Updated capabilities to indicate which handler they are tied too, th…

src/Lsp/Capabilities/Client/CodeActionCapability.cs

@@ -1,4 +1,7 @@
-namespace OmniSharp.Extensions.LanguageServer.Capabilities.Client
+using OmniSharp.Extensions.LanguageServer.Abstractions;
+using OmniSharp.Extensions.LanguageServer.Protocol;
+
+namespace OmniSharp.Extensions.LanguageServer.Capabilities.Client
 {
-    public class CodeActionCapability : DynamicCapability { }
+    public class CodeActionCapability : DynamicCapability, ConnectedCapability<ICodeActionHandler> { }
 }

src/Lsp/Capabilities/Client/CodeLensCapability.cs

@@ -1,4 +1,7 @@
-namespace OmniSharp.Extensions.LanguageServer.Capabilities.Client
+using OmniSharp.Extensions.LanguageServer.Capabilities.Server;
+using OmniSharp.Extensions.LanguageServer.Protocol;
+
+namespace OmniSharp.Extensions.LanguageServer.Capabilities.Client
 {
-    public class CodeLensCapability : DynamicCapability { }
+    public class CodeLensCapability : DynamicCapability, ConnectedCapability<ICodeLensHandler> { }
 }

src/Lsp/Capabilities/Client/CompletionCapability.cs

@@ -1,6 +1,8 @@
-namespace OmniSharp.Extensions.LanguageServer.Capabilities.Client
+using OmniSharp.Extensions.LanguageServer.Protocol;
+
+namespace OmniSharp.Extensions.LanguageServer.Capabilities.Client
 {
-    public class CompletionCapability : DynamicCapability
+    public class CompletionCapability : DynamicCapability, ConnectedCapability<ICompletionHandler>
     {
         /// <summary>
         /// The client supports the following `CompletionItem` specific

src/Lsp/Capabilities/Client/ConnectedCapability.cs

@@ -0,0 +1,8 @@
+using OmniSharp.Extensions.JsonRpc;
+
+namespace OmniSharp.Extensions.LanguageServer.Capabilities.Client
+{
+    internal interface ConnectedCapability<out T>
+        where T : IJsonRpcHandler
+    { }
+}

src/Lsp/Capabilities/Client/DefinitionCapability.cs

@@ -1,4 +1,6 @@
-namespace OmniSharp.Extensions.LanguageServer.Capabilities.Client
+using OmniSharp.Extensions.LanguageServer.Protocol;
+
+namespace OmniSharp.Extensions.LanguageServer.Capabilities.Client
 {
-    public class DefinitionCapability : DynamicCapability { }
+    public class DefinitionCapability : DynamicCapability, ConnectedCapability<IDefinitionHandler> { }
 }

src/Lsp/Capabilities/Client/DocumentFormattingCapability.cs

@@ -1,4 +1,6 @@
-namespace OmniSharp.Extensions.LanguageServer.Capabilities.Client
+using OmniSharp.Extensions.LanguageServer.Protocol;
+
+namespace OmniSharp.Extensions.LanguageServer.Capabilities.Client
 {
-    public class DocumentFormattingCapability : DynamicCapability { }
+    public class DocumentFormattingCapability : DynamicCapability, ConnectedCapability<IDocumentFormattingHandler> { }
 }

src/Lsp/Capabilities/Client/DocumentHighlightCapability.cs

@@ -1,4 +1,6 @@
-namespace OmniSharp.Extensions.LanguageServer.Capabilities.Client
+using OmniSharp.Extensions.LanguageServer.Protocol;
+
+namespace OmniSharp.Extensions.LanguageServer.Capabilities.Client
 {
-    public class DocumentHighlightCapability : DynamicCapability { }
+    public class DocumentHighlightCapability : DynamicCapability, ConnectedCapability<IDocumentHighlightHandler> { }
 }

src/Lsp/Capabilities/Client/DocumentLinkCapability.cs

@@ -1,4 +1,6 @@
-namespace OmniSharp.Extensions.LanguageServer.Capabilities.Client
+using OmniSharp.Extensions.LanguageServer.Protocol;
+
+namespace OmniSharp.Extensions.LanguageServer.Capabilities.Client
 {
-    public class DocumentLinkCapability : DynamicCapability { }
+    public class DocumentLinkCapability : DynamicCapability, ConnectedCapability<IDocumentLinkHandler> { }
 }

