Fix layering of IEmbeddedLanguagesProvider

src/EditorFeatures/CSharp/EmbeddedLanguages/CSharpEmbeddedLanguageEditorFeaturesProvider.cs

@@ -4,15 +4,15 @@
 using Microsoft.CodeAnalysis.CSharp.EmbeddedLanguages.LanguageServices;
 using Microsoft.CodeAnalysis.CSharp.Features.EmbeddedLanguages;
 using Microsoft.CodeAnalysis.Editor.EmbeddedLanguages;
-using Microsoft.CodeAnalysis.Features.EmbeddedLanguages;
+using Microsoft.CodeAnalysis.EmbeddedLanguages.LanguageServices;
 using Microsoft.CodeAnalysis.Host.Mef;
 
 namespace Microsoft.CodeAnalysis.CSharp.Editor.EmbeddedLanguages
 {
-    [ExportLanguageService(typeof(IEmbeddedLanguageEditorFeaturesProvider), LanguageNames.CSharp), Shared]
+    [ExportLanguageService(typeof(IEmbeddedLanguagesProvider), LanguageNames.CSharp, ServiceLayer.Editor), Shared]
     internal class CSharpEmbeddedLanguageEditorFeaturesProvider : AbstractEmbeddedLanguageEditorFeaturesProvider
     {
-        public static IEmbeddedLanguageFeaturesProvider Instance = new CSharpEmbeddedLanguageEditorFeaturesProvider();
+        public static IEmbeddedLanguagesProvider Instance = new CSharpEmbeddedLanguageEditorFeaturesProvider();
 
         public CSharpEmbeddedLanguageEditorFeaturesProvider() : base(CSharpEmbeddedLanguagesProvider.Info)
         {

src/EditorFeatures/Core/EmbeddedLanguages/AbstractEmbeddedLanguageEditorFeaturesProvider.cs

@@ -11,17 +11,15 @@ namespace Microsoft.CodeAnalysis.Editor.EmbeddedLanguages
     /// Abstract implementation of the C# and VB embedded language providers.
     /// </summary>
     internal abstract class AbstractEmbeddedLanguageEditorFeaturesProvider
-        : AbstractEmbeddedLanguageFeaturesProvider, IEmbeddedLanguageEditorFeaturesProvider
+        : AbstractEmbeddedLanguageFeaturesProvider
     {
-        new public ImmutableArray<IEmbeddedLanguageEditorFeatures> Languages { get; }
+        public override ImmutableArray<IEmbeddedLanguage> Languages { get; }
 
         protected AbstractEmbeddedLanguageEditorFeaturesProvider(EmbeddedLanguageInfo info) : base(info)
         {
-            // No 'Fallback' language added here.  That's because the Fallback language doesn't
-            // support any of the IEmbeddedLanguageFeatures or IEmbeddedLanguageEditorFeatures
-            // capabilities.
-            Languages = ImmutableArray.Create<IEmbeddedLanguageEditorFeatures>(
-                new RegexEmbeddedLanguageEditorFeatures(this, info));
+            Languages = ImmutableArray.Create<IEmbeddedLanguage>(
+                new RegexEmbeddedLanguageEditorFeatures(this, info),
+                new FallbackEmbeddedLanguage(info));
         }
     }
 }

src/EditorFeatures/Core/EmbeddedLanguages/IEmbeddedLanguageEditorFeaturesProvider.cs

-// Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the Apache License, Version 2.0.  See License.txt in the project root for license information.
-
-using System.Collections.Immutable;
-using Microsoft.CodeAnalysis.Features.EmbeddedLanguages;
-
-namespace Microsoft.CodeAnalysis.Editor.EmbeddedLanguages
-{
-    /// <summary>
-    /// Service that returns all the embedded languages supported.  Each embedded language can expose
-    /// individual language services through the <see cref="IEmbeddedLanguageEditorFeatures"/> interface.
-    /// </summary>
-    internal interface IEmbeddedLanguageEditorFeaturesProvider : IEmbeddedLanguageFeaturesProvider
-    {
-        new ImmutableArray<IEmbeddedLanguageEditorFeatures> Languages { get; }
-    }
-}

src/EditorFeatures/Core/Implementation/BraceMatching/AbstractEmbeddedLanguageBraceMatcher.cs

