Parse fractional second

[mremond]

I added the s library as a requirement. It is probably possible to do without it.
This is my first elisp patch, so I still need to learn ;)
This solve a problem I had with server that implement fractional second for more accurate message sorting.

However, @legoscia please, let me know if you have some tips to do without the slice command and I will update the PR.

Thanks !

[legoscia]

Thanks for the patch! I think you could do this with split-string instead of s-slice-at, thus avoiding the need for an extra dependency.

Could you add a test case in the tests directory as well? Create a new file, parse-time.el, and add something like:

(unless (equal (jabber-parse-time "2015-02-07T15:56:17.12Z") '(21718 13729))
  (error "fractional time parse failed"))

Then add the file in tests/Makefile.am and test with make check.

I'll need to think about what to do about notifications vs history. In principle, all history comes before the room subject, and all fresh messages come after it (XEP-0045 section 7.2.16), but if the MUC server doesn't obey that and never sends a subject, we might end up never showing notifications, which would be bad. Perhaps a good heuristic would be to turn notifications on for a certain room whenever we see a timestamp within the last minute...

[legoscia]

Oh, a second test case would be a time stamp with fractional seconds and a time zone that's not Z.

[legoscia]

Hm wait, on further thought split-string is not the right function, since it drops the "separator". string-match and match-string are probably the way to go.

[mremond]

Thanks, that's good advice and good exercise or me to perfect my elisp learning :)