src/Lsp/Capabilities/Client/DocumentOnTypeFormattingCapability.cs

@@ -1,4 +1,6 @@
-namespace OmniSharp.Extensions.LanguageServer.Capabilities.Client
+using OmniSharp.Extensions.LanguageServer.Protocol;
+
+namespace OmniSharp.Extensions.LanguageServer.Capabilities.Client
 {
-    public class DocumentOnTypeFormattingCapability : DynamicCapability { }
+    public class DocumentOnTypeFormattingCapability : DynamicCapability, ConnectedCapability<IDocumentOnTypeFormatHandler> { }
 }

src/Lsp/Capabilities/Client/DocumentRangeFormattingCapability.cs

@@ -1,4 +1,6 @@
-namespace OmniSharp.Extensions.LanguageServer.Capabilities.Client
+using OmniSharp.Extensions.LanguageServer.Protocol.Document;
+
+namespace OmniSharp.Extensions.LanguageServer.Capabilities.Client
 {
-    public class DocumentRangeFormattingCapability : DynamicCapability { }
+    public class DocumentRangeFormattingCapability : DynamicCapability, ConnectedCapability<IDocumentRangeFormattingHandler> { }
 }

src/Lsp/Capabilities/Client/DocumentSymbolCapability.cs

@@ -1,4 +1,6 @@
-namespace OmniSharp.Extensions.LanguageServer.Capabilities.Client
+using OmniSharp.Extensions.LanguageServer.Protocol;
+
+namespace OmniSharp.Extensions.LanguageServer.Capabilities.Client
 {
-    public class DocumentSymbolCapability : DynamicCapability { }
+    public class DocumentSymbolCapability : DynamicCapability, ConnectedCapability<IDocumentSymbolHandler> { }
 }

src/Lsp/Capabilities/Client/ExecuteCommandCapability.cs

@@ -1,4 +1,6 @@
-namespace OmniSharp.Extensions.LanguageServer.Capabilities.Client
+using OmniSharp.Extensions.LanguageServer.Protocol;
+
+namespace OmniSharp.Extensions.LanguageServer.Capabilities.Client
 {
-    public class ExecuteCommandCapability : DynamicCapability { }
+    public class ExecuteCommandCapability : DynamicCapability, ConnectedCapability<IExecuteCommandHandler> { }
 }

src/Lsp/Capabilities/Client/HoverCapability.cs

@@ -1,4 +1,6 @@
-namespace OmniSharp.Extensions.LanguageServer.Capabilities.Client
+using OmniSharp.Extensions.LanguageServer.Protocol;
+
+namespace OmniSharp.Extensions.LanguageServer.Capabilities.Client
 {
-    public class HoverCapability : DynamicCapability { }
+    public class HoverCapability : DynamicCapability, ConnectedCapability<IHoverHandler> { }
 }

src/Lsp/Capabilities/Client/ReferencesCapability.cs

@@ -1,4 +1,6 @@
-namespace OmniSharp.Extensions.LanguageServer.Capabilities.Client
+using OmniSharp.Extensions.LanguageServer.Protocol;
+
+namespace OmniSharp.Extensions.LanguageServer.Capabilities.Client
 {
-    public class ReferencesCapability : DynamicCapability { }
+    public class ReferencesCapability : DynamicCapability, ConnectedCapability<IReferencesHandler> { }
 }

src/Lsp/Capabilities/Client/RenameCapability.cs

@@ -1,4 +1,6 @@
-namespace OmniSharp.Extensions.LanguageServer.Capabilities.Client
+using OmniSharp.Extensions.LanguageServer.Protocol;
+
+namespace OmniSharp.Extensions.LanguageServer.Capabilities.Client
 {
-    public class RenameCapability : DynamicCapability { }
+    public class RenameCapability : DynamicCapability, ConnectedCapability<IRenameHandler> { }
 }

src/Lsp/Capabilities/Client/SignatureHelpCapability.cs

@@ -1,4 +1,6 @@
-namespace OmniSharp.Extensions.LanguageServer.Capabilities.Client
+using OmniSharp.Extensions.LanguageServer.Protocol;
+
+namespace OmniSharp.Extensions.LanguageServer.Capabilities.Client
 {
-    public class SignatureHelpCapability : DynamicCapability { }
+    public class SignatureHelpCapability : DynamicCapability, ConnectedCapability<ISignatureHelpHandler> { }
 }

src/Lsp/Capabilities/Client/WorkspaceSymbolCapability.cs

@@ -1,4 +1,6 @@
-namespace OmniSharp.Extensions.LanguageServer.Capabilities.Client
+using OmniSharp.Extensions.LanguageServer.Protocol;
+
+namespace OmniSharp.Extensions.LanguageServer.Capabilities.Client
 {
-    public class WorkspaceSymbolCapability : DynamicCapability { }
+    public class WorkspaceSymbolCapability : DynamicCapability, ConnectedCapability<IWorkspaceSymbolsHandler> { }
 }

