/* $Id: CrConsiderSingleton.java 17831 2010-01-12 18:56:55Z linus $

  *****************************************************************************

  * Copyright (c) 2009 Contributors - see below

  * All rights reserved. This program and the accompanying materials

  * are made available under the terms of the Eclipse Public License v1.0

  * which accompanies this distribution, and is available at

  * http://www.eclipse.org/legal/epl-v10.html

  *

  * Contributors:

  *    tfmorris

  *****************************************************************************

  *

  * Some portions of this file was previously release using the BSD License:

  */

 // Copyright (c) 1996-2007 The Regents of the University of California. All

 // Rights Reserved. Permission to use, copy, modify, and distribute this

 // software and its documentation without fee, and without a written

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 package org.argouml.pattern.cognitive.critics;

 import java.util.Iterator;

 import org.argouml.cognitive.Designer;

 import org.argouml.cognitive.ToDoItem;

 import org.argouml.model.Model;

 import org.argouml.uml.cognitive.UMLDecision;

 import org.argouml.uml.cognitive.critics.CrUML;

 /**

  * A critic to detect when a class can never have more than one instance (of

  * itself of any subclasses), and thus whether it is suitable for declaration

  * as a Singleton (with stereotype &laquo;Singleton&raquo;.<p>

  * <p>

  * see the ArgoUML User Manual: Consider Using Singleton Pattern for Class

  *

  * @author jrobbins

  */

 public class CrConsiderSingleton extends CrUML {

     /**

      * Constructor for the critic.<p>

      *

      * Sets up the resource name, which will allow headline and description

      * to be found for the current locale. Provides a design issue category

      * (PATTERNS), sets a priority for any to-do items (LOW) and adds triggers

      * for metaclasses "stereotype", "structuralFeature" and

      * "associationEnd".

      */

     public CrConsiderSingleton() {

         setupHeadAndDesc();

         addSupportedDecision(UMLDecision.PATTERNS);

         setPriority(ToDoItem.LOW_PRIORITY);

         // These may not actually make any difference at present (the code

         // behind addTrigger needs more work).

         addTrigger("stereotype");

         addTrigger("structuralFeature");

         addTrigger("associationEnd");

     }

     /**

      * The trigger for the critic.<p>

      *

      * First check we are already a Singleton.<p>

      *

      * Otherwise plausible candidates for the Singleton design pattern are

      * classes with no instance variables (i.e. non-static attributes) and no

      * outgoing associations.<p>

      *

      * @param  dm    the {@link java.lang.Object Object} to be checked against

      *               the critic.

      *

      * @param  dsgr  the {@link org.argouml.cognitive.Designer Designer}

      *               creating the model. Not used, this is for future

      *               development of ArgoUML.

      *

      * @return       {@link #PROBLEM_FOUND PROBLEM_FOUND} if the critic is

      *               triggered, otherwise {@link #NO_PROBLEM NO_PROBLEM}.

      */

     @Override

     public boolean predicate2(Object dm, Designer dsgr) {

         // Only look at classes...

         if (!(Model.getFacade().isAClass(dm))) {

             return NO_PROBLEM;

         }

         // and not association classes

         if (Model.getFacade().isAAssociationClass(dm)) {

             return NO_PROBLEM;

         }

         // with a name...

         if (Model.getFacade().getName(dm) == null

                 || "".equals(Model.getFacade().getName(dm))) {

             return NO_PROBLEM;

         }

         // ... and not incompletely imported

         if (!(Model.getFacade().isPrimaryObject(dm))) {

             return NO_PROBLEM;

         }

         // abstract classes are hardly ever singletons

         if (Model.getFacade().isAbstract(dm)) {

             return NO_PROBLEM;

         }

         // Check for Singleton stereotype, uninitialised instance variables and

         // outgoing associations, as per JavaDoc above.

         if (Model.getFacade().isSingleton(dm)) {

             return NO_PROBLEM;

         }

         if (Model.getFacade().isUtility(dm)) {

             return NO_PROBLEM;

         }

         // If there is an attribute which is not static => no problem

         Iterator iter = Model.getFacade().getAttributes(dm).iterator();

         while (iter.hasNext()) {

             if (!Model.getFacade().isStatic(iter.next())) {

                 return NO_PROBLEM;

             }

         }

         // If there is an outgoing association => no problem

         Iterator ends = Model.getFacade().getAssociationEnds(dm).iterator();

         while (ends.hasNext()) {

             Iterator otherends =

                 Model.getFacade()

                         .getOtherAssociationEnds(ends.next()).iterator();

             while (otherends.hasNext()) {

                 if (Model.getFacade().isNavigable(otherends.next())) {

                     return NO_PROBLEM;

                 }

             }

         }

         return PROBLEM_FOUND;

     }

     /**

      * The UID.

      */

     private static final long serialVersionUID = -178026888698499288L;

 }