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/*

 * 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>NodeIterators</code> are used to step through a set of nodes, e.g.

 * the set of nodes in a <code>NodeList</code>, the document subtree

 * governed by a particular <code>Node</code>, the results of a query, or

 * any other set of nodes. The set of nodes to be iterated is determined by

 * the implementation of the <code>NodeIterator</code>. DOM Level 2

 * specifies a single <code>NodeIterator</code> implementation for

 * document-order traversal of a document subtree. Instances of these

 * <code>NodeIterators</code> are created by calling

 * <code>DocumentTraversal</code><code>.createNodeIterator()</code>.

 * <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 DOM Level 2

 */

public interface NodeIterator {

    /**

     * The root node of the <code>NodeIterator</code>, as specified when it

     * was created.

     */

    public Node getRoot();

    /**

     * This attribute determines which node types are presented via the

     * <code>NodeIterator</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 <code>NodeFilter</code> 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>NodeIterator</code>. If

     * false, these children  and their descendants will be rejected. Note

     * that this rejection takes precedence over <code>whatToShow</code> and

     * the filter. Also note that this is currently the only situation where

     * <code>NodeIterators</code> may reject a complete subtree rather than

     * skipping individual nodes.

     * <br>

     * <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>NodeIterator</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();

    /**

     * Returns the next node in the set and advances the position of the

     * <code>NodeIterator</code> in the set. After a

     * <code>NodeIterator</code> is created, the first call to

     * <code>nextNode()</code> returns the first node in the set.

     * @return The next <code>Node</code> in the set being iterated over, or

     *   <code>null</code> if there are no more members in that set.

     * @exception DOMException

     *   INVALID_STATE_ERR: Raised if this method is called after the

     *   <code>detach</code> method was invoked.

     */

    public Node nextNode()

                         throws DOMException;

    /**

     * Returns the previous node in the set and moves the position of the

     * <code>NodeIterator</code> backwards in the set.

     * @return The previous <code>Node</code> in the set being iterated over,

     *   or <code>null</code> if there are no more members in that set.

     * @exception DOMException

     *   INVALID_STATE_ERR: Raised if this method is called after the

     *   <code>detach</code> method was invoked.

     */

    public Node previousNode()

                             throws DOMException;

    /**

     * Detaches the <code>NodeIterator</code> from the set which it iterated

     * over, releasing any computational resources and placing the

     * <code>NodeIterator</code> in the INVALID state. After

     * <code>detach</code> has been invoked, calls to <code>nextNode</code>

     * or <code>previousNode</code> will raise the exception

     * INVALID_STATE_ERR.

     */

    public void detach();

}