Re: how to translate lua pattern "(.*)and(.*)" with lpeg re ?

[Albert Chan <albertmcchan@...>]

> On Jan 22, 2018, at 12:33 PM, Sean Conner <sean@conman.org> wrote:
> 
> It was thus said that the Great albertmcchan once stated:
>> during testing, lpeg backtracking can only handle max string length of 199:
>> is this a lpeg bug ? only 199 chars limit ?
> 
>  Nope.  It's documented.  From the LPeg documentation:
> 
>    lpeg.setmaxstack (max)
> 
>        Sets a limit for the size of the backtrack stack used by
>        LPeg to track calls and choices. (The default limit is 400.)
>        Most well-written patterns need little backtrack levels and
>        therefore you seldom need to change this limit; before
>        changing it you should try to rewrite your pattern to avoid
>        the need for extra space. Nevertheless, a few useful
>        patterns may overflow. Also, with recursive grammars,
>        subjects with deep recursion may also need larger limits.
> 
> And this is exactly what you are hitting:
> 
>    lua: a.lua:18: backtrack stack overflow (current limit is 400)

but my example only need 4 backtracks, not 400 !
And it never say anything about max string length of 199

pat = re.compile "{g <- .g / &'and'} 'and' {.*}"
str = 'and*'

= pat:match( str:rep(50) )    -- string length = 4 * 50 = 200
backtrack stack overflow (current limit is 400)