LSParserFilter


1   /*
2    * Copyright (c) 2004 World Wide Web Consortium,
3    *
4    * (Massachusetts Institute of Technology, European Research Consortium for
5    * Informatics and Mathematics, Keio University). All Rights Reserved. This
6    * work is distributed under the W3C(r) Software License [1] in the hope that
7    * it will be useful, but WITHOUT ANY WARRANTY; without even the implied
8    * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
9    *
10   * [1] http://www.w3.org/Consortium/Legal/2002/copyright-software-20021231
11   */
12  
13  package org.w3c.dom.ls;
14  
15  import org.w3c.dom.Node  ;
16  import org.w3c.dom.Element  ;
17  
18  /**
19   *  <code>LSParserFilter</code>s provide applications the ability to examine 
20   * nodes as they are being constructed while parsing. As each node is 
21   * examined, it may be modified or removed, or the entire parse may be 
22   * terminated early. 
23   * <p> At the time any of the filter methods are called by the parser, the 
24   * owner Document and DOMImplementation objects exist and are accessible. 
25   * The document element is never passed to the <code>LSParserFilter</code> 
26   * methods, i.e. it is not possible to filter out the document element. 
27   * <code>Document</code>, <code>DocumentType</code>, <code>Notation</code>, 
28   * <code>Entity</code>, and <code>Attr</code> nodes are never passed to the 
29   * <code>acceptNode</code> method on the filter. The child nodes of an 
30   * <code>EntityReference</code> node are passed to the filter if the 
31   * parameter "<a HREF='http://www.w3.org/TR/DOM-Level-3-Core/core.html#parameter-entities'>
32   * entities</a>" is set to <code>false</code>. Note that, as described by the parameter "<a HREF='http://www.w3.org/TR/DOM-Level-3-Core/core.html#parameter-entities'>
33   * entities</a>", unexpanded entity reference nodes are never discarded and are always 
34   * passed to the filter. 
35   * <p> All validity checking while parsing a document occurs on the source 
36   * document as it appears on the input stream, not on the DOM document as it 
37   * is built in memory. With filters, the document in memory may be a subset 
38   * of the document on the stream, and its validity may have been affected by 
39   * the filtering. 
40   * <p> All default attributes must be present on elements when the elements 
41   * are passed to the filter methods. All other default content must be 
42   * passed to the filter methods. 
43   * <p> DOM applications must not raise exceptions in a filter. The effect of 
44   * throwing exceptions from a filter is DOM implementation dependent. 
45   * <p>See also the <a HREF='http://www.w3.org/TR/2004/REC-DOM-Level-3-LS-20040407'>Document Object Model (DOM) Level 3 Load
46  and Save Specification</a>.
47   */
48  public interface LSParserFilter {
49      // Constants returned by startElement and acceptNode
50      /**
51       * Accept the node.
52       */
53      public static final short FILTER_ACCEPT             = 1;
54      /**
55       * Reject the node and its children.
56       */
57      public static final short FILTER_REJECT             = 2;
58      /**
59       * Skip this single node. The children of this node will still be 
60       * considered. 
61       */
62      public static final short FILTER_SKIP               = 3;
63      /**
64       *  Interrupt the normal processing of the document. 
65       */
66      public static final short FILTER_INTERRUPT          = 4;
67  
68      /**
69       *  The parser will call this method after each <code>Element</code> start 
70       * tag has been scanned, but before the remainder of the 
71       * <code>Element</code> is processed. The intent is to allow the 
72       * element, including any children, to be efficiently skipped. Note that 
73       * only element nodes are passed to the <code>startElement</code> 
74       * function. 
75       * <br>The element node passed to <code>startElement</code> for filtering 
76       * will include all of the Element's attributes, but none of the 
77       * children nodes. The Element may not yet be in place in the document 
78       * being constructed (it may not have a parent node.) 
79       * <br>A <code>startElement</code> filter function may access or change 
80       * the attributes for the Element. Changing Namespace declarations will 
81       * have no effect on namespace resolution by the parser.
82       * <br>For efficiency, the Element node passed to the filter may not be 
83       * the same one as is actually placed in the tree if the node is 
84       * accepted. And the actual node (node object identity) may be reused 
85       * during the process of reading in and filtering a document.
