Add support for adding empty rows

This affects grids and tables.

src/.editorconfig

@@ -77,4 +77,7 @@ dotnet_diagnostic.CA1032.severity = none
 dotnet_diagnostic.CA1826.severity = none
 
 # RCS1079: Throwing of new NotImplementedException.
-dotnet_diagnostic.RCS1079.severity = warning
+dotnet_diagnostic.RCS1079.severity = warning
+
+# RCS1057: Add empty line between declarations.
+dotnet_diagnostic.RCS1057.severity = none

src/Directory.Build.props

@@ -34,7 +34,7 @@
   <ItemGroup Label="Package References">
     <PackageReference Include="MinVer" PrivateAssets="All" Version="2.3.0" />
     <PackageReference Include="Microsoft.SourceLink.GitHub" PrivateAssets="All" Version="1.0.0" />
-    <PackageReference Include="Microsoft.CodeAnalysis.FxCopAnalyzers" Version="2.9.8">
+    <PackageReference Include="Microsoft.CodeAnalysis.FxCopAnalyzers" Version="3.3.0">
       <PrivateAssets>all</PrivateAssets>
       <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
     </PackageReference>

src/Spectre.Console.Tests/Spectre.Console.Tests.csproj

@@ -7,11 +7,13 @@
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="16.5.0" />
+    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="16.7.0" />
     <PackageReference Include="Shouldly" Version="4.0.0-beta0002" />
-    <PackageReference Include="xunit" Version="2.4.0" />
-    <PackageReference Include="xunit.runner.visualstudio" Version="2.4.0" />
-    <PackageReference Include="coverlet.collector" Version="1.2.0" />
+    <PackageReference Include="xunit" Version="2.4.1" />
+    <PackageReference Include="xunit.runner.visualstudio" Version="2.4.3">
+      <PrivateAssets>all</PrivateAssets>
+      <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
+    </PackageReference>
   </ItemGroup>
 
   <ItemGroup>

src/Spectre.Console.Tests/Unit/Composition/GridTests.cs

@@ -6,6 +6,25 @@ namespace Spectre.Console.Tests.Unit.Composition
 {
     public sealed class GridTests
     {
+        public sealed class TheAddColumnMethod
+        {
+            [Fact]
+            public void Should_Throw_If_Rows_Are_Not_Empty()
+            {
+                // Given
+                var grid = new Grid();
+                grid.AddColumn();
+                grid.AddRow("Hello World!");
+
+                // When
+                var result = Record.Exception(() => grid.AddColumn());
+
+                // Then
+                result.ShouldBeOfType<InvalidOperationException>()
+                    .Message.ShouldBe("Cannot add new columns to grid with existing rows.");
+            }
+        }
+
         public sealed class TheAddRowMethod
         {
             [Fact]
@@ -54,6 +73,30 @@ namespace Spectre.Console.Tests.Unit.Composition
             }
         }
 
+        public sealed class TheAddEmptyRowMethod
+        {
+            [Fact]
+            public void Should_Add_Empty_Row()
+            {
+                // Given
+                var console = new PlainConsole(width: 80);
+                var grid = new Grid();
+                grid.AddColumns(2);
+                grid.AddRow("Foo", "Bar");
+                grid.AddEmptyRow();
+                grid.AddRow("Qux", "Corgi");
+
+                // When
+                console.Render(grid);
+
+                // Then
+                console.Lines.Count.ShouldBe(3);
+                console.Lines[0].ShouldBe("Foo  Bar  ");
+                console.Lines[1].ShouldBe("          ");
+                console.Lines[2].ShouldBe("Qux  Corgi");
+            }
+        }
+
         [Fact]
         public void Should_Render_Grid_Correctly()
         {

src/Spectre.Console.Tests/Unit/Composition/TableTests.cs

@@ -21,6 +21,22 @@ namespace Spectre.Console.Tests.Unit.Composition
                 result.ShouldBeOfType<ArgumentNullException>()
                     .ParamName.ShouldBe("column");
             }
+
+            [Fact]
+            public void Should_Throw_If_Rows_Are_Not_Empty()
+            {
+                // Given
+                var grid = new Table();
+                grid.AddColumn("Foo");
+                grid.AddRow("Hello World");
+
+                // When
+                var result = Record.Exception(() => grid.AddColumn("Bar"));
+
+                // Then
+                result.ShouldBeOfType<InvalidOperationException>()
+                    .Message.ShouldBe("Cannot add new columns to table with existing rows.");
+            }
         }
 
         public sealed class TheAddColumnsMethod
@@ -88,6 +104,34 @@ namespace Spectre.Console.Tests.Unit.Composition
             }
         }
 
