[antlr-interest] Constants in AST

[Johannes Luber]

Brisard, Fred D schrieb:
> Is there a simple way to insert constants into an AST?  It seems like 
> the operators require anything being inserted into an AST node to be 
> either a lexical token or a parser rule. 
> 
> I just want to put a simple constant in a node so that I can search on 
> it later.  Maybe that’s a bad idea so it isn’t supported.
> 
> I did notice that I could define fragment lexical tokens that could be 
> inserted.
> 
> Thanks for any clarification or suggestions.
> 
> Regards, Fred
> 
Did you try imaginary tokens? Those are defined in the tokens section 
like this:

tokens {
CONSTANT_2;
}

And they can be inserted like real tokens anywhere you need them.

Johannes