86       * @param elementArg The newly encountered element. At the time this 
87       *   method is called, the element is incomplete - it will have its 
88       *   attributes, but no children. 
89       * @return 
90       * <ul>
91       * <li> <code>FILTER_ACCEPT</code> if the <code>Element</code> should 
92       *   be included in the DOM document being built. 
93       * </li>
94       * <li> 
95       *   <code>FILTER_REJECT</code> if the <code>Element</code> and all of 
96       *   its children should be rejected. 
97       * </li>
98       * <li> <code>FILTER_SKIP</code> if the 
99       *   <code>Element</code> should be skipped. All of its children are 
100      *   inserted in place of the skipped <code>Element</code> node. 
101      * </li>
102      * <li> 
103      *   <code>FILTER_INTERRUPT</code> if the filter wants to stop the 
104      *   processing of the document. Interrupting the processing of the 
105      *   document does no longer guarantee that the resulting DOM tree is 
106      *   XML well-formed. The <code>Element</code> is rejected. 
107      * </li>
108      * </ul> Returning 
109      *   any other values will result in unspecified behavior. 
110      */
111     public short startElement(Element   elementArg);
112 
113     /**
114      * This method will be called by the parser at the completion of the 
115      * parsing of each node. The node and all of its descendants will exist 
116      * and be complete. The parent node will also exist, although it may be 
117      * incomplete, i.e. it may have additional children that have not yet 
118      * been parsed. Attribute nodes are never passed to this function.
119      * <br>From within this method, the new node may be freely modified - 
120      * children may be added or removed, text nodes modified, etc. The state 
121      * of the rest of the document outside this node is not defined, and the 
122      * affect of any attempt to navigate to, or to modify any other part of 
123      * the document is undefined. 
124      * <br>For validating parsers, the checks are made on the original 
125      * document, before any modification by the filter. No validity checks 
126      * are made on any document modifications made by the filter.
127      * <br>If this new node is rejected, the parser might reuse the new node 
128      * and any of its descendants.
129      * @param nodeArg The newly constructed element. At the time this method 
130      *   is called, the element is complete - it has all of its children 
131      *   (and their children, recursively) and attributes, and is attached 
132      *   as a child to its parent. 
133      * @return 
134      * <ul>
135      * <li> <code>FILTER_ACCEPT</code> if this <code>Node</code> should 
136      *   be included in the DOM document being built. 
137      * </li>
138      * <li> 
139      *   <code>FILTER_REJECT</code> if the <code>Node</code> and all of its 
140      *   children should be rejected. 
141      * </li>
142      * <li> <code>FILTER_SKIP</code> if the 
143      *   <code>Node</code> should be skipped and the <code>Node</code> 
144      *   should be replaced by all the children of the <code>Node</code>. 
145      * </li>
146      * <li> 
147      *   <code>FILTER_INTERRUPT</code> if the filter wants to stop the 
148      *   processing of the document. Interrupting the processing of the 
149      *   document does no longer guarantee that the resulting DOM tree is 
150      *   XML well-formed. The <code>Node</code> is accepted and will be the 
151      *   last completely parsed node. 
152      * </li>
153      * </ul>
154      */
155     public short acceptNode(Node   nodeArg);
156 
157     /**
158      *  Tells the <code>LSParser</code> what types of nodes to show to the 
159      * method <code>LSParserFilter.acceptNode</code>. If a node is not shown 
160      * to the filter using this attribute, it is automatically included in 
161      * the DOM document being built. See <code>NodeFilter</code> for 
162      * definition of the constants. The constants <code>SHOW_ATTRIBUTE</code>
163      * , <code>SHOW_DOCUMENT</code>, <code>SHOW_DOCUMENT_TYPE</code>, 
164      * <code>SHOW_NOTATION</code>, <code>SHOW_ENTITY</code>, and 
165      * <code>SHOW_DOCUMENT_FRAGMENT</code> are meaningless here. Those nodes 
166      * will never be passed to <code>LSParserFilter.acceptNode</code>. 
167      * <br> The constants used here are defined in [<a HREF='http://www.w3.org/TR/2000/REC-DOM-Level-2-Traversal-Range-20001113'>DOM Level 2 Traversal and      Range</a>]
168      * . 
169      */
170     public int getWhatToShow();
171 
172 }
173
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