@@ -16,12 +16,12 @@ internal abstract class AbstractEmbeddedLanguageBraceMatcher : IBraceMatcher
         public async Task<BraceMatchingResult?> FindBracesAsync(
             Document document, int position, CancellationToken cancellationToken)
         {
-            var languagesProvider = document.GetLanguageService<IEmbeddedLanguageEditorFeaturesProvider>();
+            var languagesProvider = document.GetLanguageService<IEmbeddedLanguagesProvider>();
             if (languagesProvider != null)
             {
                 foreach (var language in languagesProvider.Languages)
                 {
-                    var braceMatcher = language.BraceMatcher;
+                    var braceMatcher = (language as IEmbeddedLanguageEditorFeatures)?.BraceMatcher;
                     if (braceMatcher != null)
                     {
                         var result = await braceMatcher.FindBracesAsync(

src/EditorFeatures/VisualBasic/EmbeddedLanguages/VisualBasicEmbeddedLanguageEditorFeaturesProvider.vb

@@ -2,11 +2,12 @@
 
 Imports System.Composition
 Imports Microsoft.CodeAnalysis.Editor.EmbeddedLanguages
+Imports Microsoft.CodeAnalysis.EmbeddedLanguages.LanguageServices
 Imports Microsoft.CodeAnalysis.Host.Mef
 Imports Microsoft.CodeAnalysis.VisualBasic.EmbeddedLanguages.LanguageServices
 
 Namespace Microsoft.CodeAnalysis.VisualBasic.Features.EmbeddedLanguages
-    <ExportLanguageService(GetType(IEmbeddedLanguageEditorFeaturesProvider), LanguageNames.VisualBasic), [Shared]>
+    <ExportLanguageService(GetType(IEmbeddedLanguagesProvider), LanguageNames.VisualBasic, ServiceLayer.Editor), [Shared]>
     Friend Class VisualBasicEmbeddedLanguageEditorFeaturesProvider
         Inherits AbstractEmbeddedLanguageEditorFeaturesProvider
 

src/Features/CSharp/Portable/EmbeddedLanguages/CSharpEmbeddedLanguageFeaturesProvider.cs

 // Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the Apache License, Version 2.0.  See License.txt in the project root for license information.
 
 using System.Composition;
-using System.Diagnostics;
 using Microsoft.CodeAnalysis.CSharp.EmbeddedLanguages.LanguageServices;
+using Microsoft.CodeAnalysis.EmbeddedLanguages.LanguageServices;
 using Microsoft.CodeAnalysis.Features.EmbeddedLanguages;
 using Microsoft.CodeAnalysis.Host.Mef;
 
 namespace Microsoft.CodeAnalysis.CSharp.Features.EmbeddedLanguages
 {
-    [ExportLanguageService(typeof(IEmbeddedLanguageFeaturesProvider), LanguageNames.CSharp), Shared]
+    [ExportLanguageService(typeof(IEmbeddedLanguagesProvider), LanguageNames.CSharp, ServiceLayer.Desktop), Shared]
     internal class CSharpEmbeddedLanguageFeaturesProvider : AbstractEmbeddedLanguageFeaturesProvider
     {
-        public static IEmbeddedLanguageFeaturesProvider Instance = new CSharpEmbeddedLanguageFeaturesProvider();
+        public static IEmbeddedLanguagesProvider Instance = new CSharpEmbeddedLanguageFeaturesProvider();
 
         public CSharpEmbeddedLanguageFeaturesProvider() : base(CSharpEmbeddedLanguagesProvider.Info)
         {

src/Features/Core/Portable/Completion/Providers/EmbeddedLanguageCompletionProvider.cs

