Additional information:
This was executed in an Eclipse project R, with other projects in the same workspace.
The DRL file contains an experimental rule which happens to contain patterns
that refer to classes which are not in project R, but in some other project.

The FileReader is set up with an absolute path, but the succsessful building uses
   kBuilder.add( ResourceFactory.newFileResource( "...some.drl" ), ResourceType.DRL );

After omitting the "experimental rule", parser.parse(...) succeeds.

-W


On 1 November 2010 16:28, Wolfgang Laun <wolfgang.laun@gmail.com> wrote:
Trying to parse an absolutely correct DRL (a regular build succeeds)...
 
    DrlParser parser = new DrlParser();
    FileReader fr = new FileReader( "some.drl" );
    // ... read file, create String
    String drl = ...
    PackageDescr pd =  parser.parse( true, drl );
    if( pd == null ){
      System.out.println( "pd id null!" );
      System.out.println( parser.getErrors() );
    } else {
       ...
    }

...and the error is:

pd id null!
[[-1,0]: Unknown error while parsing. This is a bug. Please contact the Development team.]

?
-W