The new predictive intellisense feature in PSReadLine

[daxian-dbw]

Summary of the new document or enhancement

• New articles that need to be created:
  • about_PSReadLine.md (for 7.2)
  • Set-PSReadLineOption.md (for 7.2)
• Link(s) to related code PR(s): Add the prediction ListView and also hook up with the CommandPrediction APIs introduced in PS 7.1 PowerShell/PSReadLine#1909

Description of what changed

A new predictive intellisense feature will be added to PSReadLine 2.2.0-beta1, including 2 major functionalities:

1. Add the ListView to the predictive intellisense feature in PSReadLine.
2. Hook up PSReadLine with the CommandPrediction APIs introduced in PS 7.1, so when using PSReadLine with PS 7.1, a user can import a predictor module and PSReadLine can render the suggestions returned from the predictor module.

There will be 4 options for the PredictionSource: None, History, Plugin, HistoryAndPlugin.

• None -- disable the predictive intellisense feature, which is the default.
• History -- enable the predictive intellisense feature, and use the PSReadLine history as the only source.
• Plugin -- enable the predictive intellisense feature, and use the plugins (CommandPrediction) as the only source.
• HistoryAndPlugin -- enable the predictive intellisense feature, and use both history and plugin as the sources.

There will be 2 views for the PredictionViewStyle: InlineView and ListView.

• InlineView -- the style as existing today, similar as in fish shell and zsh.
• ListView -- suggestions are rendered in a drop down list, and users can select using UpArrow and DownArrow.

Two more color settings were added to support customization of the ListView:

• ListPredictionColor -- set color for the leading > character and the trailing source name, e.g. [History]. By default, it uses DarkYellow as the foreground color.
• ListPredictionSelectedColor -- set color for indicating a list item is selected. By default, it uses DarkBlack as the background color.

For more details and more screenshot/GIFs, please see the PR description of PowerShell/PSReadLine#1909.