[vim/vim] erlangBitType exec time (#5593)

Marcus Johansson

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Feb 7, 2020, 3:57:54 PM2/7/20

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Describe the bug
I wouldn't describe this as a bug, just letting you know.
The erlangBitType syntax match expression may cause significant lag when scrolling/redrawing.

To Reproduce
Edit any file with relatively long lines with bit syntax.
You can e.g. :set relativenumber just to make it more obvious, but but required.
This is a typical output of :syntime report after jumping 5 times.

  TOTAL      COUNT  MATCH   SLOWEST     AVERAGE   NAME               PATTERN                                                                                            
  0.373476   3437   3186    0.002456    0.000109  erlangBitType      ...
  0.035630   251    0       0.000770    0.000142  erlangMacro        ...
  0.022778   2186   1944    0.002006    0.000010  erlangOperator     ...

Expected behavior
Matchtime/count of erlangBitType simillar to all others

Version
All versions I've tested. e.g. vim 8.0, neovim

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K.Takata

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Feb 7, 2020, 4:19:14 PM2/7/20

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https://github.com/vim/vim/blob/f2460a3aec89e70d4bab8d2369ee3f78cc43f09a/runtime/syntax/erlang.vim#L91

At a glance, the \%(\/\%(\s\|\n\|%.*\n\)*\)\@<= part looks very slow.
How about changing \@<= to \zs?

Christian Brabandt

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Feb 7, 2020, 4:53:31 PM2/7/20

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Looks like an expansive pattern. You might want to discuss this with the maintainer of the file, mentioned at the top. Perhaps he has an idea how to improve it (e.g. use \zs instead of the look around or at least limit the look around)

> Am 07.02.2020 um 22:18 schrieb K.Takata <notifi...@github.com>:
>
>

> https://github.com/vim/vim/blob/f2460a3aec89e70d4bab8d2369ee3f78cc43f09a/runtime/syntax/erlang.vim#L91
>
> At a glance, the \%(\/\%(\s\|\n\|%.*\n\)*\)\@<= part looks very slow.
> How about changing \@<= to \zs?
>
> —

dkearns

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Mar 25, 2026, 3:36:01 AM (yesterday) Mar 25

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dkearns left a comment (vim/vim#5593)