Optimization for notmuch tag by implicit filters

[Pieter Praet]

On Thu, 14 Apr 2011 10:23:46 +0200, Florian Friesdorf <flo at chaoflow.net> wrote:
> 
> With 60k messages and 12k tagged as sent:
> 
> $ time notmuch tag +sent -- from:flo at chaoflow.net
> 
> real	0m8.561s
> user	0m8.069s
> sys	0m0.212s
> 
> $ time notmuch tag +sent -- from:flo at chaoflow.net and not tag:sent
> 
> real	0m0.043s
> user	0m0.036s
> sys	0m0.006s
> 
> 
> This could be made implicit:
> 
> notmuch tag +A +B -- <filter>
> -->
> notmuch tag +A +B -- <filter> and not \(tag:A and tag:B\)
> 
> Apply command, if one of the tags is not set.
> 
> 
> notmuch tag -C -D -- <filter>
> -->
> notmuch tag -C -D -- <filter> and \(tag:C or tag:D\)
> 
> Apply command, if one of the tags is set.
> 
> 
> notmuch tag +A +B -C -D -- <filter>
> -->
> notmuch tag +A +B -C -D -- <filter> and \(not tag:A or not tag:B\ or tag:C or tag:D\)
> 
> 
> In order to enforce tagging and disable the filter there could be a
> flag.
> 
> I lack the knowledge/time to implement it, but I think it's at least
> worth documenting it.
> 
> -- 
> Florian Friesdorf <flo at chaoflow.net>
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Most of us already do this explicitly in our tagging scripts, so no harm
in making it standard behaviour, I guess.

Though to keep the implementation nice & clean, I'd advise against the
use of parens: no need for escape chars, no messing with De Morgan's
law, simply map the tag operations to their inverse in conjunctively
joined filters:

notmuch tag +A +B -- <filter> and not tag:A or not tag:B
notmuch tag -C -D -- <filter> and tag:C or tag:D
notmuch tag +A +B -C -D -- <filter> and not tag:A or not tag:B or tag:C or tag:D

Peace

-Pieter