001    /*
002     * Copyright (c) 2004 World Wide Web Consortium,
003     *
004     * (Massachusetts Institute of Technology, European Research Consortium for
005     * Informatics and Mathematics, Keio University). All Rights Reserved. This
006     * work is distributed under the W3C(r) Software License [1] in the hope that
007     * it will be useful, but WITHOUT ANY WARRANTY; without even the implied
008     * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
009     *
010     * [1] http://www.w3.org/Consortium/Legal/2002/copyright-software-20021231
011     */
012    
013    package org.w3c.dom.ls;
014    
015    import org.w3c.dom.Node;
016    import org.w3c.dom.Element;
017    
018    /**
019     *  <code>LSParserFilter</code>s provide applications the ability to examine 
020     * nodes as they are being constructed while parsing. As each node is 
021     * examined, it may be modified or removed, or the entire parse may be 
022     * terminated early. 
023     * <p> At the time any of the filter methods are called by the parser, the 
024     * owner Document and DOMImplementation objects exist and are accessible. 
025     * The document element is never passed to the <code>LSParserFilter</code> 
026     * methods, i.e. it is not possible to filter out the document element. 
027     * <code>Document</code>, <code>DocumentType</code>, <code>Notation</code>, 
028     * <code>Entity</code>, and <code>Attr</code> nodes are never passed to the 
029     * <code>acceptNode</code> method on the filter. The child nodes of an 
030     * <code>EntityReference</code> node are passed to the filter if the 
031     * parameter "<a href='http://www.w3.org/TR/DOM-Level-3-Core/core.html#parameter-entities'>
032     * 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'>
033     * entities</a>", unexpanded entity reference nodes are never discarded and are always 
034     * passed to the filter. 
035     * <p> All validity checking while parsing a document occurs on the source 
036     * document as it appears on the input stream, not on the DOM document as it 
037     * is built in memory. With filters, the document in memory may be a subset 
038     * of the document on the stream, and its validity may have been affected by 
039     * the filtering. 
040     * <p> All default attributes must be present on elements when the elements 
041     * are passed to the filter methods. All other default content must be 
042     * passed to the filter methods. 
043     * <p> DOM applications must not raise exceptions in a filter. The effect of 
044     * throwing exceptions from a filter is DOM implementation dependent. 
045     * <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
046    and Save Specification</a>.
047     */
048    public interface LSParserFilter {
049        // Constants returned by startElement and acceptNode
050        /**
051         * Accept the node.
052         */
053        public static final short FILTER_ACCEPT             = 1;
054        /**
055         * Reject the node and its children.
056         */
057        public static final short FILTER_REJECT             = 2;
058        /**
059         * Skip this single node. The children of this node will still be 
060         * considered. 
061         */
062        public static final short FILTER_SKIP               = 3;
063        /**
064         *  Interrupt the normal processing of the document. 
065         */
066        public static final short FILTER_INTERRUPT          = 4;
067    
068        /**
069         *  The parser will call this method after each <code>Element</code> start 
070         * tag has been scanned, but before the remainder of the 
071         * <code>Element</code> is processed. The intent is to allow the 
072         * element, including any children, to be efficiently skipped. Note that 
073         * only element nodes are passed to the <code>startElement</code> 
074         * function. 
075         * <br>The element node passed to <code>startElement</code> for filtering 
076         * will include all of the Element's attributes, but none of the 
077         * children nodes. The Element may not yet be in place in the document 
078         * being constructed (it may not have a parent node.) 
079         * <br>A <code>startElement</code> filter function may access or change 
080         * the attributes for the Element. Changing Namespace declarations will 
081         * have no effect on namespace resolution by the parser.
082         * <br>For efficiency, the Element node passed to the filter may not be 
083         * the same one as is actually placed in the tree if the node is 
084         * accepted. And the actual node (node object identity) may be reused 
085         * during the process of reading in and filtering a document.
086         * @param elementArg The newly encountered element. At the time this 
087         *   method is called, the element is incomplete - it will have its 
088         *   attributes, but no children. 
089         * @return 
090         * <ul>
091         * <li> <code>FILTER_ACCEPT</code> if the <code>Element</code> should 
092         *   be included in the DOM document being built. 
093         * </li>
094         * <li> 
095         *   <code>FILTER_REJECT</code> if the <code>Element</code> and all of 
096         *   its children should be rejected. 
097         * </li>
098         * <li> <code>FILTER_SKIP</code> if the 
099         *   <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    }