[antlr-interest] Error reporting with the C runtime: tokenNames

[Jim Idle]

Ned Gill wrote:
> Hi list.
>
> I'm writing a custom displayRecognitionError for my parser, based heavily  
> on the default in antlr3baserecognizer.c.  For reporting the names of  
> tokens, I'm using the tokenNames array passed in for messages such as "...  
> Missing ']'".  However, for named tokens (e.g. those created in the tokens  
> { ... } stanza), tokenNames contains er.. the name of the token.  So for  
> example, I'm using the names RPAREN for the token ')', and I see messages  
> like "... Missing RPAREN."  Unfortunately these names aren't going to make  
> any sense for users.
>   
It is the same as the other targets, in that you need to create a local 
function that returns/displays/adds to the message, the name you want to 
use for error display. It is just a switch statement on the token type 
basically, or you could create a local map and initialize it the first 
time it is required. It is just a bit of slog really. Java provides a 
method to override to do this, but in C, you just call your own local 
function.
> I understand why tokenNames is the way it is (named tokens could be more  
> compilcated than a simple string).  However, is there a way that I can  
> show the matching string for simple tokens rather than the name, (possibly  
> limited to just those declared with "tokens {...}")?
>
> I considered removing some or all of the simple named tokens, but this  
> would be inconvenient as my grammar generates trees which re-use the same  
> tokens.
>
> I'm already maintaining my own version of C.stg for other reasons, so I  
> could make changes to that if necessary.
>   
Let me know if there is something that you changed that really needs to 
be in the main template - I know of at least two things that I need to 
resolve (@after for instance), but obviously would prefer that you can 
use the main branch. I don't know when you split, but there have been 
one or two tweaks to C.stg, so make sure you pick them up.

Jim