libjava/org/w3c/dom/traversal/TreeWalker.java

   1 /*
   2  * Copyright (c) 2000 World Wide Web Consortium,
   3  * (Massachusetts Institute of Technology, Institut National de
   4  * Recherche en Informatique et en Automatique, Keio University). All
   5  * Rights Reserved. This program is distributed under the W3C's Software
   6  * Intellectual Property License. This program is distributed in the
   7  * hope that it will be useful, but WITHOUT ANY WARRANTY; without even
   8  * the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
   9  * PURPOSE.
  10  * See W3C License http://www.w3.org/Consortium/Legal/ for more details.
  11  */
  12
  13 package org.w3c.dom.traversal;
  14
  15 import org.w3c.dom.Node;
  16 import org.w3c.dom.DOMException;
  17
  18 /**
  19  * <code>TreeWalker</code> objects are used to navigate a document tree or
  20  * subtree using the view of the document defined by their
  21  * <code>whatToShow</code> flags and filter (if any). Any function which
  22  * performs navigation using a <code>TreeWalker</code> will automatically
  23  * support any view defined by a <code>TreeWalker</code>.
  24  * <p>Omitting nodes from the logical view of a subtree can result in a
  25  * structure that is substantially different from the same subtree in the
  26  * complete, unfiltered document. Nodes that are siblings in the
  27  * <code>TreeWalker</code> view may be children of different, widely
  28  * separated nodes in the original view. For instance, consider a
  29  * <code>NodeFilter</code> that skips all nodes except for Text nodes and
  30  * the root node of a document. In the logical view that results, all text
  31  * nodes will be siblings and appear as direct children of the root node, no
  32  * matter how deeply nested the structure of the original document.
  33  * <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>.
  34  * @since DOM Level 2
  35  */
  36 public interface TreeWalker {
  37     /**
  38      * The <code>root</code> node of the <code>TreeWalker</code>, as specified
  39      * when it was created.
  40      */
  41     public Node getRoot();
  42
  43     /**
  44      * This attribute determines which node types are presented via the
  45      * <code>TreeWalker</code>. The available set of constants is defined in
  46      * the <code>NodeFilter</code> interface.  Nodes not accepted by
  47      * <code>whatToShow</code> will be skipped, but their children may still
  48      * be considered. Note that this skip takes precedence over the filter,
  49      * if any.
  50      */
  51     public int getWhatToShow();
  52
  53     /**
  54      * The filter used to screen nodes.
  55      */
  56     public NodeFilter getFilter();
  57
  58     /**
  59      * The value of this flag determines whether the children of entity
  60      * reference nodes are visible to the <code>TreeWalker</code>. If false,
  61      * they  and their descendants will be rejected. Note that this
  62      * rejection takes precedence over <code>whatToShow</code> and the
  63      * filter, if any.
  64      * <br> To produce a view of the document that has entity references
  65      * expanded and does not expose the entity reference node itself, use
  66      * the <code>whatToShow</code> flags to hide the entity reference node
  67      * and set <code>expandEntityReferences</code> to true when creating the
  68      * <code>TreeWalker</code>. To produce a view of the document that has
  69      * entity reference nodes but no entity expansion, use the
  70      * <code>whatToShow</code> flags to show the entity reference node and
  71      * set <code>expandEntityReferences</code> to false.
  72      */
  73     public boolean getExpandEntityReferences();
  74
  75     /**
  76      * The node at which the <code>TreeWalker</code> is currently positioned.
  77      * <br>Alterations to the DOM tree may cause the current node to no longer
  78      * be accepted by the <code>TreeWalker</code>'s associated filter.
  79      * <code>currentNode</code> may also be explicitly set to any node,
  80      * whether or not it is within the subtree specified by the
  81      * <code>root</code> node or would be accepted by the filter and
  82      * <code>whatToShow</code> flags. Further traversal occurs relative to
  83      * <code>currentNode</code> even if it is not part of the current view,
  84      * by applying the filters in the requested direction; if no traversal
  85      * is possible, <code>currentNode</code> is not changed.
  86      * @exception DOMException
  87      *   NOT_SUPPORTED_ERR: Raised if an attempt is made to set
  88      *   <code>currentNode</code> to <code>null</code>.
  89      */
  90     public Node getCurrentNode();
  91     public void setCurrentNode(Node currentNode)
  92                          throws DOMException;
  93
  94     /**
  95      * Moves to and returns the closest visible ancestor node of the current
  96      * node. If the search for <code>parentNode</code> attempts to step
  97      * upward from the <code>TreeWalker</code>'s <code>root</code> node, or
  98      * if it fails to find a visible ancestor node, this method retains the
  99      * current position and returns <code>null</code>.
 100      * @return The new parent node, or <code>null</code> if the current node
 101      *   has no parent  in the <code>TreeWalker</code>'s logical view.
 102      */
 103     public Node parentNode();
 104
 105     /**
 106      * Moves the <code>TreeWalker</code> to the first visible child of the
 107      * current node, and returns the new node. If the current node has no
 108      * visible children, returns <code>null</code>, and retains the current
 109      * node.
 110      * @return The new node, or <code>null</code> if the current node has no
 111      *   visible children  in the <code>TreeWalker</code>'s logical view.
 112      */
 113     public Node firstChild();
 114
 115     /**
 116      * Moves the <code>TreeWalker</code> to the last visible child of the
 117      * current node, and returns the new node. If the current node has no
 118      * visible children, returns <code>null</code>, and retains the current
 119      * node.
 120      * @return The new node, or <code>null</code> if the current node has no
 121      *   children  in the <code>TreeWalker</code>'s logical view.
 122      */
 123     public Node lastChild();
 124
 125     /**
 126      * Moves the <code>TreeWalker</code> to the previous sibling of the
 127      * current node, and returns the new node. If the current node has no
 128      * visible previous sibling, returns <code>null</code>, and retains the
 129      * current node.
 130      * @return The new node, or <code>null</code> if the current node has no
 131      *   previous sibling.  in the <code>TreeWalker</code>'s logical view.
 132      */
 133     public Node previousSibling();
 134
 135     /**
 136      * Moves the <code>TreeWalker</code> to the next sibling of the current
 137      * node, and returns the new node. If the current node has no visible
 138      * next sibling, returns <code>null</code>, and retains the current node.
 139      * @return The new node, or <code>null</code> if the current node has no
 140      *   next sibling.  in the <code>TreeWalker</code>'s logical view.
 141      */
 142     public Node nextSibling();
 143
 144     /**
 145      * Moves the <code>TreeWalker</code> to the previous visible node in
 146      * document order relative to the current node, and returns the new
 147      * node. If the current node has no previous node,  or if the search for
 148      * <code>previousNode</code> attempts to step upward from the
 149      * <code>TreeWalker</code>'s <code>root</code> node,  returns
 150      * <code>null</code>, and retains the current node.
 151      * @return The new node, or <code>null</code> if the current node has no
 152      *   previous node  in the <code>TreeWalker</code>'s logical view.
 153      */
 154     public Node previousNode();
 155
 156     /**
 157      * Moves the <code>TreeWalker</code> to the next visible node in document
 158      * order relative to the current node, and returns the new node. If the
 159      * current node has no next node, or if the search for nextNode attempts
 160      * to step upward from the <code>TreeWalker</code>'s <code>root</code>
 161      * node, returns <code>null</code>, and retains the current node.
 162      * @return The new node, or <code>null</code> if the current node has no
 163      *   next node  in the <code>TreeWalker</code>'s logical view.
 164      */
 165     public Node nextNode();
 166
 167 }