[antlr-interest] bi-directional grammar

[Erel Segal]

ANTLR parsers normally work in a single direction - they get an input
document and return some information related to it (e.g. the parse tree). Is
it possible to create, using the same grammar, a generator that will work in
the opposite direction - get the information and return the original
document?

To illustrate what I mean, here is a simple grammar, with a single rule:

question returns [String issue]
    :   'What are your salary demands?' {$issue="Salary";}
    |   'What would you like as your job description?' {$issue="Job
Description";}
    |   'Do you demand a company car?' {$issue="Leased Car";}
    ;

If I create a parser from this grammar, run it on a stream that contains "What
are your salary demands?", and call its question() method, it will return
"Salary".

I would like to be able to do the opposite - send "Salary" as input, and get
"What are your salary demands?" as output, but use the same grammar for both
tasks.

Is this possible with ANTLR?