[antlr-interest] Who can tell me what's the mean of # in the .gfile of parser?

[Bryan Ewbank]

I can only speak for C++ here... have yet to use Java...

The [] are used to pass additional arguments to a production -- formally, to
pass inherited attributes.  They require the production to be declared with
additional inputs.  The current AST node is always the first argument to the
function in the generated C++ code, those you provide are added as additional
arguments.

   relExpr : typeSpec[true] ;

   // when matching a relExpr, attempt to match a typeSpec using the value
   // "true" as an inherited attribute

Note that synthesized attributes (those passed up the tree) can be passed this
way as well...

   relExpr
   { int x = 0; }
   :  myExpr[&x]
      { ... x ... }
   ;

   // the address of "x" is passed to myExpr, and we assume that myExpr will
   // change the value of x in some way before passing control back to the
   // relExpr production.

On 10/24/06, Yu Tao <yutao at td-tech.com> wrote:
> And, can I ask u one futher question?  what's the mean of []?
>
> relationalExpression
> : shiftExpression
>   (
>     (
>       ( LT^ | GT^ | LE^ | GE^ )
>       shiftExpression
>     )*
>   |
>     "instanceof"^ typeSpec[true]
>   )
> ;