+        public sealed class TheAddEmptyRowMethod
+        {
+            [Fact]
+            public void Should_Render_Table_Correctly()
+            {
+                // Given
+                var console = new PlainConsole(width: 80);
+                var table = new Table();
+                table.AddColumns("Foo", "Bar", "Baz");
+                table.AddRow("Qux", "Corgi", "Waldo");
+                table.AddEmptyRow();
+                table.AddRow("Grault", "Garply", "Fred");
+
+                // When
+                console.Render(table);
+
+                // Then
+                console.Lines.Count.ShouldBe(7);
+                console.Lines[0].ShouldBe("┌────────┬────────┬───────┐");
+                console.Lines[1].ShouldBe("│ Foo    │ Bar    │ Baz   │");
+                console.Lines[2].ShouldBe("├────────┼────────┼───────┤");
+                console.Lines[3].ShouldBe("│ Qux    │ Corgi  │ Waldo │");
+                console.Lines[4].ShouldBe("│        │        │       │");
+                console.Lines[5].ShouldBe("│ Grault │ Garply │ Fred  │");
+                console.Lines[6].ShouldBe("└────────┴────────┴───────┘");
+            }
+        }
+
         [Fact]
         public void Should_Render_Table_Correctly()
         {

src/Spectre.Console.Tests/Unit/StyleTests.cs

@@ -39,14 +39,18 @@ namespace Spectre.Console.Tests.Unit
 
             [Theory]
             [InlineData("bold", Decoration.Bold)]
+            [InlineData("b", Decoration.Bold)]
             [InlineData("dim", Decoration.Dim)]
+            [InlineData("i", Decoration.Italic)]
             [InlineData("italic", Decoration.Italic)]
             [InlineData("underline", Decoration.Underline)]
+            [InlineData("u", Decoration.Underline)]
             [InlineData("invert", Decoration.Invert)]
             [InlineData("conceal", Decoration.Conceal)]
             [InlineData("slowblink", Decoration.SlowBlink)]
             [InlineData("rapidblink", Decoration.RapidBlink)]
             [InlineData("strikethrough", Decoration.Strikethrough)]
+            [InlineData("s", Decoration.Strikethrough)]
             public void Should_Parse_Decoration(string text, Decoration decoration)
             {
                 // Given, When
@@ -126,108 +130,83 @@ namespace Spectre.Console.Tests.Unit
                 result.ShouldBeOfType<InvalidOperationException>();
                 result.Message.ShouldBe("Could not find color 'lol'.");
             }
+
+            [Theory]
+            [InlineData("#FF0000 on #0000FF")]
+            [InlineData("#F00 on #00F")]
+            public void Should_Parse_Hex_Colors_Correctly(string style)
+            {
+                // Given, When
+                var result = Style.Parse(style);
+
+                // Then
+                result.Foreground.ShouldBe(Color.Red);
+                result.Background.ShouldBe(Color.Blue);
+            }
+
+            [Theory]
+            [InlineData("#", "Invalid hex color '#'.")]
+            [InlineData("#FF00FF00FF", "Invalid hex color '#FF00FF00FF'.")]
+            [InlineData("#FOO", "Invalid hex color '#FOO'. Could not find any recognizable digits.")]
+            public void Should_Return_Error_If_Hex_Color_Is_Invalid(string style, string expected)
+            {
+                // Given, When
+                var result = Record.Exception(() => Style.Parse(style));
+
+                // Then
+                result.ShouldNotBeNull();
+                result.Message.ShouldBe(expected);
+            }
+
+            [Theory]
+            [InlineData("rgb(255,0,0) on rgb(0,0,255)")]
+            public void Should_Parse_Rgb_Colors_Correctly(string style)
+            {
+                // Given, When
+                var result = Style.Parse(style);
+
+                // Then
+                result.Foreground.ShouldBe(Color.Red);
+                result.Background.ShouldBe(Color.Blue);
+            }
+
+            [Theory]
+            [InlineData("rgb()", "Invalid RGB color 'rgb()'.")]
+            [InlineData("rgb(", "Invalid RGB color 'rgb('.")]
+            [InlineData("rgb(255)", "Invalid RGB color 'rgb(255)'.")]
+            [InlineData("rgb(255,255)", "Invalid RGB color 'rgb(255,255)'.")]
+            [InlineData("rgb(255,255,255", "Invalid RGB color 'rgb(255,255,255'.")]
+            [InlineData("rgb(A,B,C)", "Invalid RGB color 'rgb(A,B,C)'. Input string was not in a correct format.")]
+            public void Should_Return_Error_If_Rgb_Color_Is_Invalid(string style, string expected)
+            {
+                // Given, When
+                var result = Record.Exception(() => Style.Parse(style));
+
+                // Then
+                result.ShouldNotBeNull();
+                result.Message.ShouldBe(expected);
+            }
         }
 
         public sealed class TheTryParseMethod
         {
             [Fact]
-            public void Default_Keyword_Should_Return_Default_Style()
+            public void Should_Return_True_If_Parsing_Succeeded()
             {
                 // Given, When
-                var result = Style.TryParse("default", out var style);
+                var result = Style.TryParse("bold", out var style);
 
