path completion: completing a folder should retrigger code completion

[aeschli]

Testing #44460

Version 1.21.0-insider
Commit 9a04587
Date 2018-03-01T06:47:39.037Z

• create foo.html, bar.html in a folder 'a/b/c'
• in `foo.html' have

<a href="../../../"

and do code completion after /.

• pick a
• this should result in <a href="../a/" (slash at the end) and reopen code completion again so that the user can continue completing

[octref]

I was modeling after TS's path complete, but I guess for html it's a bit different since you can import from folder and it defaults to index.js, and there is no such behavior in html.

[aeschli]

A folder path is also valid in HTML (once navigated there, it's up to the web server to decide what to return), but I'd think it's the less common case and it users would rather continue to enter a path.

[octref]

I would want to hear more people's feedback before doing this. Current behavior is in-line with TS and the two most popular path completion extensions:

https://marketplace.visualstudio.com/items?itemName=christian-kohler.path-intellisense
https://marketplace.visualstudio.com/items?itemName=ionutvmi.path-autocomplete

[aeschli]

Think of the many keystokes necessary to enter a path like aaa/bbb/foo.html

a, ctrl+space (code assist), enter to select aaa, /, b, ctrl+space, enter to select bbb, /, f, ctrl+space, enter to select foo.html

That's 11 keystrokes to enter a path, almost as long as the path itself!

With the suggested change: 5 keystrokes

• a, ctrl+space (code assist), enter select aaa, enter select bbb, enter select foo.html

To complete 'aaa/bbb' : 5 keystrokes

• a, ctrl+space (code assist), enter select aaa, enter select bbb, escape to close code assist window

Let's be better than the extensions.
Also, it's what we do when completing HTML properties:
Try <input t| pick type