svn commit: r641539 - /commons/proper/configuration/branches/configuration2_experimental/src/main/java/org/apache/commons/configuration2/expr/AbstractNodeHandler.java

[oh...@apache.org]

Author: oheger
Date: Wed Mar 26 13:12:51 2008
New Revision: 641539

URL: http://svn.apache.org/viewvc?rev=641539&view=rev
Log:
A new abstract base class for simple node handlers

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

Added: commons/proper/configuration/branches/configuration2_experimental/src/main/java/org/apache/commons/configuration2/expr/AbstractNodeHandler.java
URL: http://svn.apache.org/viewvc/commons/proper/configuration/branches/configuration2_experimental/src/main/java/org/apache/commons/configuration2/expr/AbstractNodeHandler.java?rev=641539&view=auto
==============================================================================
--- commons/proper/configuration/branches/configuration2_experimental/src/main/java/org/apache/commons/configuration2/expr/AbstractNodeHandler.java (added)
+++ commons/proper/configuration/branches/configuration2_experimental/src/main/java/org/apache/commons/configuration2/expr/AbstractNodeHandler.java Wed Mar 26 13:12:51 2008
@@ -0,0 +1,74 @@
+/*
+ * 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>
+ * An abstract base class that simplifies concrete <code>NodeHandler</code>
+ * implementations.
+ * </p>
+ * <p>
+ * This class already provides default implementations for some of the methods
+ * defined by the <code>NodeHandler</code> interface. It is especially useful
+ * for simple handlers that operate on a concrete node type.
+ * </p>
+ *
+ * @author <a
+ *         href="http://commons.apache.org/configuration/team-list.html">Commons
+ *         Configuration team</a>
+ * @version $Id$
+ * @param <T> the type of the nodes this handler can handle
+ */
+public abstract class AbstractNodeHandler<T> implements NodeHandler<T>
+{
+    /**
+     * Returns a flag whether the passed in node has any attributes. This base
+     * implementation delegates to <code>getAttributes()</code> and checks
+     * whether the returned list is empty. Derived classes may override this
+     * method to implement a more efficient algorithm.
+     *
+     * @param node the node
+     * @return a flag whether this node has attributes
+     */
+    public boolean hasAttributes(T node)
+    {
+        return !getAttributes(node).isEmpty();
+    }
+
+    /**
+     * Initializes this <code>NodeHandler</code> with a reference to a
+     * <code>NodeHandlerRegistry</code>. This is just a dummy implementation;
+     * the passed in reference is ignored.
+     *
+     * @param registry the registry
+     */
+    public void initNodeHandlerRegistry(NodeHandlerRegistry registry)
+    {
+    }
+
+    /**
+     * Tests whether the passed in node is defined. This base implementation
+     * checks whether the node has a value or any attributes.
+     *
+     * @param node the node to test
+     * @return a flag whether this node is defined
+     */
+    public boolean isDefined(T node)
+    {
+        return getValue(node) != null || hasAttributes(node);
+    }
+}

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