Add keybindings for CTRL, ALT, SHIFT + UP, DOWN, RIGHT, LEFT, HOME, END, BACKSPACE, DELETE & more

[masmu]

This PR implements some missing key bindings.

In particular all possible combinations of

• CTRL
• ALT
• SHIFT
• ALT+SHIFT
• CTRL+ALT
• CTRL+SHIFT
• CTRL+ALT+SHIFT

in conjunction with Up, Down, Left, Right, Home, End, Backspace, Delete, PageUp, PageDown.

I added tests to the LightRenderer beforehand to make sure I wasn't breaking anything, and expanded them when I added new key bindings.

So you can actually do stuff like:

fzf
  --bind 'ctrl-up:up+up+up+up+up'
  --bind 'ctrl-down:down+down+down+down+down'
  --bind 'ctrl-right:forward-word'
  --bind 'ctrl-left:backward-word'
  --bind 'alt-delete:delete-char'
  --bind 'alt-backspace:backward-kill-word'

This PR fixes #1747.

[junegunn]

Thanks, I'll review the code when I get some time.

A few things.

• We also have to update tcell renderer for Windows
• man page needs to be updated accordingly
• Terminal emulators I use (kitty, iterm2, etc) don't distinguish between the CTRL-* chords you added from the ones without CTRL. Which terminal emulator do you use on what platform? If these chords are not widely supported by the terminal emulators, we should warn about that on the manual.
• Allowing all possible names (ctrl-alt-shift, alt-shift-ctrl, shift-ctrl-alt, etc) will make the code harder to maintain. I'd just allow one sequence. i.e. ctrl-alt-shift.

[masmu]

No worries, take your time.

We also have to update tcell renderer for Windows

Yep, I checked tcell.go and most of it should be pretty straight forward to implement. My biggest issue is that I do not have any Windows machine to test on. So I can do an implementation, make sure it compiles but that's probably it. Would you mind to assist here and test it? Or is there a way to do this on Linux?

man page needs to be updated accordingly

True. Do you write the man page by hand? I was hoping it might be generated by some docstring, although I didn't find one when I searched for it.

Terminal emulators I use (kitty, iterm2, etc) don't distinguish between the CTRL-* chords you added from the ones without CTRL. Which terminal emulator do you use on what platform? If these chords are not widely supported by the terminal emulators, we should warn about that on the manual.

SGTM. I use gnome-terminal and ddterm both running most of the time zsh + tmux, sometimes just zsh or bash. Platform is Linux.

Allowing all possible names (ctrl-alt-shift, alt-shift-ctrl, shift-ctrl-alt, etc) will make the code harder to maintain. I'd just allow one sequence. i.e. ctrl-alt-shift.

I tried to stick as close to your implementation as possible and saw this case "alt-shift-right", "shift-alt-right": case where you actually support both combinations. But I don't mind removing the redundant ones. Actually I like that choice 😄

[masmu]

I made the mentioned changes and the remaining exciting question is if the following block (tcell.go:~390) is correct:

case tcell.KeyBackspace2:
	if ctrlAlt {
		return Event{CtrlAltBackspace, 0, nil}
	}
	if ctrl {
		return Event{CtrlBackspace, 0, nil}
	}
	if alt {
		return Event{AltBackspace, 0, nil}
	}
	return Event{Backspace, 0, nil}

My educated guess is that it is actually not and has to be covered in the following block:

case tcell.KeyCtrlH:
	switch ev.Rune() {
	case 0:
		if ctrl {
			return Event{Backspace, 0, nil}
		}
	case rune(tcell.KeyCtrlH):
		switch {
		case ctrl:
			return keyfn('h')
		case alt:
			return Event{AltBackspace, 0, nil}
		case none, shift:
			return Event{Backspace, 0, nil}
		}
	}

[junegunn]

Or is there a way to do this on Linux?

You can run go run -tags tcell main.go.

[masmu]

Thanks for the hint!

But I am trying to get my hands on a windows machine as well because it all depends on what the OS is really gonna send. I will report back after that.

[nirodhvana]

is this ready for merging?

[masmu]

Nope, not yet.

The Linux implementation is done. Windows implementation potentially as well, but requires a patch in tcell to make the following shortcuts work:

• Ctrl-Alt-*
• Ctrl-Alt-Shift-*

That's why this PR currently points to my own fork of tcell and that keeps this from being reviewed and merged. I created a PR upstream and hope for a quick review.

You can build this PR yourself. That should work.