Robert Sanderson wrote:
>>If it's the last grammar you put up, it is unabiguous which is good.
>>And, yes, it doesn't allow
>> >p1 b and >p2 c
>>I can live with that. Especially, since
>> >p1 b and/a>p2 c
>>would be ambiguous - and hard to read. To achive this with Alan's
>>grammar you would have to use
>> >p1 and/a (>p2 c)
>Can parsers have a rule (not in the BNF) that makes /a>b always a single
>modifier, rather than a modifier and a prefix?
Well, if I use my grammar and let YACC use it, it will choose that
>Making /a >b=c a parse error, but it would be in the BNF anyway as it's
>not ()ed, so you're not losing anything?
Don't know what you mean? What BNF? Alan's? Mine?
Alan's BNF disallows a prefix specification following a boolean operator
(no matter what). So anything following a boolean operator will be
treated as a modifier.
The YACC grammar allows both, but is ambiguous - still works in an
implementation since YACC chooses the right thing - when a conflict arises.
I propose we choose Alans unambiguous BNF as the spec.
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