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From ohe...@apache.org
Subject svn commit: r632836 - /commons/proper/configuration/branches/configuration2_experimental/src/main/java/org/apache/commons/configuration2/expr/NodeVisitor.java
Date Sun, 02 Mar 2008 20:35:04 GMT
Author: oheger
Date: Sun Mar  2 12:35:03 2008
New Revision: 632836

URL: http://svn.apache.org/viewvc?rev=632836&view=rev
Log:
Added generic NodeVisitor interface

Added:
    commons/proper/configuration/branches/configuration2_experimental/src/main/java/org/apache/commons/configuration2/expr/NodeVisitor.java
  (with props)

Added: commons/proper/configuration/branches/configuration2_experimental/src/main/java/org/apache/commons/configuration2/expr/NodeVisitor.java
URL: http://svn.apache.org/viewvc/commons/proper/configuration/branches/configuration2_experimental/src/main/java/org/apache/commons/configuration2/expr/NodeVisitor.java?rev=632836&view=auto
==============================================================================
--- commons/proper/configuration/branches/configuration2_experimental/src/main/java/org/apache/commons/configuration2/expr/NodeVisitor.java
(added)
+++ commons/proper/configuration/branches/configuration2_experimental/src/main/java/org/apache/commons/configuration2/expr/NodeVisitor.java
Sun Mar  2 12:35:03 2008
@@ -0,0 +1,75 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.commons.configuration2.expr;
+
+/**
+ * <p>
+ * Definition of a <em>visitor</em> interface for a node structure used by a
+ * configuration.
+ * </p>
+ * <p>
+ * Hierarchical configurations often need to traverse their internal nodes in a
+ * structured manner. While the concrete type of the nodes used differs for
+ * specific configuration implementations, the overall structure is always
+ * similar: The nodes form a tree-like structure, each node can have a value and
+ * an arbitrary number of attributes.
+ * </p>
+ * <p>
+ * This interface defines a generic visitor (according to the GoF
+ * <em>Visitor</em> pattern) that can deal with such structures. It defines
+ * methods for visiting each node of a structure before or after its children
+ * have been processed. These methods are also passed a
+ * <code>{@link NodeHandler}</code> reference, which can be used for accessing
+ * further properties of the node (e.g. its attributes) or manipulating it. With
+ * an additional method the traversal process can be aborted.
+ * </p>
+ *
+ * @author Oliver Heger
+ * @version $Id$
+ * @param <T> the type of the involved nodes
+ */
+public interface NodeVisitor<T>
+{
+    /**
+     * Visits the specified node before its children are processed. This method
+     * is called for all nodes in the currently processed hierarchy.
+     *
+     * @param node the node to be visited
+     * @param handler the node handler
+     */
+    void visitBeforeChildren(T node, NodeHandler<T> handler);
+
+    /**
+     * Visits the specified node after its children have been processed. This
+     * method is called for all nodes in the currently processed hierarchy.
+     *
+     * @param node the node to be visited
+     * @param handler the node handler
+     */
+    void visitAfterChildren(T node, NodeHandler<T> handler);
+
+    /**
+     * Returns a flag whether the actual visit process should be aborted. This
+     * method allows a visitor implementation to state that it does not need any
+     * further data. It may be used e.g. by visitors that search for a certain
+     * node in the hierarchy. After that node was found, there is no need to
+     * process the remaining nodes, too.
+     *
+     * @return a flag if the visit process should be stopped
+     */
+    boolean terminate();
+}

Propchange: commons/proper/configuration/branches/configuration2_experimental/src/main/java/org/apache/commons/configuration2/expr/NodeVisitor.java
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Propchange: commons/proper/configuration/branches/configuration2_experimental/src/main/java/org/apache/commons/configuration2/expr/NodeVisitor.java
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Propchange: commons/proper/configuration/branches/configuration2_experimental/src/main/java/org/apache/commons/configuration2/expr/NodeVisitor.java
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