Re: Regex negative lookahead failed

[David Bremner <david@tethera.net>]

Erwan Hingant <erwan.hingant@mailo.com> writes:

> Hello,
>
>   I have some troubles with regex negative lookahead. When searching 
> in 
> all directories but one (say inbox), I do the following query:
>
>  > notmuch search folder:"/^(?!inbox)/"
>

As far as I know, lookaheads are not supported by POSIX regex, which is
what notmuch uses. regex(7) is a bit terse, but the relevant section
seems to be

       An atom is a regular expression enclosed in "()" (matching a match  for
       the  regular  expression),  an  empty  set  of  "()" (matching the null
       string)(!), a bracket expression (see below), '.' (matching any  single
       character),  '^' (matching the null string at the beginning of a line),
       '$' (matching the null string at the end of a line), a '\' followed  by
       one  of the characters "^.[$()|*+?{\" (matching that character taken as
       an ordinary character),  a  '\'  followed  by  any  other  character(!)
       (matching  that character taken as an ordinary character, as if the '\'
       had not been present(!)), or a single character with no other  signifi‐
       cance  (matching  that character).  A '{' followed by a character other
       than a digit is an ordinary character, not the beginning of a bound(!).
       It is illegal to end an RE with '\'.

I'm not sure your whole problem, but maybe regex is not the right answer
here. In general they should be a last resort in notmuch, for efficiency
reasons. Does "not folder:inbox"  do what you want?