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 * Licensed to the Apache Software Foundation (ASF) under one or more

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 * this work for additional information regarding copyright ownership.

 * The ASF licenses this file to You under the Apache License, Version 2.0

 * (the "License"); you may not use this file except in compliance with

 * the License.  You may obtain a copy of the License at

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 *      http://www.apache.org/licenses/LICENSE-2.0

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 * distributed under the License is distributed on an "AS IS" BASIS,

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

/**

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

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

 * character entities, should instead have been translated into text

 * by the code which generated the DOM tree.

 * <P>

 * An XML processor has the alternative of fully expanding Entities

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

 * will appear.

 * <P>

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

 * or process entity declarations made in the external subset or

 * declared in external parameter entities. Hence, some applications

 * may not make the replacement value available for Parsed Entities

 * of these types.

 * <P>

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

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

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

 * supposed to automagically stay in synch if the DocumentType is

 * updated with new values for the Entity.

 * <P>

 * The defined behavior makes efficient storage difficult for the DOM

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

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

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

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

 * issue of keeping the reference synchronized with its parent.

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

 * solution, much as I dislike it.

 * <P>

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

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

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

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

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

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

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

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

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

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

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

 * <P>

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

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

 * structure-change-monitoring code I implemented to support

 * DeepNodeList.

 *

 * @xerces.internal

 *

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

 */

public class DeferredEntityReferenceImpl

    extends EntityReferenceImpl

    implements DeferredNode {

    //

    // Constants

    //

    /** Serialization version. */

    static final long serialVersionUID = 390319091370032223L;

    //

    // Data

    //

    /** Node index. */

    protected transient int fNodeIndex;

    //

    // Constructors

    //

    /**

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

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

     */

    DeferredEntityReferenceImpl(DeferredDocumentImpl ownerDocument,

                                int nodeIndex) {

        super(ownerDocument, null);

        fNodeIndex = nodeIndex;

        needsSyncData(true);

    } // <init>(DeferredDocumentImpl,int)

    //

    // DeferredNode methods

    //

    /** Returns the node index. */

    public int getNodeIndex() {

        return fNodeIndex;

    }

    //

    // Protected methods

    //

    /**

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

     * that the "fast" version stores the information.

     */

    protected void synchronizeData() {

        // no need to sychronize again

        needsSyncData(false);

        // get the node data

        DeferredDocumentImpl ownerDocument =

            (DeferredDocumentImpl)this.ownerDocument;

        name = ownerDocument.getNodeName(fNodeIndex);

        baseURI = ownerDocument.getNodeValue(fNodeIndex);

    } // synchronizeData()

    /** Synchronize the children. */

    protected void synchronizeChildren() {

        // no need to synchronize again

        needsSyncChildren(false);

        // get children

        isReadOnly(false);

        DeferredDocumentImpl ownerDocument =

            (DeferredDocumentImpl) ownerDocument();

        ownerDocument.synchronizeChildren(this, fNodeIndex);

        setReadOnly(true, true);

    } // synchronizeChildren()

} // class DeferredEntityReferenceImpl