[antlr-interest] Can someone please explain

Terence Parr parrt at jguru.com
Wed Jun 26 11:03:31 PDT 2002

On Tuesday, June 25, 2002, at 05:57  AM, Bogdan Mitu wrote:

> --- Tom Moog <tmoog at polhode.com> wrote:
>> Well, there's always pccts (aka antlr v1) for C++.
>> It does full LL(k) when linear lookahead isn't sufficient.
> Just out of curiosity:
> What is the difficulty of using full LL(k)? Is it just the space 
> required to
> store lookahead sets (trees?)?

Space and time go from O(n*k) to O(n^k) ;)  Obviously it can be done in 
most cases (see PCCTS) with some tricks combining approx and full to 
render full lookahead, but it can still generate land mines.  I'll be 
using a thread to do the computations in the future so I can kill it if 
it takes too long to compute and fall back on approx.



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