Add forerunner job status sign and a delay timer for running maple

[liuchengxu]

• Add the forerunner job status sign:

  • !files: the forerunner job is not finished yet. If you type something rightnow, the result is incomplete and uncertain.

  • *files: the forerunner job is done, now the responose of vim-clap should be fast and deterministic.

  The forerunner job is normally super fast and imperceptible unless you have 1 million items, in which case it may take seconds but Vim/NeoVim is still well responsive and you won't feel any typing lag.

• Add the delay for running maple.

I proposed serveral solutions for the perfornce improvement in #140. Although I have not tried all of them, the maple extension written in Rust already works very well. If you want to a performant vim-clap, please install Rust and then run :call clap#helper#build_all() in Vim/NeoVim.

Close #140.

[ImmemorConsultrixContrarie]

I should say, all this flickering looks just bad. Maybe text field should be cleared by new results, not just wiped at the time user changes input? Because that doesn't look as bad as gif in this PR.

Also, this may be more perceptible and smooth if results would be shown line by line with very short delay, not just dropped on the screen all at once. Though I'm not quite sure about it.

[liuchengxu]

The redraw is caused by the job inherently to my knowledge, not the rendering strategy used by vim-clap. Rendering the content linewise does not help.

:Clap blines in this gif does not use the async job, but the built-in filter which is sync, so it does not have the redraw issue.

[liuchengxu]

Hmm, I just tried not clearing the previous content anyway, which seems to help indeed. Can you also check it out, see if it's really helpful? @ImmemorConsultrixContrarie

diff --git a/autoload/clap/impl.vim b/autoload/clap/impl.vim
index ec5c2cd..092a389 100644
--- a/autoload/clap/impl.vim
+++ b/autoload/clap/impl.vim
@@ -201,7 +201,7 @@ function! s:on_typed_async_impl() abort
     return
   endif
 
-  call g:clap.display.clear()
+  " call g:clap.display.clear()
 
   let cmd = g:clap.provider.source_async_or_default()

[ImmemorConsultrixContrarie]

Hmm, I just tried not clearing the previous content anyway, which seems to help indeed. Can you also check it out, see if it's really helpful?

Err... No. I don't use either vim or vim-clap. I just write code blindly, heh.

[liuchengxu]

I just write code blindly

I actually very admire this..., I can't live without these tools.

Anyway I have confirmed that not clearing the outdated result immedidately indeed avoids the visual flicker. Thank you! @ImmemorConsultrixContrarie