Re: [Boost-users] Comparison boost spirit and ANTLR

Subject: Re: [Boost-users] Comparison boost spirit and ANTLR
From: salvatore dario minonne (dario.minonne_at_[hidden])
Date: 2013-05-29 12:18:38

I'd like to apologize for my previous email which was somehow laconic.
My goal was to stress the fact that ANTLR does not generate LR parser.

To add something to original question I'd like to add that TTBOMK the
latest version of ANTLR (v4) doesn't generate C/C++ code and the v3
generates only C.

Hope it useful for Olivier

On Wed, May 29, 2013 at 6:05 PM, Evan Driscoll <driscoll_at_[hidden]> wrote:

> On 05/29/2013 09:51 AM, Larry Evans wrote:
> > On 05/29/13 07:59, salvatore dario minonne wrote:
> >> ATLR is LL as well
> > More specifically, ANTLR is LL(k) for some k>0:
> >
> > http://en.wikipedia.org/wiki/LL_parser
>
> Actually *that's* not true either. Antlr generates LL(*) parsers. With
> some restrictions, the generated parsers have infinite lookahead.
>
> For instance,
>
>   nonterm1 : (term1)* term2
>              (term1)* term3
>
> is not LL(k) for any k as if you give me a k I give you the string
> "term1^k term2" and you can't decide between those alternatives, but
> that grammar is is LL(*).
>
> I'm not sure how much this actually affects real usage, just trying to
> be accurate. There is at least one example of something you may want to
> do which is LL(*) but not LL(k)
>
>    classMember: modifier* type ident SEMI
>               | modifier* type ident LPAREN arglist RPAREN body
>
>    modifier: PUBLIC | PRIVATE | PROTECTED | STATIC | ...
>
>
> (The description of what makes a grammar LL(*) requires more than I feel
> like explaining now.)
>
> Evan
>
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-- 
SDM