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
13package org.w3c.dom.ls;
14
15import org.w3c.dom.Element;
16import org.w3c.dom.Node;
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
46and Save Specification</a>.
47 */
48public 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