001/*
002 * Copyright (c) 2000 World Wide Web Consortium,
003 * (Massachusetts Institute of Technology, Institut National de
004 * Recherche en Informatique et en Automatique, Keio University). All
005 * Rights Reserved. This program is distributed under the W3C's Software
006 * Intellectual Property License. This program is distributed in the
007 * hope that it will be useful, but WITHOUT ANY WARRANTY; without even
008 * the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
009 * PURPOSE.
010 * See W3C License http://www.w3.org/Consortium/Legal/ for more details.
011 */
012
013package org.w3c.dom.traversal;
014
015import org.w3c.dom.Node;
016import org.w3c.dom.DOMException;
017
018/**
019 * <code>Iterators</code> are used to step through a set of nodes, e.g. the 
020 * set of nodes in a <code>NodeList</code>, the document subtree governed by 
021 * a particular <code>Node</code>, the results of a query, or any other set 
022 * of nodes. The set of nodes to be iterated is determined by the 
023 * implementation of the <code>NodeIterator</code>. DOM Level 2 specifies a 
024 * single <code>NodeIterator</code> implementation for document-order 
025 * traversal of a document subtree. Instances of these iterators are created 
026 * by calling <code>DocumentTraversal</code>
027 * <code>.createNodeIterator()</code>.
028 * <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>.
029 * @since DOM Level 2
030 */
031public interface NodeIterator {
032    /**
033     * The root node of the <code>NodeIterator</code>, as specified when it 
034     * was created.
035     */
036    public Node getRoot();
037
038    /**
039     * This attribute determines which node types are presented via the 
040     * iterator. The available set of constants is defined in the 
041     * <code>NodeFilter</code> interface.  Nodes not accepted by 
042     * <code>whatToShow</code> will be skipped, but their children may still 
043     * be considered. Note that this skip takes precedence over the filter, 
044     * if any. 
045     */
046    public int getWhatToShow();
047
048    /**
049     * The <code>NodeFilter</code> used to screen nodes.
050     */
051    public NodeFilter getFilter();
052
053    /**
054     *  The value of this flag determines whether the children of entity 
055     * reference nodes are visible to the iterator. If false, they  and 
056     * their descendants will be rejected. Note that this rejection takes 
057     * precedence over <code>whatToShow</code> and the filter. Also note 
058     * that this is currently the only situation where 
059     * <code>NodeIterators</code> may reject a complete subtree rather than 
060     * skipping individual nodes. 
061     * <br>
062     * <br> To produce a view of the document that has entity references 
063     * expanded and does not expose the entity reference node itself, use 
064     * the <code>whatToShow</code> flags to hide the entity reference node 
065     * and set <code>expandEntityReferences</code> to true when creating the 
066     * iterator. To produce a view of the document that has entity reference 
067     * nodes but no entity expansion, use the <code>whatToShow</code> flags 
068     * to show the entity reference node and set 
069     * <code>expandEntityReferences</code> to false.
070     */
071    public boolean getExpandEntityReferences();
072
073    /**
074     * Returns the next node in the set and advances the position of the 
075     * iterator in the set. After a <code>NodeIterator</code> is created, 
076     * the first call to <code>nextNode()</code> returns the first node in 
077     * the set.
078     * @return The next <code>Node</code> in the set being iterated over, or 
079     *   <code>null</code> if there are no more members in that set.
080     * @exception DOMException
081     *   INVALID_STATE_ERR: Raised if this method is called after the 
082     *   <code>detach</code> method was invoked.
083     */
084    public Node nextNode()
085                         throws DOMException;
086
087    /**
088     * Returns the previous node in the set and moves the position of the 
089     * <code>NodeIterator</code> backwards in the set.
090     * @return The previous <code>Node</code> in the set being iterated over, 
091     *   or <code>null</code> if there are no more members in that set. 
092     * @exception DOMException
093     *   INVALID_STATE_ERR: Raised if this method is called after the 
094     *   <code>detach</code> method was invoked.
095     */
096    public Node previousNode()
097                             throws DOMException;
098
099    /**
100     * Detaches the <code>NodeIterator</code> from the set which it iterated 
101     * over, releasing any computational resources and placing the iterator 
102     * in the INVALID state. After <code>detach</code> has been invoked, 
103     * calls to <code>nextNode</code> or <code>previousNode</code> will 
104     * raise the exception INVALID_STATE_ERR.
105     */
106    public void detach();
107
108}