/*
* The Apache Software License, Version 1.1
*
*
* Copyright (c) 1999 The Apache Software Foundation. All rights
* reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* 3. The end-user documentation included with the redistribution,
* if any, must include the following acknowledgment:
* "This product includes software developed by the
* Apache Software Foundation (http://www.apache.org/)."
* Alternately, this acknowledgment may appear in the software itself,
* if and wherever such third-party acknowledgments normally appear.
*
* 4. The names "Xerces" and "Apache Software Foundation" must
* not be used to endorse or promote products derived from this
* software without prior written permission. For written
* permission, please contact apache@apache.org.
*
* 5. Products derived from this software may not be called "Apache",
* nor may "Apache" appear in their name, without prior written
* permission of the Apache Software Foundation.
*
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
* ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
* USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
* ====================================================================
*
* This software consists of voluntary contributions made by many
* individuals on behalf of the Apache Software Foundation and was
* originally based on software copyright (c) 1999, International
* Business Machines, Inc., http://www.apache.org. For more
* information on the Apache Software Foundation, please see
* <http://www.apache.org/>.
*/
package org.apache.xerces.dom;
import org.w3c.dom.DocumentType;
import org.w3c.dom.EntityReference;
import org.w3c.dom.NamedNodeMap;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
/**
* 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.
*
* @author Arnaud Le Hors, IBM
* @author Joe Kesselman, IBM
* @author Andy Clark, IBM
* @author Ralf Pfeiffer, IBM
* @version
* @since PR-DOM-Level-1-19980818.
*/
public class EntityReferenceImpl
extends ParentNode
implements EntityReference {
//
// Constants
//
/** Serialization version. */
static final long serialVersionUID = -7381452955687102062L;
//
// Data
//
/** Name of Entity referenced */
protected String name;
/** Entity changes. */
//protected int entityChanges = -1;
/** Enable synchronize. */
//protected boolean fEnableSynchronize = false;
//
// Constructors
//
/** Factory constructor. */
public EntityReferenceImpl(CoreDocumentImpl ownerDoc, String name) {
super(ownerDoc);
this.name = name;
isReadOnly(true);
}
//
// Node methods
//
/**
* A short integer indicating what type of node this is. The named
* constants for this value are defined in the org.w3c.dom.Node interface.
*/
public short getNodeType() {
return Node.ENTITY_REFERENCE_NODE;
}
/**
* Returns the name of the entity referenced
*/
public String getNodeName() {
if (needsSyncData()) {
synchronizeData();
}
return name;
}
// REVISIT: Return original entity reference code. -Ac
/**
* Perform synchronize() before accessing children.
*
* @return org.w3c.dom.NodeList
*/
public NodeList getChildNodes() {
synchronize();
return super.getChildNodes();
}
/**
* Perform synchronize() before accessing children.
*
* @return org.w3c.dom.NodeList
*/
public Node getFirstChild() {
synchronize();
return super.getFirstChild();
}
/**
* Perform synchronize() before accessing children.
*
* @return org.w3c.dom.NodeList
*/
public Node getLastChild() {
synchronize();
return super.getLastChild();
}
/**
* Query the number of children in the entity definition.
* (A bit more work than asking locally, but may be able to avoid
* or defer building the clone subtree.)
*
* @return org.w3c.dom.NodeList
*/
public int getLength() {
synchronize();
return super.getLength();
}
/**
* Returns whether this node has any children.
* @return boolean
*/
public boolean hasChildNodes() {
synchronize();
return super.hasChildNodes();
}
/** Returns the node at the given index. */
public Node item(int index) {
synchronize();
return super.item(index);
}
/**
* EntityReference's children are a reflection of those defined in the
* named Entity. This method creates them if they haven't been created yet.
* This doesn't really support editing the Entity though.
*/
protected void synchronize() {
if (firstChild != null) {
return;
}
DocumentType doctype;
NamedNodeMap entities;
EntityImpl entDef;
if (null != (doctype = getOwnerDocument().getDoctype()) &&
null != (entities = doctype.getEntities())) {
entDef = (EntityImpl)entities.getNamedItem(getNodeName());
// No Entity by this name, stop here.
if (entDef == null)
return;
// If entity's definition exists, clone its kids
isReadOnly(false);
for (Node defkid = entDef.getFirstChild();
defkid != null;
defkid = defkid.getNextSibling()) {
Node newkid = defkid.cloneNode(true);
insertBefore(newkid,null);
}
setReadOnly(true, true);
}
}
/**
* Enable the synchronize method which may do cloning. This method is enabled
* when the parser is done with an EntityReference.
/***
// revisit: enable editing of Entity
public void enableSynchronize(boolean enableSynchronize) {
fEnableSynchronize= enableSynchronize;
}
/***/
/**
* EntityReference's children are a reflection of those defined in the
* named Entity. This method updates them if the Entity is changed.
* <P>
* It is unclear what the least-cost resynch mechanism is.
* If we expect the kids to be shallow, and/or expect changes
* to the Entity contents to be rare, wiping them all out
* and recloning is simplest.
* <P>
* If we expect them to be deep,
* it might be better to first decide which kids (if any)
* persist, and keep the ones (if any) that are unchanged
* rather than doing all the work of cloning them again.
* But that latter gets into having to convolve the two child lists,
* insert new information in the right order (and possibly reorder
* the existing kids), and a few other complexities that I really
* don't want to deal with in this implementation.
* <P>
* Note that if we decide that we need to update the EntityReference's
* contents, we have to turn off the readOnly flag temporarily to do so.
* When we get around to adding multitasking support, this whole method
* should probably be an atomic operation.
*
* @see DocumentTypeImpl
* @see EntityImpl
*/
// The Xerces parser invokes callbacks for startEnityReference
// the parsed value of the entity EACH TIME, so it is actually
// easier to create the nodes through the callbacks rather than
// clone the Entity.
/***
// revisit: enable editing of Entity
private void synchronize() {
if (!fEnableSynchronize) {
return;
}
DocumentType doctype;
NamedNodeMap entities;
EntityImpl entDef;
if (null != (doctype = getOwnerDocument().getDoctype()) &&
null != (entities = doctype.getEntities())) {
entDef = (EntityImpl)entities.getNamedItem(getNodeName());
// No Entity by this name. If we had a change count, reset it.
if(null==entDef)
entityChanges=-1;
// If no kids availalble, wipe any pre-existing children.
// (See discussion above.)
// Note that we have to use the superclass to avoid recursion
// through Synchronize.
readOnly=false;
if(null==entDef || !entDef.hasChildNodes())
for(Node kid=super.getFirstChild();
kid!=null;
kid=super.getFirstChild())
removeChild(kid);
// If entity's definition changed, clone its kids
// (See discussion above.)
if(null!=entDef && entDef.changes!=entityChanges) {
for(Node defkid=entDef.getFirstChild();
defkid!=null;
defkid=defkid.getNextSibling()) {
NodeImpl newkid=(NodeImpl) defkid.cloneNode(true);
newkid.setReadOnly(true,true);
insertBefore(newkid,null);
}
entityChanges=entDef.changes;
}
readOnly=true;
}
}
/***/
} // class EntityReferenceImpl