@@ -4,6 +4,7 @@
 using System.Linq;
 using System.Threading;
 using System.Threading.Tasks;
+using Microsoft.CodeAnalysis.EmbeddedLanguages.LanguageServices;
 using Microsoft.CodeAnalysis.Features.EmbeddedLanguages;
 using Microsoft.CodeAnalysis.Options;
 using Microsoft.CodeAnalysis.Text;
@@ -21,18 +22,18 @@ internal class EmbeddedLanguageCompletionProvider : CompletionProvider
     {
         public const string EmbeddedProviderName = "EmbeddedProvider";
 
-        private readonly ImmutableArray<IEmbeddedLanguageFeatures> _languageProviders;
+        private readonly ImmutableArray<IEmbeddedLanguage> _languageProviders;
 
-        public EmbeddedLanguageCompletionProvider(IEmbeddedLanguageFeaturesProvider languagesProvider)
+        public EmbeddedLanguageCompletionProvider(IEmbeddedLanguagesProvider languagesProvider)
         {
-            _languageProviders = languagesProvider?.Languages ?? ImmutableArray<IEmbeddedLanguageFeatures>.Empty;
+            _languageProviders = languagesProvider?.Languages ?? ImmutableArray<IEmbeddedLanguage>.Empty;
         }
 
         public override bool ShouldTriggerCompletion(SourceText text, int caretPosition, CompletionTrigger trigger, OptionSet options)
         {
             foreach (var language in _languageProviders)
             {
-                var completionProvider = language.CompletionProvider;
+                var completionProvider = (language as IEmbeddedLanguageFeatures)?.CompletionProvider;
                 if (completionProvider != null)
                 {
                     if (completionProvider.ShouldTriggerCompletion(
@@ -50,7 +51,7 @@ public override async Task ProvideCompletionsAsync(CompletionContext context)
         {
             foreach (var language in _languageProviders)
             {
-                var completionProvider = language.CompletionProvider;
+                var completionProvider = (language as IEmbeddedLanguageFeatures)?.CompletionProvider;
                 if (completionProvider != null)
                 {
                     var count = context.Items.Count;
@@ -71,6 +72,6 @@ public override Task<CompletionDescription> GetDescriptionAsync(Document documen
             => GetLanguage(item).CompletionProvider.GetDescriptionAsync(document, item, cancellationToken);
 
         private IEmbeddedLanguageFeatures GetLanguage(CompletionItem item)
-            => _languageProviders.Single(lang => lang.CompletionProvider?.Name == item.Properties[EmbeddedProviderName]);
+            => (IEmbeddedLanguageFeatures)_languageProviders.Single(lang => (lang as IEmbeddedLanguageFeatures)?.CompletionProvider?.Name == item.Properties[EmbeddedProviderName]);
     }
 }

src/Features/Core/Portable/DocumentHighlighting/AbstractDocumentHighlightsService.cs

@@ -95,12 +95,12 @@ internal abstract partial class AbstractDocumentHighlightsService : IDocumentHig
         private async Task<ImmutableArray<DocumentHighlights>> TryGetEmbeddedLanguageHighlightsAsync(
             Document document, int position, IImmutableSet<Document> documentsToSearch, CancellationToken cancellationToken)
         {
-            var languagesProvider = document.GetLanguageService<IEmbeddedLanguageFeaturesProvider>();
+            var languagesProvider = document.GetLanguageService<IEmbeddedLanguagesProvider>();
             if (languagesProvider != null)
             {
                 foreach (var language in languagesProvider.Languages)
                 {
-                    var highlighter = language.DocumentHighlightsService;
+                    var highlighter = (language as IEmbeddedLanguageFeatures)?.DocumentHighlightsService;
                     if (highlighter != null)
                     {
                         var highlights = await highlighter.GetDocumentHighlightsAsync(

src/Features/Core/Portable/EmbeddedLanguages/AbstractEmbeddedLanguageDiagnosticAnalyzer.cs

