[antlr-interest] Line number help

[Micheal J]

Hi,

> > However, if I have a rule such as:
> >
> > expression
> >         :       #(EXPR expr)
> >         ;
> >
> > the line number and column number within the AST are always 
> zero.  I 
> > suspect this has to do with the way they are constructed in the 
> > parser. As an interim measure, I have developed routines which walk 
> > the expression structure to find the starting and ending 
> line numbers, 
> > but is there any easy way of appending this information 
> right into the 
> > EXPR node?  That is, any way short of modifying each and every rule 
> > where I create such a tree structure when parsing the code?

> 
> I've had to fix the same problem with my grammar today. I 
> ended up defining a method like this:
> 
>     private void setLineCol(AST t, LineColAST child) {
>         ((LineColAST)t).setLine(child.getLine());
>         ((LineColAST)t).setCol(child.getCol());
>     }
> 
> This is for C#. Then, in my grammar, I replace rules like this one:
> 
> expression
>     : start:exp
>       {## = #([EXPR,"EXPR"], #expression);  }
>     ;
> 
> by this
> 
> expression
>     : start:exp
>       {## = #([EXPR,"EXPR"], #expression); setLineCol(##, #start); }
>     ;
> 
> I noticed this is how it is done in the grammar for SDL 2000, 
> available at the antlr website, so I'm doing the same.

KCSParse/csharp_v1 uses a similar scheme: ##.CopyPositionFrom( #some_node );


One difference is that CopyPositionFrom(node) is a method on a custom AST
class.

Micheal


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