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Programs in most computer languages, like Perl, are one-dimensional linear strings. The 'language' above (these used to be called railroad diagrams) is two-dimensional and parsing nonlinear languages is known to be difficult in general.

Another example of a two-dimensional language is Befunge, a language whose sole purpose is to be hard to parse :-) You might try looking at Befunge parsers to get an idea of how to go about it.

I have not tried to understand your compiler, but if I was to go about this, I would split each diagram into a two-dimensional array of single characters. Then I would 'walk' the diagram, building up a topological graph. Finally, I would convert that graph/NFA into a grammar.

But the fastest method might just be to convert the diagrams manually yourself.


In reply to Re: Parsing BNF syntax diagrams.. by kvale
in thread Parsing BNF syntax diagrams.. by castaway

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