Add LspPeekDefinition

[thomasfaingnaert]

Adds :LspPeekDefinition, which displays the definition in the preview window, similar to VSCode's peek definition.

Fixes #411

[prabirshrestha]

Can you make use of the changes that came in this PR which just got merged. #395

[thomasfaingnaert]

I pushed a basic version that works using:

• preview:
  

• Vim popups:
  

• Neovim floats:
  

I just need to implement alignment in Vim popups and clean the code up a bit as well.

[prabirshrestha]

@jerdna-regeiz could you have a look at this PR first.

[jerdna-regeiz]

Nice!
I'll love that feature.
Still have some remarks (other than the already TODO-comments from yourself).

[jerdna-regeiz]

When win_execute is implemented in nvim we should use that instead of switching focus multiple times (maybe we could even manage without switching at all). But for now I have found no other solution as well :( Variables could be set with nvim_win_set_{var,option}, but I have no alternative for calling zz and the like for adjustment.

[thomasfaingnaert]

@jerdna-regeiz Thanks for reviewing my PR! Regarding my TODO, I tried win_execute with normal! zz and friends, and that doesn't seem to work. Do you know a way to do the alignment in Vim? At the moment, only setting the firstline seems to work, but that's kind of annoying to use because you would have to know the window height in advance, and calculate the position based on that. (At least for center and bottom)

[jerdna-regeiz]

@thomasfaingnaert Have you tried to set the option afterwards with popup_setoptions like when the resize is done for nvim, because the size/content is known then?
We should up the version check to patch 8.1.1561 for popup_setoptions to work.

[thomasfaingnaert]

There's also quite a bit of complex conditionals, which I'm not a big fan of. Perhaps we should set 3 boolean script variables s:use_preview, s:use_vim_popup, s:use_neovim_float instead of always having to type things like

if s:supports_floating && g:lsp_preview_float && !has('nvim')

[jerdna-regeiz]

There's also quite a bit of complex conditionals, which I'm not a big fan of. Perhaps we should set 3 boolean script variables s:use_preview, s:use_vim_popup, s:use_neovim_float instead of always having to type things like

I agree, but it could be done in a separate PR to not mix a new feature with refactoring.

[thomasfaingnaert]

Tried fixing Vim alignment of the popup window in ccaf0f9, but I'm facing one more issue: l:height is 1, as if the popup still contains ..., even though the content should already be set by then, right?

[thomasfaingnaert]

Seems like using a timer and specifying the width and height explicitly works.

Top:

Center:

Bottom:

Remaining problems:

• There are artifacts of a bigger popup window Fixed using redraw!
• The logic breaks down when the popup window is above the cursor Fixed

[thomasfaingnaert]

Added Peek commands for implementation, type definition and declaration. I have not been able to test these, because I don't have a language server that supports these, but they should work the same as LspPeekDefinition.

As for LspReferences, I'm not sure if it would make sense to use the popup window for those, because you have to interact with the quickfix list to go through the list of references?

[clason]

I think it's fine as is -- if somebody comes up with a use case for PeekReferences (I don't see one either), that could be added in a future PR. LGTM!

[prabirshrestha]

@thomasfaingnaert This has merge conflicts. Can you fix it?

[thomasfaingnaert]

@prabirshrestha Fixed merge conflicts.
I'm not sure what changed in the meantime, but Vim's floating window isn't positioned well anymore: it seems to place the preview above the cursor even when there are only 2 lines available above:

I fixed this in 18fcb43 by forcing the popup above/below the cursor depending on if the cursor is in the first or second half of the screen.
Should I change this, or do we leave it as is?

[prabirshrestha]

@thomasfaingnaert Current behavior is good.

I had also sent you an email but haven't got any reply. Can you send me an email. You can find my email at https://github.com/prabirshrestha