Re: Parser LL(*)

From	George Neuner <gneuner2@comcast.net>
Newsgroups	comp.compilers
Subject	Re: Parser LL(*)
Date	2022-03-19 21:14 -0400
Organization	A noiseless patient Spider
Message-ID	<22-03-043@comp.compilers> (permalink)
References	<22-03-039@comp.compilers>

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On Fri, 18 Mar 2022 11:38:48 -0700 (PDT), Andy
<borucki.andrzej@gmail.com> wrote:

>Many language construction needs lookahead depth known in runtime, for
>example difference between function declarations and definitions.
>LL(*) is described in
> https://www.antlr.org/papers/allstar-techreport.pdf.
>This is only one place about LL(*) info?

Terence Parr both invented LL(*) and is the author of the ANTLR tool.
AFAIK, Parr's own papers and books are the only sources of information
about the method.

>If is the simplest idea make LL(1) with several conflicts and first
>speculative trying all paths, and backtrack?

No, the simplest idea was LL(k) with a fixed value of 'k'.  I don't
believe Parr developed the method, but he was one of the pioneers of
using it. Parr authored PCCTS which used LL(k), and early versions of
ANTLR [prior to LL(*)] also used it.

LL(*) eliminates the need for the developer to figure out what 'k' is
optimal for the grammar: too low results in conflicts, too high may
waste processing effort.

>How do speedup it with cache?

??? Lookahead tokens already are cached.

>How make speculative trying in function calls?

Sorry, I'm not sure what you are asking.

George

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Parser LL(*) Andy <borucki.andrzej@gmail.com> - 2022-03-18 11:38 -0700
  Re: Parser LL(*) George Neuner <gneuner2@comcast.net> - 2022-03-19 21:14 -0400
    LL(*) Christopher F Clark <christopher.f.clark@compiler-resources.com> - 2022-03-20 20:05 +0200
      Re: LL(*) George Neuner <gneuner2@comcast.net> - 2022-03-21 15:47 -0400

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