Pegged, From EBNF to PEG

[Philippe Sigaud]

On Wed, Mar 14, 2012 at 10:48, Dmitry Olshansky <dmitry.olsh at gmail.com> wrote:

>> That's one of the caveats on PEG. That and greedy operators.
>>
>> 'a*a' never succeeds because 'a*' consumes all the available a's.
>>
>
> Hey, wait, I thought there has to be backtrack here, i.e. when second 'a'
> finally fails?

PEG only do local backtracking in 'or' choices, not in sequences. I
think that's because the original author was dealing with packrat
parsing and its O(input-size) guarantee.

I remember trying compile-time backtracking in another similar library
in D 1-2 years ago and getting lots of pb. I might add that in Pegged,
but I don't know the consequences. How do you do that in std.regex?

(nice article btw, I learnt some about regexes)