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	/*
	* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
	*
	* This code is free software; you can redistribute it and/or modify it
	* under the terms of the GNU General Public License version 2 only, as
	* published by the Free Software Foundation. Oracle designates this
	* particular file as subject to the "Classpath" exception as provided
	* by Oracle in the LICENSE file that accompanied this code.
	*
	* This code is distributed in the hope that it will be useful, but WITHOUT
	* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
	* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
	* version 2 for more details (a copy is included in the LICENSE file that
	* accompanied this code).
	*
	* You should have received a copy of the GNU General Public License version
	* 2 along with this work; if not, write to the Free Software Foundation,
	* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
	*
	* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
	* or visit www.oracle.com if you need additional information or have any
	* questions.
	*/

	/*
	* This file is available under and governed by the GNU General Public
	* License version 2 only, as published by the Free Software Foundation.
	* However, the following notice accompanied the original version of this
	* file and, per its terms, should not be removed:
	*
	* Copyright (c) 2000 World Wide Web Consortium,
	* (Massachusetts Institute of Technology, Institut National de
	* Recherche en Informatique et en Automatique, Keio University). All
	* Rights Reserved. This program is distributed under the W3C's Software
	* Intellectual Property License. This program is distributed in the
	* hope that it will be useful, but WITHOUT ANY WARRANTY; without even
	* the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
	* PURPOSE.
	* See W3C License http://www.w3.org/Consortium/Legal/ for more details.
	*/

	package org.w3c.dom.traversal;

	import org.w3c.dom.Node;
	import org.w3c.dom.DOMException;

	/**
	* <code>TreeWalker</code> objects are used to navigate a document tree or
	* subtree using the view of the document defined by their
	* <code>whatToShow</code> flags and filter (if any). Any function which
	* performs navigation using a <code>TreeWalker</code> will automatically
	* support any view defined by a <code>TreeWalker</code>.
	* <p>Omitting nodes from the logical view of a subtree can result in a
	* structure that is substantially different from the same subtree in the
	* complete, unfiltered document. Nodes that are siblings in the
	* <code>TreeWalker</code> view may be children of different, widely
	* separated nodes in the original view. For instance, consider a
	* <code>NodeFilter</code> that skips all nodes except for Text nodes and
	* the root node of a document. In the logical view that results, all text
	* nodes will be siblings and appear as direct children of the root node, no
	* matter how deeply nested the structure of the original document.
	* <p>See also the <a href='http://www.w3.org/TR/2000/REC-DOM-Level-2-Traversal-Range-20001113'>Document Object Model (DOM) Level 2 Traversal and Range Specification</a>.
	* @since 9, DOM Level 2
	*/
	public interface TreeWalker {
	/**
	* The <code>root</code> node of the <code>TreeWalker</code>, as specified
	* when it was created.
	*/
	public Node getRoot();

	/**
	* This attribute determines which node types are presented via the
	* <code>TreeWalker</code>. The available set of constants is defined in
	* the <code>NodeFilter</code> interface. Nodes not accepted by
	* <code>whatToShow</code> will be skipped, but their children may still
	* be considered. Note that this skip takes precedence over the filter,
	* if any.
	*/
	public int getWhatToShow();

	/**
	* The filter used to screen nodes.
	*/
	public NodeFilter getFilter();

	/**
	* The value of this flag determines whether the children of entity
	* reference nodes are visible to the <code>TreeWalker</code>. If false,
	* these children and their descendants will be rejected. Note that
	* this rejection takes precedence over <code>whatToShow</code> and the
	* filter, if any.
	* <br> To produce a view of the document that has entity references
	* expanded and does not expose the entity reference node itself, use
	* the <code>whatToShow</code> flags to hide the entity reference node
	* and set <code>expandEntityReferences</code> to true when creating the
	* <code>TreeWalker</code>. To produce a view of the document that has
	* entity reference nodes but no entity expansion, use the
	* <code>whatToShow</code> flags to show the entity reference node and
	* set <code>expandEntityReferences</code> to false.
	*/
	public boolean getExpandEntityReferences();

