Make alert block headers case-invariant

src/Markdig/Extensions/Alerts/AlertBlockRenderer.cs

@@ -50,6 +50,7 @@ protected override void Write(HtmlRenderer renderer, AlertBlock obj)
         {
             renderer.WriteLine("</div>");
         }
+
         renderer.EnsureLine();
     }
 
@@ -61,7 +62,14 @@ protected override void Write(HtmlRenderer renderer, AlertBlock obj)
     /// <param name="kind">The kind of the alert to render</param>
     public static void DefaultRenderKind(HtmlRenderer renderer, StringSlice kind)
     {
-        string? html = kind.AsSpan() switch
+        if (kind.Length >= 16)
+        {
+            return;
+        }
+
+        Span<char> upperKind = stackalloc char[kind.Length];
+        kind.AsSpan().ToUpperInvariant(upperKind);
+        string? html = upperKind switch
         {
             "NOTE" => "<p class=\"markdown-alert-title\"><svg viewBox=\"0 0 16 16\" version=\"1.1\" width=\"16\" height=\"16\" aria-hidden=\"true\"><path d=\"M0 8a8 8 0 1 1 16 0A8 8 0 0 1 0 8Zm8-6.5a6.5 6.5 0 1 0 0 13 6.5 6.5 0 0 0 0-13ZM6.5 7.75A.75.75 0 0 1 7.25 7h1a.75.75 0 0 1 .75.75v2.75h.25a.75.75 0 0 1 0 1.5h-2a.75.75 0 0 1 0-1.5h.25v-2h-.25a.75.75 0 0 1-.75-.75ZM8 6a1 1 0 1 1 0-2 1 1 0 0 1 0 2Z\"></path></svg>Note</p>",
             "TIP" => "<p class=\"markdown-alert-title\"><svg viewBox=\"0 0 16 16\" version=\"1.1\" width=\"16\" height=\"16\" aria-hidden=\"true\"><path d=\"M8 1.5c-2.363 0-4 1.69-4 3.75 0 .984.424 1.625.984 2.304l.214.253c.223.264.47.556.673.848.284.411.537.896.621 1.49a.75.75 0 0 1-1.484.211c-.04-.282-.163-.547-.37-.847a8.456 8.456 0 0 0-.542-.68c-.084-.1-.173-.205-.268-.32C3.201 7.75 2.5 6.766 2.5 5.25 2.5 2.31 4.863 0 8 0s5.5 2.31 5.5 5.25c0 1.516-.701 2.5-1.328 3.259-.095.115-.184.22-.268.319-.207.245-.383.453-.541.681-.208.3-.33.565-.37.847a.751.751 0 0 1-1.485-.212c.084-.593.337-1.078.621-1.489.203-.292.45-.584.673-.848.075-.088.147-.173.213-.253.561-.679.985-1.32.985-2.304 0-2.06-1.637-3.75-4-3.75ZM5.75 12h4.5a.75.75 0 0 1 0 1.5h-4.5a.75.75 0 0 1 0-1.5ZM6 15.25a.75.75 0 0 1 .75-.75h2.5a.75.75 0 0 1 0 1.5h-2.5a.75.75 0 0 1-.75-.75Z\"></path></svg>Tip</p>",

src/Markdig/Extensions/Alerts/AlertInlineParser.cs

@@ -46,7 +46,7 @@ public override bool Match(InlineProcessor processor, ref StringSlice slice)
 
         var start = slice.Start;
         var end = start;
-        while (c.IsAlphaUpper())
+        while (c.IsAlpha())
         {
             end = slice.Start;
             c = slice.NextChar();
@@ -86,7 +86,7 @@ public override bool Match(InlineProcessor processor, ref StringSlice slice)
                 }
                 break;
             }
-            else if (!c.IsSpaceOrTab()) 
+            else if (!c.IsSpaceOrTab())
             {
                 slice = saved;
                 return false;

src/Markdig/Extensions/Bootstrap/BootstrapExtension.cs

@@ -41,6 +41,7 @@ public void Setup(MarkdownPipeline pipeline, IMarkdownRenderer renderer)
 
     private static void PipelineOnDocumentProcessed(MarkdownDocument document)
     {
+        Span<char> upperKind = new char[16];
         foreach (var node in document.Descendants())
         {
             if (node.IsInline)
@@ -61,19 +62,18 @@ private static void PipelineOnDocumentProcessed(MarkdownDocument document)
                     var attributes = node.GetAttributes();
                     attributes.AddClass("alert");
                     attributes.AddProperty("role", "alert");
-                    string? @class = alertBlock.Kind.AsSpan() switch
+                    if (alertBlock.Kind.Length <= upperKind.Length)
                     {
-                        "NOTE" => "alert-primary",
-                        "TIP" => "alert-success",
-                        "IMPORTANT" => "alert-info",
-                        "WARNING" => "alert-warning",
-                        "CAUTION" => "alert-danger",
-                        _ => null,
-                    };
-
-                    if (@class is not null)
-                    {
-                        attributes.AddClass(@class);
+                        alertBlock.Kind.AsSpan().ToUpperInvariant(upperKind);
+                        attributes.AddClass(upperKind.Slice(0, alertBlock.Kind.Length) switch
+                        {
+                            "NOTE" => "alert-primary",
+                            "TIP" => "alert-success",
+                            "IMPORTANT" => "alert-info",
+                            "WARNING" => "alert-warning",
+                            "CAUTION" => "alert-danger",
+                            _ => "alert-dark",
+                        });
                     }
 
                     var lastParagraph = alertBlock.Descendants().OfType<ParagraphBlock>().LastOrDefault();