Add dynamic registration for razor and cshtml files

src/Features/LanguageServer/Microsoft.CodeAnalysis.LanguageServer/LanguageServer/RazorDynamicDocumentSyncRegistration.cs

@@ -0,0 +1,84 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using System;
+using System.Composition;
+using System.Threading;
+using System.Threading.Tasks;
+using Microsoft.CodeAnalysis.Host.Mef;
+using Microsoft.CodeAnalysis.LanguageServer;
+using Microsoft.CodeAnalysis.LanguageServer.Handler;
+using Microsoft.CodeAnalysis.Options;
+using Roslyn.LanguageServer.Protocol;
+
+namespace Microsoft.CodeAnalysis.LanguageServer.LanguageServer;
+
+[ExportCSharpVisualBasicLspServiceFactory(typeof(OnInitialized)), Shared]
+[method: ImportingConstructor]
+[method: Obsolete(MefConstruction.ImportingConstructorMessage, error: true)]
+internal sealed class RazorDynamicDocumentSyncRegistration(IGlobalOptionService globalOptionService) : ILspServiceFactory
+{
+    public ILspService CreateILspService(LspServices lspServices, WellKnownLspServerKinds serverKind)
+        => new OnInitialized(globalOptionService);
+
+    public class OnInitialized : IOnInitialized, ILspService
+    {
+        private readonly IGlobalOptionService _globalOptionService;
+
+        public OnInitialized(IGlobalOptionService globalOptionService)
+        {
+            _globalOptionService = globalOptionService;
+        }
+
+        public async Task OnInitializedAsync(ClientCapabilities clientCapabilities, RequestContext context, CancellationToken cancellationToken)
+        {
+            // Hot reload only works in devkit scenarios. Without, there is no need to register for dynamic document sync.
+            if (!_globalOptionService.GetOption(LspOptionsStorage.LspUsingDevkitFeatures))
+            {
+                return;
+            }
+
+            // If dynamic registration for text document synchronization is supported, register for .razor and .cshtml files
+            // so that they are up to date for hot reload scenarios rather than depending on the file watchers to update
+            // the contents.
+            if (clientCapabilities.TextDocument?.Synchronization?.DynamicRegistration is true)
+            {
+                var languageServerManager = context.GetRequiredLspService<IClientLanguageServerManager>();
+
+                var documentFilters = new[] { new DocumentFilter() { Pattern = "**/*.razor" }, new DocumentFilter() { Pattern = "**/*.cshtml" } };
+                var registrationOptions = new TextDocumentRegistrationOptions()
+                {
+                    DocumentSelector = documentFilters
+                };
+
+                await languageServerManager.SendRequestAsync(Methods.ClientRegisterCapabilityName,
+                    new RegistrationParams()
+                    {
+                        Registrations = [
+                            new()
+                            {
+                                Id = Guid.NewGuid().ToString(), // No need to save this for unregistering
+                                Method = Methods.TextDocumentDidOpenName,
+                                RegisterOptions = registrationOptions
+                            },
+                            new()
+                            {
+                                Id = Guid.NewGuid().ToString(), // No need to save this for unregistering
+                                Method = Methods.TextDocumentDidChangeName,
+                                RegisterOptions = registrationOptions
+                            },
+                            new()
+                            {
+                                Id = Guid.NewGuid().ToString(), // No need to save this for unregistering
+                                Method = Methods.TextDocumentDidCloseName,
+                                RegisterOptions = registrationOptions
+                            }
+                        ]
+                    },
+                    cancellationToken).ConfigureAwait(false);
+            }
+        }
+    }
+}
+