                 // Then
                 result.ShouldBeTrue();
                 style.ShouldNotBeNull();
-                style.Foreground.ShouldBe(Color.Default);
-                style.Background.ShouldBe(Color.Default);
-                style.Decoration.ShouldBe(Decoration.None);
-            }
-
-            [Theory]
-            [InlineData("bold", Decoration.Bold)]
-            [InlineData("dim", Decoration.Dim)]
-            [InlineData("italic", Decoration.Italic)]
-            [InlineData("underline", Decoration.Underline)]
-            [InlineData("invert", Decoration.Invert)]
-            [InlineData("conceal", Decoration.Conceal)]
-            [InlineData("slowblink", Decoration.SlowBlink)]
-            [InlineData("rapidblink", Decoration.RapidBlink)]
-            [InlineData("strikethrough", Decoration.Strikethrough)]
-            public void Should_Parse_Decoration(string text, Decoration decoration)
-            {
-                // Given, When
-                var result = Style.TryParse(text, out var style);
-
-                // Then
-                result.ShouldBeTrue();
-                style.ShouldNotBeNull();
-                style.Decoration.ShouldBe(decoration);
+                style.Decoration.ShouldBe(Decoration.Bold);
             }
 
             [Fact]
-            public void Should_Parse_Text_And_Decoration()
+            public void Should_Return_False_If_Parsing_Failed()
             {
                 // Given, When
-                var result = Style.TryParse("bold underline blue on green", out var style);
-
-                // Then
-                result.ShouldBeTrue();
-                style.ShouldNotBeNull();
-                style.Decoration.ShouldBe(Decoration.Bold | Decoration.Underline);
-                style.Foreground.ShouldBe(Color.Blue);
-                style.Background.ShouldBe(Color.Green);
-            }
-
-            [Fact]
-            public void Should_Parse_Background_If_Foreground_Is_Set_To_Default()
-            {
-                // Given, When
-                var result = Style.TryParse("default on green", out var style);
-
-                // Then
-                result.ShouldBeTrue();
-                style.ShouldNotBeNull();
-                style.Decoration.ShouldBe(Decoration.None);
-                style.Foreground.ShouldBe(Color.Default);
-                style.Background.ShouldBe(Color.Green);
-            }
-
-            [Fact]
-            public void Should_Throw_If_Foreground_Is_Set_Twice()
-            {
-                // Given, When
-                var result = Style.TryParse("green yellow", out _);
-
-                // Then
-                result.ShouldBeFalse();
-            }
-
-            [Fact]
-            public void Should_Throw_If_Background_Is_Set_Twice()
-            {
-                // Given, When
-                var result = Style.TryParse("green on blue yellow", out _);
-
-                // Then
-                result.ShouldBeFalse();
-            }
-
-            [Fact]
-            public void Should_Throw_If_Color_Name_Could_Not_Be_Found()
-            {
-                // Given, When
-                var result = Style.TryParse("bold lol", out _);
-
-                // Then
-                result.ShouldBeFalse();
-            }
-
-            [Fact]
-            public void Should_Throw_If_Background_Color_Name_Could_Not_Be_Found()
-            {
-                // Given, When
-                var result = Style.TryParse("blue on lol", out _);
+                var result = Style.TryParse("lol", out _);
 
                 // Then
                 result.ShouldBeFalse();

src/Spectre.Console/AnsiConsoleSettings.cs

@@ -21,6 +21,6 @@ namespace Spectre.Console
         /// <summary>
         /// Gets or sets the out buffer.
         /// </summary>
-        public TextWriter Out { get; set; }
+        public TextWriter? Out { get; set; }
     }
 }

src/Spectre.Console/Capabilities.cs

@@ -50,7 +50,7 @@ namespace Spectre.Console
                 ColorSystem.Standard => "4 bits",
                 ColorSystem.EightBit => "8 bits",
                 ColorSystem.TrueColor => "24 bits",
-                _ => "?"
+                _ => "?",
             };
 
