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/*

 * Copyright (c) 2004 World Wide Web Consortium,

 *

 * (Massachusetts Institute of Technology, European Research Consortium for

 * Informatics and Mathematics, Keio University). All Rights Reserved. This

 * work is distributed under the W3C(r) Software License [1] in the hope that

 * it will be useful, but WITHOUT ANY WARRANTY; without even the implied

 * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

 *

 * [1] http://www.w3.org/Consortium/Legal/2002/copyright-software-20021231

 */

package org.w3c.dom.ls;

import org.w3c.dom.Node;

import org.w3c.dom.Element;

/**

 *  <code>LSParserFilter</code>s provide applications the ability to examine

 * nodes as they are being constructed while parsing. As each node is

 * examined, it may be modified or removed, or the entire parse may be

 * terminated early.

 * <p> At the time any of the filter methods are called by the parser, the

 * owner Document and DOMImplementation objects exist and are accessible.

 * The document element is never passed to the <code>LSParserFilter</code>

 * methods, i.e. it is not possible to filter out the document element.

 * <code>Document</code>, <code>DocumentType</code>, <code>Notation</code>,

 * <code>Entity</code>, and <code>Attr</code> nodes are never passed to the

 * <code>acceptNode</code> method on the filter. The child nodes of an

 * <code>EntityReference</code> node are passed to the filter if the

 * parameter "<a href='http://www.w3.org/TR/DOM-Level-3-Core/core.html#parameter-entities'>

 * 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'>

 * entities</a>", unexpanded entity reference nodes are never discarded and are always

 * passed to the filter.

 * <p> All validity checking while parsing a document occurs on the source

 * document as it appears on the input stream, not on the DOM document as it

 * is built in memory. With filters, the document in memory may be a subset

 * of the document on the stream, and its validity may have been affected by

 * the filtering.

 * <p> All default attributes must be present on elements when the elements

 * are passed to the filter methods. All other default content must be

 * passed to the filter methods.

 * <p> DOM applications must not raise exceptions in a filter. The effect of

 * throwing exceptions from a filter is DOM implementation dependent.

 * <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

and Save Specification</a>.

 */

public interface LSParserFilter {

    // Constants returned by startElement and acceptNode

    /**

     * Accept the node.

     */

    public static final short FILTER_ACCEPT             = 1;

    /**

     * Reject the node and its children.

     */

    public static final short FILTER_REJECT             = 2;

    /**

     * Skip this single node. The children of this node will still be

     * considered.

     */

    public static final short FILTER_SKIP               = 3;

    /**

     *  Interrupt the normal processing of the document.

     */

    public static final short FILTER_INTERRUPT          = 4;

    /**

     *  The parser will call this method after each <code>Element</code> start

     * tag has been scanned, but before the remainder of the

     * <code>Element</code> is processed. The intent is to allow the

     * element, including any children, to be efficiently skipped. Note that

     * only element nodes are passed to the <code>startElement</code>

     * function.

     * <br>The element node passed to <code>startElement</code> for filtering

     * will include all of the Element's attributes, but none of the

     * children nodes. The Element may not yet be in place in the document

     * being constructed (it may not have a parent node.)

     * <br>A <code>startElement</code> filter function may access or change

     * the attributes for the Element. Changing Namespace declarations will

     * have no effect on namespace resolution by the parser.

     * <br>For efficiency, the Element node passed to the filter may not be

     * the same one as is actually placed in the tree if the node is

     * accepted. And the actual node (node object identity) may be reused

     * during the process of reading in and filtering a document.

     * @param elementArg The newly encountered element. At the time this

     *   method is called, the element is incomplete - it will have its

     *   attributes, but no children.

     * @return

     * <ul>

     * <li> <code>FILTER_ACCEPT</code> if the <code>Element</code> should

     *   be included in the DOM document being built.

     * </li>

     * <li>

     *   <code>FILTER_REJECT</code> if the <code>Element</code> and all of

     *   its children should be rejected.

     * </li>

     * <li> <code>FILTER_SKIP</code> if the

     *   <code>Element</code> should be skipped. All of its children are

     *   inserted in place of the skipped <code>Element</code> node.

     * </li>

     * <li>

     *   <code>FILTER_INTERRUPT</code> if the filter wants to stop the

     *   processing of the document. Interrupting the processing of the

     *   document does no longer guarantee that the resulting DOM tree is

     *   XML well-formed. The <code>Element</code> is rejected.

     * </li>

     * </ul> Returning

     *   any other values will result in unspecified behavior.

     */

    public short startElement(Element elementArg);

    /**

     * This method will be called by the parser at the completion of the

     * parsing of each node. The node and all of its descendants will exist

     * and be complete. The parent node will also exist, although it may be

     * incomplete, i.e. it may have additional children that have not yet

     * been parsed. Attribute nodes are never passed to this function.

     * <br>From within this method, the new node may be freely modified -

     * children may be added or removed, text nodes modified, etc. The state

     * of the rest of the document outside this node is not defined, and the

     * affect of any attempt to navigate to, or to modify any other part of

     * the document is undefined.

     * <br>For validating parsers, the checks are made on the original

     * document, before any modification by the filter. No validity checks

     * are made on any document modifications made by the filter.

     * <br>If this new node is rejected, the parser might reuse the new node

     * and any of its descendants.

     * @param nodeArg The newly constructed element. At the time this method

     *   is called, the element is complete - it has all of its children

     *   (and their children, recursively) and attributes, and is attached

     *   as a child to its parent.

     * @return

     * <ul>

     * <li> <code>FILTER_ACCEPT</code> if this <code>Node</code> should

     *   be included in the DOM document being built.

     * </li>

     * <li>

     *   <code>FILTER_REJECT</code> if the <code>Node</code> and all of its

     *   children should be rejected.

     * </li>

     * <li> <code>FILTER_SKIP</code> if the

     *   <code>Node</code> should be skipped and the <code>Node</code>

     *   should be replaced by all the children of the <code>Node</code>.

     * </li>

     * <li>

     *   <code>FILTER_INTERRUPT</code> if the filter wants to stop the

     *   processing of the document. Interrupting the processing of the

     *   document does no longer guarantee that the resulting DOM tree is

     *   XML well-formed. The <code>Node</code> is accepted and will be the

     *   last completely parsed node.

     * </li>

     * </ul>

     */

    public short acceptNode(Node nodeArg);

    /**

     *  Tells the <code>LSParser</code> what types of nodes to show to the

     * method <code>LSParserFilter.acceptNode</code>. If a node is not shown

     * to the filter using this attribute, it is automatically included in

     * the DOM document being built. See <code>NodeFilter</code> for

     * definition of the constants. The constants <code>SHOW_ATTRIBUTE</code>

     * , <code>SHOW_DOCUMENT</code>, <code>SHOW_DOCUMENT_TYPE</code>,

     * <code>SHOW_NOTATION</code>, <code>SHOW_ENTITY</code>, and

     * <code>SHOW_DOCUMENT_FRAGMENT</code> are meaningless here. Those nodes

     * will never be passed to <code>LSParserFilter.acceptNode</code>.

     * <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>]

     * .

     */

    public int getWhatToShow();

}