tabs breaking paren matching

[numberten]

Parentheses matching breaks when tab characters are used. Explanation and possible solution:

11:22 < numberten> technomancy: the lein repl does this thing where it goes back momentarily to your opening paren when you enter a closing paren. and that feature is bugged with tabs
11:22 < technomancy> numberten: oh, gotcha
11:22 < numberten> it calculates go-back distance based on characters entered and since tabs take up way more space it breaks
11:22 < technomancy> numberten: bleaugh
11:22 < technomancy> numberten: pretty sure that's a jline2
11:23 < technomancy> *jline2 bug though
11:23 < numberten> i see
11:23 < technomancy> I'd love to just prevent the insertion of tabs entirely though
11:23 < numberten> just figured it might be easier to handle lein side if there was a config file
11:24 < technomancy> numberten: we might be able to add a workaround in lein, yeah
11:24 < technomancy> by binding tab to insert two spaces
11:24 < technomancy> even though the bug itself is in jline

[trptcolin]

Hmm, that's pretty strange, and yeah I agree with @technomancy - definitely a jline issue.

How are you getting tabs into the REPL? Copy/paste? What version of Leiningen, OS, terminal, and shell are you using?

I haven't been able to reproduce this in any released versions of REPLy, even by pasting tabs. I assume this is because tab triggers completion. Due to jline/jline2@2766027, if I actually go into the code and .setCopyPasteDetection to true on the ConsoleReader, I can get this to happen. But REPLy doesn't set that by default. Perhaps there's some way that I don't know about to put tab literals into REPLy without pasting them or hitting the tab key?

[numberten]

I'm using Leiningen 2.3.4
Ubuntu 13.10
Terminator (http://gnometerminator.blogspot.com/p/introduction.html)
bash

I'm using alt+tab to tab.

[numberten]

I get the same behaviour in gnome-terminal.
In xterm, alt+tab doesn't seem to print tabs, but multiple tabs followed by a backspace seems to make it jump forward.

[trptcolin]

Cool, yeah, I see that with alt-tab now too, had no idea one could do that.

This is actually way deeper than just paren-matching in jline - beginning-of-line/end-of-line don't work in the presence of tab characters either. I'd encourage you to submit a bug report at https://github.com/jline/jline2 - I guess the easy route for jline would be to compress tab characters to only take up 1 column in the console line it manages, but I'm not sure whether that's possible.

[technomancy]

Is there any way we could configure our usage of jline to treat tab insertions as spaces when it's not doing completion?

[trptcolin]

Not that I can think of, though that'd be nice. The only thing that comes to mind is terrible: some sort of intermediate stream between us & jline where we change tab characters to spaces. But (a) that's evil and (b) it would break completion.

I was pleasantly surprised to see that there is some notion of TAB_WIDTH in jline, so it probably means that needs to be taken into account in viMatch() (which paren matching uses), moveToEnd (end-of-line), and probably other places as well.