[antlr-interest] Problems with AST parsers in Antlrworks 1.0.1

[Robin Davies]

Probably a very beginner antlr question, but maybe not.

I'm trying to debug the CMinus.g AST parser sample from the manual:

http://media.pragprog.com/titles/tpantlr/code/trees/CMinus/CMinus.g

When I start the AnltrWorks debugger, and step through a couple of steps, in AntlrWorks 1.01, I get the following exception:

Exception in thread "main" java.lang.NullPointerException
 at org.antlr.runtime.debug.DebugTreeAdaptor.nil(DebugTreeAdaptor.java:45)
 at CMinusParser.aexpr(CMinusParser.java:1731)
 at __Test__.main(__Test__.java:22)

(And the same with pretty much anything that has options {output=AST;} // build trees, I think.

I'm coming to this with a C# background and not a whole lot of Java experience. There's a very real risk that I have my classpath set up properly. I have a classpath to the source distribution, but no classpath to the Antlworks jar. Is that wrong? 

My classpath:

.;C:\Program Files\Java\jre1.5.0_10\lib\ext\QTJava.zip;C:\usr\src\antlr-3.0\lib\
antlr-2.7.7.jar;C:\usr\src\antlr-3.0\lib\antlr-2.7.7.jar;C:\usr\src\antlr-3.0\li
b\antlr-3.0.jar;C:\usr\src\antlr-3.0\lib\antlr-runtime-3.0.jar;C:\usr\src\antlr-
3.0\lib\stringtemplate-3.0.jar

Environment: Vista, JRE 1.5.
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