@@ -6,6 +6,7 @@
 using System.Linq;
 using Microsoft.CodeAnalysis.CodeStyle;
 using Microsoft.CodeAnalysis.Diagnostics;
+using Microsoft.CodeAnalysis.EmbeddedLanguages.LanguageServices;
 using Microsoft.CodeAnalysis.PooledObjects;
 
 namespace Microsoft.CodeAnalysis.Features.EmbeddedLanguages
@@ -17,8 +18,7 @@ internal abstract class AbstractEmbeddedLanguageDiagnosticAnalyzer : DiagnosticA
 
         public override ImmutableArray<DiagnosticDescriptor> SupportedDiagnostics { get; }
 
-        protected AbstractEmbeddedLanguageDiagnosticAnalyzer(
-            IEmbeddedLanguageFeaturesProvider languagesProvider)
+        protected AbstractEmbeddedLanguageDiagnosticAnalyzer(IEmbeddedLanguagesProvider languagesProvider)
         {
             var supportedDiagnostics = ArrayBuilder<DiagnosticDescriptor>.GetInstance();
 
@@ -28,7 +28,7 @@ internal abstract class AbstractEmbeddedLanguageDiagnosticAnalyzer : DiagnosticA
             Debug.Assert(languagesProvider.Languages.Length > 0);
             foreach (var language in languagesProvider.Languages)
             {
-                var analyzer = language.DiagnosticAnalyzer;
+                var analyzer = (language as IEmbeddedLanguageFeatures)?.DiagnosticAnalyzer;
                 if (analyzer != null)
                 {
                     analyzers.Add(analyzer);

src/Features/Core/Portable/EmbeddedLanguages/AbstractEmbeddedLanguagesProvider.cs

@@ -9,17 +9,15 @@ namespace Microsoft.CodeAnalysis.Features.EmbeddedLanguages
     /// <summary>
     /// Abstract implementation of the C# and VB embedded language providers.
     /// </summary>
-    internal abstract class AbstractEmbeddedLanguageFeaturesProvider : AbstractEmbeddedLanguagesProvider, IEmbeddedLanguageFeaturesProvider
+    internal abstract class AbstractEmbeddedLanguageFeaturesProvider : AbstractEmbeddedLanguagesProvider
     {
-        new public ImmutableArray<IEmbeddedLanguageFeatures> Languages { get; }
+        public override ImmutableArray<IEmbeddedLanguage> Languages { get; }
 
         protected AbstractEmbeddedLanguageFeaturesProvider(EmbeddedLanguageInfo info) : base(info)
         {
-            // No 'Fallback' language added here.  That's because the Fallback language doesn't
-            // support any of the IEmbeddedLanguageFeatures or IEmbeddedLanguageEditorFeatures
-            // capabilities.
-            Languages = ImmutableArray.Create<IEmbeddedLanguageFeatures>(
-                new RegexEmbeddedLanguageFeatures(this, info));
+            Languages = ImmutableArray.Create<IEmbeddedLanguage>(
+                new RegexEmbeddedLanguageFeatures(this, info),
+                new FallbackEmbeddedLanguage(info));
         }
 
         /// <summary>Escapes <paramref name="text"/> appropriately so it can be inserted into 

src/Features/Core/Portable/EmbeddedLanguages/IEmbeddedLanguageFeaturesProvider.cs

-// Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the Apache License, Version 2.0.  See License.txt in the project root for license information.
-
-using System.Collections.Immutable;
-using Microsoft.CodeAnalysis.EmbeddedLanguages.LanguageServices;
-using Microsoft.CodeAnalysis.Host;
-
-namespace Microsoft.CodeAnalysis.Features.EmbeddedLanguages
-{
-    /// <summary>
-    /// Service that returns all the embedded languages supported.  Each embedded language can expose
-    /// individual language services through the <see cref="IEmbeddedLanguageFeatures"/> interface.
-    /// </summary>
-    internal interface IEmbeddedLanguageFeaturesProvider : IEmbeddedLanguagesProvider
-    {
-        new ImmutableArray<IEmbeddedLanguageFeatures> Languages { get; }
-    }
-}

src/Features/VisualBasic/Portable/EmbeddedLanguages/VisualBasicEmbeddedLanguageFeaturesProvider.vb

 ' Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the Apache License, Version 2.0.  See License.txt in the project root for license information.
 
