[antlr-interest] backtrack=false and AST generation

[Giampaolo Tomassoni]

Hello everybody,

I'm facing a problem for which it seems I can't find a reply in the site
docs and faqs.

I would like to parse text based on a very simple grammar (arithmetic
expressions with some boolean enhancement). Every example in the site seems
to adopt a non-LLR notation, while I would instead prefer to use
backtrack=false.

In example, I have stuff like this:


protected
expression
    :	(e=conditionalOrExpression -> $e) c=conditionalExpression
    ;

protected
conditionalExpression
    :	QMARK t=expression COMMA f=expression	-> ???
    |
    ;


Where conditionalExpression should possibly substitute the AST element
produced by "expression" with something like

	-> ^(ITE [TheActualASTRoot] $t $f)

in case the first case is matched.

The fact is that I can't find in the site docs how to replace the top of a
parent rule, if at all possible.

Am I completely headed toward the wrong direction?

Giampaolo