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1   /*
2    *  XNap Commons
3    *
4    *  Copyright (C) 2005  Steffen Pingel
5    *
6    *  This library is free software; you can redistribute it and/or
7    *  modify it under the terms of the GNU Lesser General Public
8    *  License as published by the Free Software Foundation; either
9    *  version 2.1 of the License.
10   *
11   *  This library is distributed in the hope that it will be useful,
12   *  but WITHOUT ANY WARRANTY; without even the implied warranty of
13   *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
14   *  Lesser General Public License for more details.
15   *
16   *  You should have received a copy of the GNU Lesser General Public
17   *  License along with this library; if not, write to the Free Software
18   *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
19   */
20  package org.xnap.commons.pkg;
21  
22  public abstract class AbstractDependencyNode implements DependencyNode
23  {
24  
25  	private Object id;
26  	private boolean required;
27  
28  	public AbstractDependencyNode(Object id)
29  	{
30  		this.id = id;
31  	}
32  
33  	public Object getID()
34  	{
35  		return id;
36  	}
37  
38  	public boolean isRequired()
39  	{
40  		return required;
41  	}
42  
43  	public void require(boolean requireInstalled)
44  		throws UnsatisfiedDependenciesException
45  	{
46  		if (required) {
47  			// already visited this node
48  			return;
49  		}
50  
51  		required = true;
52  		try {
53  			checkDepends(requireInstalled);
54  		}
55  		catch (UnsatisfiedDependenciesException e) {
56  			required = false;
57  			throw e;
58  		}
59  	}
60  
61  	public abstract void checkDepends(boolean requireInstalled) 
62  		throws UnsatisfiedDependenciesException;
63  
64  	public void setRequired(boolean required)
65  	{
66  		this.required = required;
67  	}
68  
69  	public String toString()
70  	{
71  		return getID().toString();
72  	}
73  
74  }
75