Create a new 'BlockStructure' API that can back the VS Outlining and Indent-Guides.

src/EditorFeatures/CSharp/CSharpEditorFeatures.csproj

@@ -146,46 +146,6 @@
     <Compile Include="LineSeparators\CSharpLineSeparatorService.cs" />
     <Compile Include="NavigateTo\CSharpNavigateToSearchService.cs" />
     <Compile Include="NavigationBar\CSharpNavigationBarItemService.cs" />
-    <Compile Include="Outlining\CSharpOutliningHelpers.cs" />
-    <Compile Include="Outlining\CSharpOutliningService.cs" />
-    <Compile Include="Outlining\Outliners\AccessorDeclarationOutliner.cs" />
-    <Compile Include="Outlining\Outliners\AnonymousMethodExpressionOutliner.cs" />
-    <Compile Include="Outlining\Outliners\CompilationUnitOutliner.cs" />
-    <Compile Include="Outlining\Outliners\ConstructorDeclarationOutliner.cs" />
-    <Compile Include="Outlining\Outliners\ConversionOperatorDeclarationOutliner.cs" />
-    <Compile Include="Outlining\Outliners\DelegateDeclarationOutliner.cs" />
-    <Compile Include="Outlining\Outliners\DestructorDeclarationOutliner.cs" />
-    <Compile Include="Outlining\Outliners\DisabledTextTriviaOutliner.cs" />
-    <Compile Include="Outlining\Outliners\DocumentationCommentOutliner.cs" />
-    <Compile Include="Outlining\Outliners\EnumDeclarationOutliner.cs" />
-    <Compile Include="Outlining\Outliners\EventDeclarationOutliner.cs" />
-    <Compile Include="Outlining\Outliners\EventFieldDeclarationOutliner.cs" />
-    <Compile Include="Outlining\Outliners\FieldDeclarationOutliner.cs" />
-    <Compile Include="Outlining\Outliners\IndexerDeclarationOutliner.cs" />
-    <Compile Include="Outlining\Outliners\MetadataAsSource\AbstractMetadataAsSourceOutliner.cs" />
-    <Compile Include="Outlining\Outliners\MetadataAsSource\ConstructorDeclarationOutliner.cs" />
-    <Compile Include="Outlining\Outliners\MetadataAsSource\ConversionOperatorDeclarationOutliner.cs" />
-    <Compile Include="Outlining\Outliners\MetadataAsSource\DelegateDeclarationOutliner.cs" />
-    <Compile Include="Outlining\Outliners\MetadataAsSource\DestructorDeclarationOutliner.cs" />
-    <Compile Include="Outlining\Outliners\MetadataAsSource\EnumDeclarationOutliner.cs" />
-    <Compile Include="Outlining\Outliners\MetadataAsSource\EnumMemberDeclarationOutliner.cs" />
-    <Compile Include="Outlining\Outliners\MetadataAsSource\EventDeclarationOutliner.cs" />
-    <Compile Include="Outlining\Outliners\MetadataAsSource\EventFieldDeclarationOutliner.cs" />
-    <Compile Include="Outlining\Outliners\MetadataAsSource\FieldDeclarationOutliner.cs" />
-    <Compile Include="Outlining\Outliners\MetadataAsSource\IndexerDeclarationOutliner.cs" />
-    <Compile Include="Outlining\Outliners\MetadataAsSource\MethodDeclarationOutliner.cs" />
-    <Compile Include="Outlining\Outliners\MetadataAsSource\OperatorDeclarationOutliner.cs" />
-    <Compile Include="Outlining\Outliners\MetadataAsSource\PropertyDeclarationOutliner.cs" />
-    <Compile Include="Outlining\Outliners\MetadataAsSource\RegionDirectiveOutliner.cs" />
-    <Compile Include="Outlining\Outliners\MetadataAsSource\TypeDeclarationOutliner.cs" />
-    <Compile Include="Outlining\Outliners\MethodDeclarationOutliner.cs" />
-    <Compile Include="Outlining\Outliners\NamespaceDeclarationOutliner.cs" />
-    <Compile Include="Outlining\Outliners\OperatorDeclarationOutliner.cs" />
-    <Compile Include="Outlining\Outliners\ParenthesizedLambdaExpressionOutliner.cs" />
-    <Compile Include="Outlining\Outliners\PropertyDeclarationOutliner.cs" />
-    <Compile Include="Outlining\Outliners\RegionDirectiveOutliner.cs" />
-    <Compile Include="Outlining\Outliners\SimpleLambdaExpressionOutliner.cs" />
-    <Compile Include="Outlining\Outliners\TypeDeclarationOutliner.cs" />
     <Compile Include="QuickInfo\SemanticQuickInfoProvider.cs" />
     <Compile Include="QuickInfo\SyntacticQuickInfoProvider.cs" />
     <Compile Include="ReferenceHighlighting\ReferenceHighlightingAdditionalReferenceProvider.cs" />
@@ -224,4 +184,4 @@
   </ItemGroup>
   <ItemGroup />
   <Import Project="..\..\..\build\Targets\VSL.Imports.targets" />
-</Project>
+</Project>
\ No newline at end of file

src/EditorFeatures/CSharpTest/Outlining/AbstractCSharpSyntaxNodeOutlinerTests.cs

@@ -4,7 +4,8 @@
 
 namespace Microsoft.CodeAnalysis.Editor.CSharp.UnitTests.Outlining
 {
-    public abstract class AbstractCSharpSyntaxNodeOutlinerTests<TSyntaxNode> : AbstractSyntaxNodeOutlinerTests<TSyntaxNode>
+    public abstract class AbstractCSharpSyntaxNodeOutlinerTests<TSyntaxNode> : 
+        AbstractSyntaxNodeOutlinerTests<TSyntaxNode>
         where TSyntaxNode : SyntaxNode
     {
         protected sealed override string LanguageName => LanguageNames.CSharp;

src/EditorFeatures/CSharpTest/Outlining/AccessorDeclarationTests.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.Threading.Tasks;
+using Microsoft.CodeAnalysis.CSharp.Structure;
 using Microsoft.CodeAnalysis.CSharp.Syntax;
-using Microsoft.CodeAnalysis.Editor.CSharp.Outlining;
-using Microsoft.CodeAnalysis.Editor.Implementation.Outlining;
+using Microsoft.CodeAnalysis.Structure;
 using Roslyn.Test.Utilities;
 using Xunit;
 
@@ -11,7 +11,7 @@ namespace Microsoft.CodeAnalysis.Editor.CSharp.UnitTests.Outlining
 {
     public class AccessorDeclarationTests : AbstractCSharpSyntaxNodeOutlinerTests<AccessorDeclarationSyntax>
     {
-        internal override AbstractSyntaxOutliner CreateOutliner() => new AccessorDeclarationOutliner();
+        internal override AbstractSyntaxStructureProvider CreateOutliner() => new AccessorDeclarationOutliner();
 
         [Fact, Trait(Traits.Feature, Traits.Features.Outlining)]
         public async Task TestPropertyGetter1()

src/EditorFeatures/CSharpTest/Outlining/AnonymousMethodExpressionTests.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.Threading.Tasks;
+using Microsoft.CodeAnalysis.CSharp.Structure;
 using Microsoft.CodeAnalysis.CSharp.Syntax;
-using Microsoft.CodeAnalysis.Editor.CSharp.Outlining;
-using Microsoft.CodeAnalysis.Editor.Implementation.Outlining;
+using Microsoft.CodeAnalysis.Structure;
 using Roslyn.Test.Utilities;
 using Xunit;
 
@@ -11,7 +11,7 @@ namespace Microsoft.CodeAnalysis.Editor.CSharp.UnitTests.Outlining
 {
     public class AnonymousMethodExpressionTests : AbstractCSharpSyntaxNodeOutlinerTests<AnonymousMethodExpressionSyntax>
     {
-        internal override AbstractSyntaxOutliner CreateOutliner() => new AnonymousMethodExpressionOutliner();
+        internal override AbstractSyntaxStructureProvider CreateOutliner() => new AnonymousMethodExpressionOutliner();
 
         [Fact, Trait(Traits.Feature, Traits.Features.Outlining)]
         public async Task TestAnonymousMethod()

src/EditorFeatures/CSharpTest/Outlining/CommentTests.cs

@@ -2,9 +2,9 @@
 
 using System.Linq;
 using System.Threading.Tasks;
-using Microsoft.CodeAnalysis.Editor.CSharp.Outlining;
-using Microsoft.CodeAnalysis.Editor.Implementation.Outlining;
+using Microsoft.CodeAnalysis.CSharp.Structure;
 using Microsoft.CodeAnalysis.Editor.UnitTests.Outlining;
+using Microsoft.CodeAnalysis.Structure;
 using Roslyn.Test.Utilities;
 using Roslyn.Utilities;
 using Xunit;
@@ -15,7 +15,7 @@ public class CommentTests : AbstractSyntaxOutlinerTests
     {
         protected override string LanguageName => LanguageNames.CSharp;
 
-        internal override async Task<OutliningSpan[]> GetRegionsAsync(Document document, int position)
+        internal override async Task<BlockSpan[]> GetRegionsAsync(Document document, int position)
         {
             var root = await document.GetSyntaxRootAsync();
             var trivia = root.FindTrivia(position, findInsideTrivia: true);
@@ -32,7 +32,7 @@ internal override async Task<OutliningSpan[]> GetRegionsAsync(Document document,
             }
             else
             {
-                return Contract.FailWithReturn<OutliningSpan[]>();
+                return Contract.FailWithReturn<BlockSpan[]>();
             }
         }
 

src/EditorFeatures/CSharpTest/Outlining/CompilationUnitOutlinerTests.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.Threading.Tasks;
+using Microsoft.CodeAnalysis.CSharp.Structure;
 using Microsoft.CodeAnalysis.CSharp.Syntax;
-using Microsoft.CodeAnalysis.Editor.CSharp.Outlining;
-using Microsoft.CodeAnalysis.Editor.Implementation.Outlining;
+using Microsoft.CodeAnalysis.Structure;
 using Roslyn.Test.Utilities;
 using Xunit;
 
@@ -11,7 +11,7 @@ namespace Microsoft.CodeAnalysis.Editor.CSharp.UnitTests.Outlining
 {
     public class CompilationUnitOutlinerTests : AbstractCSharpSyntaxNodeOutlinerTests<CompilationUnitSyntax>
     {
-        internal override AbstractSyntaxOutliner CreateOutliner() => new CompilationUnitOutliner();
+        internal override AbstractSyntaxStructureProvider CreateOutliner() => new CompilationUnitOutliner();
 
         [Fact, Trait(Traits.Feature, Traits.Features.Outlining)]
         public async Task TestUsings()

src/EditorFeatures/CSharpTest/Outlining/ConstructorDeclarationOutlinerTests.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.Threading.Tasks;
+using Microsoft.CodeAnalysis.CSharp.Structure;
 using Microsoft.CodeAnalysis.CSharp.Syntax;
-using Microsoft.CodeAnalysis.Editor.CSharp.Outlining;
-using Microsoft.CodeAnalysis.Editor.Implementation.Outlining;
+using Microsoft.CodeAnalysis.Structure;
 using Roslyn.Test.Utilities;
 using Xunit;
 
@@ -11,7 +11,7 @@ namespace Microsoft.CodeAnalysis.Editor.CSharp.UnitTests.Outlining
 {
     public class ConstructorDeclarationOutlinerTests : AbstractCSharpSyntaxNodeOutlinerTests<ConstructorDeclarationSyntax>
     {
-        internal override AbstractSyntaxOutliner CreateOutliner() => new ConstructorDeclarationOutliner();
+        internal override AbstractSyntaxStructureProvider CreateOutliner() => new ConstructorDeclarationOutliner();
 
