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Java > Open Source Codes > groovy > util > BuilderSupport


1 /*
2  $Id: BuilderSupport.java,v 1.7 2004/07/31 03:37:31 jstrachan Exp $
3
4  Copyright 2003 (C) James Strachan and Bob Mcwhirter. All Rights Reserved.
5
6  Redistribution and use of this software and associated documentation
7  ("Software"), with or without modification, are permitted provided
8  that the following conditions are met:
9
10  1. Redistributions of source code must retain copyright
11     statements and notices. Redistributions must also contain a
12     copy of this document.
13
14  2. Redistributions in binary form must reproduce the
15     above copyright notice, this list of conditions and the
16     following disclaimer in the documentation and/or other
17     materials provided with the distribution.
18
19  3. The name "groovy" must not be used to endorse or promote
20     products derived from this Software without prior written
21     permission of The Codehaus. For written permission,
22     please contact info@codehaus.org.
23
24  4. Products derived from this Software may not be called "groovy"
25     nor may "groovy" appear in their names without prior written
26     permission of The Codehaus. "groovy" is a registered
27     trademark of The Codehaus.
28
29  5. Due credit should be given to The Codehaus -
30     http://groovy.codehaus.org/
31
32  THIS SOFTWARE IS PROVIDED BY THE CODEHAUS AND CONTRIBUTORS
33  ``AS IS'' AND ANY EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT
34  NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
35  FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
36  THE CODEHAUS OR ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
37  INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
38  (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
39  SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
40  HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
41  STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
42  ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
43  OF THE POSSIBILITY OF SUCH DAMAGE.
44
45  */
46 package groovy.util;
47
48
49 import groovy.lang.Closure;
50 import groovy.lang.GroovyObjectSupport;
51
52 import java.util.List JavaDoc;
53 import java.util.Map JavaDoc;
54
55 import org.codehaus.groovy.runtime.InvokerHelper;
56
57 /**
58  * An abstract base class for creating arbitrary nested trees of objects
59  * or events
60  *
61  * @author <a HREF="mailto:james@coredevelopers.net">James Strachan</a>
62  * @version $Revision: 1.7 $
63  */
64 public abstract class BuilderSupport extends GroovyObjectSupport {
65
66     private Object JavaDoc current;
67     private Closure nameMappingClosure;
68     private BuilderSupport proxyBuilder;
69     
70     public BuilderSupport() {
71         this.proxyBuilder = this;
72     }
73     
74     public BuilderSupport(BuilderSupport proxyBuilder) {
75         this(null, proxyBuilder);
76     }
77     
78     public BuilderSupport(Closure nameMappingClosure, BuilderSupport proxyBuilder) {
79         this.nameMappingClosure = nameMappingClosure;
80         this.proxyBuilder = proxyBuilder;
81     }
82     
83     public Object JavaDoc invokeMethod(String JavaDoc methodName, Object JavaDoc args) {
84         Object JavaDoc name = getName(methodName);
85         return doInvokeMethod(methodName, name, args);
86     }
87     
88     protected Object JavaDoc doInvokeMethod(String JavaDoc methodName, Object JavaDoc name, Object JavaDoc args) {
89         Object JavaDoc node = null;
90         Closure closure = null;
91         List JavaDoc list = InvokerHelper.asList(args);
92
93         //System.out.println("Called invokeMethod with name: " + name + " arguments: " + list);
94
95         switch (list.size()) {
96                 case 0:
97                     break;
98                     case 1:
99                     {
100                             Object JavaDoc object = list.get(0);
101                             if (object instanceof Map JavaDoc) {
102                                 node = proxyBuilder.createNode(name, (Map JavaDoc) object);
103                             } else if (object instanceof Closure) {
104                                 closure = (Closure) object;
105                                 node = proxyBuilder.createNode(name);
106                             } else {
107                                 node = proxyBuilder.createNode(name, object);
108                             }
109                     }
110                     break;
111                     case 2:
112                     {
113                         Object JavaDoc object1 = list.get(0);
114                         Object JavaDoc object2 = list.get(1);
115                         if (object1 instanceof Map JavaDoc) {
116                             if (object2 instanceof Closure) {
117                                 closure = (Closure) object2;
118                                 node = proxyBuilder.createNode(name, (Map JavaDoc) object1);
119                             } else {
120                                 node = proxyBuilder.createNode(name, (Map JavaDoc) object1, object2);
121                             }
122                         } else {
123                             if (object2 instanceof Closure) {
124                                 closure = (Closure) object2;
125                                 node = proxyBuilder.createNode(name, object1);
126                             }
127                         }
128                     }
129                     break;
130                     case 3:
131                     {
132                         Object JavaDoc attributes = list.get(0);
133                         Object JavaDoc value = list.get(1);
134                         closure = (Closure) list.get(2);
135                         node = proxyBuilder.createNode(name, (Map JavaDoc) attributes, value);
136                     }
137                     break;
138         }
139
140             if (node == null) {
141                 node = proxyBuilder.createNode(name);
142             }
143         
144         if (current != null) {
145             proxyBuilder.setParent(current, node);
146         }
147
148         if (closure != null) {
149             // push new node on stack
150 Object JavaDoc oldCurrent = current;
151             current = node;
152
153             // lets register the builder as the delegate
154 setClosureDelegate(closure, node);
155             closure.call();
156
157             current = oldCurrent;
158         }
159
160         proxyBuilder.nodeCompleted(current, node);
161         return node;
162     }
163
164     /**
165      * A strategy method to allow derived builders to use
166      * builder-trees and switch in different kinds of builders.
167      * This method should call the setDelegate() method on the closure
168      * which by default passes in this but if node is-a builder
169      * we could pass that in instead (or do something wacky too)
170      *
171      * @param closure the closure on which to call setDelegate()
172      * @param node the node value that we've just created, which could be
173      * a builder
174      */
175     protected void setClosureDelegate(Closure closure, Object JavaDoc node) {
176         closure.setDelegate(this);
177     }
178
179     protected abstract void setParent(Object JavaDoc parent, Object JavaDoc child);
180     protected abstract Object JavaDoc createNode(Object JavaDoc name);
181     protected abstract Object JavaDoc createNode(Object JavaDoc name, Object JavaDoc value);
182     protected abstract Object JavaDoc createNode(Object JavaDoc name, Map JavaDoc attributes);
183     protected abstract Object JavaDoc createNode(Object JavaDoc name, Map JavaDoc attributes, Object JavaDoc value);
184
185     /**
186      * A hook to allow names to be converted into some other object
187      * such as a QName in XML or ObjectName in JMX
188      * @param methodName
189      * @return
190      */
191     protected Object JavaDoc getName(String JavaDoc methodName) {
192         if (nameMappingClosure != null) {
193             return nameMappingClosure.call(methodName);
194         }
195         return methodName;
196     }
197
198
199     /**
200      * A hook to allow nodes to be processed once they have had all of their
201      * children applied
202      */
203     protected void nodeCompleted(Object JavaDoc parent, Object JavaDoc node) {
204     }
205
206     protected Object JavaDoc getCurrent() {
207         return current;
208     }
209     
210     protected void setCurrent(Object JavaDoc current) {
211         this.current = current;
212     }
213 }
214
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