On 7 Mar 2006, at 16:55, Frans Englich wrote:
sometimes I really feel like writing rules like this:
Rule: (A | B) C D
Which would allow A C D or B C D. What is the reason to that such
constructs
are not possible?
Simply because nobody has implemented it. I think some grads at
Berkeley made a Bison version with such constructs.
Interesting. So who knows, it will be interesting to see if
something pops up
at somepoint.
If somebody gets interested in implementing it. It should not be too
difficult, at this point, as Bison itself has a .y grammar, making
grammar extensions fairly easy, and the method used to implement this
kind of extensions is merely by introducing some new hidden
variables, in a similar way empty rules are implemented.
Hans Aberg
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