Let's stop parser Hell

[Roman D. Boiko]

On Saturday, 7 July 2012 at 20:27:14 UTC, Dmitry Olshansky wrote:
> So my view on the matter: whether or not lexer is integrated is 
> two-fold question: notation vs implementation.
>
> E.g. it may make regular lexer-like things a part of notation 
> thus having rules like:
> 	Identifier  -> Alpha (Alpha|Number|_)*
>
> Yet it may or may use the same engine for _all_ _rules_, in 
> fact if implementation optimize things by ripping off regular 
> parts of grammar to small DFA engines it would make some kind 
> of lexer behind the scenes!

This is the implementation I have in mind as the only sane way to 
parse PEG efficiently. Plus specializing DFA to only check for 
those terminals which are allowed according to available 
structural information at the moment of their invocation.

>
> Anyway highly hybrid parsers are all the rage now, and reasons 
> are obvious - they runs fast and can be bend by some magic to 
> quite convoluted grammars of modern languages ;)