             return $"ANSI={supportsAnsi}, Colors={ColorSystem}, Kind={legacyConsole} ({bits})";

src/Spectre.Console/Color.cs

@@ -74,7 +74,7 @@ namespace Spectre.Console
         }
 
         /// <inheritdoc/>
-        public override bool Equals(object obj)
+        public override bool Equals(object? obj)
         {
             return obj is Color color && Equals(color);
         }

src/Spectre.Console/Composition/Border.cs

@@ -57,15 +57,20 @@ namespace Spectre.Console.Composition
         private Dictionary<BorderPart, string> Initialize()
         {
             var lookup = new Dictionary<BorderPart, string>();
-            foreach (BorderPart part in Enum.GetValues(typeof(BorderPart)))
+            foreach (BorderPart? part in Enum.GetValues(typeof(BorderPart)))
             {
-                var text = GetBoxPart(part);
+                if (part == null)
+                {
+                    continue;
+                }
+
+                var text = GetBoxPart(part.Value);
                 if (text.Length > 1)
                 {
                     throw new InvalidOperationException("A box part cannot contain more than one character.");
                 }
 
-                lookup.Add(part, GetBoxPart(part));
+                lookup.Add(part.Value, GetBoxPart(part.Value));
             }
 
             return lookup;

src/Spectre.Console/Composition/Grid.cs

@@ -1,6 +1,8 @@
 using System;
 using System.Collections.Generic;
+using System.Linq;
 using Spectre.Console.Composition;
+using Spectre.Console.Internal;
 
 namespace Spectre.Console
 {
@@ -56,6 +58,11 @@ namespace Spectre.Console
                 throw new ArgumentNullException(nameof(column));
             }
 
+            if (_table.RowCount > 0)
+            {
+                throw new InvalidOperationException("Cannot add new columns to grid with existing rows.");
+            }
+
             // Only pad the most right cell if we've explicitly set a padding.
             _table.PadRightCell = column.Padding != null;
 
@@ -97,6 +104,16 @@ namespace Spectre.Console
             }
         }
 
+        /// <summary>
+        /// Adds an empty row to the grid.
+        /// </summary>
+        public void AddEmptyRow()
+        {
+            var columns = new string[_table.ColumnCount];
+            Enumerable.Range(0, _table.ColumnCount).ForEach(index => columns[index] = string.Empty);
+            AddRow(columns);
+        }
+
         /// <summary>
         /// Adds a new row to the grid.
         /// </summary>

src/Spectre.Console/Composition/GridColumn.cs

@@ -9,22 +9,22 @@ namespace Spectre.Console
         /// Gets or sets the width of the column.
         /// If <c>null</c>, the column will adapt to it's contents.
         /// </summary>
-        public int? Width { get; set; } = null;
+        public int? Width { get; set; }
 
         /// <summary>
         /// Gets or sets a value indicating whether wrapping of
         /// text within the column should be prevented.
         /// </summary>
-        public bool NoWrap { get; set; } = false;
+        public bool NoWrap { get; set; }
 
         /// <summary>
         /// Gets or sets the padding of the column.
         /// </summary>
-        public Padding? Padding { get; set; } = null;
+        public Padding? Padding { get; set; }
 
         /// <summary>
         /// Gets or sets the alignment of the column.
         /// </summary>
-        public Justify? Alignment { get; set; } = null;
+        public Justify? Alignment { get; set; }
     }
 }

src/Spectre.Console/Composition/Justify.cs

@@ -16,7 +16,7 @@ namespace Spectre.Console
         Right = 1,
 
         /// <summary>
-        /// Centered
+        /// Centered.
         /// </summary>
         Center = 2,
     }

src/Spectre.Console/Composition/Measurement.cs

@@ -29,7 +29,7 @@ namespace Spectre.Console.Composition
         }
 
         /// <inheritdoc/>
-        public override bool Equals(object obj)
+        public override bool Equals(object? obj)
         {
             return obj is Measurement measurement && Equals(measurement);
         }

src/Spectre.Console/Composition/Padding.cs

@@ -29,7 +29,7 @@ namespace Spectre.Console
         }
 
         /// <inheritdoc/>
-        public override bool Equals(object obj)
+        public override bool Equals(object? obj)
         {
             return obj is Padding padding && Equals(padding);
         }

src/Spectre.Console/Composition/Panel.cs

@@ -9,6 +9,8 @@ namespace Spectre.Console
     /// </summary>
     public sealed class Panel : IRenderable
     {
+        private const int EdgeWidth = 2;
+
         private readonly IRenderable _child;
 
