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Posted to j-dev@xerces.apache.org by László Bartos <la...@ovitas.hu> on 2005/09/09 10:41:12 UTC
Parameter entity refs in the internal subset using DOM

I have a problem using xerces-2_7_1: I have to print out the internal subset of XML documents, but the parameter entity refs are always resolved by DOM parser. If I set the feature http://xml.org/sax/features/external-parameter-entities to false, then it is resolved to empty string (so the parameter entity ref disappears.
 
To reproduce the problem:
 
1. Save this as an XML document  
 
<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE PEtest PUBLIC "-//TEST//DTD PETest XML//EN" "petest.dtd" [
<!ENTITY % local.ent PUBLIC "-//TEST//DTD PETest Extension XML//EN" "">
%local.ent;
]>
<PETest>
<front>
</front>
<body>
</body></PETest>
 
2. Set the feature http://xml.org/sax/features/external-parameter-entities to false  and call the DOM parser. Here is a sample program:

public static void main(String argv[]) {

        ParserWrapper parser = null;
        // create parser
        try {
            parser = (ParserWrapper)Class.forName("dom.wrappers.Xerces").newInstance();
            parser.setFeature("http://xml.org/sax/features/namespaces", false);
            parser.setFeature("http://xml.org/sax/features/validation", false);
            parser.setFeature("http://apache.org/xml/features/nonvalidating/load-external-dtd", false);
            parser.setFeature("http://apache.org/xml/features/validation/schema", false);
            parser.setFeature("http://apache.org/xml/features/validation/dynamic", false);
            parser.setFeature("http://apache.org/xml/features/xinclude", false);
            parser.setFeature("http://xml.org/sax/features/external-parameter-entities", false);
            // parse file
            Document document = parser.parse(argv[0]);
            System.out.println(document.getDoctype().getInternalSubset());
        }
        catch (Exception e) {
          e.printStackTrace(System.err);
        }
    } // main(String[])


Result: The getInternalSubset will return 

<!ENTITY % local.ent PUBLIC "-//TEST//DTD PETest Extension XML//EN" "">

which means that the entity ref is resolved to empty string. (If I set http://xml.org/sax/features/external-parameter-entities to true, then the parameter entity ref is correctly resolved and returned bu getInternalSubset, however I need the reference without resolving it.)  


I have found that if I add the following code into org.apache.xerces.parsers.AbstractDOMParser.startParameterEntity(String, XMLResourceIdentifier, String, Augmentations): 

 
   ...
   //append the paremeter entity reference if it was not resolved
        if (fInDTD && fInternalSubset != null && !fInDTDExternalSubset && augs != null) {
          Object skip = augs.getItem(Constants.ENTITY_SKIPPED);
          if (skip instanceof Boolean && (Boolean)skip == Boolean.TRUE) { 
            fInternalSubset.append(name);
            fInternalSubset.append(";\n");
          }
        }
 
then the parameter entity ref is included in the internal subset. 
 
Can somebody confirm whether this is a bug or a feature?
 
Thanks!
 
Laszlo Bartos