NodeFilter


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  
17  /**
18   * Filters are objects that know how to "filter out" nodes. If a 
19   * <code>NodeIterator</code> or <code>TreeWalker</code> is given a 
20   * <code>NodeFilter</code>, it applies the filter before it returns the next 
21   * node. If the filter says to accept the node, the traversal logic returns 
22   * it; otherwise, traversal looks for the next node and pretends that the 
23   * node that was rejected was not there.
24   * <p>The DOM does not provide any filters. <code>NodeFilter</code> is just an 
25   * interface that users can implement to provide their own filters. 
26   * <p><code>NodeFilters</code> do not need to know how to traverse from node 
27   * to node, nor do they need to know anything about the data structure that 
28   * is being traversed. This makes it very easy to write filters, since the 
29   * only thing they have to know how to do is evaluate a single node. One 
30   * filter may be used with a number of different kinds of traversals, 
31   * encouraging code reuse.
32   * <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>.
33   * @since DOM Level 2
34   */
35  public interface NodeFilter {
36      // Constants returned by acceptNode
37      /**
38       * Accept the node. Navigation methods defined for 
39       * <code>NodeIterator</code> or <code>TreeWalker</code> will return this 
40       * node.
41       */
42      public static final short FILTER_ACCEPT             = 1;
43      /**
44       * Reject the node. Navigation methods defined for 
45       * <code>NodeIterator</code> or <code>TreeWalker</code> will not return 
46       * this node. For <code>TreeWalker</code>, the children of this node 
47       * will also be rejected. <code>NodeIterators</code> treat this as a 
48       * synonym for <code>FILTER_SKIP</code>.
49       */
50      public static final short FILTER_REJECT             = 2;
51      /**
52       * Skip this single node. Navigation methods defined for 
53       * <code>NodeIterator</code> or <code>TreeWalker</code> will not return 
54       * this node. For both <code>NodeIterator</code> and 
55       * <code>TreeWalker</code>, the children of this node will still be 
56       * considered. 
57       */
58      public static final short FILTER_SKIP               = 3;
59  
60      // Constants for whatToShow
61      /**
62       * Show all <code>Nodes</code>.
63       */
64      public static final int SHOW_ALL                  = 0xFFFFFFFF;
65      /**
66       * Show <code>Element</code> nodes.
67       */
68      public static final int SHOW_ELEMENT              = 0x00000001;
69      /**
70       * Show <code>Attr</code> nodes. This is meaningful only when creating an 
71       * <code>NodeIterator</code> or <code>TreeWalker</code> with an 
72       * attribute node as its <code>root</code>; in this case, it means that 
73       * the attribute node will appear in the first position of the iteration 
74       * or traversal. Since attributes are never children of other nodes, 
75       * they do not appear when traversing over the document tree.
76       */
77      public static final int SHOW_ATTRIBUTE            = 0x00000002;
78      /**
79       * Show <code>Text</code> nodes.
80       */
81      public static final int SHOW_TEXT                 = 0x00000004;
82      /**
83       * Show <code>CDATASection</code> nodes.
84       */
85      public static final int SHOW_CDATA_SECTION        = 0x00000008;
86      /**
87       * Show <code>EntityReference</code> nodes.
88       */
89      public static final int SHOW_ENTITY_REFERENCE     = 0x00000010;
90      /**
91       * Show <code>Entity</code> nodes. This is meaningful only when creating 
92       * an <code>NodeIterator</code> or <code>TreeWalker</code> with an 
93       * <code>Entity</code> node as its <code>root</code>; in this case, it 
94       * means that the <code>Entity</code> node will appear in the first 
95       * position of the traversal. Since entities are not part of the 
96       * document tree, they do not appear when traversing over the document 
97       * tree.
98       */
99      public static final int SHOW_ENTITY               = 0x00000020;
100     /**
101      * Show <code>ProcessingInstruction</code> nodes.
102      */
103     public static final int SHOW_PROCESSING_INSTRUCTION = 0x00000040;
104     /**
105      * Show <code>Comment</code> nodes.
106      */
107     public static final int SHOW_COMMENT              = 0x00000080;
108     /**
109      * Show <code>Document</code> nodes.
110      */
111     public static final int SHOW_DOCUMENT             = 0x00000100;
112     /**
113      * Show <code>DocumentType</code> nodes.
114      */
115     public static final int SHOW_DOCUMENT_TYPE        = 0x00000200;
116     /**
117      * Show <code>DocumentFragment</code> nodes.
118      */
119     public static final int SHOW_DOCUMENT_FRAGMENT    = 0x00000400;
120     /**
121      * Show <code>Notation</code> nodes. This is meaningful only when creating 
122      * an <code>NodeIterator</code> or <code>TreeWalker</code> with a 
123      * <code>Notation</code> node as its <code>root</code>; in this case, it 
124      * means that the <code>Notation</code> node will appear in the first 
125      * position of the traversal. Since notations are not part of the 
126      * document tree, they do not appear when traversing over the document 
127      * tree.
128      */
129     public static final int SHOW_NOTATION             = 0x00000800;
130 
131     /**
132      * Test whether a specified node is visible in the logical view of a 
133      * <code>TreeWalker</code> or <code>NodeIterator</code>. This function 
134      * will be called by the implementation of <code>TreeWalker</code> and 
135      * <code>NodeIterator</code>; it is not normally called directly from 
136      * user code. (Though you could do so if you wanted to use the same 
137      * filter to guide your own application logic.)
138      * @param n The node to check to see if it passes the filter or not.
139      * @return A constant to determine whether the node is accepted, 
140      *   rejected, or skipped, as defined above.
141      */
142     public short acceptNode(Node   n);
143 
144 }
145
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