         /// <summary>
@@ -26,14 +28,14 @@ namespace Spectre.Console
         /// <summary>
         /// Gets or sets the alignment of the panel contents.
         /// </summary>
-        public Justify? Alignment { get; set; } = null;
+        public Justify? Alignment { get; set; }
 
         /// <summary>
         /// Gets or sets a value indicating whether or not the panel should
         /// fit the available space. If <c>false</c>, the panel width will be
         /// auto calculated. Defaults to <c>false</c>.
         /// </summary>
-        public bool Expand { get; set; } = false;
+        public bool Expand { get; set; }
 
         /// <summary>
         /// Gets or sets the padding.
@@ -61,13 +63,12 @@ namespace Spectre.Console
         {
             var border = Composition.Border.GetBorder(Border, (context.LegacyConsole || !context.Unicode) && SafeBorder);
 
-            var edgeWidth = 2;
             var paddingWidth = Padding.GetHorizontalPadding();
-            var childWidth = width - edgeWidth - paddingWidth;
+            var childWidth = width - EdgeWidth - paddingWidth;
 
             if (!Expand)
             {
-                var measurement = _child.Measure(context, width - edgeWidth - paddingWidth);
+                var measurement = _child.Measure(context, width - EdgeWidth - paddingWidth);
                 childWidth = measurement.Max;
             }
 

src/Spectre.Console/Composition/Segment.cs

@@ -50,7 +50,12 @@ namespace Spectre.Console.Composition
 
         private Segment(string text, Style style, bool lineBreak)
         {
-            Text = text?.NormalizeLineEndings() ?? throw new ArgumentNullException(nameof(text));
+            if (text is null)
+            {
+                throw new ArgumentNullException(nameof(text));
+            }
+
+            Text = text.NormalizeLineEndings();
             Style = style;
             IsLineBreak = lineBreak;
         }
@@ -89,7 +94,7 @@ namespace Spectre.Console.Composition
         /// </summary>
         /// <param name="offset">The offset where to split the segment.</param>
         /// <returns>One or two new segments representing the split.</returns>
-        public (Segment First, Segment Second) Split(int offset)
+        public (Segment First, Segment? Second) Split(int offset)
         {
             if (offset < 0)
             {

src/Spectre.Console/Composition/Table.Calculations.cs

@@ -11,6 +11,8 @@ namespace Spectre.Console
     /// </summary>
     public sealed partial class Table
     {
+        private const int EdgeCount = 2;
+
         // Calculate the widths of each column, including padding, not including borders.
         // Ported from Rich by Will McGugan, licensed under MIT.
         // https://github.com/willmcgugan/rich/blob/527475837ebbfc427530b3ee0d4d0741d2d0fc6d/rich/table.py#L394
@@ -115,10 +117,9 @@ namespace Spectre.Console
 
         private int GetExtraWidth(bool includePadding)
         {
-            var edges = 2;
             var separators = _columns.Count - 1;
             var padding = includePadding ? _columns.Select(x => x.Padding.GetHorizontalPadding()).Sum() : 0;
-            return separators + edges + padding;
+            return separators + EdgeCount + padding;
         }
     }
 }

src/Spectre.Console/Composition/Table.cs

@@ -39,12 +39,12 @@ namespace Spectre.Console
         /// fit the available space. If <c>false</c>, the table width will be
         /// auto calculated. Defaults to <c>false</c>.
         /// </summary>
-        public bool Expand { get; set; } = false;
+        public bool Expand { get; set; }
 
         /// <summary>
         /// Gets or sets the width of the table.
         /// </summary>
-        public int? Width { get; set; } = null;
+        public int? Width { get; set; }
 
         /// <summary>
         /// Gets or sets a value indicating whether or not to use
@@ -54,7 +54,7 @@ namespace Spectre.Console
         public bool SafeBorder { get; set; } = true;
 
         // Whether this is a grid or not.
-        internal bool IsGrid { get; set; } = false;
+        internal bool IsGrid { get; set; }
 
         // Whether or not the most right cell should be padded.
         // This is almost always the case, unless we're rendering
@@ -81,7 +81,7 @@ namespace Spectre.Console
                 throw new ArgumentNullException(nameof(column));
             }
 
-            _columns.Add(new TableColumn(column));
+            AddColumn(new TableColumn(column));
         }
 
         /// <summary>
@@ -95,6 +95,11 @@ namespace Spectre.Console
                 throw new ArgumentNullException(nameof(column));
             }
 
+            if (_rows.Count > 0)
+            {
+                throw new InvalidOperationException("Cannot add new columns to table with existing rows.");
+            }
+
             _columns.Add(column);
         }
 
