[antlr-interest] exception when generating code from CLI , but not from ANTLRWorks

Roberto Attias Roberto.Attias at arc.com
Tue Dec 11 15:12:20 PST 2007


Hi,
I'm new to ANTLR, so this may be a naive question, please bear with me.

I've written a grammar to parse my own type of expressions. This grammar 
was derived by the C grammar, mainly by stripping out some rules. The 
problem I'm having is that if I generate code from ANTRLWorks 
(Generate/Generate Code) it works ok, but If I run the following:

java -classpath 
"antlr-3.0b7/lib/antlr-3.0b7.jar;antlr-3.0b7/lib/stringtemplate-3.0.jar;antlr-3.0b7/lib/antlr-2.7.7.jar" 
org.antlr.Tool MyExpression.g

I get the following error:

ANTLR Parser Generator  Version 3.0b7 (April 12, 2007)  1989-2007
error(100): ARCPlotterExpression.g:0:0: syntax error: assign.types: 
<AST>:0:0: u
nexpected end of subtree
error(10):  internal error: ARCPlotterExpression.g : 
java.lang.ClassCastExceptio
n: antlr.ASTNULLType cannot be cast to org.antlr.tool.GrammarAST
org.antlr.tool.AssignTokenTypesWalker.block(AssignTokenTypesWalker.java:1215)
org.antlr.tool.AssignTokenTypesWalker.rule(AssignTokenTypesWalker.java:1030)
org.antlr.tool.AssignTokenTypesWalker.rules(AssignTokenTypesWalker.java:610)
org.antlr.tool.AssignTokenTypesWalker.grammarSpec(AssignTokenTypesWalker.java:49
2)
org.antlr.tool.AssignTokenTypesWalker.grammar(AssignTokenTypesWalker.java:363)
org.antlr.tool.Grammar.setGrammarContent(Grammar.java:539)
org.antlr.tool.Grammar.<init>(Grammar.java:448)
org.antlr.Tool.getGrammar(Tool.java:331)
org.antlr.Tool.process(Tool.java:267)
org.antlr.Tool.main(Tool.java:70)


Can anybody hints to what might be wrong?

         Thanks,
                         Roberto 
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