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    
013    package org.w3c.dom.traversal;
014    
015    import org.w3c.dom.Node;
016    import 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     */
036    public 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    }