// $Id: CheckManager.java,v 1.9 2004/09/05 06:46:44 mvw Exp $
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// software and its documentation without fee, and without a written
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// File: CheckManager.java
// Class: CheckManager
// Original Author: jrobbins@ics.uci.edu
// $Id: CheckManager.java,v 1.9 2004/09/05 06:46:44 mvw Exp $

package org.argouml.cognitive.checklist;

import java.io.Serializable;
import java.util.Hashtable;
import java.util.Enumeration;

/** The CheckManager keeps track of which Checklists should be
 *  presented for a given design material.  CheckManager also keeps
 *  track of which CheckItem's are checked off for a given design
 *  element.
 */
public class CheckManager implements Serializable {

    ////////////////////////////////////////////////////////////////
    // static variables

    /** List of checklists.
     *
     * Indexed on the object type of the element that this checklist is
     * appropriate for.
     */
    private static Hashtable lists = new Hashtable();
    
    /** List of ChecklistStatus:es.
     *
     * Indexed on the model element itself.
     * TODO: Should use weak references so that this is forgotten about
     * when the object is removed.
     */
    private static Hashtable statuses = new Hashtable();

    /**
     * Constructor.
     */
    public CheckManager() { }

    ////////////////////////////////////////////////////////////////
    // static accessors

    /** Gets the checklist for an element.
     *
     * @param dm is the element
     * @return a checklist
     */
    public static Checklist getChecklistFor(Object dm) {
        Checklist cl;
        
	java.lang.Class cls = dm.getClass();
	while (cls != null) {
	    cl = (Checklist) lookupChecklist(cls);
	    if (cl != null) return cl;
	    cls = cls.getSuperclass();
	}
	return null;
    }
    
    /**
     * Find an element in the list.
     *
     * This is a little more complex than the simple lookup since it might be
     * that we are indexing with a class and the list contains interfaces.
     *
     * Since the hashtable lookup is a lot faster than the linear search we
     * add the result of the linear search to the hashtable so that the next
     * time we need not do it.
     *
     * @return Checklist or null if noone exist.
     * @param cls the class to lookup.
     */
    private static Checklist lookupChecklist(Class cls) {
        if (lists.contains(cls))
            return (Checklist) lists.get(cls);
        
        // Now lets search
        Enumeration enumeration = lists.keys();
        
        while (enumeration.hasMoreElements()) {
            Class index = (Class) enumeration.nextElement();
            
            Class[] intfs = cls.getInterfaces();
            for (int i = 0; i < intfs.length; i++) {
                if (intfs[i].equals(index))
                {
                    // We found it!
                    Checklist chlist = (Checklist) lists.get(index);
                    
                    // Enter the class to speed up the next search.
                    lists.put(cls, chlist);
                    return chlist;
                }
            }
        }
        
        return null;
    }
                    

    /** 
     * Registers a new list. Used when setting up the checklist stuff.
     *
     * @param dm the class for which the Checklist holds
     * @param cl the Checklist
     */
    public static void register(Object dm, Checklist cl) {
	lists.put(dm, cl);
    }

    /**
     * Get the ChecklistStatus for some object.
     *
     * If there is none, then create one.
     *
     * @return ChecklistStatus, a half filled list.
     * @param dm is the object that we retrieve the checklist for
     */ 
    public static ChecklistStatus getStatusFor(Object dm) {
	ChecklistStatus cls = (ChecklistStatus) statuses.get(dm);
	if (cls == null) {
	    cls = new ChecklistStatus();
	    statuses.put(dm, cls);
	}
	return cls;
    }
} /* end class CheckManager */