grammar T; options { language=Python; } program : method ; method /* name is visible to any rule called by method directly or indirectly. * There is also a stack of these names, one slot for each nested * invocation of method. If you have a method nested within another * method then you have name strings on the stack. Referencing * $method.name access the topmost always. I have no way at the moment * to access earlier elements on the stack. */ scope { name } : 'method' ID '(' ')' {$method::name=$ID.text;} body ; body: '{' stat* '}' ; stat: ID '=' expr ';' | method // allow nested methods to demo stack nature of dynamic attributes ; expr: mul ('+' mul)* ; mul : atom ('*' atom)* ; /** Demonstrate that 'name' is a dynamically-scoped attribute defined * within rule method. With lexical-scoping (variables go away at * the end of the '}'), you'd have to pass the current method name * down through all rules as a parameter. Ick. This is much much better. */ atom: ID {print "ref "+$ID.text+" from method "+$method::name} | INT {print "int "+$INT.text+" in method "+$method::name} ; ID : ('a'..'z'|'A'..'Z')+ ; INT : '0'..'9'+ ; WS : (' '|'\t'|'\n')+ {$channel=HIDDEN} ;
