Comments (3)
Optional rules are supported in Bullwinkle, but they have to be written following the BNF syntax, where the "?" symbol is not allowed. So instead of writing:
<S> := <A> <B>?;
you should write instead:
<S> := <A> <B> | <A>;
There are two ways to parse S: either as A followed by B, or as A alone --which has the effect of making B optional.
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I came to the same conclusion. But I felt re-writing the whole Java BNF this way would be too much work and would make for a really ugly BNF anyway. So I added the feature myself.
I'm thinking of sharing the code but will wait until Bullwinkle is released under MIT.
from bullwinkle.
I just changed the header comments to the MIT license.
from bullwinkle.
Related Issues (15)
- Change getRules to parseRules in BnfParser
- Refactor parseRule
- InvalidGrammarException should be a RuntimeException
- Ellaborate error messages HOT 4
- A more permissive license HOT 2
- Not an issue HOT 4
- BNF command line parser
- NoClassDefFoundError
- Cannot get example working HOT 1
- Count number of times a production is fired
- Cannot find rule for token HOT 3
- Help with "one or more" string HOT 5
- Allow regex case in multi-case rule
- Maven dependency HOT 2
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