LSP Folding provider

[DeltaEvo]

I saw some commits these days on the css-language-service about folding https://github.com/Microsoft/vscode-languageserver-protocol-foldingprovider/blob/master/protocol.foldingProvider.md :tada:

I think we can play a lot with this thing xD

TODO:

• [ ] Update vscode-css-langserver-bin
• [ ] Implement protocol on oni
• [ ] Give folding information to neovim

Now the only question that I have is how do we gave back these information to neovim ?

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[DeltaEvo]

From my knowledge of vim folding I think the best solution is to set foldmethod=manual and use http://vimdoc.sourceforge.net/htmldoc/fold.html#zf but with this solution to remove a fold we need to use http://vimdoc.sourceforge.net/htmldoc/fold.html#zd and so move the cursor

Edit: for zd we can use :normal ex command to avoid moving the cursor

[CrossR]

I think ideally, there would be an upstream change with neovim to expose a nvim_create_fold() function that we could call with the API, so we don't have to mess with the cursor etc.

Unless I'm reading the changes wrong, it looks like this PR (https://github.com/neovim/neovim/pull/6073) is adding that functionality, which would make this much easier.

[teto]

The PR you mentioned does add nvim_create/delete_fold. Now the API has not been discussed so I am not sure how easy it would be to merge as it is. Maybe folds should have an id for instance (to help remove them rather than clearing all folds) ?

Kinda related request (fold API) https://github.com/neovim/neovim/issues/7544#issuecomment-386788893