Allow lines to be moved up and down

[lhecker]

This was requested a few times internally. VS Code allows moving lines up and down with Alt+Up/Down.

[Szeraax]

If you're going to support VSCode type shortcuts, can you please also add in Alt + Shift + Down to copy line down? That's a big QoL upgrade :D

[JanluOfficial]

I'm working on implementing basic line shifting (Alt+Up/Down)
I'll submit a PR once I can figure out why going to the right just broke... for some reason.

Edit, I fixed going to the right, pr coming soon

[juemrami]

I was also working on PR for this since it seemed easy to tackle.
Moving 1 line was easy enough to implement,
but i was wondering if it was out of scope to allowing moving multiple lines at a time (VSCode default behavior)

[lhecker]

If it's a core editing feature of VS Code, and not that difficult to support, I'd definitely consider it "in scope". 🙂

[juemrami]

Alright. I've got a prototype going but, im trying to setup some basic tests for edge cases that were causing issues.
(not sure what your philosophy on testing UI features is)

However i've hit a snag trying to write to a TextBuffer using the .write method in my tests.

For some reason i keep hitting memory allocation panics when .write attempts to do:

newline_buffer.push_str(if self.newlines_are_crlf { "\r\n" } else { "\n" });

edit:
nvm i hadnt see that scratch_arena needed to be initiliazed first.
May open a draft to share my work soon 😄

[lhecker]

nvm i hadnt see that scratch_arena needed to be initiliazed first.

We should probably add a debug_assert!() to scratch_arena to make it easier to notice this when building new code. If you want to you can add it to your PR if you'd like.