UglyPrompt 0.4.0

UglyPrompt

A no-frills readline-style console line editor for .NET. Backslash continuation, ambient completion hints, bracketed paste, and history — with no external dependencies.

A permissively-licensed alternative to PrettyPrompt.

Installation

dotnet add package UglyPrompt

Usage

var editor = new LineEditor();

while (true)
{
    string? input = editor.ReadLine(">> ");
    if (input == null) continue; // whitespace-only input
    Console.WriteLine(input);
}

ReadLine returns null on whitespace-only input. It handles backslash continuation internally — the returned string is the fully-joined multi-line value.

Completion Hints

Register one or more CompletionSources to enable ambient hint dispatch. Each source carries a trigger character, an anchor rule (LineStart or WordStart), and a Lookup callback that returns matching candidates for the body typed after the trigger:

var commands = new[]
{
    new CompletionHint("/help",  "Show help"),
    new CompletionHint("/clear", "Clear the screen"),
};

var editor = new LineEditor();

editor.AddSource(new CompletionSource('/', TriggerAnchor.LineStart,
    body => commands
        .Where(c => c.Name.StartsWith("/" + body, StringComparison.OrdinalIgnoreCase))
        .ToList()));

editor.AddSource(new CompletionSource('@', TriggerAnchor.WordStart,
    body => EnumerateMatchingFiles(body)));

When the cursor is preceded by a registered trigger satisfying its anchor, a terse comma-separated list of matching names from Lookup is shown on an ephemeral line below the input. Closer-to-cursor triggers win when multiple are present. The hint is display-only — the user still types the full input and presses Enter to submit. Editing (arrows, history, Ctrl+U/W, etc.) works normally throughout.

AddSource rejects duplicate trigger chars; if you want to overload a trigger, combine candidates inside a single Lookup callback.

Lookup runs synchronously on every keystroke. Cheap for static lists; if your source needs heavy I/O, gate it behind a body-length threshold (body.Length < 3 ? [] : Search(body)) or pre-cache.

See UglyPrompt.Demo/Program.cs for a runnable example wiring /, +, and @ together.

Features

• History — Up/Down arrows or Ctrl+P/N to navigate previous inputs
• Backslash continuation — Lines ending with \ prompt for more input; the full value is returned joined with newlines
• Bracketed paste — Handles terminal paste sequences including embedded newlines
• Standard line editing — Home/End, Ctrl+A/E, Ctrl+U/K/W, Ctrl+T, and more (see below)
• No dependencies — Only the .NET standard library; targets .NET 10.0

Keyboard Shortcuts

License

MIT