Re: export dot from lpeg grammar?

[Peter Odding <peter@...>]

Graham Wakefield wrote:
> Before I try to do this, I was wondering if somebody could tell me whether it is even possible...
>
> I'd like to graphically render an lpeg grammar, by traversing the grammar nodes and creating a dot-syntax (GraphViz) representation of the nodes and relationships. I don't necessarily have access to how the grammar was made (assume it was passed to me externally), so I just wanted to know if it is possible to query the grammar structure directly by stepping through key-value pairs, or whether some parts of it are opaque?

I can't tell whether it's useful for you or far too low level but the 
LPeg module includes a print function which prints IIRC a representation 
of an LPeg pattern's byte code. I don't see lpeg.print() in the manual 
but last time I checked (just now with Ubuntu's liblua5.1-lpeg2 package) 
it worked. I'm not sure whether lpeg.print() supports io.output() so 
that could be an interesting exercise :-).

Alternatively you could write a "proxy module" that looks like LPeg but 
also maintains an internal tree of grammar nodes which you can query 
however you want to.

 - Peter Odding