<rect x=\"-30\" y=\"-15\" "
078                        + "width=\"60\" height=\"30\" "
079                        + "style=\"fill:white\"/>\n" + "<text x=\"-14\" y=\"8\""
080                        + "style=\"font-size:24\">==</text>\n" + "</svg>\n");
081    }
082
083    ///////////////////////////////////////////////////////////////////
084    ////                         public methods                    ////
085
086    /** Consume at most one token from each input channel, and output
087     *  the result of comparing these tokens using the isEqualTo() method
088     *  of the Token class.  If the input has width 1, then the output
089     *  is always true.  If the input has width 0, or there are no
090     *  no input tokens available, then no output is produced.
091     *  @exception IllegalActionException If there is no director.
092     */
093    @Override
094    public void fire() throws IllegalActionException {
095        super.fire();
096        BooleanToken result = BooleanToken.TRUE;
097        Token reference = null;
098        boolean foundOne = false;
099
100        for (int i = 0; i < input.getWidth(); i++) {
101            if (!input.hasToken(i)) {
102                continue;
103            }
104
105            foundOne = true;
106
107            Token next = input.get(i);
108
109            if (reference == null) {
110                reference = next;
111            } else if (!next.isEqualTo(reference).booleanValue()) {
112                result = BooleanToken.FALSE;
113            }
114        }
115
116        if (foundOne) {
117            output.send(0, result);
118        }
119    }
120}