src/Lsp/ClientCapabilityProvider.cs

@@ -0,0 +1,73 @@
+using System;
+using System.Linq;
+using System.Reflection;
+using OmniSharp.Extensions.JsonRpc;
+using OmniSharp.Extensions.LanguageServer.Abstractions;
+using OmniSharp.Extensions.LanguageServer.Capabilities.Client;
+
+namespace OmniSharp.Extensions.LanguageServer
+{
+    internal class ClientCapabilityProvider
+    {
+        private readonly IHandlerCollection _collection;
+
+        public ClientCapabilityProvider(IHandlerCollection collection)
+        {
+            _collection = collection;
+        }
+
+        public bool HasHandler<T>(Supports<T> capability)
+            where T : DynamicCapability, ConnectedCapability<IJsonRpcHandler>
+        {
+            if (!capability.IsSupported) return false;
+            if (capability.Value == null) return false;
+            if (capability.Value.DynamicRegistration) return false;
+
+            var handlerType = typeof(T).GetTypeInfo().ImplementedInterfaces
+                .Single(x => x.GetTypeInfo().IsGenericType && x.GetTypeInfo().GetGenericTypeDefinition() == typeof(ConnectedCapability<>))
+                .GetTypeInfo().GetGenericArguments()[0].GetTypeInfo();
+            return !capability.Value.DynamicRegistration && _collection.Any(z => z.HandlerType.GetTypeInfo().IsAssignableFrom(handlerType));
+        }
+
+        public IOptionsGetter GetOptions<T>(Supports<T> capability)
+            where T : DynamicCapability, ConnectedCapability<IJsonRpcHandler>
+        {
+            return !HasHandler(capability) ? Null : new OptionsGetter(_collection);
+        }
+
+        private static readonly IOptionsGetter Null = new NullOptionsGetter();
+
+        public interface IOptionsGetter
+        {
+            TOptions Get<TInterface, TOptions>(Func<TInterface, TOptions> action)
+                where TOptions : class;
+        }
+
+        private class NullOptionsGetter : IOptionsGetter
+        {
+            public TOptions Get<TInterface, TOptions>(Func<TInterface, TOptions> action)
+                where TOptions : class
+            {
+                return null;
+            }
+        }
+
+        private class OptionsGetter : IOptionsGetter
+        {
+            private readonly IHandlerCollection _collection;
+
+            public OptionsGetter(IHandlerCollection collection)
+            {
+                _collection = collection;
+            }
+
+            public TOptions Get<TInterface, TOptions>(Func<TInterface, TOptions> action)
+                where TOptions : class
+            {
+                return _collection
+                    .Select(x => x.Registration?.RegisterOptions is TInterface cl ? action(cl) : null)
+                    .FirstOrDefault(x => x != null);
+            }
+        }
+    }
+}

src/Lsp/HandlerCollection.cs

@@ -50,10 +50,10 @@ public IDisposable Add(params IJsonRpcHandler[] handlers)
                     var key = "default";
                     if (handler is IRegistration<TextDocumentRegistrationOptions>)
                     {
-                        var options = GetTextDocumentRegistrationOptionsMethod
+                        if (GetTextDocumentRegistrationOptionsMethod
                             .MakeGenericMethod(registration)
-                            .Invoke(handler, new object[] { handler }) as TextDocumentRegistrationOptions;
-                        key = options.DocumentSelector;
+                            .Invoke(handler, new object[] { handler }) is TextDocumentRegistrationOptions options)
+                            key = options.DocumentSelector;
                     }
 
                     var h = new HandlerDescriptor(

src/Lsp/HandlerDescriptor.cs

@@ -1,4 +1,4 @@
-using System;
+using System;
 using System.Reflection;
 using OmniSharp.Extensions.JsonRpc;
 using OmniSharp.Extensions.LanguageServer.Abstractions;
@@ -59,17 +59,17 @@ public Registration Registration
 
         public void SetCapability(object instance)
         {
+            if (instance is DynamicCapability dc)
+            {
+                AllowsDynamicRegistration = dc.DynamicRegistration;
+            }
+
             // TODO: Cache this
             GetType()
                 .GetTypeInfo()
                 .GetMethod(nameof(SetCapability), BindingFlags.NonPublic | BindingFlags.Static)
                 .MakeGenericMethod(CapabilityType)
                 .Invoke(this, new[] { Handler, instance });
-
-            if (instance is DynamicCapability dc)
-            {
-                AllowsDynamicRegistration = dc.DynamicRegistration;
-            }
         }
 
         public string Method { get; }