Hi List,
I've been revisiting the work I did with the DNP3 parser, aiming to
produce a proper context-free grammar for the application layer
messages. Two questions have popped up and I would appreciate pointers
to any previous work in these areas.
1. Parsing binary (i.e. bitwise) structures below the byte boundary,
e.g. flags and 4-bit numbers. Has there been any work on adapting,
say, LR parsing to efficiently work on a (theoretical) alphabet of
{0,1,$}? I'm assuming that simply using the standard algorithms with
that alphabet would ruin performance. I've spent some thought on
optimizations or ways of side-stepping this issue but my literature
searches have come up empty so far.
2. Classes of finite languages. A lot of practical languages and
structures are actually finite (DNP3 messages have a maximum size,
for instance), but enumerating them for the purpose of parsing or
even pure recognition is impractical/inefficient/undesirable.
Are there any formal categorizations here, maybe along the lines of
"admits a grammar with the number of rules linear/logarithmic/... in
the maximum word length/size of language/..."?
Regards,
Sven
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