01: /*
02: * Licensed to the Apache Software Foundation (ASF) under one or more
03: * contributor license agreements. See the NOTICE file distributed with
04: * this work for additional information regarding copyright ownership.
05: * The ASF licenses this file to You under the Apache License, Version 2.0
06: * (the "License"); you may not use this file except in compliance with
07: * the License. You may obtain a copy of the License at
08: *
09: * http://www.apache.org/licenses/LICENSE-2.0
10: *
11: * Unless required by applicable law or agreed to in writing, software
12: * distributed under the License is distributed on an "AS IS" BASIS,
13: * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14: * See the License for the specific language governing permissions and
15: * limitations under the License.
16: */
17: package org.apache.commons.configuration.tree;
18:
19: /**
20: * <p>
21: * Definition of a <em>Visitor</em> interface for a configuration node
22: * structure.
23: * </p>
24: * <p>
25: * The <code>ConfigurationNode</code> interface defines a <code>visit()</code>,
26: * which simplifies traversal of a complex node hierarchy. A configuration node
27: * implementation must provide a way of visiting all nodes in the current
28: * hierarchy. This is a typical application of the GoF <em>Visitor</em>
29: * pattern.
30: * </p>
31: *
32: * @since 1.3
33: * @see ConfigurationNode
34: * @author Oliver Heger
35: */
36: public interface ConfigurationNodeVisitor {
37: /**
38: * Visits the specified node. This method is called before eventually
39: * existing children of this node are processed.
40: *
41: * @param node the node to be visited
42: */
43: void visitBeforeChildren(ConfigurationNode node);
44:
45: /**
46: * Visits the specified node. This method is called after eventually
47: * existing children of this node have been processed.
48: *
49: * @param node the node to be visited
50: */
51: void visitAfterChildren(ConfigurationNode node);
52:
53: /**
54: * Returns a flag whether the actual visit process should be aborted. This
55: * method allows a visitor implementation to state that it does not need any
56: * further data. It may be used e.g. by visitors that search for a certain
57: * node in the hierarchy. After that node was found, there is no need to
58: * process the remaining nodes, too.
59: *
60: * @return a flag if the visit process should be stopped
61: */
62: boolean terminate();
63: }
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