@@ -109,7 +114,10 @@ namespace Spectre.Console
                 throw new ArgumentNullException(nameof(columns));
             }
 
-            _columns.AddRange(columns.Select(column => new TableColumn(column)));
+            foreach (var column in columns)
+            {
+                AddColumn(column);
+            }
         }
 
         /// <summary>
@@ -123,7 +131,20 @@ namespace Spectre.Console
                 throw new ArgumentNullException(nameof(columns));
             }
 
-            _columns.AddRange(columns.Select(column => column));
+            foreach (var column in columns)
+            {
+                AddColumn(column);
+            }
+        }
+
+        /// <summary>
+        /// Adds an empty row to the table.
+        /// </summary>
+        public void AddEmptyRow()
+        {
+            var columns = new string[ColumnCount];
+            Enumerable.Range(0, ColumnCount).ForEach(index => columns[index] = string.Empty);
+            AddRow(columns);
         }
 
         /// <summary>

src/Spectre.Console/Composition/Text.cs

@@ -201,7 +201,7 @@ namespace Spectre.Console
             return result;
         }
 
-        private IEnumerable<Segment> SplitLineBreaks(IEnumerable<Segment> segments)
+        private static IEnumerable<Segment> SplitLineBreaks(IEnumerable<Segment> segments)
         {
             // Creates individual segments of line breaks.
             var result = new List<Segment>();
@@ -228,7 +228,11 @@ namespace Spectre.Console
                     }
 
                     result.Add(Segment.LineBreak());
-                    queue.Push(new Segment(second.Text.Substring(1), second.Style));
+
+                    if (second != null)
+                    {
+                        queue.Push(new Segment(second.Text.Substring(1), second.Style));
+                    }
                 }
             }
 

src/Spectre.Console/Internal/Colors/ColorTable.cs

@@ -45,7 +45,7 @@ namespace Spectre.Console.Internal
             return ColorPalette.EightBit[number];
         }
 
-        public static string GetName(int number)
+        public static string? GetName(int number)
         {
             _nameLookup.TryGetValue(number, out var name);
             return name;

src/Spectre.Console/Internal/DecorationTable.cs

@@ -15,14 +15,18 @@ namespace Spectre.Console.Internal
             {
                 { "none", Decoration.None },
                 { "bold", Decoration.Bold },
+                { "b", Decoration.Bold },
                 { "dim", Decoration.Dim },
                 { "italic", Decoration.Italic },
+                { "i", Decoration.Italic },
                 { "underline", Decoration.Underline },
+                { "u", Decoration.Underline },
                 { "invert", Decoration.Invert },
                 { "conceal", Decoration.Conceal },
                 { "slowblink", Decoration.SlowBlink },
                 { "rapidblink", Decoration.RapidBlink },
                 { "strikethrough", Decoration.Strikethrough },
+                { "s", Decoration.Strikethrough },
             };
         }
 

src/Spectre.Console/Internal/Extensions/StringExtensions.cs

@@ -17,14 +17,9 @@ namespace Spectre.Console.Internal
 
         public static string NormalizeLineEndings(this string text, bool native = false)
         {
-            if (text == null)
-            {
-                return null;
-            }
-
-            var normalized = text?.Replace("\r\n", "\n")
-                ?.Replace("\r", string.Empty);
+            text ??= string.Empty;
 
+            var normalized = text?.Replace("\r\n", "\n")?.Replace("\r", string.Empty) ?? string.Empty;
             if (native && !_alreadyNormalized)
             {
                 normalized = normalized.Replace("\n", Environment.NewLine);
@@ -35,7 +30,8 @@ namespace Spectre.Console.Internal
 
         public static string[] SplitLines(this string text)
         {
-            return text.NormalizeLineEndings().Split(new[] { '\n' }, StringSplitOptions.None);
+            var result = text?.NormalizeLineEndings()?.Split(new[] { '\n' }, StringSplitOptions.None);
+            return result ?? Array.Empty<string>();
         }
     }
 }

src/Spectre.Console/Internal/Text/Markup/MarkupParser.cs

@@ -6,7 +6,7 @@ namespace Spectre.Console.Internal
 {
     internal static class MarkupParser
     {
-        public static Text Parse(string text, Style style = null)
+        public static Text Parse(string text, Style? style = null)
         {
             style ??= Style.Plain;
 
@@ -18,6 +18,10 @@ namespace Spectre.Console.Internal
             while (tokenizer.MoveNext())
             {
                 var token = tokenizer.Current;
+                if (token == null)
+                {
+                    break;
+                }
 
                 if (token.Kind == MarkupTokenKind.Open)
                 {

src/Spectre.Console/Internal/Text/Markup/MarkupTokenizer.cs

@@ -7,7 +7,7 @@ namespace Spectre.Console.Internal
     {
         private readonly StringBuffer _reader;
 
