Add basic support for inline predictive suggestion

[daxian-dbw]

This PR is to merge the existing predictive suggestion changes to the master branch.
Changes were refactored and cleaned up. Also tests are added.

• Currently, the only suggestion source is the PSReadLine history file.
• By default, the suggestion text is rendered with the dark black color \x1b[38;5;238m, which works OK with a black background.
  You can change it by running Set-PSReadLineOption -Colors @{ Prediction = '<your-choice-of-color>' }
• Parameter -PredictionSource is added to Set-PSReadLineOption, currently with the options None and History.
  The value is None by default, meaning that the predictive suggestion feature is disabled by default.
  A user can enable the prediction feature by set it to History. The feature cannot be enabled when the console output doesn't support VT.
• Make AcceptSuggestion and AcceptNextSuggestionWord bindable.
• Also fix System.ArgumentOutOfRangeException PSReadLine: 2.1.0-beta1 PowerShell: 7.1.0-preview.2 #1495

Microsoft Reviewers: Open in CodeFlow

[daxian-dbw]

@lzybkr @SteveL-MSFT Gentle ping :) Please take a look when you have time. Thanks!

[lzybkr]

    private bool LineIsMultiLine()

Duplicate logic - you should just call your new function with _buffer as the parameter.

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Refers to: PSReadLine/Render.cs:1211 in e876ffc. [](commit_id = e876ffc, deletion_comment = False)

[lzybkr]

    {

Duplicate logic - just call your new function with _buffer as the first parameter.

---

Refers to: PSReadLine/Words.cs:92 in e876ffc. [](commit_id = e876ffc, deletion_comment = False)

[daxian-dbw]

@lzybkr I'm not sure what these 2 comments are referring to: #1496 (comment) #1496 (comment). Can you please clarify them a bit?

Other than that, I'm almost done addressing the comments, and will push the changes tomorrow.

[daxian-dbw]

@lzybkr I think I addressed all comments. A summary:

1. Two settings are used: -PredictionSource and PredictionViewStyle
PredictionSource -- options are None and History today;
   PredictionViewStyle -- option is Default only today.
2. Make the predictive suggestion feature turned off by default (PredictionSource is none by default)
3. Make AcceptSuggestion and AcceptNextSuggestionWord bindable.
4. Refactor to use the existing patterns as well as avoid redundant logic.
5. Add more tests.

[daxian-dbw]

@lzybkr All your comments are addressed. The refactoring changes to SelfInsert was separated out to #1510.
Summaries:

1. PredictionViewStyle and its related code is removed until another view is implemented.
2. Not support the predictive suggestion feature when the legacy console is in use.
3. Ignore arg for AcceptSuggestion
4. Removed LineIsMultiLine(string text)
5. Renamed the field to _lastUserInput

[JustinGrote]

@daxian-dbw I had a question about this. There is the new AcceptSuggestion bind, but even if it is unbound, ForwardChar bound to rightarrow still does the completion. Is this intended or am I missing something?

[daxian-dbw]

@JustinGrote The function ForwardChar has AcceptSuggestion built in, and similarly, ForwardWord has AcceptNextSuggestionWord built in.
The functions AcceptSuggestion and AcceptNextSuggestionWord are made public and bindable so as to allow users to use different key bindings to accept suggestion text.
For example, here is a sample to make RightArrow to accept next word instead the entire suggestion text.

[nippyin]

When i run this command Set-PSReadLineOption -PredictionSource History. I expect following settings to be persistent. PredictionSource : History

However, after VScode restart or new instance launch this is again set to None.

[JustinGrote]

@nippyin add it to your $profile

[nippyin]

@nippyin add it to your $profile
Thanks Justin, can you share me the syntax please.

[rkeithhill]

The syntax is the same - just put that command in your profile script located at this path $profile.CurrentUserAllHosts. Well, execute that to get the path. For me, that path is:

C:\Users\Keith\Documents\PowerShell\profile.ps1

It will be a bit different for you (different username at least).

If the file doesn't exist, create it. Then place this line in the file:

Set-PSReadLineOption -PredictionSource History

Now, whenever you start PowerShell, it will have this setting configured.

[nippyin]

he syntax is the same - j

this is nice, however is there VScode settings for this where we can set the parameter value as History? something similar to "powershell.codeFormatting.autoCorrectAliases": true

[rkeithhill]

The above would apply to all PowerShell hosts including the VSCode terminal and PS Integrated Console. To be clear, this is PSReadLine module configuration - not specific to VSCode. That said, if for some reason you only want this setting configured in the PS Integrated Console in VSCode, then put the command in the PSIC's profile script: $HOME\Documents\PowerShell\Microsoft.VSCode_profile.ps1.

[musm]

This is a really nice feature, many thanks.

Is it not possible to have <tab> complete the suggested completion, instead of having to use the <right> arrow key?

[JustinGrote]

@musm you can customize the keybindings
https://docs.microsoft.com/en-us/powershell/module/psreadline/set-psreadlinekeyhandler?view=powershell-7

[musm]

Right now mine is set to Function yet that doesn't seem to want to complete predictive suggestions. Any chance you know why or which keybinding I need to change it to? The documentation isn't clear on this one.

It looks like you need to set AcceptSuggestion Is it possible to set the keybinding to frist try to AcceptSuggestion (f it exists) and if not do a Complete?

[SSvilen]

Hello,

I saw Jason Helmick showing PredictionViewStyle during the session with Jeffrey on Ignite, but I don't see that feature anywhere - even in the RC. Will this be implemented at all?

[JustinGrote]

@SSvilen my understanding is that it is on a private branch and will surface for 2.2