content: /*
   * OutputNode.java July 2006
   *
   * Copyright (C) 2006, 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.stream;
  
  /**
   * The <code>OutputNode</code> object is used to represent a cursor
   * which can be used to write XML elements and attributes. Each of
   * the output node objects represents a element, and can be used 
   * to add attributes to that element as well as child elements.
   *
   * @author Niall Gallagher
   */ 
  public interface OutputNode extends Node {
     
     /**
      * This method is used to determine if this node is the root 
      * node for the XML document. The root node is the first node
      * in the document and has no sibling nodes. This is false
      * if the node has a parent node or a sibling node.
      * 
      * @return true if this is the root node within the document
      */
     boolean isRoot();  
     
     /**
      * This returns a <code>NodeMap</code> which can be used to add
      * nodes to the element before that element has been committed. 
      * Nodes can be removed or added to the map and will appear as
      * attributes on the written element when it is committed.
      *
      * @return returns the node map used to manipulate attributes
      */ 
     NodeMap<OutputNode> getAttributes();
     
     /**
      * The <code>Mode</code> is used to indicate the output mode
      * of this node. Three modes are possible, each determines
      * how a value, if specified, is written to the resulting XML
      * document. This is determined by the <code>setData</code>
      * method which will set the output to be CDATA or escaped, 
      * if neither is specified the mode is inherited.
      * 
      * @return this returns the mode of this output node object
      */
     Mode getMode();
     
     /**
      * This is used to set the output mode of this node to either
      * be CDATA, escaped, or inherited. If the mode is set to data
      * then any value specified will be written in a CDATA block, 
      * if this is set to escaped values are escaped. If however 
      * this method is set to inherited then the mode is inherited
      * from the parent node.
      * 
      * @param mode this is the output mode to set the node to 
      */
     void setMode(Mode mode);
     
     /**
      * This is used to set the output mode of this node to either
      * be CDATA or escaped. If this is set to true the any value
      * specified will be written in a CDATA block, if this is set
      * to false the values is escaped. If however this method is
      * never invoked then the mode is inherited from the parent.
      * 
      * @param data if true the value is written as a CDATA block
      */
     void setData(boolean data);
    
     /**
      * This is used to acquire the prefix for this output node. If
      * the output node is an element then this will search its parent
      * nodes until the prefix that is currently in scope is found. 
      * If however this node is an attribute then the hierarchy of 
      * nodes is not searched as attributes to not inherit namespaces.
      *
      * @return this returns the prefix associated with this node
      */  
     String getPrefix();
     
     /**
      * This is used to acquire the prefix for this output node. If
      * the output node is an element then this will search its parent
      * nodes until the prefix that is currently in scope is found. 
      * If however this node is an attribute then the hierarchy of 
      * nodes is not searched as attributes to not inherit namespaces.
      *
      * @param inherit if there is no explicit prefix then inherit
      *
      * @return this returns the prefix associated with this node
      */  
     String getPrefix(boolean inherit);
     
     /**
      * This is used to acquire the namespace URI reference associated
      * with this node. Although it is recommended that the namespace
      * reference is a URI it does not have to be, it can be any unique
      * identifier that can be used to distinguish the qualified names.
      *
      * @return this returns the namespace URI reference for this
      */
     String getReference();
    
     /**
      * This is used to set the reference for the node. Setting the
      * reference implies that the node is a qualified node within the
      * XML document. Both elements and attributes can be qualified.
      * Depending on the prefix set on this node or, failing that, any
      * parent node for the reference, the element will appear in the
      * XML document with that string prefixed to the node name.
      *
      * @param reference this is used to set the reference for the node
      */  
     void setReference(String reference);
    
     /**
      * This returns the <code>NamespaceMap</code> for this node. Only
      * an element can have namespaces, so if this node represents an
      * attribute the elements namespaces will be provided when this is
      * requested. By adding a namespace it becomes in scope for the
      * current element all all child elements of that element.
      *
      * @return this returns the namespaces associated with the node
      */  
     NamespaceMap getNamespaces();
     
     /**
      * This is used to get the text comment for the element. This can
      * be null if no comment has been set. If no comment is set on 
      * the node then no comment will be written to the resulting XML.
      * 
      * @return this is the comment associated with this element
      */
     String getComment();
     
     /**
      * This is used to set a text comment to the element. This will
      * be written just before the actual element is written. Only a
      * single comment can be set for each output node written. 
      * 
      * @param comment this is the comment to set on the node
      */
     void setComment(String comment);
     
     /**
      * This is used to set a text value to the element. This should
      * be added to the element if the element contains no child
      * elements. If the value cannot be added an exception is thrown.
      * 
      * @param value this is the text value to add to this element
      *
      * @throws Exception thrown if the text value cannot be added
      */ 
     void setValue(String value);
     
     /**
      * This is used to change the name of an output node. This will
      * only affect the name of the node if the node has not yet been
      * committed. If the node is committed then this will not be
      * reflected in the resulting XML generated.
      * 
      * @param name this is the name to change the node to
      */
     void setName(String name);
     
     /**
      * This method is used for convenience to add an attribute node 
      * to the attribute <code>NodeMap</code>. The attribute added
      * can be removed from the element by using the node map.
      * 
      * @param name this is the name of the attribute to be added
      * @param value this is the value of the node to be added
      * 
      * @return this returns the node that has just been added
      */ 
     OutputNode setAttribute(String name, String value);
     
     /**
      * This is used to acquire the <code>Node</code> that is the
      * parent of this node. This will return the node that is
      * the direct parent of this node and allows for siblings to
      * make use of nodes with their parents if required.  
      *   
      * @return this returns the parent node for this node
      */
     OutputNode getParent();
     
     /**
      * This is used to create a child element within the element that
      * this object represents. When a new child is created with this
      * method then the previous child is committed to the document.
      * The created <code>OutputNode</code> object can be used to add
      * attributes to the child element as well as other elements.
      *
      * @param name this is the name of the child element to create
      */ 
     OutputNode getChild(String name) throws Exception;        
  
     /**
      * This is used to remove any uncommitted changes. Removal of an
      * output node can only be done if it has no siblings and has
      * not yet been committed. If the node is committed then this 
      * will throw an exception to indicate that it cannot be removed. 
      * 
      * @throws Exception thrown if the node cannot be removed
      */
     void remove() throws Exception;
     
     /**
      * The <code>commit</code> method is used flush and commit any 
      * child nodes that have been created by this node. This allows
      * the output to be completed when building of the XML document
      * has been completed. If output fails an exception is thrown.
      * 
      * @throws Exception thrown if the node cannot be committed
      */ 
     void commit() throws Exception;
  
     /**
      * This is used to determine whether the node has been committed.
      * If the node has been committed, then this will return true.
      * When committed the node can no longer produce chile nodes.
      * 
      * @return true if this node has already been committed
      */
     boolean isCommitted();
  }
  