Add autocomplete for text prompt

Closes #166

src/Spectre.Console/Widgets/Progress/Columns/SpinnerColumn.cs

@@ -0,0 +1,107 @@
+using System;
+using System.Linq;
+using Spectre.Console.Internal;
+using Spectre.Console.Rendering;
+
+namespace Spectre.Console
+{
+    /// <summary>
+    /// A column showing a spinner.
+    /// </summary>
+    public sealed class SpinnerColumn : ProgressColumn
+    {
+        private const string ACCUMULATED = "SPINNER_ACCUMULATED";
+        private const string INDEX = "SPINNER_INDEX";
+
+        private readonly object _lock;
+        private Spinner _spinner;
+        private int? _maxWidth;
+
+        /// <inheritdoc/>
+        protected internal override bool NoWrap => true;
+
+        /// <summary>
+        /// Gets or sets the <see cref="Console.Spinner"/>.
+        /// </summary>
+        public Spinner Spinner
+        {
+            get => _spinner;
+            set
+            {
+                lock (_lock)
+                {
+                    _spinner = value ?? Spinner.Known.Default;
+                    _maxWidth = null;
+                }
+            }
+        }
+
+        /// <summary>
+        /// Gets or sets the style of the spinner.
+        /// </summary>
+        public Style? Style { get; set; } = new Style(foreground: Color.Yellow);
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="SpinnerColumn"/> class.
+        /// </summary>
+        public SpinnerColumn()
+            : this(Spinner.Known.Default)
+        {
+        }
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="SpinnerColumn"/> class.
+        /// </summary>
+        /// <param name="spinner">The spinner to use.</param>
+        public SpinnerColumn(Spinner spinner)
+        {
+            _spinner = spinner ?? throw new ArgumentNullException(nameof(spinner));
+            _lock = new object();
+        }
+
+        /// <inheritdoc/>
+        public override IRenderable Render(RenderContext context, ProgressTask task, TimeSpan deltaTime)
+        {
+            var useAscii = (context.LegacyConsole || !context.Unicode) && _spinner.IsUnicode;
+            var spinner = useAscii ? Spinner.Known.Ascii : _spinner ?? Spinner.Known.Default;
+
+            if (!task.IsStarted || task.IsFinished)
+            {
+                return new Markup(new string(' ', GetMaxWidth(context)));
+            }
+
+            var accumulated = task.State.Update<double>(ACCUMULATED, acc => acc + deltaTime.TotalMilliseconds);
+            if (accumulated >= spinner.Interval.TotalMilliseconds)
+            {
+                task.State.Update<double>(ACCUMULATED, _ => 0);
+                task.State.Update<int>(INDEX, index => index + 1);
+            }
+
+            var index = task.State.Get<int>(INDEX);
+            var frame = spinner.Frames[index % spinner.Frames.Count];
+            return new Markup(frame.EscapeMarkup(), Style ?? Style.Plain);
+        }
+
+        /// <inheritdoc/>
+        public override int? GetColumnWidth(RenderContext context)
+        {
+            return GetMaxWidth(context);
+        }
+
+        private int GetMaxWidth(RenderContext context)
+        {
+            lock (_lock)
+            {
+                if (_maxWidth == null)
+                {
+                    var useAscii = (context.LegacyConsole || !context.Unicode) && _spinner.IsUnicode;
+                    var spinner = useAscii ? Spinner.Known.Ascii : _spinner ?? Spinner.Known.Default;
+
+                    _maxWidth = spinner.Frames.Max(frame => Cell.GetCellLength(context, frame));
+                }
+
+                return _maxWidth.Value;
+            }
+        }
+    }
+}