         [Fact, Trait(Traits.Feature, Traits.Features.Outlining)]
         public async Task TestConstructor1()

src/EditorFeatures/CSharpTest/Outlining/ConversionOperatorDeclarationOutlinerTests.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.Threading.Tasks;
+using Microsoft.CodeAnalysis.CSharp.Structure;
 using Microsoft.CodeAnalysis.CSharp.Syntax;
-using Microsoft.CodeAnalysis.Editor.CSharp.Outlining;
-using Microsoft.CodeAnalysis.Editor.Implementation.Outlining;
+using Microsoft.CodeAnalysis.Structure;
 using Roslyn.Test.Utilities;
 using Xunit;
 
@@ -11,7 +11,7 @@ namespace Microsoft.CodeAnalysis.Editor.CSharp.UnitTests.Outlining
 {
     public class ConversionOperatorDeclarationOutlinerTests : AbstractCSharpSyntaxNodeOutlinerTests<ConversionOperatorDeclarationSyntax>
     {
-        internal override AbstractSyntaxOutliner CreateOutliner() => new ConversionOperatorDeclarationOutliner();
+        internal override AbstractSyntaxStructureProvider CreateOutliner() => new ConversionOperatorDeclarationOutliner();
 
         [Fact, Trait(Traits.Feature, Traits.Features.Outlining)]
         public async Task TestOperator()

src/EditorFeatures/CSharpTest/Outlining/DelegateDeclarationOutlinerTests.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.Threading.Tasks;
+using Microsoft.CodeAnalysis.CSharp.Structure;
 using Microsoft.CodeAnalysis.CSharp.Syntax;
-using Microsoft.CodeAnalysis.Editor.CSharp.Outlining;
-using Microsoft.CodeAnalysis.Editor.Implementation.Outlining;
+using Microsoft.CodeAnalysis.Structure;
 using Roslyn.Test.Utilities;
 using Xunit;
 
@@ -11,7 +11,7 @@ namespace Microsoft.CodeAnalysis.Editor.CSharp.UnitTests.Outlining
 {
     public class DelegateDeclarationOutlinerTests : AbstractCSharpSyntaxNodeOutlinerTests<DelegateDeclarationSyntax>
     {
-        internal override AbstractSyntaxOutliner CreateOutliner() => new DelegateDeclarationOutliner();
+        internal override AbstractSyntaxStructureProvider CreateOutliner() => new DelegateDeclarationOutliner();
 
         [Fact, Trait(Traits.Feature, Traits.Features.Outlining)]
         public async Task TestDelegateWithComments()

src/EditorFeatures/CSharpTest/Outlining/DestructorDeclarationOutlinerTests.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.Threading.Tasks;
+using Microsoft.CodeAnalysis.CSharp.Structure;
 using Microsoft.CodeAnalysis.CSharp.Syntax;
-using Microsoft.CodeAnalysis.Editor.CSharp.Outlining;
-using Microsoft.CodeAnalysis.Editor.Implementation.Outlining;
+using Microsoft.CodeAnalysis.Structure;
 using Roslyn.Test.Utilities;
 using Xunit;
 
@@ -11,7 +11,7 @@ namespace Microsoft.CodeAnalysis.Editor.CSharp.UnitTests.Outlining
 {
     public class DestructorDeclarationOutlinerTests : AbstractCSharpSyntaxNodeOutlinerTests<DestructorDeclarationSyntax>
     {
-        internal override AbstractSyntaxOutliner CreateOutliner() => new DestructorDeclarationOutliner();
+        internal override AbstractSyntaxStructureProvider CreateOutliner() => new DestructorDeclarationOutliner();
 
         [Fact, Trait(Traits.Feature, Traits.Features.Outlining)]
         public async Task TestDestructor()

src/EditorFeatures/CSharpTest/Outlining/DisabledTextOutlinerTests.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.Threading.Tasks;
-using Microsoft.CodeAnalysis.Editor.CSharp.Outlining;
-using Microsoft.CodeAnalysis.Editor.Implementation.Outlining;
+using Microsoft.CodeAnalysis.CSharp.Structure;
+using Microsoft.CodeAnalysis.Structure;
 using Roslyn.Test.Utilities;
 using Xunit;
 
@@ -10,7 +10,7 @@ namespace Microsoft.CodeAnalysis.Editor.CSharp.UnitTests.Outlining
 {
     public class DisabledTextOutlinerTests : AbstractCSharpSyntaxTriviaOutlinerTests
     {
-        internal override AbstractSyntaxOutliner CreateOutliner() => new DisabledTextTriviaOutliner();
+        internal override AbstractSyntaxStructureProvider CreateOutliner() => new DisabledTextTriviaOutliner();
 
         [Fact, Trait(Traits.Feature, Traits.Features.Outlining)]
         public async Task TestDisabledIf()

src/EditorFeatures/CSharpTest/Outlining/DocumentationCommentOutlinerTests.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.Threading.Tasks;
+using Microsoft.CodeAnalysis.CSharp.Structure;
 using Microsoft.CodeAnalysis.CSharp.Syntax;
-using Microsoft.CodeAnalysis.Editor.CSharp.Outlining;
-using Microsoft.CodeAnalysis.Editor.Implementation.Outlining;
+using Microsoft.CodeAnalysis.Structure;
 using Roslyn.Test.Utilities;
 using Xunit;
 
@@ -11,7 +11,7 @@ namespace Microsoft.CodeAnalysis.Editor.CSharp.UnitTests.Outlining
 {
     public class DocumentationCommentOutlinerTests : AbstractCSharpSyntaxNodeOutlinerTests<DocumentationCommentTriviaSyntax>
     {
-        internal override AbstractSyntaxOutliner CreateOutliner() => new DocumentationCommentOutliner();
+        internal override AbstractSyntaxStructureProvider CreateOutliner() => new DocumentationCommentOutliner();
 
         [Fact, Trait(Traits.Feature, Traits.Features.Outlining)]
         public async Task TestDocumentationCommentWithoutSummaryTag1()

src/EditorFeatures/CSharpTest/Outlining/EnumDeclarationOutlinerTests.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.Threading.Tasks;
+using Microsoft.CodeAnalysis.CSharp.Structure;
 using Microsoft.CodeAnalysis.CSharp.Syntax;
-using Microsoft.CodeAnalysis.Editor.CSharp.Outlining;
-using Microsoft.CodeAnalysis.Editor.Implementation.Outlining;
+using Microsoft.CodeAnalysis.Structure;
 using Roslyn.Test.Utilities;
 using Xunit;
 
@@ -11,7 +11,7 @@ namespace Microsoft.CodeAnalysis.Editor.CSharp.UnitTests.Outlining
 {
     public class EnumDeclarationOutlinerTests : AbstractCSharpSyntaxNodeOutlinerTests<EnumDeclarationSyntax>
     {
-        internal override AbstractSyntaxOutliner CreateOutliner() => new EnumDeclarationOutliner();
+        internal override AbstractSyntaxStructureProvider CreateOutliner() => new EnumDeclarationOutliner();
 
         [Fact, Trait(Traits.Feature, Traits.Features.Outlining)]
         public async Task TestEnum()

src/EditorFeatures/CSharpTest/Outlining/EventDeclarationOutlinerTests.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.Threading.Tasks;
+using Microsoft.CodeAnalysis.CSharp.Structure;
 using Microsoft.CodeAnalysis.CSharp.Syntax;
-using Microsoft.CodeAnalysis.Editor.CSharp.Outlining;
-using Microsoft.CodeAnalysis.Editor.Implementation.Outlining;
+using Microsoft.CodeAnalysis.Structure;
 using Roslyn.Test.Utilities;
 using Xunit;
 
@@ -11,7 +11,7 @@ namespace Microsoft.CodeAnalysis.Editor.CSharp.UnitTests.Outlining
 {
     public class EventDeclarationOutlinerTests : AbstractCSharpSyntaxNodeOutlinerTests<EventDeclarationSyntax>
     {
-        internal override AbstractSyntaxOutliner CreateOutliner() => new EventDeclarationOutliner();
+        internal override AbstractSyntaxStructureProvider CreateOutliner() => new EventDeclarationOutliner();
 
         [Fact, Trait(Traits.Feature, Traits.Features.Outlining)]
         public async Task TestEvent()

src/EditorFeatures/CSharpTest/Outlining/EventFieldDeclarationOutlinerTests.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.Threading.Tasks;
+using Microsoft.CodeAnalysis.CSharp.Structure;
 using Microsoft.CodeAnalysis.CSharp.Syntax;
-using Microsoft.CodeAnalysis.Editor.CSharp.Outlining;
-using Microsoft.CodeAnalysis.Editor.Implementation.Outlining;
+using Microsoft.CodeAnalysis.Structure;
 using Roslyn.Test.Utilities;
 using Xunit;
 
@@ -11,7 +11,7 @@ namespace Microsoft.CodeAnalysis.Editor.CSharp.UnitTests.Outlining
 {
     public class EventFieldDeclarationOutlinerTests : AbstractCSharpSyntaxNodeOutlinerTests<EventFieldDeclarationSyntax>
     {
-        internal override AbstractSyntaxOutliner CreateOutliner() => new EventFieldDeclarationOutliner();
+        internal override AbstractSyntaxStructureProvider CreateOutliner() => new EventFieldDeclarationOutliner();
 
         [Fact, Trait(Traits.Feature, Traits.Features.Outlining)]
         public async Task TestEventFieldWithComments()

src/EditorFeatures/CSharpTest/Outlining/FieldDeclarationOutlinerTests.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.Threading.Tasks;
+using Microsoft.CodeAnalysis.CSharp.Structure;
 using Microsoft.CodeAnalysis.CSharp.Syntax;
-using Microsoft.CodeAnalysis.Editor.CSharp.Outlining;
-using Microsoft.CodeAnalysis.Editor.Implementation.Outlining;
+using Microsoft.CodeAnalysis.Structure;
 using Roslyn.Test.Utilities;
 using Xunit;
 
@@ -11,7 +11,7 @@ namespace Microsoft.CodeAnalysis.Editor.CSharp.UnitTests.Outlining
 {
     public class FieldDeclarationOutlinerTests : AbstractCSharpSyntaxNodeOutlinerTests<FieldDeclarationSyntax>
     {
-        internal override AbstractSyntaxOutliner CreateOutliner() => new FieldDeclarationOutliner();
+        internal override AbstractSyntaxStructureProvider CreateOutliner() => new FieldDeclarationOutliner();
 
         [Fact, Trait(Traits.Feature, Traits.Features.Outlining)]
         public async Task TestFieldWithComments()

src/EditorFeatures/CSharpTest/Outlining/IndexerDeclarationOutlinerTests.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.Threading.Tasks;
+using Microsoft.CodeAnalysis.CSharp.Structure;
 using Microsoft.CodeAnalysis.CSharp.Syntax;
-using Microsoft.CodeAnalysis.Editor.CSharp.Outlining;
-using Microsoft.CodeAnalysis.Editor.Implementation.Outlining;
+using Microsoft.CodeAnalysis.Structure;
 using Roslyn.Test.Utilities;
 using Xunit;
 
