feat: cycle through function signatures/overloads

[karthago1]

implement handle_event to cycle through the function signatures.

by pressin alt + p/n the function signature will be changed. (similar behavior as the completion popup)

fixes #5403

edit:
key bindings are changed to alt + p/n.

[pascalkuthe]

This seems like it would be better handled with a custom compoment instead of using an event handler.

The lsp always sends all signatures so you don't need to rerequest the signature help when you want to change signatures. Instead a custom component should just store all signatures and cycle trough them when keys are pressed.

The handlers are only meant to facilitate asynchronous tasks. When so.ethkng can be done synchronously like here that is preferable (both faster and less complex)

[karthago1]

Thank you for the review. Now the signatures are stored inside the SignatureHelp ui. It is faster than the previous implementation as you suggested.

[pascalkuthe]

changes look mostly good to me now but I am concerned about keybindings. Also want to test this out a bit (altough not sure how much use that will be with rust which thankfully doens't have overloading)

[karthago1]

This PR should have no side effects if the received signatures are less or equal 1. If more signatures are received, then the signature index is printed and A-n / A-p will be processed/evaluated.

(already Tested with C++ and C#)

[thomasaarholt]

I just tested it, and it works as advertised. Here's a screen recording of me using it in Python, where I added a really long docstring to ensure that it looked right with that. Gist here of the example.

The PR functionality works well. I actually reveal an unrelated bug in that video with the long output - pressing Ctrl D to scroll doesn't scroll the whole way in my small-ish window. The bug is present on the master branch too. If I use a bigger window, I can see the whole output.

[karthago1]

The PR functionality works well. I actually reveal an unrelated bug in that video with the long output - pressing Ctrl D to scroll doesn't scroll the whole way in my small-ish window. The bug is present on the master branch too. If I use a bigger window, I can see the whole output.

Thank you for the report. I create this PR #10181 to fix this issue

[the-mikedavis]

It'll be nice to have this, thanks for working on it! I have some minor comments about style and cosmetics

[the-mikedavis]

I think that we should prefer the active_signature we get from the language server here instead:

let active_signature = response
    .active_signature
    .map(|n| n as usize)
    .or_else(|| {
        old_popup
            .as_ref()
            .map(|popup| popup.contents().active_signature())
    })
    .unwrap_or_default()
    .min(signatures.len() - 1);

Some language servers update the active_signature they send when you enter enough parameters. For example with Erlang you might be typing maps:get( which is a multiarity function. maps:get(a, b should show the signature of maps:get/2 (takes 2 arguments) but for maps:get(a, b, the language server will show maps:get/3.

We could make this more complicated though and separately track which signature the language server sends and which you navigate to with A-n/A-p, preferring the signature you navigate to until the server changes which signature it considers active.

[karthago1]

I have played with your code. My c++ LSP somehow doesn't update the active signature at all. it is always 0.
so IMO it is very annoying to switch to the right signature manually, then it switches always back to the first one.

but in the same time using the C# LSP your code brings some improvements, since the suggested LSP signature is in most cases useful.

I created #10655, which implements the bit more complicated solution you have suggested