Re: How to raise an error

[Luca]

CreateIdentifierNode function can return a pointer to a struct (typically a 
pointer to a node).
You can set the error in a field inside the node; you have also to increase an error counter (increase 
the same variable inside yyerror).

Then you can parse the remaining input, for example:

exp:    
         INTEGER                        {$$ =AddIntNode($1);}
        |identifier                     {$$ = $1; }
        |exp '+' exp                    {$$ = AddNode('+',$1,$3); /*check the 
two children and returns a pNode */}      

so AddIntNode and AddNode can recognize the error and perform the right action 
(so they can propagate the error up to the root of the syntax tree).


I suggest to read the follwing pdf:
http://epaperpress.com/lexandyacc/download/lexyacc.pdf
there is an example for a calculator using node.

Bye,
Luca


BradDaBug ha scritto:
> My parser basically works by calling various functions that build a big parse
> tree. Something like this:
>
> identifier:
>    LOCALIDENTIFIER { $$ = CreateIdentifierNode(yytext); }
>
> The problem is that I need to be able to detect errors within those
> functions (for example, is the identifier name too long) and propagate them
> back to Bison. But I don't know how. I don't have access to the YYERROR
> macro in those functions, and I can't manually "goto yyerrorlab;" since I'm
> in a different function.
>
> How can I do it?
>