@@ -11,7 +11,7 @@ namespace Microsoft.CodeAnalysis.Editor.CSharp.UnitTests.Outlining
 {
     public class IndexerDeclarationOutlinerTests : AbstractCSharpSyntaxNodeOutlinerTests<IndexerDeclarationSyntax>
     {
-        internal override AbstractSyntaxOutliner CreateOutliner() => new IndexerDeclarationOutliner();
+        internal override AbstractSyntaxStructureProvider CreateOutliner() => new IndexerDeclarationOutliner();
 
         [Fact, Trait(Traits.Feature, Traits.Features.Outlining)]
         public async Task TestIndexer()

src/EditorFeatures/CSharpTest/Outlining/MetadataAsSource/ConstructorDeclarationOutlinerTests.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.Threading.Tasks;
+using Microsoft.CodeAnalysis.CSharp.Structure;
 using Microsoft.CodeAnalysis.CSharp.Syntax;
-using Microsoft.CodeAnalysis.Editor.CSharp.Outlining;
-using Microsoft.CodeAnalysis.Editor.Implementation.Outlining;
+using Microsoft.CodeAnalysis.Structure;
 using Roslyn.Test.Utilities;
 using Xunit;
-using MaSOutliners = Microsoft.CodeAnalysis.Editor.CSharp.Outlining.MetadataAsSource;
+using MaSOutliners = Microsoft.CodeAnalysis.CSharp.Structure.MetadataAsSource;
 
 namespace Microsoft.CodeAnalysis.Editor.CSharp.UnitTests.Outlining.MetadataAsSource
 {
     public class ConstructorDeclarationOutlinerTests : AbstractCSharpSyntaxNodeOutlinerTests<ConstructorDeclarationSyntax>
     {
         protected override string WorkspaceKind => CodeAnalysis.WorkspaceKind.MetadataAsSource;
-        internal override AbstractSyntaxOutliner CreateOutliner() => new MaSOutliners.ConstructorDeclarationOutliner();
+        internal override AbstractSyntaxStructureProvider CreateOutliner() => new MaSOutliners.ConstructorDeclarationOutliner();
 
         [Fact, Trait(Traits.Feature, Traits.Features.MetadataAsSource)]
         public async Task NoCommentsOrAttributes()

src/EditorFeatures/CSharpTest/Outlining/MetadataAsSource/ConversionOperatorDeclarationOutlinerTests.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.Threading.Tasks;
+using Microsoft.CodeAnalysis.CSharp.Structure;
 using Microsoft.CodeAnalysis.CSharp.Syntax;
-using Microsoft.CodeAnalysis.Editor.CSharp.Outlining;
-using Microsoft.CodeAnalysis.Editor.Implementation.Outlining;
+using Microsoft.CodeAnalysis.Structure;
 using Roslyn.Test.Utilities;
 using Xunit;
-using MaSOutliners = Microsoft.CodeAnalysis.Editor.CSharp.Outlining.MetadataAsSource;
+using MaSOutliners = Microsoft.CodeAnalysis.CSharp.Structure.MetadataAsSource;
 
 namespace Microsoft.CodeAnalysis.Editor.CSharp.UnitTests.Outlining.MetadataAsSource
 {
     public class ConversionOperatorDeclarationOutlinerTests : AbstractCSharpSyntaxNodeOutlinerTests<ConversionOperatorDeclarationSyntax>
     {
         protected override string WorkspaceKind => CodeAnalysis.WorkspaceKind.MetadataAsSource;
-        internal override AbstractSyntaxOutliner CreateOutliner() => new MaSOutliners.ConversionOperatorDeclarationOutliner();
+        internal override AbstractSyntaxStructureProvider CreateOutliner() => new MaSOutliners.ConversionOperatorDeclarationOutliner();
 
         [Fact, Trait(Traits.Feature, Traits.Features.MetadataAsSource)]
         public async Task NoCommentsOrAttributes()

src/EditorFeatures/CSharpTest/Outlining/MetadataAsSource/DelegateDeclarationOutlinerTests.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.Threading.Tasks;
+using Microsoft.CodeAnalysis.CSharp.Structure;
 using Microsoft.CodeAnalysis.CSharp.Syntax;
-using Microsoft.CodeAnalysis.Editor.CSharp.Outlining;
-using Microsoft.CodeAnalysis.Editor.Implementation.Outlining;
+using Microsoft.CodeAnalysis.Structure;
 using Roslyn.Test.Utilities;
 using Xunit;
-using MaSOutliners = Microsoft.CodeAnalysis.Editor.CSharp.Outlining.MetadataAsSource;
+using MaSOutliners = Microsoft.CodeAnalysis.CSharp.Structure.MetadataAsSource;
 
 namespace Microsoft.CodeAnalysis.Editor.CSharp.UnitTests.Outlining.MetadataAsSource
 {
     public class DelegateDeclarationOutlinerTests : AbstractCSharpSyntaxNodeOutlinerTests<DelegateDeclarationSyntax>
     {
         protected override string WorkspaceKind => CodeAnalysis.WorkspaceKind.MetadataAsSource;
-        internal override AbstractSyntaxOutliner CreateOutliner() => new MaSOutliners.DelegateDeclarationOutliner();
+        internal override AbstractSyntaxStructureProvider CreateOutliner() => new MaSOutliners.DelegateDeclarationOutliner();
 
         [Fact, Trait(Traits.Feature, Traits.Features.MetadataAsSource)]
         public async Task NoCommentsOrAttributes()

src/EditorFeatures/CSharpTest/Outlining/MetadataAsSource/DestructorDeclarationOutlinerTests.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.Threading.Tasks;
+using Microsoft.CodeAnalysis.CSharp.Structure;
 using Microsoft.CodeAnalysis.CSharp.Syntax;
-using Microsoft.CodeAnalysis.Editor.CSharp.Outlining;
-using Microsoft.CodeAnalysis.Editor.Implementation.Outlining;
+using Microsoft.CodeAnalysis.Structure;
 using Roslyn.Test.Utilities;
 using Xunit;
-using MaSOutliners = Microsoft.CodeAnalysis.Editor.CSharp.Outlining.MetadataAsSource;
+using MaSOutliners = Microsoft.CodeAnalysis.CSharp.Structure.MetadataAsSource;
 
 namespace Microsoft.CodeAnalysis.Editor.CSharp.UnitTests.Outlining.MetadataAsSource
 {
     public class DestructorDeclarationOutlinerTests : AbstractCSharpSyntaxNodeOutlinerTests<DestructorDeclarationSyntax>
     {
         protected override string WorkspaceKind => CodeAnalysis.WorkspaceKind.MetadataAsSource;
-        internal override AbstractSyntaxOutliner CreateOutliner() => new MaSOutliners.DestructorDeclarationOutliner();
+        internal override AbstractSyntaxStructureProvider CreateOutliner() => new MaSOutliners.DestructorDeclarationOutliner();
 
         [Fact, Trait(Traits.Feature, Traits.Features.MetadataAsSource)]
         public async Task NoCommentsOrAttributes()

src/EditorFeatures/CSharpTest/Outlining/MetadataAsSource/EnumDeclarationOutlinerTests.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.Threading.Tasks;
+using Microsoft.CodeAnalysis.CSharp.Structure;
 using Microsoft.CodeAnalysis.CSharp.Syntax;
-using Microsoft.CodeAnalysis.Editor.CSharp.Outlining;
-using Microsoft.CodeAnalysis.Editor.Implementation.Outlining;
+using Microsoft.CodeAnalysis.Structure;
 using Roslyn.Test.Utilities;
 using Xunit;
-using MaSOutliners = Microsoft.CodeAnalysis.Editor.CSharp.Outlining.MetadataAsSource;
+using MaSOutliners = Microsoft.CodeAnalysis.CSharp.Structure.MetadataAsSource;
 
 namespace Microsoft.CodeAnalysis.Editor.CSharp.UnitTests.Outlining.MetadataAsSource
 {
     public class EnumDeclarationOutlinerTests : AbstractCSharpSyntaxNodeOutlinerTests<EnumDeclarationSyntax>
     {
         protected override string WorkspaceKind => CodeAnalysis.WorkspaceKind.MetadataAsSource;
-        internal override AbstractSyntaxOutliner CreateOutliner() => new MaSOutliners.EnumDeclarationOutliner();
+        internal override AbstractSyntaxStructureProvider CreateOutliner() => new MaSOutliners.EnumDeclarationOutliner();
 
         [Fact, Trait(Traits.Feature, Traits.Features.MetadataAsSource)]
         public async Task NoCommentsOrAttributes()

src/EditorFeatures/CSharpTest/Outlining/MetadataAsSource/EnumMemberDeclarationOutlinerTests.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.Threading.Tasks;
+using Microsoft.CodeAnalysis.CSharp.Structure;
 using Microsoft.CodeAnalysis.CSharp.Syntax;
-using Microsoft.CodeAnalysis.Editor.CSharp.Outlining;
-using Microsoft.CodeAnalysis.Editor.Implementation.Outlining;
+using Microsoft.CodeAnalysis.Structure;
 using Roslyn.Test.Utilities;
 using Xunit;
-using MaSOutliners = Microsoft.CodeAnalysis.Editor.CSharp.Outlining.MetadataAsSource;
+using MaSOutliners = Microsoft.CodeAnalysis.CSharp.Structure.MetadataAsSource;
 
 namespace Microsoft.CodeAnalysis.Editor.CSharp.UnitTests.Outlining.MetadataAsSource
 {
     public class EnumMemberDeclarationOutlinerTests : AbstractCSharpSyntaxNodeOutlinerTests<EnumMemberDeclarationSyntax>
     {
         protected override string WorkspaceKind => CodeAnalysis.WorkspaceKind.MetadataAsSource;
-        internal override AbstractSyntaxOutliner CreateOutliner() => new MaSOutliners.EnumMemberDeclarationOutliner();
+        internal override AbstractSyntaxStructureProvider CreateOutliner() => new MaSOutliners.EnumMemberDeclarationOutliner();
 
         [Fact, Trait(Traits.Feature, Traits.Features.MetadataAsSource)]
         public async Task NoCommentsOrAttributes()

src/EditorFeatures/CSharpTest/Outlining/MetadataAsSource/EventDeclarationOutlinerTests.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.Threading.Tasks;
+using Microsoft.CodeAnalysis.CSharp.Structure;
 using Microsoft.CodeAnalysis.CSharp.Syntax;
-using Microsoft.CodeAnalysis.Editor.CSharp.Outlining;
-using Microsoft.CodeAnalysis.Editor.Implementation.Outlining;
+using Microsoft.CodeAnalysis.Structure;
 using Roslyn.Test.Utilities;
 using Xunit;
-using MaSOutliners = Microsoft.CodeAnalysis.Editor.CSharp.Outlining.MetadataAsSource;
+using MaSOutliners = Microsoft.CodeAnalysis.CSharp.Structure.MetadataAsSource;
 
 namespace Microsoft.CodeAnalysis.Editor.CSharp.UnitTests.Outlining.MetadataAsSource
 {
     public class EventDeclarationOutlinerTests : AbstractCSharpSyntaxNodeOutlinerTests<EventDeclarationSyntax>
     {
         protected override string WorkspaceKind => CodeAnalysis.WorkspaceKind.MetadataAsSource;
-        internal override AbstractSyntaxOutliner CreateOutliner() => new MaSOutliners.EventDeclarationOutliner();
+        internal override AbstractSyntaxStructureProvider CreateOutliner() => new MaSOutliners.EventDeclarationOutliner();
 
