WIP: First pass at terminal-mode completions

[wurli]

Hi :)

Following #305 I thought I'd have a crack at terminal-mode completions. This is very much at proof-of-concept stage, but I've enjoyed tinkering with it so far so would be happy to keep working on it if you don't mind feeding back on current progress and advising about design for next steps.

Key things to note:

• I created cmp/lib/term_events.lua to listen for edits in the terminal. I used vim.on_key() to achieve this as there's no terminal equivalent for the InsertCharPre event. I was pretty torn about simply lifting the code from cmp/lib/cmdline_events.lua, but decided against this as there's a few things there I didn't quite understand, e.g. the use of timers and everything being accomplished by on_cursor_moved(). If you don't mind explaining what these are doing I'll be happy to add equivalent functionality if needed :)

• AFAIK Neovim doesn't provide a convenient API for inserting text into the terminal prompt, so I had to cobble something together using vim.feedkeys(). I also experimented with vim.paste(), but the results didn't feel good.

• Still to do:

  • Autocompletion immediately triggers after accepting a suggestion. It looks like after accepting a suggestion like Bla, the final character in the accepted text, in this case a, is once again used to trigger a completion. Unfortunately I couldn't work out how this is avoided in cmdline/insert mode, so very grateful for any pointers here. My guess is that this has something to do with my omission of on_cursor_moved(), but playing with this functionality hasn't (yet) led me to a fix.

  • I haven't added any user-facing configuration for terminal mode. I can imagine this is something most users will want quite fine-grained control over, so I thought I'd seek some pointers on this before diving in.

Thanks in advance for review!

[Shougo]

AFAIK Neovim doesn't provide a convenient API for inserting text into the terminal prompt, so I had to cobble something together using vim.feedkeys(). I also experimented with vim.paste(), but the results didn't feel good.

You can use chansend() instead.

[Shougo]

Autocompletion immediately triggers after accepting a suggestion. It looks like after accepting a suggestion like Bla, the final character in the accepted text, in this case a, is once again used to trigger a completion. Unfortunately I couldn't work out how this is avoided in cmdline/insert mode, so very grateful for any pointers here. My guess is that this has something to do with my omission of on_cursor_moved(), but playing with this functionality hasn't (yet) led me to a fix.

It is known issue. I think auto insert feature should be disabled in terminal mode.

[wurli]

You can use chansend() instead.

Thanks, done! This has also fixed the issue with completions being triggered after accepting :)

It is known issue. I think auto insert feature should be disabled in terminal mode.

Thanks, good to know. Agreed - I'll look into this.

[Saghen]

Wow, this looks great, thank you!

I was pretty torn about simply lifting the code from cmp/lib/cmdline_events.lua, but decided against this as there's a few things there I didn't quite understand, e.g. the use of timers and everything being accomplished by on_cursor_moved()

That code is truly cursed 😂 The idea is that when the user types, we trigger the on_text_changed(char) and when the user moves the cursor or deletes a character, we trigger on_cursor_moved(). There's no CursorMovedC event in neovim 0.10 (coming in 0.11), so for on_cursor_moved, I've written a hack that checks every 16ms if the cursor position has changed, and that the text hasn't changed (unless backspace was pressed). It's likely that with your on_key solution, you could use CursorMoved directly similar to buffer_events.lua, rather than hacking around.

I haven't added any user-facing configuration for terminal mode. I can imagine this is something most users will want quite fine-grained control over, so I thought I'd seek some pointers on this before diving in.

For now, I think it would be enough to support keymaps.term and sources.term as that would match where cmdline is at