Re: Re. Is PASCAL LL/LR

>>>>> In article <1990Oct26.213044.28243@Neon.Stanford.EDU>, sankar@Neon.Stanford.EDU (Sriram Sankar) (SS) writes:


SS> Since PASCAL has a rule that dangling else's associate with the
SS> innermost 'if', it seems obvious to me that PASCAL (at least wrt to the
SS> if statement) is LR. If the dangling else was associated with the
SS> outermost 'if' you can still make the necessary S/R decisions, so I do
SS> think (not looked at it carefully enough though) that this too is LR.


It is even very easy to rewrite the grammar to be LR(1). Someone did that a
few postings ago. See also the dragon book [1], p. 175


The dragon book also states that it is impossible to change the
if-then-else grammar to an equivalent one that is LL(1) (page 192). I have
not seen a proof of this, so I accept this by faith.


[1] Aho, Sethi and Ullman, Compilers, Principles, Techniques and Tools,
Addison-Wesley.
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