         [Fact, Trait(Traits.Feature, Traits.Features.MetadataAsSource)]
         public async Task NoCommentsOrAttributes()

src/EditorFeatures/CSharpTest/Outlining/MetadataAsSource/EventFieldDeclarationOutlinerTests.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.Threading.Tasks;
+using Microsoft.CodeAnalysis.CSharp.Structure;
 using Microsoft.CodeAnalysis.CSharp.Syntax;
-using Microsoft.CodeAnalysis.Editor.CSharp.Outlining;
-using Microsoft.CodeAnalysis.Editor.Implementation.Outlining;
+using Microsoft.CodeAnalysis.Structure;
 using Roslyn.Test.Utilities;
 using Xunit;
-using MaSOutliners = Microsoft.CodeAnalysis.Editor.CSharp.Outlining.MetadataAsSource;
+using MaSOutliners = Microsoft.CodeAnalysis.CSharp.Structure.MetadataAsSource;
 
 namespace Microsoft.CodeAnalysis.Editor.CSharp.UnitTests.Outlining.MetadataAsSource
 {
     public class EventFieldDeclarationOutlinerTests : AbstractCSharpSyntaxNodeOutlinerTests<EventFieldDeclarationSyntax>
     {
         protected override string WorkspaceKind => CodeAnalysis.WorkspaceKind.MetadataAsSource;
-        internal override AbstractSyntaxOutliner CreateOutliner() => new MaSOutliners.EventFieldDeclarationOutliner();
+        internal override AbstractSyntaxStructureProvider CreateOutliner() => new MaSOutliners.EventFieldDeclarationOutliner();
 
         [Fact, Trait(Traits.Feature, Traits.Features.MetadataAsSource)]
         public async Task NoCommentsOrAttributes()

src/EditorFeatures/CSharpTest/Outlining/MetadataAsSource/FieldDeclarationOutlinerTests.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.Threading.Tasks;
+using Microsoft.CodeAnalysis.CSharp.Structure;
 using Microsoft.CodeAnalysis.CSharp.Syntax;
-using Microsoft.CodeAnalysis.Editor.CSharp.Outlining;
-using Microsoft.CodeAnalysis.Editor.Implementation.Outlining;
+using Microsoft.CodeAnalysis.Structure;
 using Roslyn.Test.Utilities;
 using Xunit;
-using MaSOutliners = Microsoft.CodeAnalysis.Editor.CSharp.Outlining.MetadataAsSource;
+using MaSOutliners = Microsoft.CodeAnalysis.CSharp.Structure.MetadataAsSource;
 
 namespace Microsoft.CodeAnalysis.Editor.CSharp.UnitTests.Outlining.MetadataAsSource
 {
     public class FieldDeclarationOutlinerTests : AbstractCSharpSyntaxNodeOutlinerTests<FieldDeclarationSyntax>
     {
         protected override string WorkspaceKind => CodeAnalysis.WorkspaceKind.MetadataAsSource;
-        internal override AbstractSyntaxOutliner CreateOutliner() => new MaSOutliners.FieldDeclarationOutliner();
+        internal override AbstractSyntaxStructureProvider CreateOutliner() => new MaSOutliners.FieldDeclarationOutliner();
 
         [Fact, Trait(Traits.Feature, Traits.Features.MetadataAsSource)]
         public async Task NoCommentsOrAttributes()

src/EditorFeatures/CSharpTest/Outlining/MetadataAsSource/IndexerDeclarationOutlinerTests.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.Threading.Tasks;
+using Microsoft.CodeAnalysis.CSharp.Structure;
 using Microsoft.CodeAnalysis.CSharp.Syntax;
-using Microsoft.CodeAnalysis.Editor.CSharp.Outlining;
-using Microsoft.CodeAnalysis.Editor.Implementation.Outlining;
+using Microsoft.CodeAnalysis.Structure;
 using Roslyn.Test.Utilities;
 using Xunit;
-using MaSOutliners = Microsoft.CodeAnalysis.Editor.CSharp.Outlining.MetadataAsSource;
+using MaSOutliners = Microsoft.CodeAnalysis.CSharp.Structure.MetadataAsSource;
 
 namespace Microsoft.CodeAnalysis.Editor.CSharp.UnitTests.Outlining.MetadataAsSource
 {
     public class IndexerDeclarationOutlinerTests : AbstractCSharpSyntaxNodeOutlinerTests<IndexerDeclarationSyntax>
     {
         protected override string WorkspaceKind => CodeAnalysis.WorkspaceKind.MetadataAsSource;
-        internal override AbstractSyntaxOutliner CreateOutliner() => new MaSOutliners.IndexerDeclarationOutliner();
+        internal override AbstractSyntaxStructureProvider CreateOutliner() => new MaSOutliners.IndexerDeclarationOutliner();
 
         [Fact, Trait(Traits.Feature, Traits.Features.MetadataAsSource)]
         public async Task NoCommentsOrAttributes()

src/EditorFeatures/CSharpTest/Outlining/MetadataAsSource/InvalidIdentifierTests.cs

@@ -3,8 +3,8 @@
 using System.Linq;
 using System.Threading;
 using System.Threading.Tasks;
-using Microsoft.CodeAnalysis.Editor.Implementation.Outlining;
 using Microsoft.CodeAnalysis.Editor.UnitTests.Outlining;
+using Microsoft.CodeAnalysis.Structure;
 using Roslyn.Test.Utilities;
 using Roslyn.Utilities;
 using Xunit;
@@ -20,12 +20,12 @@ public class InvalidIdentifierTests : AbstractSyntaxOutlinerTests
         protected override string LanguageName => LanguageNames.CSharp;
         protected override string WorkspaceKind => CodeAnalysis.WorkspaceKind.MetadataAsSource;
 
-        internal override async Task<OutliningSpan[]> GetRegionsAsync(Document document, int position)
+        internal override async Task<BlockSpan[]> GetRegionsAsync(Document document, int position)
         {
-            var outliningService = document.Project.LanguageServices.GetService<IOutliningService>();
+            var outliningService = document.Project.LanguageServices.GetService<BlockStructureService>();
 
-            return (await outliningService.GetOutliningSpansAsync(document, CancellationToken.None))
-                .WhereNotNull().ToArray();
+            return (await outliningService.GetBlockStructureAsync(document, CancellationToken.None))
+                .Spans.WhereNotNull().ToArray();
         }
 
         [WorkItem(1174405, "http://vstfdevdiv:8080/DevDiv2/DevDiv/_workitems/edit/1174405")]

src/EditorFeatures/CSharpTest/Outlining/MetadataAsSource/MethodDeclarationOutlinerTests.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.Threading.Tasks;
+using Microsoft.CodeAnalysis.CSharp.Structure;
 using Microsoft.CodeAnalysis.CSharp.Syntax;
-using Microsoft.CodeAnalysis.Editor.CSharp.Outlining;
-using Microsoft.CodeAnalysis.Editor.Implementation.Outlining;
+using Microsoft.CodeAnalysis.Structure;
 using Roslyn.Test.Utilities;
 using Xunit;
-using MaSOutliners = Microsoft.CodeAnalysis.Editor.CSharp.Outlining.MetadataAsSource;
+using MaSOutliners = Microsoft.CodeAnalysis.CSharp.Structure.MetadataAsSource;
 
 namespace Microsoft.CodeAnalysis.Editor.CSharp.UnitTests.Outlining.MetadataAsSource
 {
     public class MethodDeclarationOutlinerTests : AbstractCSharpSyntaxNodeOutlinerTests<MethodDeclarationSyntax>
     {
         protected override string WorkspaceKind => CodeAnalysis.WorkspaceKind.MetadataAsSource;
-        internal override AbstractSyntaxOutliner CreateOutliner() => new MaSOutliners.MethodDeclarationOutliner();
+        internal override AbstractSyntaxStructureProvider CreateOutliner() => new MaSOutliners.MethodDeclarationOutliner();
 
         [Fact, Trait(Traits.Feature, Traits.Features.MetadataAsSource)]
         public async Task NoCommentsOrAttributes()
@@ -73,4 +73,4 @@ class Foo
                 Region("collapse", "hint", CSharpOutliningHelpers.Ellipsis, autoCollapse: true));
         }
     }
-}
+}
\ No newline at end of file

src/EditorFeatures/CSharpTest/Outlining/MetadataAsSource/OperatorDeclarationOutlinerTests.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.Threading.Tasks;
+using Microsoft.CodeAnalysis.CSharp.Structure;
 using Microsoft.CodeAnalysis.CSharp.Syntax;
-using Microsoft.CodeAnalysis.Editor.CSharp.Outlining;
-using Microsoft.CodeAnalysis.Editor.Implementation.Outlining;
+using Microsoft.CodeAnalysis.Structure;
 using Roslyn.Test.Utilities;
 using Xunit;
-using MaSOutliners = Microsoft.CodeAnalysis.Editor.CSharp.Outlining.MetadataAsSource;
+using MaSOutliners = Microsoft.CodeAnalysis.CSharp.Structure.MetadataAsSource;
 
 namespace Microsoft.CodeAnalysis.Editor.CSharp.UnitTests.Outlining.MetadataAsSource
 {
     public class OperatorDeclarationOutlinerTests : AbstractCSharpSyntaxNodeOutlinerTests<OperatorDeclarationSyntax>
     {
         protected override string WorkspaceKind => CodeAnalysis.WorkspaceKind.MetadataAsSource;
-        internal override AbstractSyntaxOutliner CreateOutliner() => new MaSOutliners.OperatorDeclarationOutliner();
+        internal override AbstractSyntaxStructureProvider CreateOutliner() => new MaSOutliners.OperatorDeclarationOutliner();
 
         [Fact, Trait(Traits.Feature, Traits.Features.MetadataAsSource)]
         public async Task NoCommentsOrAttributes()
@@ -73,4 +73,4 @@ class Foo
                 Region("collapse", "hint", CSharpOutliningHelpers.Ellipsis, autoCollapse: true));
         }
     }
-}
+}
\ No newline at end of file

src/EditorFeatures/CSharpTest/Outlining/MetadataAsSource/PropertyDeclarationOutlinerTests.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.Threading.Tasks;
+using Microsoft.CodeAnalysis.CSharp.Structure;
 using Microsoft.CodeAnalysis.CSharp.Syntax;
-using Microsoft.CodeAnalysis.Editor.CSharp.Outlining;
-using Microsoft.CodeAnalysis.Editor.Implementation.Outlining;
+using Microsoft.CodeAnalysis.Structure;
 using Roslyn.Test.Utilities;
 using Xunit;
-using MaSOutliners = Microsoft.CodeAnalysis.Editor.CSharp.Outlining.MetadataAsSource;
+using MaSOutliners = Microsoft.CodeAnalysis.CSharp.Structure.MetadataAsSource;
 
 namespace Microsoft.CodeAnalysis.Editor.CSharp.UnitTests.Outlining.MetadataAsSource
 {
     public class PropertyDeclarationOutlinerTests : AbstractCSharpSyntaxNodeOutlinerTests<PropertyDeclarationSyntax>
     {
         protected override string WorkspaceKind => CodeAnalysis.WorkspaceKind.MetadataAsSource;
-        internal override AbstractSyntaxOutliner CreateOutliner() => new MaSOutliners.PropertyDeclarationOutliner();
+        internal override AbstractSyntaxStructureProvider CreateOutliner() => new MaSOutliners.PropertyDeclarationOutliner();
 
         [Fact, Trait(Traits.Feature, Traits.Features.MetadataAsSource)]
         public async Task NoCommentsOrAttributes()
@@ -73,4 +73,4 @@ class Foo
                 Region("collapse", "hint", CSharpOutliningHelpers.Ellipsis, autoCollapse: true));
         }
     }
-}
+}
\ No newline at end of file

src/EditorFeatures/CSharpTest/Outlining/MetadataAsSource/RegionDirectiveOutlinerTests.cs

