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>TreeWalker</code> objects are used to navigate a document tree or 
020 * subtree using the view of the document defined by their 
021 * <code>whatToShow</code> flags and filter (if any). Any function which 
022 * performs navigation using a <code>TreeWalker</code> will automatically 
023 * support any view defined by a <code>TreeWalker</code>.
024 * <p>Omitting nodes from the logical view of a subtree can result in a 
025 * structure that is substantially different from the same subtree in the 
026 * complete, unfiltered document. Nodes that are siblings in the 
027 * <code>TreeWalker</code> view may be children of different, widely 
028 * separated nodes in the original view. For instance, consider a 
029 * <code>NodeFilter</code> that skips all nodes except for Text nodes and 
030 * the root node of a document. In the logical view that results, all text 
031 * nodes will be siblings and appear as direct children of the root node, no 
032 * matter how deeply nested the structure of the original document.
033 * <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>.
034 * @since DOM Level 2
035 */
036public interface TreeWalker {
037    /**
038     * The <code>root</code> node of the <code>TreeWalker</code>, as specified 
039     * when it was created.
040     */
041    public Node getRoot();
042
043    /**
044     * This attribute determines which node types are presented via the 
045     * <code>TreeWalker</code>. The available set of constants is defined in 
046     * the <code>NodeFilter</code> interface.  Nodes not accepted by 
047     * <code>whatToShow</code> will be skipped, but their children may still 
048     * be considered. Note that this skip takes precedence over the filter, 
049     * if any. 
050     */
051    public int getWhatToShow();
052
053    /**
054     * The filter used to screen nodes.
055     */
056    public NodeFilter getFilter();
057
058    /**
059     * The value of this flag determines whether the children of entity 
060     * reference nodes are visible to the <code>TreeWalker</code>. If false, 
061     * these children  and their descendants will be rejected. Note that 
062     * this rejection takes precedence over <code>whatToShow</code> and the 
063     * filter, if any. 
064     * <br> To produce a view of the document that has entity references 
065     * expanded and does not expose the entity reference node itself, use 
066     * the <code>whatToShow</code> flags to hide the entity reference node 
067     * and set <code>expandEntityReferences</code> to true when creating the 
068     * <code>TreeWalker</code>. To produce a view of the document that has 
069     * entity reference nodes but no entity expansion, use the 
070     * <code>whatToShow</code> flags to show the entity reference node and 
071     * set <code>expandEntityReferences</code> to false.
072     */
073    public boolean getExpandEntityReferences();
074
075    /**
076     * The node at which the <code>TreeWalker</code> is currently positioned.
077     * <br>Alterations to the DOM tree may cause the current node to no longer 
078     * be accepted by the <code>TreeWalker</code>'s associated filter. 
079     * <code>currentNode</code> may also be explicitly set to any node, 
080     * whether or not it is within the subtree specified by the 
081     * <code>root</code> node or would be accepted by the filter and 
082     * <code>whatToShow</code> flags. Further traversal occurs relative to 
083     * <code>currentNode</code> even if it is not part of the current view, 
084     * by applying the filters in the requested direction; if no traversal 
085     * is possible, <code>currentNode</code> is not changed. 
086     */
087    public Node getCurrentNode();
088    /**
089     * The node at which the <code>TreeWalker</code> is currently positioned.
090     * <br>Alterations to the DOM tree may cause the current node to no longer 
091     * be accepted by the <code>TreeWalker</code>'s associated filter. 
092     * <code>currentNode</code> may also be explicitly set to any node, 
093     * whether or not it is within the subtree specified by the 
094     * <code>root</code> node or would be accepted by the filter and 
095     * <code>whatToShow</code> flags. Further traversal occurs relative to 
096     * <code>currentNode</code> even if it is not part of the current view, 
097     * by applying the filters in the requested direction; if no traversal 
098     * is possible, <code>currentNode</code> is not changed. 
099     * @exception DOMException
100     *   NOT_SUPPORTED_ERR: Raised if an attempt is made to set 
101     *   <code>currentNode</code> to <code>null</code>.
102     */
103    public void setCurrentNode(Node currentNode)
104                         throws DOMException;
105
106    /**
107     * Moves to and returns the closest visible ancestor node of the current 
108     * node. If the search for <code>parentNode</code> attempts to step 
109     * upward from the <code>TreeWalker</code>'s <code>root</code> node, or 
110     * if it fails to find a visible ancestor node, this method retains the 
111     * current position and returns <code>null</code>.
112     * @return The new parent node, or <code>null</code> if the current node 
113     *   has no parent  in the <code>TreeWalker</code>'s logical view.  
114     */
115    public Node parentNode();
116
117    /**
118     * Moves the <code>TreeWalker</code> to the first visible child of the 
119     * current node, and returns the new node. If the current node has no 
120     * visible children, returns <code>null</code>, and retains the current 
121     * node.
122     * @return The new node, or <code>null</code> if the current node has no 
123     *   visible children  in the <code>TreeWalker</code>'s logical view.  
124     */
125    public Node firstChild();
126
127    /**
128     * Moves the <code>TreeWalker</code> to the last visible child of the 
129     * current node, and returns the new node. If the current node has no 
130     * visible children, returns <code>null</code>, and retains the current 
131     * node.
132     * @return The new node, or <code>null</code> if the current node has no 
133     *   children  in the <code>TreeWalker</code>'s logical view.  
134     */
135    public Node lastChild();
136
137    /**
138     * Moves the <code>TreeWalker</code> to the previous sibling of the 
139     * current node, and returns the new node. If the current node has no 
140     * visible previous sibling, returns <code>null</code>, and retains the 
141     * current node.
142     * @return The new node, or <code>null</code> if the current node has no 
143     *   previous sibling.  in the <code>TreeWalker</code>'s logical view.  
144     */
145    public Node previousSibling();
146
147    /**
148     * Moves the <code>TreeWalker</code> to the next sibling of the current 
149     * node, and returns the new node. If the current node has no visible 
150     * next sibling, returns <code>null</code>, and retains the current node.
151     * @return The new node, or <code>null</code> if the current node has no 
152     *   next sibling.  in the <code>TreeWalker</code>'s logical view.  
153     */
154    public Node nextSibling();
155
156    /**
157     * Moves the <code>TreeWalker</code> to the previous visible node in 
158     * document order relative to the current node, and returns the new 
159     * node. If the current node has no previous node,  or if the search for 
160     * <code>previousNode</code> attempts to step upward from the 
161     * <code>TreeWalker</code>'s <code>root</code> node,  returns 
162     * <code>null</code>, and retains the current node. 
163     * @return The new node, or <code>null</code> if the current node has no 
164     *   previous node  in the <code>TreeWalker</code>'s logical view.  
165     */
166    public Node previousNode();
167
168    /**
169     * Moves the <code>TreeWalker</code> to the next visible node in document 
170     * order relative to the current node, and returns the new node. If the 
171     * current node has no next node, or if the search for nextNode attempts 
172     * to step upward from the <code>TreeWalker</code>'s <code>root</code> 
173     * node, returns <code>null</code>, and retains the current node.
174     * @return The new node, or <code>null</code> if the current node has no 
175     *   next node  in the <code>TreeWalker</code>'s logical view.  
176     */
177    public Node nextNode();
178
179}