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    
017    /**
018     * Filters are objects that know how to "filter out" nodes. If a 
019     * <code>NodeIterator</code> or <code>TreeWalker</code> is given a 
020     * <code>NodeFilter</code>, it applies the filter before it returns the next 
021     * node. If the filter says to accept the node, the traversal logic returns 
022     * it; otherwise, traversal looks for the next node and pretends that the 
023     * node that was rejected was not there.
024     * <p>The DOM does not provide any filters. <code>NodeFilter</code> is just an 
025     * interface that users can implement to provide their own filters. 
026     * <p><code>NodeFilters</code> do not need to know how to traverse from node 
027     * to node, nor do they need to know anything about the data structure that 
028     * is being traversed. This makes it very easy to write filters, since the 
029     * only thing they have to know how to do is evaluate a single node. One 
030     * filter may be used with a number of different kinds of traversals, 
031     * encouraging code reuse.
032     * <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>.
033     * @since DOM Level 2
034     */
035    public interface NodeFilter {
036        // Constants returned by acceptNode
037        /**
038         * Accept the node. Navigation methods defined for 
039         * <code>NodeIterator</code> or <code>TreeWalker</code> will return this 
040         * node.
041         */
042        public static final short FILTER_ACCEPT             = 1;
043        /**
044         * Reject the node. Navigation methods defined for 
045         * <code>NodeIterator</code> or <code>TreeWalker</code> will not return 
046         * this node. For <code>TreeWalker</code>, the children of this node 
047         * will also be rejected. <code>NodeIterators</code> treat this as a 
048         * synonym for <code>FILTER_SKIP</code>.
049         */
050        public static final short FILTER_REJECT             = 2;
051        /**
052         * Skip this single node. Navigation methods defined for 
053         * <code>NodeIterator</code> or <code>TreeWalker</code> will not return 
054         * this node. For both <code>NodeIterator</code> and 
055         * <code>TreeWalker</code>, the children of this node will still be 
056         * considered. 
057         */
058        public static final short FILTER_SKIP               = 3;
059    
060        // Constants for whatToShow
061        /**
062         * Show all <code>Nodes</code>.
063         */
064        public static final int SHOW_ALL                  = 0xFFFFFFFF;
065        /**
066         * Show <code>Element</code> nodes.
067         */
068        public static final int SHOW_ELEMENT              = 0x00000001;
069        /**
070         * Show <code>Attr</code> nodes. This is meaningful only when creating an 
071         * <code>NodeIterator</code> or <code>TreeWalker</code> with an 
072         * attribute node as its <code>root</code>; in this case, it means that 
073         * the attribute node will appear in the first position of the iteration 
074         * or traversal. Since attributes are never children of other nodes, 
075         * they do not appear when traversing over the document tree.
076         */
077        public static final int SHOW_ATTRIBUTE            = 0x00000002;
078        /**
079         * Show <code>Text</code> nodes.
080         */
081        public static final int SHOW_TEXT                 = 0x00000004;
082        /**
083         * Show <code>CDATASection</code> nodes.
084         */
085        public static final int SHOW_CDATA_SECTION        = 0x00000008;
086        /**
087         * Show <code>EntityReference</code> nodes.
088         */
089        public static final int SHOW_ENTITY_REFERENCE     = 0x00000010;
090        /**
091         * Show <code>Entity</code> nodes. This is meaningful only when creating 
092         * an <code>NodeIterator</code> or <code>TreeWalker</code> with an 
093         * <code>Entity</code> node as its <code>root</code>; in this case, it 
094         * means that the <code>Entity</code> node will appear in the first 
095         * position of the traversal. Since entities are not part of the 
096         * document tree, they do not appear when traversing over the document 
097         * tree.
098         */
099        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    }