@@ -2,17 +2,17 @@
 
 using System.Threading.Tasks;
 using Microsoft.CodeAnalysis.CSharp.Syntax;
-using Microsoft.CodeAnalysis.Editor.Implementation.Outlining;
+using Microsoft.CodeAnalysis.Structure;
 using Roslyn.Test.Utilities;
 using Xunit;
-using MaSOutliners = Microsoft.CodeAnalysis.Editor.CSharp.Outlining.MetadataAsSource;
+using MaSOutliners = Microsoft.CodeAnalysis.CSharp.Structure.MetadataAsSource;
 
 namespace Microsoft.CodeAnalysis.Editor.CSharp.UnitTests.Outlining.MetadataAsSource
 {
     public class RegionDirectiveOutlinerTests : AbstractCSharpSyntaxNodeOutlinerTests<RegionDirectiveTriviaSyntax>
     {
         protected override string WorkspaceKind => CodeAnalysis.WorkspaceKind.MetadataAsSource;
-        internal override AbstractSyntaxOutliner CreateOutliner() => new MaSOutliners.RegionDirectiveOutliner();
+        internal override AbstractSyntaxStructureProvider CreateOutliner() => new MaSOutliners.RegionDirectiveOutliner();
 
         [Fact, Trait(Traits.Feature, Traits.Features.MetadataAsSource)]
         public async Task FileHeader()
@@ -38,4 +38,4 @@ public async Task EmptyFileHeader()
                 Region("span", "#region", autoCollapse: true));
         }
     }
-}
+}
\ No newline at end of file

src/EditorFeatures/CSharpTest/Outlining/MetadataAsSource/TypeDeclarationOutlinerTests.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.Threading.Tasks;
+using Microsoft.CodeAnalysis.CSharp.Structure;
 using Microsoft.CodeAnalysis.CSharp.Syntax;
-using Microsoft.CodeAnalysis.Editor.CSharp.Outlining;
-using Microsoft.CodeAnalysis.Editor.Implementation.Outlining;
+using Microsoft.CodeAnalysis.Structure;
 using Roslyn.Test.Utilities;
 using Xunit;
-using MaSOutliners = Microsoft.CodeAnalysis.Editor.CSharp.Outlining.MetadataAsSource;
+using MaSOutliners = Microsoft.CodeAnalysis.CSharp.Structure.MetadataAsSource;
 
 namespace Microsoft.CodeAnalysis.Editor.CSharp.UnitTests.Outlining.MetadataAsSource
 {
     public class TypeDeclarationOutlinerTests : AbstractCSharpSyntaxNodeOutlinerTests<TypeDeclarationSyntax>
     {
         protected override string WorkspaceKind => CodeAnalysis.WorkspaceKind.MetadataAsSource;
-        internal override AbstractSyntaxOutliner CreateOutliner() => new MaSOutliners.TypeDeclarationOutliner();
+        internal override AbstractSyntaxStructureProvider CreateOutliner() => new MaSOutliners.TypeDeclarationOutliner();
 
         [Fact, Trait(Traits.Feature, Traits.Features.MetadataAsSource)]
         public async Task NoCommentsOrAttributes()
@@ -58,4 +58,4 @@ public async Task WithCommentsAndAttributes()
                 Region("collapse", "hint", CSharpOutliningHelpers.Ellipsis, autoCollapse: true));
         }
     }
-}
+}
\ No newline at end of file

src/EditorFeatures/CSharpTest/Outlining/MethodDeclarationOutlinerTests.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.Threading.Tasks;
+using Microsoft.CodeAnalysis.CSharp.Structure;
 using Microsoft.CodeAnalysis.CSharp.Syntax;
-using Microsoft.CodeAnalysis.Editor.CSharp.Outlining;
-using Microsoft.CodeAnalysis.Editor.Implementation.Outlining;
+using Microsoft.CodeAnalysis.Structure;
 using Roslyn.Test.Utilities;
 using Xunit;
 
@@ -11,7 +11,7 @@ namespace Microsoft.CodeAnalysis.Editor.CSharp.UnitTests.Outlining
 {
     public class MethodDeclarationOutlinerTests : AbstractCSharpSyntaxNodeOutlinerTests<MethodDeclarationSyntax>
     {
-        internal override AbstractSyntaxOutliner CreateOutliner() => new MethodDeclarationOutliner();
+        internal override AbstractSyntaxStructureProvider CreateOutliner() => new MethodDeclarationOutliner();
 
         [Fact, Trait(Traits.Feature, Traits.Features.Outlining)]
         public async Task TestMethod()

src/EditorFeatures/CSharpTest/Outlining/NamespaceDeclarationOutlinerTests.cs

@@ -2,16 +2,16 @@
 
 using System.Threading.Tasks;
 using Microsoft.CodeAnalysis.CSharp.Syntax;
-using Microsoft.CodeAnalysis.Editor.CSharp.Outlining;
-using Microsoft.CodeAnalysis.Editor.Implementation.Outlining;
+using Microsoft.CodeAnalysis.Editor.CSharp.UnitTests.Outlining;
+using Microsoft.CodeAnalysis.Structure;
 using Roslyn.Test.Utilities;
 using Xunit;
 
-namespace Microsoft.CodeAnalysis.Editor.CSharp.UnitTests.Outlining
+namespace Microsoft.CodeAnalysis.CSharp.Structure.Outlining
 {
     public class NamespaceDeclarationOutlinerTests : AbstractCSharpSyntaxNodeOutlinerTests<NamespaceDeclarationSyntax>
     {
-        internal override AbstractSyntaxOutliner CreateOutliner() => new NamespaceDeclarationOutliner();
+        internal override AbstractSyntaxStructureProvider CreateOutliner() => new NamespaceDeclarationOutliner();
 
         [Fact, Trait(Traits.Feature, Traits.Features.Outlining)]
         public async Task TestNamespace()
@@ -103,4 +103,4 @@ class C
                 Region("span2", "// Foo ...", autoCollapse: true));
         }
     }
-}
+}
\ No newline at end of file

src/EditorFeatures/CSharpTest/Outlining/OperatorDeclarationOutlinerTests.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.Threading.Tasks;
+using Microsoft.CodeAnalysis.CSharp.Structure;
 using Microsoft.CodeAnalysis.CSharp.Syntax;
-using Microsoft.CodeAnalysis.Editor.CSharp.Outlining;
-using Microsoft.CodeAnalysis.Editor.Implementation.Outlining;
+using Microsoft.CodeAnalysis.Structure;
 using Roslyn.Test.Utilities;
 using Xunit;
 
@@ -11,7 +11,7 @@ namespace Microsoft.CodeAnalysis.Editor.CSharp.UnitTests.Outlining
 {
     public class OperatorDeclarationOutlinerTests : AbstractCSharpSyntaxNodeOutlinerTests<OperatorDeclarationSyntax>
     {
-        internal override AbstractSyntaxOutliner CreateOutliner() => new OperatorDeclarationOutliner();
+        internal override AbstractSyntaxStructureProvider CreateOutliner() => new OperatorDeclarationOutliner();
 
         [Fact, Trait(Traits.Feature, Traits.Features.Outlining)]
         public async Task TestOperator()
@@ -46,4 +46,4 @@ class C
                 Region("collapse2", "hint2", CSharpOutliningHelpers.Ellipsis, autoCollapse: true));
         }
     }
-}
+}
\ No newline at end of file

src/EditorFeatures/CSharpTest/Outlining/ParenthesizedLambdaOutlinerTests.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.Threading.Tasks;
+using Microsoft.CodeAnalysis.CSharp.Structure;
 using Microsoft.CodeAnalysis.CSharp.Syntax;
-using Microsoft.CodeAnalysis.Editor.CSharp.Outlining;
-using Microsoft.CodeAnalysis.Editor.Implementation.Outlining;
+using Microsoft.CodeAnalysis.Structure;
 using Roslyn.Test.Utilities;
 using Xunit;
 
@@ -11,7 +11,7 @@ namespace Microsoft.CodeAnalysis.Editor.CSharp.UnitTests.Outlining
 {
     public class ParenthesizedLambdaOutlinerTests : AbstractCSharpSyntaxNodeOutlinerTests<ParenthesizedLambdaExpressionSyntax>
     {
-        internal override AbstractSyntaxOutliner CreateOutliner() => new ParenthesizedLambdaExpressionOutliner();
+        internal override AbstractSyntaxStructureProvider CreateOutliner() => new ParenthesizedLambdaExpressionOutliner();
 
         [Fact, Trait(Traits.Feature, Traits.Features.Outlining)]
         public async Task TestLambda()
@@ -82,4 +82,4 @@ void M()
                 Region("collapse", "hint", CSharpOutliningHelpers.Ellipsis, autoCollapse: false));
         }
     }
-}
+}
\ No newline at end of file

src/EditorFeatures/CSharpTest/Outlining/PropertyDeclarationOutlinerTests.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.Threading.Tasks;
+using Microsoft.CodeAnalysis.CSharp.Structure;
 using Microsoft.CodeAnalysis.CSharp.Syntax;
-using Microsoft.CodeAnalysis.Editor.CSharp.Outlining;
-using Microsoft.CodeAnalysis.Editor.Implementation.Outlining;
+using Microsoft.CodeAnalysis.Structure;
 using Roslyn.Test.Utilities;
 using Xunit;
 
@@ -11,7 +11,7 @@ namespace Microsoft.CodeAnalysis.Editor.CSharp.UnitTests.Outlining
 {
     public class PropertyDeclarationOutlinerTests : AbstractCSharpSyntaxNodeOutlinerTests<PropertyDeclarationSyntax>
     {
-        internal override AbstractSyntaxOutliner CreateOutliner() => new PropertyDeclarationOutliner();
+        internal override AbstractSyntaxStructureProvider CreateOutliner() => new PropertyDeclarationOutliner();
 
         [Fact, Trait(Traits.Feature, Traits.Features.Outlining)]
         public async Task TestProperty()

src/EditorFeatures/CSharpTest/Outlining/RegionDirectiveOutlinerTests.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.Threading.Tasks;
+using Microsoft.CodeAnalysis.CSharp.Structure;
 using Microsoft.CodeAnalysis.CSharp.Syntax;
-using Microsoft.CodeAnalysis.Editor.CSharp.Outlining;
-using Microsoft.CodeAnalysis.Editor.Implementation.Outlining;
+using Microsoft.CodeAnalysis.Structure;
 using Roslyn.Test.Utilities;
 using Xunit;
 
@@ -11,7 +11,7 @@ namespace Microsoft.CodeAnalysis.Editor.CSharp.UnitTests.Outlining
 {
     public class RegionDirectiveOutlinerTests : AbstractCSharpSyntaxNodeOutlinerTests<RegionDirectiveTriviaSyntax>
     {
-        internal override AbstractSyntaxOutliner CreateOutliner() => new RegionDirectiveOutliner();
+        internal override AbstractSyntaxStructureProvider CreateOutliner() => new RegionDirectiveOutliner();
 
         [Fact, Trait(Traits.Feature, Traits.Features.Outlining)]
         public async Task BrokenRegion()
@@ -105,4 +105,4 @@ static void Main(string[] args)
                 Region("span", "Region", autoCollapse: true, isDefaultCollapsed: true));
         }
     }
-}
+}
\ No newline at end of file

src/EditorFeatures/CSharpTest/Outlining/SimpleLambdaExpressionOutlinerTests.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.Threading.Tasks;
+using Microsoft.CodeAnalysis.CSharp.Structure;
 using Microsoft.CodeAnalysis.CSharp.Syntax;
-using Microsoft.CodeAnalysis.Editor.CSharp.Outlining;
-using Microsoft.CodeAnalysis.Editor.Implementation.Outlining;
+using Microsoft.CodeAnalysis.Structure;
 using Roslyn.Test.Utilities;
 using Xunit;
 
