Adding Predictive IntelliSense to PowerShell VSCode Extension

Adding Predictive IntelliSense to PowerShell VSCode Extension

Summary of new feature

Predictive IntelliSense is an addition to the concept of tab completion that assists the user in successfully completing commands. This enables new and experienced users of PowerShell to discover, edit, and execute full commands based on matching predictions from the users history and additional domain specific plugins such as Az.Tools.Predictor.

PowerShell users would benefit from predictions in VSCode Terminal (PowerShell Integrated Console) and Editor:

• PowerShell users with previous cmdlet experience receive suggestions from history and additional plugins, accelerating the time to command completion. Historical predictions come from the users PSReadLine history of completed commands, allowing them to quickly accept the prediction.

• PowerShell users without previous cmdlet experience receive guided suggestions from plugin predictors like Az.Tools.Predictor to help successfully complete the command. These plugins may provide a range of guided assistance in the form of complete commands or suggesting parameters and arguments.

Terminal

Terminal (PowerShell Integrated Console), should have the same features as PowerShell (shell) with predictions as described in this blog.

This includes InLineView and ListView for predictions, switchable with F2 key.

• Example of InLineView in PowerShell Integrated Console:

• Example of ListView in PowerShell Integrated Console:

Editor

Displaying predictions in the editor could be similar to IntelliCode for Visual Studio described here.

When the user begins to type a cmdlet, a prediction using InLineView appears above other cmdlet names. A star indicates that the suggestion comes from a predictor, followed by the InLineView prediction, followed by the prediction source.

After the cmdlet name, when the user types dash (-) to begin a parameter, the first suggestion pair (parameter and argument) is displayed along with the prediction source. As the user continues to type the next parameter with a dash, the next suggestion pair is displayed until the prediction is complete.

In the above example, the Az.Tools.Predictor will suggest the parameter and argument based on:

• Examples - Ml-based plugins may learn the most common uses of a cmdlet from documentation examples.
• Reuse - If the parameter and argument pair has been previously typed within the current session, the predictor will supply the previously typed argument.
• Syntax - If no examples or history is available, the predictor will display the parameter with the Object type for the argument.

Enabling/Disabling

Predictions are enabled and disabled using the Set-PSReadLineOption -PredictionSource <argument> and may be stored in the users profile. Accepted values for the argument are None, History, HistoryAndPlugin.

Configuring a predictor

Customizing prediction color, keybindings, and additional plugins is accomplished through PSReadLine Set-PSReadLineOption and Set-PSReadLineKeyHandler cmdlets. Custom settings may be stored in the users profile.

[daxian-dbw]

The static type CommandPrediction contains the APIs to obtain prediction results, see https://github.com/PowerShell/PowerShell/blob/master/src/System.Management.Automation/engine/Subsystem/CommandPrediction/CommandPrediction.cs#L53 But, to be honest, I’m not very confident how effective those APIs are aligned with the VSCode editor scenario. For the editor experience, it may be better for the prediction to not go through SMA at all, but work in a similar way as IntelliCode.

[TylerLeonhardt]

Yeah it is. Some extensions have “smart snippets” that are better than normal snippets because they can be context aware. Just have to add a CompletionItem to the list of Completions getting sent back to vscode.

whether you’re completing a whole line, or just a word, it doesn’t really matter. Details: https://microsoft.github.io/language-server-protocol/specifications/specification-current/#textDocument_completion