content: /*
   * InputNode.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>InputNode</code> object represents an iterator for the
   * elements within an element. This allows the input node object to
   * become a self contained iterator for an element and its children.
   * Each child taken from the input node object, is itself an input
   * node, and can be used to explore its sub elements without having
   * any affect on its outer elements.
   *
   * @author Niall Gallagher
   */ 
  public interface InputNode 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 is used to determine if this node is an element. This
      * allows users of the framework to make a distinction between
      * nodes that represent attributes and nodes that represent
      * elements. This is particularly useful given that attribute
      * nodes do not maintain a node map of attributes.
      *
      * @return this returns true if the node is an element node
      */ 
     boolean isElement();
     
     /**
      * This is used to acquire the namespace prefix for the node.
      * If there is no namespace prefix for the node then this will
      * return null. Acquiring the prefix enables the qualification
      * of the node to be determined. It also allows nodes to be
      * grouped by its prefix and allows group operations.
      * 
      * @return this returns the prefix associated with this node
      */
     String getPrefix();
     
     /**
      * This allows the namespace reference URI to be determined.
      * A reference is a globally unique string that allows the
      * node to be identified. Typically the reference will be a URI
      * but it can be any unique string used to identify the node.
      * This allows the node to be identified within the namespace.
      * 
      * @return this returns the associated namespace reference URI 
      */
     String getReference();
     
     /**
      * This provides the position of this node within the document.
      * This allows the user of this node to report problems with
      * the location within the document, allowing the XML to be
      * debugged if it does not match the class schema.
      *
      * @return this returns the position of the XML read cursor
      */         
     Position getPosition();
          
     /**
      * Provides an attribute from the element represented. If an
      * attribute for the specified name does not exist within the
      * element represented then this method will return null.
      *
      * @param name this is the name of the attribute to retrieve
      *
      * @return this returns the value for the named attribute
      */ 
     InputNode getAttribute(String name);
  
     /**
      * This returns a map of the attributes contained within the
      * element. If no elements exist within the element then this
      * returns an empty map. 
      * 
      * @return this returns a map of attributes for the element
      */  
     NodeMap<InputNode> getAttributes();
     
     /**
      * 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
      */
     InputNode getParent();
     
     /**
      * This is used to return the source object for this node. This
      * is used primarily as a means to determine which XML provider
      * is parsing the source document and producing the nodes. It
      * is useful to be able to determine the XML provider like this.
      * 
      * @return this returns the source of this input node
      */
     Object getSource();
     
     /**
      * This returns the next child element within this element if
      * one exists. If all children have been read, or if there are
      * no child elements for this element then this returns null.
      *
      * @return this returns an input node for the next child
      *
      * @exception Exception thrown if there was a parse error
      */ 
     InputNode getNext() throws Exception;  
     
     /**
      * This returns the next child in this element if that child
      * has the name provided. If the next child element in this
      * node does not have the name given then null is returned.
      * 
      * @param name this is the name of the next child element 
      * 
      * @return the next element if it has the name specified
      * 
      * @exception Exception thrown if there was a parse error
      */
     InputNode getNext(String name) throws Exception;
  
     /**
      * This method is used to skip all child elements from this
      * element. This allows elements to be effectively skipped such
      * that when parsing a document if an element is not required
      * then that element can be completely removed from the XML.
      *
      * @exception Exception thrown if there was a parse error
      */ 
     void skip() throws Exception;
     
     /**
      * This is used to determine if this input node is empty. An
      * empty node is one with no attributes or children. This can
      * be used to determine if a given node represents an empty
      * entity, with which no extra data can be extracted.
      * 
      * @return this returns true if the node is an empty element
      * 
      * @throws Exception thrown if there was a parse error
      */
     boolean isEmpty() throws Exception;
  }
  