@@ -11,7 +11,7 @@ namespace Microsoft.CodeAnalysis.Editor.CSharp.UnitTests.Outlining
 {
     public class SimpleLambdaExpressionOutlinerTests : AbstractCSharpSyntaxNodeOutlinerTests<SimpleLambdaExpressionSyntax>
     {
-        internal override AbstractSyntaxOutliner CreateOutliner() => new SimpleLambdaExpressionOutliner();
+        internal override AbstractSyntaxStructureProvider CreateOutliner() => new SimpleLambdaExpressionOutliner();
 
         [Fact, Trait(Traits.Feature, Traits.Features.Outlining)]
         public async Task TestLambda()

src/EditorFeatures/CSharpTest/Outlining/TypeDeclarationOutlinerTests.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.Threading.Tasks;
+using Microsoft.CodeAnalysis.CSharp.Structure;
 using Microsoft.CodeAnalysis.CSharp.Syntax;
-using Microsoft.CodeAnalysis.Editor.CSharp.Outlining;
-using Microsoft.CodeAnalysis.Editor.Implementation.Outlining;
+using Microsoft.CodeAnalysis.Structure;
 using Roslyn.Test.Utilities;
 using Xunit;
 
@@ -11,7 +11,7 @@ namespace Microsoft.CodeAnalysis.Editor.CSharp.UnitTests.Outlining
 {
     public class TypeDeclarationOutlinerTests : AbstractCSharpSyntaxNodeOutlinerTests<TypeDeclarationSyntax>
     {
-        internal override AbstractSyntaxOutliner CreateOutliner() => new TypeDeclarationOutliner();
+        internal override AbstractSyntaxStructureProvider CreateOutliner() => new TypeDeclarationOutliner();
 
         [Fact, Trait(Traits.Feature, Traits.Features.Outlining)]
         public async Task TestClass()

src/EditorFeatures/Core/EditorFeatures.csproj

@@ -284,10 +284,8 @@
     <Compile Include="Implementation\LineSeparators\LineSeparatorAdornmentManagerProvider.cs" />
     <Compile Include="Implementation\NavigateTo\NavigateToSearchResultProvider.cs" />
     <Compile Include="Implementation\NavigateTo\INavigateToSearchResultProvider.cs" />
-    <Compile Include="Implementation\Outlining\AbstractSyntaxOutliner.cs" />
-    <Compile Include="Implementation\Outlining\InvalidOutliningRegionException.cs" />
-    <Compile Include="Implementation\Outlining\AbstractOutliningTaggerProvider.cs" />
-    <Compile Include="Implementation\Outlining\PredefinedStructureTypes2.cs" />
+    <Compile Include="Implementation\Structure\InvalidOutliningRegionException.cs" />
+    <Compile Include="Implementation\Structure\AbstractStructureTaggerProvider.cs" />
     <Compile Include="Implementation\Preview\DifferenceViewerPreview.cs" />
     <Compile Include="Implementation\Preview\PreviewReferenceHighlightingTaggerProvider.cs" />
     <Compile Include="Implementation\Suggestions\FixMultipleOccurrencesService.cs" />
@@ -568,16 +566,9 @@
     <Compile Include="Implementation\NavigationBar\NavigationBarSymbolIdIndexProvider.cs" />
     <Compile Include="Implementation\Notification\EditorNotificationServiceFactory.cs" />
     <Compile Include="Implementation\Organizing\OrganizeDocumentCommandHandler.cs" />
-    <Compile Include="Implementation\Outlining\AbstractOutliningService.cs" />
-    <Compile Include="Implementation\Outlining\AbstractSyntaxNodeOutliner.cs" />
-    <Compile Include="Implementation\Outlining\AbstractSyntaxTriviaOutliner.cs" />
-    <Compile Include="Implementation\Outlining\IOutliningService.cs" />
-    <Compile Include="Implementation\Outlining\OutliningCommandHandler.cs" />
-    <Compile Include="Implementation\Outlining\OutliningExtensions.cs" />
-    <Compile Include="Implementation\Outlining\OutliningSpan.cs" />
-    <Compile Include="Implementation\Outlining\VisualStudio14OutliningTaggerProvider.cs" />
-    <Compile Include="Implementation\Outlining\AbstractOutliningTaggerProvider.RegionTag.cs" />
-    <Compile Include="Implementation\Outlining\RegionCollector.cs" />
+    <Compile Include="Implementation\Structure\OutliningCommandHandler.cs" />
+    <Compile Include="Implementation\Structure\VisualStudio14StructureTaggerProvider.cs" />
+    <Compile Include="Implementation\Structure\AbstractStructureTaggerProvider.RegionTag.cs" />
     <Compile Include="Implementation\Peek\DefinitionPeekableItem.cs" />
     <Compile Include="Implementation\Peek\ExternalFilePeekableItem.cs" />
     <Compile Include="Implementation\Peek\PeekableItem.cs" />

src/EditorFeatures/Core/Implementation/Outlining/IOutliningService.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.Generic;
-using System.Threading;
-using System.Threading.Tasks;
-using Microsoft.CodeAnalysis.Host;
-
-namespace Microsoft.CodeAnalysis.Editor.Implementation.Outlining
-{
-    internal interface IOutliningService : ILanguageService
-    {
-        Task<IList<OutliningSpan>> GetOutliningSpansAsync(Document document, CancellationToken cancellationToken);
-    }
-
-    internal interface ISynchronousOutliningService : IOutliningService
-    {
-        IList<OutliningSpan> GetOutliningSpans(Document document, CancellationToken cancellationToken);
-    }
-}

src/EditorFeatures/Core/Implementation/Outlining/AbstractOutliningTaggerProvider.RegionTag.cs → src/EditorFeatures/Core/Implementation/Structure/AbstractStructureTaggerProvider.RegionTag.cs

@@ -4,15 +4,16 @@
 using System.Windows.Media;
 using Microsoft.CodeAnalysis.Editor.Shared.Extensions;
 using Microsoft.CodeAnalysis.Editor.Shared.Utilities;
+using Microsoft.CodeAnalysis.Structure;
 using Microsoft.CodeAnalysis.Text.Shared.Extensions;
 using Microsoft.VisualStudio.Text;
 using Microsoft.VisualStudio.Text.Editor;
 using Microsoft.VisualStudio.Text.Projection;
 using Microsoft.VisualStudio.Text.Tagging;
 
-namespace Microsoft.CodeAnalysis.Editor.Implementation.Outlining
+namespace Microsoft.CodeAnalysis.Editor.Implementation.Structure
 {
-    internal abstract partial class AbstractOutliningTaggerProvider<TRegionTag>
+    internal abstract partial class AbstractStructureTaggerProvider<TRegionTag>
     {
         // Our implementation of an outlining region tag.  The collapsedHintForm
         // is dynamically created using an elision buffer over the actual text
@@ -22,27 +23,27 @@ protected class RegionTag : IOutliningRegionTag
             private const string Ellipsis = "...";
             private const int MaxPreviewText = 1000;
 
-            private readonly AbstractOutliningTaggerProvider<TRegionTag> _provider;
+            private readonly AbstractStructureTaggerProvider<TRegionTag> _provider;
 
             private readonly ITextBuffer _subjectBuffer;
             private readonly ITrackingSpan _hintSpan;
 
-            public bool IsDefaultCollapsed => OutliningSpan.IsDefaultCollapsed;
-            public bool IsImplementation => OutliningSpan.AutoCollapse;
-            public object CollapsedForm => OutliningSpan.BannerText;
+            public bool IsDefaultCollapsed => BlockSpan.IsDefaultCollapsed;
+            public bool IsImplementation => BlockSpan.AutoCollapse;
+            public object CollapsedForm => BlockSpan.BannerText;
 
-            protected readonly OutliningSpan OutliningSpan;
+            protected readonly BlockSpan BlockSpan;
 
             public RegionTag(
-                AbstractOutliningTaggerProvider<TRegionTag> provider,
+                AbstractStructureTaggerProvider<TRegionTag> provider,
                 ITextSnapshot snapshot,
-                OutliningSpan outliningSpan)
+                BlockSpan outliningSpan)
             {
                 _provider = provider;
                 _subjectBuffer = snapshot.TextBuffer;
-                OutliningSpan = outliningSpan;
+                BlockSpan = outliningSpan;
                 
-                _hintSpan = snapshot.CreateTrackingSpan(OutliningSpan.HintSpan.ToSpan(), SpanTrackingMode.EdgeExclusive);
+                _hintSpan = snapshot.CreateTrackingSpan(BlockSpan.HintSpan.ToSpan(), SpanTrackingMode.EdgeExclusive);
             }
 
             public object CollapsedHintForm =>

src/EditorFeatures/Core/Implementation/Outlining/AbstractOutliningTaggerProvider.cs → src/EditorFeatures/Core/Implementation/Structure/AbstractStructureTaggerProvider.cs

@@ -2,6 +2,7 @@
 
 using System;
 using System.Collections.Generic;
+using System.Collections.Immutable;
 using System.ComponentModel.Composition;
 using System.Threading.Tasks;
 using Microsoft.CodeAnalysis.Editor.Shared.Tagging;
@@ -9,6 +10,7 @@
 using Microsoft.CodeAnalysis.ErrorReporting;
 using Microsoft.CodeAnalysis.Internal.Log;
 using Microsoft.CodeAnalysis.Shared.TestHooks;
+using Microsoft.CodeAnalysis.Structure;
 using Microsoft.CodeAnalysis.Text.Shared.Extensions;
 using Microsoft.VisualStudio.Text;
 using Microsoft.VisualStudio.Text.Editor;
@@ -16,7 +18,7 @@
 using Microsoft.VisualStudio.Text.Tagging;
 using Roslyn.Utilities;
 
-namespace Microsoft.CodeAnalysis.Editor.Implementation.Outlining
+namespace Microsoft.CodeAnalysis.Editor.Implementation.Structure
 {
     /// <summary>
     /// Shared implementation of the outliner tagger provider.
@@ -27,7 +29,7 @@ namespace Microsoft.CodeAnalysis.Editor.Implementation.Outlining
     /// editor doesn't know about all the regions in the file, then it wouldn't be able to
     /// persist them to the SUO file to persist this data across sessions.
     /// </summary>
-    internal abstract partial class AbstractOutliningTaggerProvider<TRegionTag> : 
+    internal abstract partial class AbstractStructureTaggerProvider<TRegionTag> : 
         AsynchronousTaggerProvider<TRegionTag>,
         IEqualityComparer<TRegionTag>
         where TRegionTag : class, ITag
@@ -38,7 +40,7 @@ internal abstract partial class AbstractOutliningTaggerProvider<TRegionTag> :
         protected readonly IEditorOptionsFactoryService EditorOptionsFactoryService;
         protected readonly IProjectionBufferFactoryService ProjectionBufferFactoryService;
 
