Feature: Add negative comparison for regex (and other things?)

[fwsmit]

Even with posix regex implemented (#1017) you cannot do negative matching (for example "appname is not firefox"). To achieve negative matching in an easy way, I'd suggest to allow writing != instead of = for regex rules. In the future this could even be used for other things like matching msg_urgency != critical.

This would look as follows:

[bigger-icons]
    appname != firefox # except for you, firefox
    icons_size = 64

[bynect]

I had this idea: provide (optional) support for extended regexes. On my machine ldd dunst shows libpcre2 (I don't know which lib pulls it in). We may want to actually use it ourselves by adding an optional compile time flag PCRE or something like that. This will allow the use of negative matches and many other nice things. (instead of posix regex)

Do you think this is feasible?

[fwsmit]

Could be feasible yeah. You'll have to see if it's worth the effort

[pancro]

Adding PCRE support would allow for negative matches, e.g.

^(?!.*firefox)

and it would also allow more useful features like case-insensitive matches which can be extremely useful, e.g.

(?i)^(?!.*firefox)

Although the syntax is heavier on the eye.

Is it worth opening a specific issue for implementing PCRE support as well as POSIX regex support?

e.g. a global option like:

enable_pcre = true

and the necessary logic to ensure that only one of enable_posix_regex and enable_pcre can be true.

The rationale for implementing both (instead of a compile-time option) would be:

• dunst seem to link libpcre2 as noted in this issue
• configuration files would be compatible with dunst irrespective of compile-time options
• users already using POSIX regex wouldn't have to change anything