1. /*

  2.  * The Apache Software License, Version 1.1

  3.  *

  4.  *

  5.  * Copyright (c) 1999-2002 The Apache Software Foundation.  All rights 

  6.  * reserved.

  7.  *

  8.  * Redistribution and use in source and binary forms, with or without

  9.  * modification, are permitted provided that the following conditions

  10.  * are met:

  11.  *

  12.  * 1. Redistributions of source code must retain the above copyright

  13.  *    notice, this list of conditions and the following disclaimer. 

  14.  *

  15.  * 2. Redistributions in binary form must reproduce the above copyright

  16.  *    notice, this list of conditions and the following disclaimer in

  17.  *    the documentation and/or other materials provided with the

  18.  *    distribution.

  19.  *

  20.  * 3. The end-user documentation included with the redistribution,

  21.  *    if any, must include the following acknowledgment:  

  22.  *       "This product includes software developed by the

  23.  *        Apache Software Foundation (http://www.apache.org/)."

  24.  *    Alternately, this acknowledgment may appear in the software itself,

  25.  *    if and wherever such third-party acknowledgments normally appear.

  26.  *

  27.  * 4. The names "Xerces" and "Apache Software Foundation" must

  28.  *    not be used to endorse or promote products derived from this

  29.  *    software without prior written permission. For written 

  30.  *    permission, please contact apache@apache.org.

  31.  *

  32.  * 5. Products derived from this software may not be called "Apache",

  33.  *    nor may "Apache" appear in their name, without prior written

  34.  *    permission of the Apache Software Foundation.

  35.  *

  36.  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED

  37.  * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES

  38.  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE

  39.  * DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR

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  44.  * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,

  45.  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT

  46.  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF

  47.  * SUCH DAMAGE.

  48.  * ====================================================================

  49.  *

  50.  * This software consists of voluntary contributions made by many

  51.  * individuals on behalf of the Apache Software Foundation and was

  52.  * originally based on software copyright (c) 1999, International

  53.  * Business Machines, Inc., http://www.apache.org.  For more

  54.  * information on the Apache Software Foundation, please see

  55.  * <http://www.apache.org/>.

  56.  */

  57. 

  58. package com.sun.org.apache.xerces.internal.dom;

  59. 

  60. /**

  61.  * EntityReference models the XML &entityname; syntax, when used for

  62.  * entities defined by the DOM. Entities hardcoded into XML, such as

  63.  * character entities, should instead have been translated into text

  64.  * by the code which generated the DOM tree.

  65.  * <P>

  66.  * An XML processor has the alternative of fully expanding Entities

  67.  * into the normal document tree. If it does so, no EntityReference nodes

  68.  * will appear.

  69.  * <P>

  70.  * Similarly, non-validating XML processors are not required to read

  71.  * or process entity declarations made in the external subset or

  72.  * declared in external parameter entities. Hence, some applications

  73.  * may not make the replacement value available for Parsed Entities 

  74.  * of these types.

  75.  * <P>

  76.  * EntityReference behaves as a read-only node, and the children of 

  77.  * the EntityReference (which reflect those of the Entity, and should

  78.  * also be read-only) give its replacement value, if any. They are 

  79.  * supposed to automagically stay in synch if the DocumentType is 

  80.  * updated with new values for the Entity.

  81.  * <P>

  82.  * The defined behavior makes efficient storage difficult for the DOM

  83.  * implementor. We can't just look aside to the Entity's definition

  84.  * in the DocumentType since those nodes have the wrong parent (unless

  85.  * we can come up with a clever "imaginary parent" mechanism). We

  86.  * must at least appear to clone those children... which raises the

  87.  * issue of keeping the reference synchronized with its parent.

  88.  * This leads me back to the "cached image of centrally defined data"

  89.  * solution, much as I dislike it.

  90.  * <P>

  91.  * For now I have decided, since REC-DOM-Level-1-19980818 doesn't

  92.  * cover this in much detail, that synchronization doesn't have to be

  93.  * considered while the user is deep in the tree. That is, if you're

  94.  * looking within one of the EntityReferennce's children and the Entity

  95.  * changes, you won't be informed; instead, you will continue to access

  96.  * the same object -- which may or may not still be part of the tree.

  97.  * This is the same behavior that obtains elsewhere in the DOM if the

  98.  * subtree you're looking at is deleted from its parent, so it's

  99.  * acceptable here. (If it really bothers folks, we could set things

  100.  * up so deleted subtrees are walked and marked invalid, but that's

  101.  * not part of the DOM's defined behavior.)

  102.  * <P>

  103.  * As a result, only the EntityReference itself has to be aware of

  104.  * changes in the Entity. And it can take advantage of the same

  105.  * structure-change-monitoring code I implemented to support

  106.  * DeepNodeList.

  107.  * 

  108.  * @version $Id: DeferredEntityReferenceImpl.java,v 1.19 2003/05/08 19:52:40 elena Exp $

  109.  * @since  PR-DOM-Level-1-19980818.

  110.  */

  111. public class DeferredEntityReferenceImpl 

  112.     extends EntityReferenceImpl 

  113.     implements DeferredNode {

  114. 

  115.     //

  116.     // Constants

  117.     //

  118. 

  119.     /** Serialization version. */

  120.     static final long serialVersionUID = 390319091370032223L;

  121.     

  122.     //

  123.     // Data

  124.     //

  125. 

  126.     /** Node index. */

  127.     protected transient int fNodeIndex;

  128. 

  129.     //

  130.     // Constructors

  131.     //

  132. 

  133.     /**

  134.      * This is the deferred constructor. Only the fNodeIndex is given here. 

  135.      * All other data, can be requested from the ownerDocument via the index.

  136.      */

  137.     DeferredEntityReferenceImpl(DeferredDocumentImpl ownerDocument,

  138.                                 int nodeIndex) {

  139.         super(ownerDocument, null);

  140. 

  141.         fNodeIndex = nodeIndex;

  142.         needsSyncData(true);

  143. 

  144.     } // <init>(DeferredDocumentImpl,int)

  145. 

  146.     //

  147.     // DeferredNode methods

  148.     //

  149. 

  150.     /** Returns the node index. */

  151.     public int getNodeIndex() {

  152.         return fNodeIndex;

  153.     }

  154. 

  155.     //

  156.     // Protected methods

  157.     //

  158. 

  159.     /** 

  160.      * Synchronize the entity data. This is special because of the way

  161.      * that the "fast" version stores the information.

  162.      */

  163.     protected void synchronizeData() {

  164. 

  165.         // no need to sychronize again

  166.         needsSyncData(false);

  167. 

  168.         // get the node data

  169.         DeferredDocumentImpl ownerDocument =

  170.             (DeferredDocumentImpl)this.ownerDocument;

  171.         name = ownerDocument.getNodeName(fNodeIndex);

  172.         baseURI = ownerDocument.getNodeValue(fNodeIndex);

  173.         

  174.     } // synchronizeData()

  175. 

  176.     /** Synchronize the children. */

  177.     protected void synchronizeChildren() {

  178. 

  179.         // no need to synchronize again

  180.         needsSyncChildren(false);

  181. 

  182.         // get children

  183.         isReadOnly(false);

  184.         DeferredDocumentImpl ownerDocument =

  185.             (DeferredDocumentImpl) ownerDocument();

  186.         ownerDocument.synchronizeChildren(this, fNodeIndex);

  187.         setReadOnly(true, true);

  188. 

  189.     } // synchronizeChildren()

  190. 

  191. } // class DeferredEntityReferenceImpl