-        protected AbstractOutliningTaggerProvider(
+        protected AbstractStructureTaggerProvider(
             IForegroundNotificationService notificationService,
             ITextEditorFactoryService textEditorFactoryService,
             IEditorOptionsFactoryService editorOptionsFactoryService,
@@ -87,9 +89,11 @@ protected sealed override ITaggerEventSource CreateEventSource(ITextView textVie
                 var outliningService = TryGetOutliningService(context, documentSnapshotSpan);
                 if (outliningService != null)
                 {
-                    var regions = await outliningService.GetOutliningSpansAsync(
+                    var blockStructure = await outliningService.GetBlockStructureAsync(
                         documentSnapshotSpan.Document, context.CancellationToken).ConfigureAwait(false);
-                    ProcessOutliningSpans(context, documentSnapshotSpan.SnapshotSpan, outliningService, regions);
+                    ProcessOutliningSpans(
+                        context, documentSnapshotSpan.SnapshotSpan, outliningService,
+                        blockStructure.Spans);
                 }
             }
             catch (Exception e) when (FatalError.ReportUnlessCanceled(e))
@@ -114,13 +118,11 @@ protected sealed override ITaggerEventSource CreateEventSource(ITextView textVie
 
                     // Try to call through the synchronous service if possible. Otherwise, fallback
                     // and make a blocking call against the async service.
-                    var synchronousOutliningService = outliningService as ISynchronousOutliningService;
 
-                    var regions = synchronousOutliningService != null
-                        ? synchronousOutliningService.GetOutliningSpans(document, cancellationToken)
-                        : outliningService.GetOutliningSpansAsync(document, cancellationToken).WaitAndGetResult(cancellationToken);
-
-                    ProcessOutliningSpans(context, documentSnapshotSpan.SnapshotSpan, outliningService, regions);
+                    var blockStructure = outliningService.GetBlockStructure(document, cancellationToken);
+                    ProcessOutliningSpans(
+                        context, documentSnapshotSpan.SnapshotSpan, outliningService,
+                        blockStructure.Spans);
                 }
             }
             catch (Exception e) when (FatalError.ReportUnlessCanceled(e))
@@ -129,7 +131,7 @@ protected sealed override ITaggerEventSource CreateEventSource(ITextView textVie
             }
         }
 
-        private IOutliningService TryGetOutliningService(
+        private BlockStructureService TryGetOutliningService(
             TaggerContext<TRegionTag> context,
             DocumentSnapshotSpan documentSnapshotSpan)
         {
@@ -137,12 +139,9 @@ protected sealed override ITaggerEventSource CreateEventSource(ITextView textVie
             using (Logger.LogBlock(FunctionId.Tagger_Outlining_TagProducer_ProduceTags, cancellationToken))
             {
                 var document = documentSnapshotSpan.Document;
-                var snapshotSpan = documentSnapshotSpan.SnapshotSpan;
-                var snapshot = snapshotSpan.Snapshot;
-
                 if (document != null)
                 {
-                    return document.Project.LanguageServices.GetService<IOutliningService>();
+                    return BlockStructureService.GetService(document);
                 }
             }
 
@@ -150,7 +149,10 @@ protected sealed override ITaggerEventSource CreateEventSource(ITextView textVie
         }
 
         private void ProcessOutliningSpans(
-            TaggerContext<TRegionTag> context, SnapshotSpan snapshotSpan, IOutliningService outliningService, IList<OutliningSpan> regions)
+            TaggerContext<TRegionTag> context,
+            SnapshotSpan snapshotSpan,
+            BlockStructureService outliningService,
+            ImmutableArray<BlockSpan> regions)
         {
             if (regions != null)
             {
@@ -182,14 +184,16 @@ protected sealed override ITaggerEventSource CreateEventSource(ITextView textVie
         }
 
         protected abstract TRegionTag CreateTag(
-            TRegionTag parentTag, ITextSnapshot snapshot, OutliningSpan region);
+            TRegionTag parentTag, ITextSnapshot snapshot, BlockSpan region);
 
         private static bool s_exceptionReported = false;
 
-        private List<OutliningSpan> GetMultiLineRegions(IOutliningService service, IList<OutliningSpan> regions, ITextSnapshot snapshot)
+        private ImmutableArray<BlockSpan> GetMultiLineRegions(
+            BlockStructureService service, 
+            ImmutableArray<BlockSpan> regions, ITextSnapshot snapshot)
         {
             // Remove any spans that aren't multiline.
-            var multiLineRegions = new List<OutliningSpan>(regions.Count);
+            var multiLineRegions = ImmutableArray.CreateBuilder<BlockSpan>();
             foreach (var region in regions)
             {
                 if (region != null && region.TextSpan.Length > 0)
@@ -227,7 +231,7 @@ private List<OutliningSpan> GetMultiLineRegions(IOutliningService service, IList
             // Make sure the regions are lexicographically sorted.  This is needed
             // so we can appropriately parent them for BlockTags.
             multiLineRegions.Sort((s1, s2) => s1.TextSpan.Start - s2.TextSpan.Start);
-            return multiLineRegions;
+            return multiLineRegions.ToImmutable();
         }
     }
-}
+}
\ No newline at end of file

src/EditorFeatures/Core/Implementation/Outlining/InvalidOutliningRegionException.cs → src/EditorFeatures/Core/Implementation/Structure/InvalidOutliningRegionException.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;
+using Microsoft.CodeAnalysis.Structure;
 using Microsoft.VisualStudio.Text;
 
-namespace Microsoft.CodeAnalysis.Editor.Implementation.Outlining
+namespace Microsoft.CodeAnalysis.Editor.Implementation.Structure
 {
     internal class InvalidOutliningRegionException : Exception
     {
-        private readonly IOutliningService _service;
+        private readonly BlockStructureService _service;
         private readonly ITextSnapshot _snapshot;
         private readonly Span _snapshotSpan;
         private readonly Span _regionSpan;
 
-        public InvalidOutliningRegionException(IOutliningService service, ITextSnapshot snapshot, Span snapshotSpan, Span regionSpan)
+        public InvalidOutliningRegionException(BlockStructureService service, ITextSnapshot snapshot, Span snapshotSpan, Span regionSpan)
             : base(GetExceptionMessage(service, snapshot, snapshotSpan, regionSpan))
         {
             _service = service;
@@ -21,7 +22,7 @@ public InvalidOutliningRegionException(IOutliningService service, ITextSnapshot
             _regionSpan = regionSpan;
         }
 
-        private static string GetExceptionMessage(IOutliningService service, ITextSnapshot snapshot, Span snapshotSpan, Span regionSpan)
+        private static string GetExceptionMessage(BlockStructureService service, ITextSnapshot snapshot, Span snapshotSpan, Span regionSpan)
         {
             return $"OutliningService({service.GetType()}) produced an invalid region.  ITextSnapshot span is {snapshotSpan}. OutliningSpan is {regionSpan}.";
         }

src/EditorFeatures/Core/Implementation/Outlining/OutliningCommandHandler.cs → src/EditorFeatures/Core/Implementation/Structure/OutliningCommandHandler.cs

@@ -5,7 +5,7 @@
 using Microsoft.CodeAnalysis.Editor.Commands;
 using Microsoft.VisualStudio.Text.Outlining;
 
-namespace Microsoft.CodeAnalysis.Editor.Implementation.Outlining
+namespace Microsoft.CodeAnalysis.Editor.Implementation.Structure
 {
     [ExportCommandHandler("Outlining Command Handler", ContentTypeNames.RoslynContentType)]
     internal sealed class OutliningCommandHandler : ICommandHandler<StartAutomaticOutliningCommandArgs>

src/EditorFeatures/Core/Implementation/Outlining/VisualStudio14OutliningTaggerProvider.cs → src/EditorFeatures/Core/Implementation/Structure/VisualStudio14StructureTaggerProvider.cs

@@ -4,14 +4,14 @@
 using System.Collections.Generic;
 using System.ComponentModel.Composition;
 using Microsoft.CodeAnalysis.Shared.TestHooks;
-using Microsoft.CodeAnalysis.Text.Shared.Extensions;
+using Microsoft.CodeAnalysis.Structure;
 using Microsoft.VisualStudio.Text;
 using Microsoft.VisualStudio.Text.Editor;
 using Microsoft.VisualStudio.Text.Projection;
 using Microsoft.VisualStudio.Text.Tagging;
 using Microsoft.VisualStudio.Utilities;
 
-namespace Microsoft.CodeAnalysis.Editor.Implementation.Outlining
+namespace Microsoft.CodeAnalysis.Editor.Implementation.Structure
 {
     /// <summary>
     /// Shared implementation of the outliner tagger provider.
@@ -23,14 +23,14 @@ namespace Microsoft.CodeAnalysis.Editor.Implementation.Outlining
     /// persist them to the SUO file to persist this data across sessions.
     /// </summary>
     [Export(typeof(ITaggerProvider))]
-    [Export(typeof(VisualStudio14OutliningTaggerProvider))]
+    [Export(typeof(VisualStudio14StructureTaggerProvider))]
     [TagType(typeof(IOutliningRegionTag))]
     [ContentType(ContentTypeNames.RoslynContentType)]
-    internal partial class VisualStudio14OutliningTaggerProvider : 
-        AbstractOutliningTaggerProvider<IOutliningRegionTag>
+    internal partial class VisualStudio14StructureTaggerProvider :
+        AbstractStructureTaggerProvider<IOutliningRegionTag>
     {
         [ImportingConstructor]
-        public VisualStudio14OutliningTaggerProvider(
+        public VisualStudio14StructureTaggerProvider(
             IForegroundNotificationService notificationService,
             ITextEditorFactoryService textEditorFactoryService,
             IEditorOptionsFactoryService editorOptionsFactoryService,
@@ -53,7 +53,7 @@ public override int GetHashCode(IOutliningRegionTag obj)
         }
 
         protected override IOutliningRegionTag CreateTag(
-            IOutliningRegionTag parentTag, ITextSnapshot snapshot, OutliningSpan region)
+            IOutliningRegionTag parentTag, ITextSnapshot snapshot, BlockSpan region)
         {
             return new RegionTag(this, snapshot, region);
         }

src/EditorFeatures/Next/EditorFeatures.Next.csproj

@@ -70,9 +70,9 @@
     <Compile Include="IntelliSense\Completion\Presentation\Roslyn15CompletionSet.cs" />
     <Compile Include="IntelliSense\Completion\Presentation\VisualStudio15CompletionSetFactory.cs" />
     <Compile Include="IntelliSense\Completion\Presentation\VisualStudio15CompletionSet.cs" />
-    <Compile Include="Outlining\BlockTag2.cs" />
-    <Compile Include="Outlining\IBlockTag2.cs" />
-    <Compile Include="Outlining\VisualStudio15OutliningTaggerProvider.cs" />
+    <Compile Include="Structure\BlockTag2.cs" />
+    <Compile Include="Structure\IBlockTag2.cs" />
+    <Compile Include="Structure\VisualStudio15OutliningTaggerProvider.cs" />
   </ItemGroup>
   <ItemGroup />
   <Import Project="..\..\..\build\Targets\VSL.Imports.targets" />

src/EditorFeatures/Next/Outlining/VisualStudio15OutliningTaggerProvider.cs → src/EditorFeatures/Next/Structure/VisualStudio15OutliningTaggerProvider.cs

@@ -3,7 +3,9 @@
 using System;
 using System.Collections.Generic;
 using System.ComponentModel.Composition;
+using Microsoft.CodeAnalysis.Editor.Implementation.Structure;
 using Microsoft.CodeAnalysis.Shared.TestHooks;
+using Microsoft.CodeAnalysis.Structure;
 using Microsoft.CodeAnalysis.Text.Shared.Extensions;
 using Microsoft.VisualStudio.Text;
 using Microsoft.VisualStudio.Text.Editor;
@@ -11,14 +13,14 @@
 using Microsoft.VisualStudio.Text.Tagging;
 using Microsoft.VisualStudio.Utilities;
 