 Imports System.Composition
+Imports Microsoft.CodeAnalysis.EmbeddedLanguages.LanguageServices
 Imports Microsoft.CodeAnalysis.Features.EmbeddedLanguages
 Imports Microsoft.CodeAnalysis.Host.Mef
 Imports Microsoft.CodeAnalysis.VisualBasic.EmbeddedLanguages.LanguageServices
 
 Namespace Microsoft.CodeAnalysis.VisualBasic.Features.EmbeddedLanguages
-    <ExportLanguageService(GetType(IEmbeddedLanguageFeaturesProvider), LanguageNames.VisualBasic), [Shared]>
+    <ExportLanguageService(GetType(IEmbeddedLanguagesProvider), LanguageNames.VisualBasic, ServiceLayer.Desktop), [Shared]>
     Friend Class VisualBasicEmbeddedLanguageFeaturesProvider
         Inherits AbstractEmbeddedLanguageFeaturesProvider
 

src/Workspaces/CSharp/Portable/EmbeddedLanguages/LanguageServices/CSharpEmbeddedLanguagesProvider.cs

 // Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the Apache License, Version 2.0.  See License.txt in the project root for license information.
 
 using System.Composition;
-using System.Diagnostics;
 using Microsoft.CodeAnalysis.CSharp.EmbeddedLanguages.VirtualChars;
 using Microsoft.CodeAnalysis.EmbeddedLanguages.LanguageServices;
 using Microsoft.CodeAnalysis.Host.Mef;
 
 namespace Microsoft.CodeAnalysis.CSharp.EmbeddedLanguages.LanguageServices
 {
-    [ExportLanguageService(typeof(IEmbeddedLanguagesProvider), LanguageNames.CSharp), Shared]
+    [ExportLanguageService(typeof(IEmbeddedLanguagesProvider), LanguageNames.CSharp, ServiceLayer.Default), Shared]
     internal class CSharpEmbeddedLanguagesProvider : AbstractEmbeddedLanguagesProvider
     {
         public static EmbeddedLanguageInfo Info = new EmbeddedLanguageInfo(

src/Workspaces/Core/Portable/EmbeddedLanguages/LanguageServices/AbstractEmbeddedLanguagesProvider.cs

@@ -10,7 +10,7 @@ namespace Microsoft.CodeAnalysis.EmbeddedLanguages.LanguageServices
     /// </summary>
     internal abstract class AbstractEmbeddedLanguagesProvider : IEmbeddedLanguagesProvider
     {
-        public ImmutableArray<IEmbeddedLanguage> Languages { get; }
+        public virtual ImmutableArray<IEmbeddedLanguage> Languages { get; }
 
         protected AbstractEmbeddedLanguagesProvider(EmbeddedLanguageInfo info)
         {

src/Workspaces/VisualBasic/Portable/EmbeddedLanguages/LanguageServices/VisualBasicEmbeddedLanguagesProvider.vb

@@ -6,7 +6,7 @@ Imports Microsoft.CodeAnalysis.Host.Mef
 Imports Microsoft.CodeAnalysis.VisualBasic.EmbeddedLanguages.VirtualChars
 
 Namespace Microsoft.CodeAnalysis.VisualBasic.EmbeddedLanguages.LanguageServices
-    <ExportLanguageService(GetType(IEmbeddedLanguagesProvider), LanguageNames.VisualBasic), [Shared]>
+    <ExportLanguageService(GetType(IEmbeddedLanguagesProvider), LanguageNames.VisualBasic, ServiceLayer.Default), [Shared]>
     Friend Class VisualBasicEmbeddedLanguagesProvider
         Inherits AbstractEmbeddedLanguagesProvider