	/**
	* The node at which the <code>TreeWalker</code> is currently positioned.
	* <br>Alterations to the DOM tree may cause the current node to no longer
	* be accepted by the <code>TreeWalker</code>'s associated filter.
	* <code>currentNode</code> may also be explicitly set to any node,
	* whether or not it is within the subtree specified by the
	* <code>root</code> node or would be accepted by the filter and
	* <code>whatToShow</code> flags. Further traversal occurs relative to
	* <code>currentNode</code> even if it is not part of the current view,
	* by applying the filters in the requested direction; if no traversal
	* is possible, <code>currentNode</code> is not changed.
	*/
	public Node getCurrentNode();
	/**
	* The node at which the <code>TreeWalker</code> is currently positioned.
	* <br>Alterations to the DOM tree may cause the current node to no longer
	* be accepted by the <code>TreeWalker</code>'s associated filter.
	* <code>currentNode</code> may also be explicitly set to any node,
	* whether or not it is within the subtree specified by the
	* <code>root</code> node or would be accepted by the filter and
	* <code>whatToShow</code> flags. Further traversal occurs relative to
	* <code>currentNode</code> even if it is not part of the current view,
	* by applying the filters in the requested direction; if no traversal
	* is possible, <code>currentNode</code> is not changed.
	* @exception DOMException
	* NOT_SUPPORTED_ERR: Raised if an attempt is made to set
	* <code>currentNode</code> to <code>null</code>.
	*/
	public void setCurrentNode(Node currentNode)
	throws DOMException;

	/**
	* Moves to and returns the closest visible ancestor node of the current
	* node. If the search for <code>parentNode</code> attempts to step
	* upward from the <code>TreeWalker</code>'s <code>root</code> node, or
	* if it fails to find a visible ancestor node, this method retains the
	* current position and returns <code>null</code>.
	* @return The new parent node, or <code>null</code> if the current node
	* has no parent in the <code>TreeWalker</code>'s logical view.
	*/
	public Node parentNode();

	/**
	* Moves the <code>TreeWalker</code> to the first visible child of the
	* current node, and returns the new node. If the current node has no
	* visible children, returns <code>null</code>, and retains the current
	* node.
	* @return The new node, or <code>null</code> if the current node has no
	* visible children in the <code>TreeWalker</code>'s logical view.
	*/
	public Node firstChild();

	/**
	* Moves the <code>TreeWalker</code> to the last visible child of the
	* current node, and returns the new node. If the current node has no
	* visible children, returns <code>null</code>, and retains the current
	* node.
	* @return The new node, or <code>null</code> if the current node has no
	* children in the <code>TreeWalker</code>'s logical view.
	*/
	public Node lastChild();

	/**
	* Moves the <code>TreeWalker</code> to the previous sibling of the
	* current node, and returns the new node. If the current node has no
	* visible previous sibling, returns <code>null</code>, and retains the
	* current node.
	* @return The new node, or <code>null</code> if the current node has no
	* previous sibling. in the <code>TreeWalker</code>'s logical view.
	*/
	public Node previousSibling();

	/**
	* Moves the <code>TreeWalker</code> to the next sibling of the current
	* node, and returns the new node. If the current node has no visible
	* next sibling, returns <code>null</code>, and retains the current node.
	* @return The new node, or <code>null</code> if the current node has no
	* next sibling. in the <code>TreeWalker</code>'s logical view.
	*/
	public Node nextSibling();

	/**
	* Moves the <code>TreeWalker</code> to the previous visible node in
	* document order relative to the current node, and returns the new
	* node. If the current node has no previous node, or if the search for
	* <code>previousNode</code> attempts to step upward from the
	* <code>TreeWalker</code>'s <code>root</code> node, returns
	* <code>null</code>, and retains the current node.
	* @return The new node, or <code>null</code> if the current node has no
	* previous node in the <code>TreeWalker</code>'s logical view.
	*/
	public Node previousNode();

	/**
	* Moves the <code>TreeWalker</code> to the next visible node in document
	* order relative to the current node, and returns the new node. If the
	* current node has no next node, or if the search for nextNode attempts
	* to step upward from the <code>TreeWalker</code>'s <code>root</code>
	* node, returns <code>null</code>, and retains the current node.
	* @return The new node, or <code>null</code> if the current node has no
	* next node in the <code>TreeWalker</code>'s logical view.
	*/
	public Node nextNode();

	}

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