Re: why is entity ref expanded in the internal subset (and related questions)?...

[Michael Glavassevich <mr...@ca.ibm.com>]

Hi Jacob,

Jacob Kjome <ho...@visi.com> wrote on 04/08/2006 06:09:30 PM:

> Still haven't found a good answer my previous question below, but at 
> least I have it generally working with the expanded Entity and hack 
> to turn "%BigEntity" into "% BigEntity" so that I don't get parse 
> error upon reparsing the serialized document.  However, I've got a 
> larger issue than any of that, and I think it is my last major issue 
> to figure out....
> 
> When I add EntityReference nodes to the DOM I'm building up, they 
> don't get expanded in the parse tree.  That is, when I print out the 
> DOM tree, all I see are the EntityReference nodes, but none of their 
> children, even though I iterate recursively over all the child 
> nodes.  For instance, for the example listed in my previous question 
> (below), here is the parse tree...
> 
> Document MIME type: null
> Document encoding: UTF-8
> DOM hierarchy:
>      XercesLinkedDocument:
>          DocumentTypeImpl: name=vxml
>           internalSubset=
> <!ENTITY % BigEntity SYSTEM "BigEntity.ent">
> <!ENTITY BigEntity "
>                  <prompt>another prompt</prompt>
>                  <prompt>another prompt</prompt>
>                  <prompt>another prompt</prompt>
>                  <prompt>another prompt</prompt>
>                  <prompt>another prompt</prompt>
>                  <prompt>another prompt</prompt>
>                  <prompt>another prompt</prompt>
> ">
> 
>          ElementNSImpl: vxml
>              Attributes:
>                  AttrImpl: version
>                      TextImpl: 1.0
>              ElementImpl: form
>                  Attributes:
>                      AttrImpl: id
>                          TextImpl: init
>                  ElementImpl: block
>                      TextImpl:
> 
>                      EntityReferenceImpl: name=BigEntity
>                      TextImpl:
> 
> 
> Notice that EntityReferenceImpl has no children.  I expected it to 
> include child nodes of the EntityReference; that is, nodes 
> representing the 7 cases of "<prompt>another prompt</prompt>" defined 
> in the Entity "BigEntity".
> 
> I shouldn't have to manually populate the children of the 
> EntityReference, should I?  I have noticed that I get events on the 
> EntityReference contents as I parse the document using XNI, but all I 
> should have to do for the DOM is simply do the following, no?...
> 
>          EntityReference entityRef = 
> fDocument.createEntityReference(entityName);
>          fCurrentNode.appendChild(entityRef);
> 
> ...where "fCurrentNode" is the current parent node to which children 
> are being appended.  I've read that EntityReference children might be 
> lazily expanded, so that if they aren't accessed no work is 
> performed, but I am accessing the EntityReference children in order 
> to print the DOM tree.  Why don't they show up???  Shouldn't the DOM 
> do this for me?  It clearly has all the information it needs.  What 
> am I missing?

An EntityReference created with Document.createEntityReference() will only 
have children if there's a corresponding Entity node and the replacement 
text for the Entity is available. Strictly using the DOM interfaces you 
cannot create Entity nodes or modify them since they're read-only. 
EntityReference nodes and their children are also read-only. If you're 
wondering how Xerces builds these things take a look at AbstractDOMParser 
[2] and EntityReferenceImpl [3] (particularly synchronizeChildren()).

> thanks,
> 
> Jake
>
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[1] 
http://www.w3.org/TR/2004/REC-DOM-Level-3-Core-20040407/core.html#ID-392B75AE
[2] 
http://svn.apache.org/viewcvs.cgi/xerces/java/trunk/src/org/apache/xerces/parsers/AbstractDOMParser.java
[3] 
http://svn.apache.org/viewcvs.cgi/xerces/java/trunk/src/org/apache/xerces/dom/EntityReferenceImpl.java


Michael Glavassevich
XML Parser Development
IBM Toronto Lab
E-mail: mrglavas@ca.ibm.com
E-mail: mrglavas@apache.org

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