-        public MarkupToken Current { get; private set; }
+        public MarkupToken? Current { get; private set; }
 
         public MarkupTokenizer(string text)
         {

src/Spectre.Console/Internal/Text/StringBuffer.cs

@@ -1,10 +1,12 @@
 using System;
+using System.Diagnostics.CodeAnalysis;
 using System.IO;
 
 namespace Spectre.Console.Internal
 {
     internal sealed class StringBuffer : IDisposable
     {
+        [SuppressMessage("Usage", "CA2213:Disposable fields should be disposed", Justification = "False positive")]
         private readonly StringReader _reader;
         private readonly int _length;
 

src/Spectre.Console/Internal/Text/StyleParser.cs

@@ -1,4 +1,6 @@
 using System;
+using System.Diagnostics.CodeAnalysis;
+using System.Globalization;
 
 namespace Spectre.Console.Internal
 {
@@ -12,16 +14,23 @@ namespace Spectre.Console.Internal
                 throw new InvalidOperationException(error);
             }
 
+            if (style == null)
+            {
+                // This should not happen, but we need to please the compiler
+                // which cannot know that style isn't null here.
+                throw new InvalidOperationException("Could not parse style.");
+            }
+
             return style;
         }
 
-        public static bool TryParse(string text, out Style style)
+        public static bool TryParse(string text, out Style? style)
         {
             style = Parse(text, out var error);
             return error == null;
         }
 
-        private static Style Parse(string text, out string error)
+        private static Style? Parse(string text, out string? error)
         {
             var effectiveDecoration = (Decoration?)null;
             var effectiveForeground = (Color?)null;
@@ -57,16 +66,30 @@ namespace Spectre.Console.Internal
                     var color = ColorTable.GetColor(part);
                     if (color == null)
                     {
-                        if (!foreground)
+                        if (part.StartsWith("#", StringComparison.OrdinalIgnoreCase))
                         {
-                            error = $"Could not find color '{part}'.";
+                            color = ParseHexColor(part, out error);
+                            if (!string.IsNullOrWhiteSpace(error))
+                            {
+                                return null;
+                            }
+                        }
+                        else if (part.StartsWith("rgb", StringComparison.OrdinalIgnoreCase))
+                        {
+                            color = ParseRgbColor(part, out error);
+                            if (!string.IsNullOrWhiteSpace(error))
+                            {
+                                return null;
+                            }
                         }
                         else
                         {
-                            error = $"Could not find color or style '{part}'.";
-                        }
+                            error = !foreground
+                                ? $"Could not find color '{part}'."
+                                : $"Could not find color or style '{part}'.";
 
-                        return null;
+                            return null;
+                        }
                     }
 
                     if (foreground)
@@ -95,5 +118,82 @@ namespace Spectre.Console.Internal
             error = null;
             return new Style(effectiveForeground, effectiveBackground, effectiveDecoration);
         }
+
+        [SuppressMessage("Design", "CA1031:Do not catch general exception types")]
+        private static Color? ParseHexColor(string hex, out string? error)
+        {
+            error = null;
+
+            hex ??= string.Empty;
+            hex = hex.Replace("#", string.Empty).Trim();
+
+            try
+            {
+                if (!string.IsNullOrWhiteSpace(hex))
+                {
+                    if (hex.Length == 6)
+                    {
+                        return new Color(
+                            (byte)Convert.ToUInt32(hex.Substring(0, 2), 16),
+                            (byte)Convert.ToUInt32(hex.Substring(2, 2), 16),
+                            (byte)Convert.ToUInt32(hex.Substring(4, 2), 16));
+                    }
+                    else if (hex.Length == 3)
+                    {
+                        return new Color(
+                            (byte)Convert.ToUInt32(new string(hex[0], 2), 16),
+                            (byte)Convert.ToUInt32(new string(hex[1], 2), 16),
+                            (byte)Convert.ToUInt32(new string(hex[2], 2), 16));
+                    }
+                }
+            }
+            catch (Exception ex)
+            {
+                error = $"Invalid hex color '#{hex}'. {ex.Message}";
+                return null;
+            }
+
+            error = $"Invalid hex color '#{hex}'.";
+            return null;
+        }
+
+        [SuppressMessage("Design", "CA1031:Do not catch general exception types")]
+        private static Color? ParseRgbColor(string rgb, out string? error)
+        {
+            try
+            {
+                error = null;
+
+                var normalized = rgb ?? string.Empty;
+                if (normalized.Length >= 3)
+                {
+                    // Trim parenthesises
+                    normalized = normalized.Substring(3).Trim();
+
+                    if (normalized.StartsWith("(", StringComparison.OrdinalIgnoreCase) &&
+                       normalized.EndsWith(")", StringComparison.OrdinalIgnoreCase))
+                    {
+                        normalized = normalized.Trim('(').Trim(')');
+
+                        var parts = normalized.Split(new[] { ',' }, StringSplitOptions.RemoveEmptyEntries);
+                        if (parts.Length == 3)
+                        {
+                            return new Color(
+                                (byte)Convert.ToInt32(parts[0], CultureInfo.InvariantCulture),
+                                (byte)Convert.ToInt32(parts[1], CultureInfo.InvariantCulture),
+                                (byte)Convert.ToInt32(parts[2], CultureInfo.InvariantCulture));
+                        }
+                    }
+                }
+            }
+            catch (Exception ex)
+            {
+                error = $"Invalid RGB color '{rgb}'. {ex.Message}";
+                return null;
+            }
+
+            error = $"Invalid RGB color '{rgb}'.";
+            return null;
+        }
     }
 }

