add line numbers

src/Spectre.Console.Tests/Expectations/Public_API.Output.verified.txt

@@ -2297,6 +2297,13 @@
         public static Spectre.Console.Layout Ratio(this Spectre.Console.Layout layout, int ratio) { }
         public static Spectre.Console.Layout Size(this Spectre.Console.Layout layout, int size) { }
     }
+    public sealed class LineNumbers : Spectre.Console.Rendering.Renderable
+    {
+        public LineNumbers(params Spectre.Console.Rendering.IRenderable[] items) { }
+        public LineNumbers(System.Collections.Generic.IEnumerable<Spectre.Console.Rendering.IRenderable> children) { }
+        protected override Spectre.Console.Rendering.Measurement Measure(Spectre.Console.Rendering.RenderOptions options, int maxWidth) { }
+        protected override System.Collections.Generic.IEnumerable<Spectre.Console.Rendering.Segment> Render(Spectre.Console.Rendering.RenderOptions options, int maxWidth) { }
+    }
     public sealed class LiveDisplay
     {
         public LiveDisplay(Spectre.Console.IAnsiConsole console, Spectre.Console.Rendering.IRenderable target) { }

src/Spectre.Console/Widgets/LineNumbers.cs

@@ -0,0 +1,81 @@
+namespace Spectre.Console;
+
+/// <summary>
+/// Renders things in rows.
+/// </summary>
+public sealed class LineNumbers : Renderable
+{
+    private readonly List<IRenderable> _children;
+
+    /// <summary>
+    /// Initializes a new instance of the <see cref="LineNumbers"/> class.
+    /// </summary>
+    /// <param name="items">The items to render with line numbers.</param>
+    public LineNumbers(params IRenderable[] items)
+        : this((IEnumerable<IRenderable>)items)
+    {
+    }
+
+    /// <summary>
+    /// Initializes a new instance of the <see cref="LineNumbers"/> class.
+    /// </summary>
+    /// <param name="children">The items to render with line numbers.</param>
+    public LineNumbers(IEnumerable<IRenderable> children)
+    {
+        _children = new List<IRenderable>(children ?? throw new ArgumentNullException(nameof(children)));
+    }
+
+    /// <inheritdoc/>
+    protected override Measurement Measure(RenderOptions options, int maxWidth)
+    {
+        var measurements = _children.Select(c => c.Measure(options, maxWidth)).ToArray();
+        if (measurements.Length > 0)
+        {
+            return new Measurement(
+                measurements.Max(c => c.Min),
+                measurements.Max(c => c.Max));
+        }
+
+        return new Measurement(0, 0);
+    }
+
+    /// <inheritdoc/>
+    protected override IEnumerable<Segment> Render(RenderOptions options, int maxWidth)
+    {
+        var segments = new List<Segment>();
+        var result = new List<Segment>();
+
+        foreach (var child in _children)
+        {
+            var childSegments = child.Render(options, maxWidth);
+            foreach (var (_, _, _, segment) in childSegments.Enumerate())
+                segments.Add(segment);
+        }
+
+        var lineNumber = 1;
+        var totalLines = segments.Count(s => s.IsLineBreak) + 1;
+        var padding = totalLines.ToString().Length + 1;
+
+        if (segments.Count > 0)
+            result.Add(GetLineNumber(lineNumber, padding));
+
+        foreach (var segment in segments)
+        {
+            result.Add(segment);
+
+            if (segment.IsLineBreak)
+            {
+                lineNumber++;
+                result.Add(GetLineNumber(lineNumber, padding));
+            }
+        }
+
+        return result;
+    }
+
+    private static Segment GetLineNumber(int lineNumber, int padding)
+    {
+        var paddedLineNumber = lineNumber.ToString().PadRight(padding);
+        return new Segment(paddedLineNumber);
+    }
+}