Fish-like autocompletion

[felixfbecker]

I tried to figure this out but couldn't find out. Is there a way to get autocompletion like in the fish shell?

Basically what I am looking for is automatically searching the history on every keystroke, then showing a grey suggestion behind the cursor that can be accepted with → (if the cursor is at the end of the line).

We can get close with Set-PSReadLineKeyHandler -Key ArrowRight -Function HistorySearchBackward but it doesn't show the suggestion and it prevents moving the cursor to the right.

[lzybkr]

This feature wasn't much of a priority with limited console support for VT sequences, but now Windows has real support for VT sequences, it makes sense to add this capability.

[SteveL-MSFT]

This type of experience is what we envisioned when we originally thought about "Machine Learning autocompletion". Since then, we dropped the ML part and thought about simply exposing an interface to enable this (https://github.com/PowerShell/PowerShell-RFC/pull/123/files) and just use local history.

[felixfbecker]

@lzybkr is there any way this is currently already possible with PSReadLine customization? If not, what would be needed to make it possible? It would really improve my workflow so I would be willing to put some work in

@SteveL-MSFT So the plan would be to ship a function that handles the searching logic with Get-History so it is easy to opt-in to using that with PSReadLine?

[lzybkr]

PSReadLine doesn't use Get-History - it keeps it's own history.

Here are my thoughts on implementing this feature:

• Add an option to Set-PSReadLineOption and document it
• Add a configuration color for the autosuggestion text with a suitable default.
• In SelfInsert, you will add smarts to find the autosuggestion. If you want command history, HistorySearchBackward has much of what you want, for other completions, GetCompletions is probably what you should use.
• The autosuggestion text which is not accepted could be stored in a different StringBuilder. In ReallyRender, you would write this text out with the autosuggestion color.
• In ForwardChar, if you are at the end of the buffer and there is autosuggestion text, add it to the buffer and clear the autosuggestion.
• Probably add a binding to Ctrl+f in Windows mode to ForwardChar.
• Add a new function AcceptFirstSuggestedWord and maybe AcceptFirstSuggestedShellWord, binding one or the other to Alt+RightArrow and Alt+f if the keys are not already bound (Emacs binds Alt+f by default, and hmm, maybe Alt+RightArrow won't work at all.) At any rate, the functions should be available so folks can get this functionality if they want as well.

As for relying on PowerShell for any new fancy suggestions - I'm not excited about that unless it means no api changes. Today a single build of PSReadLine works with any version of PowerShell > 5.0 and I'd like to keep it that way.

[phiter]

So, is it coming? :D

[potatoqualitee]

Yessss! Please. Looks like there's a whole lot of interest in this. I just saw similar functionality on a livestream and it was awesome!

https://i.vgy.me/PAn45j.mp4

[daxian-dbw]

I'm working on a prototype of this, and here is the zip package if any of you want to try it (any feedback would be very helpful!).

PSReadLine.zip

Currently:

• The only suggestion source is the PSReadLine history. The ultimate goal is to call into a prediction API in S.M.A that is powered by a prediction plugin.
• Currently there is no way to configure the style that the suggestion text is rendered with, the default style (color only) works OK with a black background. (of course, more work is needed here)
• VI mode - now the suggestion is disabled when switching to the command mode, and enabled when switching to insert mode.
• So far, I haven't really focused on the VI/Emacs experience, so it could be pretty raw, and feedback is very welcome.

When using this PSReadLine, please add the following key binding to your profile:

Set-PSReadLineKeyHandler -Key "Ctrl+f" -Function ForwardWord

• Pressing RightArrow at the end of current typing will accept the suggestion text
• Pressing Ctrl+f at the end of current typing will accept a word from the suggestion text
• Pressing Ctrl+z will get you back to where you were before accepting all or part of the suggestion

Important note: don't forget to unblock the zip file after you download it, otherwise you will face weird exceptions thrown from PowerShell.

[mpearon]

This is great to hear! I would love to see the previous pipeline command considered in the prediction.
For instance, Get-ADUser shouldn't suggest Get-ACL when used in the pipeline.