option-left / alt-left should skip between words

[slingamn]

As discussed here: wader/fq#940 this is a normal readline feature. I checked our v0.0.1 (last upstream release) and it does not work there, so it's not a regression, it was never implemented.

[wader]

Sorry i was confused about keys, it't not cmd+left/right, it's alt+left/right. For me it stopped working after 727da2a, maybe we're testing differently? i'm using iterm2 on macOS.
Looking at the default profile key setting it says:
alt+left sends ^[b
alt+right send ^[f

Maps quite well to what was removed here 727da2a#diff-8b7f25bac2ae04c2ce2abb628c6aa28103fd113103a62f3e9d232fa995684915L174 got lost in the refactor somehow?

[slingamn]

Hmm, that makes sense. I was testing on Linux, not MacOS --- I'll try it in iterm2 when I get a chance. (Alt-Left and Alt-Right work for me with GNU Readline in the same Linux terminal, e.g. with the CPython REPL, but they do not work with v0.0.1.)

[wader]

Tried hackily to add this in consumeANSIEscape

	switch initial {
	case 'f':
		return readResult{r: MetaForward, ok: true}, nil
	case 'b':
		return readResult{r: MetaBackward, ok: true}, nil
	}

seems to work but i'm a bit unsure how to refactor/restructure things to do it in a sane way

[slingamn]

Just clarifying, the sequence is the ANSI escape \x1b followed immediately by b or f, and that's the whole sequence?

[wader]

Yeap i think so

[wader]

Got annoyed with this again today 😬 any suggestion how to fix? my change felt a bit too hacky

[slingamn]

Sorry about the delay. Your implementation strategy looks fine to me :-) I pushed a version of it here:

• https://github.com/ergochat/readline/tree/metaforward
• e9aabe5

It did not work for me in iTerm2 3.5.2 with default settings. Here are the keybindings I see with default settings:

According to this, option-right would actually send \x1b\x1b[C, which is consistent with what I see in iTerm2 before and after this patch (option-right prints [C).

I implemented a hack to read sequences of this form and it works for me in iTerm2 and also on Linux with urxvt, although I haven't tested other Linux terminals yet.

What I would really like is some documentation about these sequences and also more clarity about sequences that start with a double \x1b. As it is, the patch linked above is safe to merge (it shouldn't break any existing functionality) but I don't feel like I can changelog it as "option-left now skips between words on MacOS", since it didn't actually work in my iTerm2 :-)

[slingamn]

I found a project dealing with a similar issue, although it didn't clarify things to my satisfaction: c-bata/go-prompt#63 (comment)

[slingamn]

More links:

• readline: emitKeypressEvents does not properly recognize Alt+Arrow nodejs/node#8934
• https://gitlab.com/gnachman/iterm2/-/issues/5451

[slingamn]

It looks like the "Natural text editing" presets in iTerm2 enable the short sequences \x1bb and \x1bf? So e9aabe5 seems OK to merge then, although it might be nice to fix this on Linux as well for parity with GNU Readline.

[slingamn]

GNU Readline also accepts Alt-b and Alt-f for this, apparently.

[slingamn]

Alt-b and Alt-f in xterm/urxvt produce \x1bb and \x1bf respectively.

[slingamn]

Someone told me that in general with xterm, combining alt with a key will produce an additional \x1b in front of whatever sequence that key would normally produce. This explains the alt-right and alt-left behaviors.

[wader]

Sorry for delay also, out traveling a bit. Think i'm using "Natural text editing" with iterm2 also. Nice research and it sounds like you have figure out how to make opt|alt+left/right work in most popular terminals?

[wader]

🥳 planning a new release soonish?

[slingamn]

Yeah I tagged this as 0.1.2-rc1, I'll probably tag 0.1.2 in a day or two but you can also pick up the rc1 in fq and dogfood it :-)

[wader]

rc1 seems to work fine and all tests pass, but the readline-parts are not exercised much

[slingamn]

Nice, I felt pretty confident so I went ahead and tagged v0.1.2 :-)