src/Spectre.Console/Internal/Utilities/Ratio.cs

@@ -40,7 +40,7 @@ namespace Spectre.Console.Internal
             return result;
         }
 
-        public static List<int> Distribute(int total, List<int> ratios, List<int> minimums = null)
+        public static List<int> Distribute(int total, List<int> ratios, List<int>? minimums = null)
         {
             if (minimums != null)
             {

src/Spectre.Console/Spectre.Console.csproj

@@ -2,6 +2,7 @@
 
   <PropertyGroup>
     <TargetFramework>netstandard2.0</TargetFramework>
+    <Nullable>enable</Nullable>
   </PropertyGroup>
 
   <ItemGroup>
@@ -9,27 +10,21 @@
     <None Include="../../gfx/small-logo.png" Pack="true" PackagePath="\" Link="Properties/small-logo.png" />
   </ItemGroup>
 
-  <ItemGroup>
-    <Compile Update="**/ColorPalette.*.cs">
-      <DependentUpon>**/ColorPalette.cs</DependentUpon>
-    </Compile>
-    <Compile Update="Color.*.cs">
-      <DependentUpon>Color.cs</DependentUpon>
-    </Compile>
-    <Compile Update="AnsiConsole.*.cs">
-      <DependentUpon>AnsiConsole.cs</DependentUpon>
-    </Compile>
-    <Compile Update="ConsoleExtensions.*.cs">
-      <DependentUpon>ConsoleExtensions.cs</DependentUpon>
-    </Compile>
-    <Compile Update="**/Table.*.cs">
-      <DependentUpon>**/Table.cs</DependentUpon>
-    </Compile>
-
-  </ItemGroup>
-
   <ItemGroup>
     <PackageReference Include="System.Memory" Version="4.5.4" />
   </ItemGroup>
 
+  <ItemGroup>
+    <PackageReference Include="TunnelVisionLabs.ReferenceAssemblyAnnotator" Version="1.0.0-alpha.160" PrivateAssets="all" />
+    <PackageDownload Include="Microsoft.NETCore.App.Ref" Version="[$(AnnotatedReferenceAssemblyVersion)]" />
+    <PackageReference Include="Nullable" Version="1.2.1">
+      <PrivateAssets>all</PrivateAssets>
+      <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
+    </PackageReference>
+  </ItemGroup>
+  <PropertyGroup>
+    <AnnotatedReferenceAssemblyVersion>3.0.0</AnnotatedReferenceAssemblyVersion>
+    <GenerateNullableAttributes>False</GenerateNullableAttributes>
+  </PropertyGroup>
+
 </Project>

src/Spectre.Console/Style.cs

@@ -67,7 +67,7 @@ namespace Spectre.Console
         /// if the conversion succeeded, or <c>null</c> if the conversion failed.
         /// </param>
         /// <returns><c>true</c> if s was converted successfully; otherwise, <c>false</c>.</returns>
-        public static bool TryParse(string text, out Style result)
+        public static bool TryParse(string text, out Style? result)
         {
             return StyleParser.TryParse(text, out result);
         }
@@ -113,13 +113,13 @@ namespace Spectre.Console
         }
 
         /// <inheritdoc/>
-        public override bool Equals(object obj)
+        public override bool Equals(object? obj)
         {
             return Equals(obj as Style);
         }
 
         /// <inheritdoc/>
-        public bool Equals(Style other)
+        public bool Equals(Style? other)
         {
             if (other == null)
             {