Popup (hover) with Markdown from a Language Service Protocol (LSP)

Question

I'm building a language server in C# (with VS2022) that implements the Language Server Protocol (LSP) 17.2.8 (https://www.nuget.org/packages/Microsoft.VisualStudio.LanguageServer.Protocol.Extensions)

I'm new to the Language service protocol, and there might be a simple solution to my problem. I created markdown content for a Hover popup, but the content is displayed as plain text.

This is the OnHover,

     [JsonRpcMethod(Methods.TextDocumentHoverName)]
     public Hover OnHover(JToken arg)
     {
         LogInfo($"OnHover: Received: {arg}");
         var parameter = arg.ToObject<TextDocumentPositionParams>();

         [SNIP details]

         var hoverContent = new SumType<string, MarkedString>[]{
             new SumType<string, MarkedString>(new MarkedString
             {
                 Language = MarkupKind.PlainText.ToString(),
                 Value = full_Descr + "\n",
             }),
             new SumType<string, MarkedString>(new MarkedString
             {
                 Language = MarkupKind.Markdown.ToString(),
                 Value = "```text\n" + performanceStr + "\n```",
             })
         };

         var result = new Hover()
         {
             Contents = hoverContent
         };

         LogInfo($"OnHover: Sent: {JToken.FromObject(result)}");
         return result;
     }

The language service sends the following message to my VisualStudio extension (vsix):

{
  "contents": [
    {
      "language": "PlainText",
      "value": "VPCONFLICTQ : [NONE,AVX512_CD] Detect Conflicts Within a Vector of Packed Dword/Qword Values into Dense Memory/ Register\n"
    },
    {
      "language": "Markdown",
      "value": "```text\n                                      µOps   µOps     µOps                                              \nArchitecture  Instruction             Fused  Unfused  Port                Latency  Throughput           \nSkylakeX      VPCONFLICTQ x,x         3      3        p01 p5              4        2                    \nSkylakeX      VPCONFLICTQ y,y         15     15       p01 p5              13       7                    \nSkylakeX      VPCONFLICTQ z,z         22     22       p0 p5               17       12                   \n```"
    }
  ]
}

When the language service initialized, it sends (to my VS-extension) a JSON with capabilities (removed all other capabilities).

{
  "capabilities": {
    "hoverProvider": {}
  }
}

Question: Is there something else that I need to configure to get a popup with Markdown layout? Is Markdown not supported from the Visual studio side? Do I need HoverClientCapabilities to configure stuff?

The de facto reference implementation can be found in the VSSDK-Extensibility-Samples (https://github.com/microsoft/VSSDK-Extensibility-Samples/tree/master/LanguageServerProtocol), but it does not have a markdown popup. Even a link to working C# code would be appreciated.

Popup (hover) with Markdown from a Language Service Protocol (LSP)

0 Answers0