[antlr-interest] packrat vs. LL(*)

Michael micha-1 at fantasymail.de
Mon Jun 8 03:43:53 PDT 2009


Am Monday 08 June 2009 11:19:49 schrieb Steven Obua:
> Hi,
>
>
> So, as I understand, with backtrack=true and memoize=true I basically
> switch to linear time / linear space packrat parsing.

I'm not sure if it's a the same as a packrat parser (like rats! for example).
There are some differences, the biggest is in a packrat parser you have 
ordered choises:  
if in a rule  e1 | e2   the first (e1) succeeds. the second is ignored. So 
unlike normal BNF definitions you cannot simply switch the order of the 
alternatives.

And you don't use a separate lexer, it's all in one grammar

 Michael


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