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Autosuggestions

JLine provides powerful autosuggestion capabilities that can enhance the user experience by suggesting commands as they type. This page explains how to use autosuggestions in your JLine applications.

AutosuggestionWidgets​

Fish-like autosuggestions for JLine. AutosuggestionWidgets suggests commands as you type based on command history.

Loading snippet: AutosuggestionWidgetsExample...

Usage​

As you type commands, you will see a completion offered after the cursor in a muted gray color.

If you press the → key (forward-char widget) or End (end-of-line widget) with the cursor at the end of the buffer, it will accept the suggestion, replacing the contents of the command line buffer with the suggestion.

If you invoke the forward-word widget, it will partially accept the suggestion up to the point that the cursor moves to.

Key Bindings​

This plugin provides autosuggest-toggle widget that toggles between enabled/disabled suggestions.

TailTipWidgets​

TailTipWidgets suggests commands as you type based on command completer data and/or command arguments and options descriptions.

Loading snippet: TailTipWidgetsExample...

Usage​

As you type commands, you will see a completion offered after the cursor in a muted gray color and argument/option description on status pane.

Command line tab completion works as normal.

Configuration​

Description pane can be disabled by setting descriptionSize = 0. Suggestions type can be configured using constructor parameter tipType:

  1. COMPLETER - Tab completions are displayed below command line. No suggestions are displayed after cursor.
  2. TAIL_TIP - Argument suggestions are displayed after cursor. No tab completions are displayed.
  3. COMBINED - Argument suggestions are shown if available otherwise tab completions are displayed.

The maximum number of completer suggestions displayed can be controlled by JLine variable list-max.

For example, creating TailTipWidgets as:

TailTipWidgets tailtipWidgets = new TailTipWidgets(reader, tailTips, 0, TipType.TAIL_TIP);

you will obtain Redis-like suggestions.

Key Bindings​

This plugin provides two widgets:

  1. tailtip-toggle - Toggles between enabled/disabled suggestions.
  2. tailtip-window - Toggles tailtip description pane.

For example, this would bind alt + w to toggle tailtip description pane:

reader.getKeyMaps().get(LineReader.MAIN).bind(new Reference("tailtip-window"), KeyMap.alt('w'));

Best Practices​

When using autosuggestions in JLine, consider these best practices:

  1. Selective Enabling: Enable autosuggestions only when they add value to the user experience.

  2. Performance: Be mindful of performance, especially with large history files or complex completers.

  3. Visual Distinction: Ensure that suggestions are visually distinct from user input.

  4. User Control: Always provide a way for users to toggle autosuggestions on/off.

  5. Combine with History: Autosuggestions work best when combined with a well-maintained history.

  6. Context Awareness: Use TailTipWidgets for context-aware suggestions based on command syntax.

  7. Documentation: Document the autosuggestion features and key bindings for your users.

  8. Testing: Test autosuggestions with various input patterns to ensure they behave as expected.