[antlr-interest] Creation of new tree nodes

[Greg Smolyn]

Hi,

I'm trying to perform an AST transformation that will effectively  
replace a node + subnodes with a mostly artificial new node.

However, ANTLR 3.1 seems to be unhappy with the syntax.

Here's the problem code in question  (assume DocumentWriteContents  
gets set somewhere down in the expression rule):


statement
scope { IToken DocumentWriteContents; }
     : ^(STMT emptyStatement)
     | ^(STMT variableDeclaration)
	| ^(STMT expression) -> { $statement::DocumentWriteContents!=null }?
                              ^(STMT
                                (BLOCK
                                 (STMT (VAR["var"] (ASSIGN["="]  
Identifier["_SL_temp"] (CALL (BYFIELD Identifier["document"]  
Identifier["createElement"]) (ARGS StringLiteral["'div'"])))))
                                 (STMT (ASSIGN["var"] (BYFIELD  
Identifier["_SL_Temp"] Identifier["innerHTML"])  
$statement::DocumentWriteContents ))
                                 (STMT (CALL (BYFIELD (BYFIELD  
Identifier["document"] Identifier["body"]) Identifier["appendChild"])  
(ARGS Identifier["_SL_Temp"])))))
                            -> ^(STMT expression)
	| ^(STMT ifStatement)
	| ^(STMT doStatement)
	| ^(STMT whileStatement)
	| ^(STMT forStatement)
	| ^(STMT continueStatement)
	| ^(STMT breakStatement)
	| ^(STMT returnStatement)
	| ^(STMT withStatement)
	| ^(STMT labelledStatement)
	| ^(STMT switchStatement)
	| ^(STMT throwStatement)
	| ^(STMT tryStatement )
     ;

STMT, BLOCK,  CALL, BYFIELD and ARGS are all artificial tokens.

Thanks for your help!

-greg