Re: Parsing Roman numbers

joe@erix.ericsson.se (Joe Armstrong) writes:
>Has anybody got a grammar (preferably yacc) for parsing roman numbers?


I don't understand why you need a parser for this. Roman numerals are
described by the regular expression


M*(CM|DC{0,3}|CD|C{0,3})(XC|LX{0,3}|XL|X{0,3})(IX|VI{0,3}|IV|I{0,3})


(using POSIX 1003.2 regular-expression notation) unless you want to write
in a requirement that they be non-null, which would take a slightly more
complex form to deal with the requirement that at least one of the parts
be non-empty. Variations in notation, like allowing VIIII (which was
legitimate Roman practice at one time) are trivial to accommodate.


>Are they LL(k) LR(k) or what?


Since they can be described by a regular expression, they can be parsed
by a regular grammar, which is a still more restricted form. So the
answer is "all of the above".
--
Henry Spencer @ U of Toronto Zoology, henry@zoo.toronto.edu utzoo!henry
--

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