content: /*
   * Visitor.java January 2010
   *
   * Copyright (C) 2010, Niall Gallagher <niallg@users.sf.net>
   *
   * Licensed 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 com.aliyun.odps.simpleframework.xml.strategy;
  
  import com.aliyun.odps.simpleframework.xml.stream.NodeMap;
  import com.aliyun.odps.simpleframework.xml.stream.OutputNode;
  import com.aliyun.odps.simpleframework.xml.stream.InputNode;
  
  /**
   * The <code>Visitor</code> interface represents an object that is 
   * used to visit each XML element during serialization. For the
   * deserialization process each XML element is visited before 
   * control is returned to the serializer. This allows a visitor
   * implementation to perform some operation based on the node 
   * that is being deserialized. Typically a visitor is used to
   * edit the node, for example it may remove or insert attributes.
   * <p>
   * In effect this can act much like a transformer that sits
   * between a <code>Strategy</code> implementation and the core
   * serializer. It enables interception and manipulation of the
   * node so that the resulting XML document can be customized in 
   * a way that can not be performed by the underlying strategy.
   * 
   * @author Niall Gallagher
   * 
   * @see VisitorStrategy
   */
  public interface Visitor {
     
     /**
      * This is used to intercept an XML element before it is read
      * by the underlying <code>Strategy</code> implementation. When
      * a node is intercepted it can be manipulated in such a way
      * that its semantics change. For example, this could be used 
      * to change the way a "class" attribute is represented, which
      * would allow the XML to appear in a language neutral format.
      *
      * @param type this is the type that represents the element
      * @param node this is the XML element to be intercepted
      */
     void read(Type type, NodeMap<InputNode> node) throws Exception;
     
     /**
      * This is used to intercept an XML element after it is written
      * by the underlying <code>Strategy</code> implementation. When
      * a node is intercepted it can be manipulated in such a way
      * that its semantics change. For example, this could be used 
      * to change the way a "class" attribute is represented, which
      * would allow the XML to appear in a language neutral format.
      *
      * @param type this is the type that represents the element
      * @param node this is the XML element to be intercepted
      */
     void write(Type type, NodeMap<OutputNode> node) throws Exception;
  }
  