01: /*
02: * uDig - User Friendly Desktop Internet GIS client
03: * http://udig.refractions.net
04: * (C) 2004, Refractions Research Inc.
05: *
06: * This library is free software; you can redistribute it and/or
07: * modify it under the terms of the GNU Lesser General Public
08: * License as published by the Free Software Foundation;
09: * 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: */
17: package net.refractions.udig.core.internal;
18:
19: import java.util.List;
20:
21: import org.eclipse.core.runtime.IConfigurationElement;
22: import org.eclipse.core.runtime.IExtension;
23:
24: /**
25: * Process an Extention Point into items for a List.
26: * <p>
27: * This interface works with a different set of assumptions then Jesse's origional. It is influenced
28: * by the guidelines in "Contributing to Eclipse", and is focused on Object (possibly proxy)
29: * creation.
30: * </p>
31: * <p>
32: * Assumptions:
33: * <ul>
34: * <li>Most of the time client code just wants to create an Object, or Proxy
35: * <li>Good Fences Rule / Safe Platform Rule - processor makes sure to trap any exceptions, so a
36: * single extention point cannot hinder others
37: * <li>Conformance Rule - contributions must conform to expected interfaces, we can use Java 5
38: * generics to force this point
39: * <li>Is an abstract class allowing safe api extention in the future.
40: * </ul>
41: * </p>
42: * <p>
43: * Example Use:
44: *
45: * <pre><code>
46: * List<Thingy> stuff = ExtentionPointUtil.list( new ExtentionPointProcessor2(){
47: * public Object process( IExtention extention, IConfigurationElement element ){
48: * return new Thingy( element );
49: * }
50: * }
51: * </code></pre>
52: *
53: * </p>
54: *
55: * @author jgarnett
56: * @since 0.6
57: */
58: public abstract class ExtensionPointItemCreator {
59: /**
60: * Process this extention point into a List.
61: *
62: * @param xpid Extention point to process
63: * @return List of items created
64: */
65: public List process(String xpid) {
66: return ExtensionPointUtil.list(xpid, this );
67: }
68:
69: /**
70: * Method called to create a List item from an extention point. This is a callback method for
71: * the ExtensionPointUtil class.
72: *
73: * @param extension An extension that extends the Extension point id specified in the
74: * ExtensionPointUtil.process() call.
75: * @param element One of the configuration element of the extension. The process method is
76: * called once for each configuration element
77: * @return Created Object (often a Proxy), throws an Exception if extention could not be
78: * processed returns true if this methods wants the ExtensionPointUtil#process() method
79: * to continue calling this method. false if no more calls need to be made.
80: * @throws Exception If extention point could not be processed, a ExtentionPointUtil will create
81: * the appropriate log message
82: */
83: public abstract Object createItem(IExtension extension,
84: IConfigurationElement element) throws Exception;
85:
86: }
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