-namespace Microsoft.CodeAnalysis.Editor.Implementation.Outlining
+namespace Microsoft.CodeAnalysis.Editor.Structure
 {
     [Export(typeof(ITaggerProvider))]
     [Export(typeof(VisualStudio15OutliningTaggerProvider))]
     [TagType(typeof(IBlockTag2))]
     [ContentType(ContentTypeNames.RoslynContentType)]
     internal partial class VisualStudio15OutliningTaggerProvider : 
-        AbstractOutliningTaggerProvider<IBlockTag2>
+        AbstractStructureTaggerProvider<IBlockTag2>
     {
         [ImportingConstructor]
         public VisualStudio15OutliningTaggerProvider(
@@ -44,7 +46,7 @@ public override int GetHashCode(IBlockTag2 obj)
         }
 
         protected override IBlockTag2 CreateTag(
-            IBlockTag2 parentTag, ITextSnapshot snapshot, OutliningSpan region)
+            IBlockTag2 parentTag, ITextSnapshot snapshot, BlockSpan region)
         {
             return new RoslynRegionTag(this, parentTag, snapshot, region);
         }
@@ -56,14 +58,14 @@ private class RoslynRegionTag : RegionTag, IBlockTag2
             public SnapshotSpan Span { get; }
             public SnapshotSpan StatementSpan { get; }
 
-            public string Type => OutliningSpan.Type;
+            public string Type => BlockSpan.Type;
             public bool IsCollapsible => true;
 
             public RoslynRegionTag(
-                AbstractOutliningTaggerProvider<IBlockTag2> provider,
+                AbstractStructureTaggerProvider<IBlockTag2> provider,
                 IBlockTag2 parent,
                 ITextSnapshot snapshot,
-                OutliningSpan outliningSpan) : 
+                BlockSpan outliningSpan) : 
                 base(provider, snapshot, outliningSpan)
             {
                 Parent = parent;

src/EditorFeatures/Test/Outlining/AbstractSyntaxNodeOutlinerTests.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.Generic;
+using System.Collections.Immutable;
 using System.Linq;
 using System.Threading;
 using System.Threading.Tasks;
-using Microsoft.CodeAnalysis.Editor.Implementation.Outlining;
+using Microsoft.CodeAnalysis.Structure;
 using Roslyn.Utilities;
 using Xunit;
 
@@ -13,9 +13,9 @@ namespace Microsoft.CodeAnalysis.Editor.UnitTests.Outlining
     public abstract class AbstractSyntaxNodeOutlinerTests<TSyntaxNode> : AbstractSyntaxOutlinerTests
         where TSyntaxNode : SyntaxNode
     {
-        internal abstract AbstractSyntaxOutliner CreateOutliner();
+        internal abstract AbstractSyntaxStructureProvider CreateOutliner();
 
-        internal sealed override async Task<OutliningSpan[]> GetRegionsAsync(Document document, int position)
+        internal sealed override async Task<BlockSpan[]> GetRegionsAsync(Document document, int position)
         {
             var root = await document.GetSyntaxRootAsync(CancellationToken.None);
             var token = root.FindToken(position, findInsideTrivia: true);
@@ -37,8 +37,8 @@ internal sealed override async Task<OutliningSpan[]> GetRegionsAsync(Document do
             }
 
             var outliner = CreateOutliner();
-            var actualRegions = new List<OutliningSpan>();
-            outliner.CollectOutliningSpans(document, node, actualRegions, CancellationToken.None);
+            var actualRegions = ImmutableArray.CreateBuilder<BlockSpan>();
+            outliner.CollectBlockSpans(document, node, actualRegions, CancellationToken.None);
 
             // TODO: Determine why we get null outlining spans.
             return actualRegions.WhereNotNull().ToArray();

src/EditorFeatures/Test/Outlining/AbstractSyntaxOutlinerTests.cs

@@ -4,8 +4,8 @@
 using System.Collections.Generic;
 using System.Linq;
 using System.Threading.Tasks;
-using Microsoft.CodeAnalysis.Editor.Implementation.Outlining;
 using Microsoft.CodeAnalysis.Editor.UnitTests.Workspaces;
+using Microsoft.CodeAnalysis.Structure;
 using Microsoft.CodeAnalysis.Text;
 using Xunit;
 
@@ -17,7 +17,7 @@ public abstract class AbstractSyntaxOutlinerTests
 
         protected virtual string WorkspaceKind => TestWorkspace.WorkspaceName;
 
-        internal abstract Task<OutliningSpan[]> GetRegionsAsync(Document document, int position);
+        internal abstract Task<BlockSpan[]> GetRegionsAsync(Document document, int position);
 
         protected async Task VerifyRegionsAsync(string markupCode, params Tuple<string, string, string, bool, bool>[] expectedRegionData)
         {
@@ -66,7 +66,7 @@ protected async Task VerifyNoRegionsAsync(string markupCode)
             return Tuple.Create(collapseSpanName, collapseSpanName, bannerText, autoCollapse, isDefaultCollapsed);
         }
 
-        private static OutliningSpan CreateOutliningSpan(Tuple<string, string, string, bool, bool> regionData, IDictionary<string, IList<TextSpan>> spans)
+        private static BlockSpan CreateOutliningSpan(Tuple<string, string, string, bool, bool> regionData, IDictionary<string, IList<TextSpan>> spans)
         {
             var collapseSpanName = regionData.Item1;
             var hintSpanName = regionData.Item2;
@@ -80,10 +80,15 @@ private static OutliningSpan CreateOutliningSpan(Tuple<string, string, string, b
             var collapseSpan = spans[collapseSpanName][0];
             var hintSpan = spans[hintSpanName][0];
 
-            return new OutliningSpan(collapseSpan, hintSpan, bannerText, autoCollapse, isDefaultCollapsed);
+            return new BlockSpan(isCollapsible: true,
+                textSpan: collapseSpan, 
+                hintSpan: hintSpan,
+                bannerText: bannerText,
+                autoCollapse: autoCollapse, 
+                isDefaultCollapsed: isDefaultCollapsed);
         }
 
-        internal static void AssertRegion(OutliningSpan expected, OutliningSpan actual)
+        internal static void AssertRegion(BlockSpan expected, BlockSpan actual)
         {
             Assert.Equal(expected.TextSpan.Start, actual.TextSpan.Start);
             Assert.Equal(expected.TextSpan.End, actual.TextSpan.End);
@@ -94,4 +99,4 @@ internal static void AssertRegion(OutliningSpan expected, OutliningSpan actual)
             Assert.Equal(expected.IsDefaultCollapsed, actual.IsDefaultCollapsed);
         }
     }
-}
+}
\ No newline at end of file

src/EditorFeatures/Test/Outlining/AbstractSyntaxTriviaOutlinerTests.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.Generic;
+using System.Collections.Immutable;
 using System.Linq;
 using System.Threading;
 using System.Threading.Tasks;
-using Microsoft.CodeAnalysis.Editor.Implementation.Outlining;
+using Microsoft.CodeAnalysis.Editor.Implementation.Structure;
+using Microsoft.CodeAnalysis.Structure;
 using Roslyn.Utilities;
 
 namespace Microsoft.CodeAnalysis.Editor.UnitTests.Outlining
 {
     public abstract class AbstractSyntaxTriviaOutlinerTests : AbstractSyntaxOutlinerTests
     {
-        internal abstract AbstractSyntaxOutliner CreateOutliner();
+        internal abstract AbstractSyntaxStructureProvider CreateOutliner();
 
-        internal sealed override async Task<OutliningSpan[]> GetRegionsAsync(Document document, int position)
+        internal sealed override async Task<BlockSpan[]> GetRegionsAsync(Document document, int position)
         {
             var root = await document.GetSyntaxRootAsync(CancellationToken.None);
             var trivia = root.FindTrivia(position, findInsideTrivia: true);
 
             var outliner = CreateOutliner();
-            var actualRegions = new List<OutliningSpan>();
-            outliner.CollectOutliningSpans(document, trivia, actualRegions, CancellationToken.None);
+            var actualRegions = ImmutableArray.CreateBuilder<BlockSpan>();
+            outliner.CollectBlockSpans(document, trivia, actualRegions, CancellationToken.None);
 
             // TODO: Determine why we get null outlining spans.
             return actualRegions.WhereNotNull().ToArray();

src/EditorFeatures/Test/Outlining/OutliningServiceTests.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.Generic;
+using System.Collections.Immutable;
 using System.Linq;
 using System.Threading;
 using System.Threading.Tasks;
-using Microsoft.CodeAnalysis.Editor.Implementation.Outlining;
+using Microsoft.CodeAnalysis.Editor.Implementation.Structure;
 using Microsoft.CodeAnalysis.Editor.UnitTests.Workspaces;
+using Microsoft.CodeAnalysis.Structure;
 using Roslyn.Test.Utilities;
 using Xunit;
 
@@ -35,7 +37,7 @@ static void Foo()
                 var spans = await GetSpansFromWorkspaceAsync(workspace);
 
                 // ensure all 4 outlining region tags were found (usings, class, method, lambda)
-                Assert.Equal(4, spans.Count);
+                Assert.Equal(4, spans.Length);
             }
         }
 
@@ -61,7 +63,7 @@ static void Foo()
                 var spans = await GetSpansFromWorkspaceAsync(workspace);
 
                 // ensure all 4 outlining region tags were found (usings, class, method, lambda)
-                Assert.Equal(4, spans.Count);
+                Assert.Equal(4, spans.Length);
             }
         }
 
@@ -87,17 +89,19 @@ static void Foo()
                 var spans = await GetSpansFromWorkspaceAsync(workspace);
 
                 // ensure all 4 outlining region tags were found (usings, class, method, anonymous delegate)
-                Assert.Equal(4, spans.Count);
+                Assert.Equal(4, spans.Length);
             }
         }
 
-        private static async Task<IList<OutliningSpan>> GetSpansFromWorkspaceAsync(TestWorkspace workspace)
+        private static async Task<ImmutableArray<BlockSpan>> GetSpansFromWorkspaceAsync(
+            TestWorkspace workspace)
         {
             var hostDocument = workspace.Documents.First();
             var document = workspace.CurrentSolution.GetDocument(hostDocument.Id);
-            var outliningService = document.Project.LanguageServices.GetService<IOutliningService>();
+            var outliningService = document.Project.LanguageServices.GetService<BlockStructureService>();
 
-            return await outliningService.GetOutliningSpansAsync(document, CancellationToken.None);
+            var structure = await outliningService.GetBlockStructureAsync(document, CancellationToken.None);
+            return structure.Spans;
         }
     }
 }

src/EditorFeatures/Test/Outlining/OutliningSpanTests.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 Microsoft.CodeAnalysis.Editor.Implementation.Outlining;
+using Microsoft.CodeAnalysis.Structure;
 using Microsoft.CodeAnalysis.Text;
-using Roslyn.Test.Utilities;
 using Xunit;
 
 namespace Microsoft.CodeAnalysis.Editor.UnitTests.Outlining
@@ -17,7 +16,8 @@ public void TestProperties()
             var bannerText = "Foo";
             var autoCollapse = true;
 
-            var outliningRegion = new OutliningSpan(span, hintSpan, bannerText, autoCollapse);
+            var outliningRegion = new BlockSpan(true, span, hintSpan, 
+                bannerText: bannerText, autoCollapse: autoCollapse);
 
             Assert.Equal(span, outliningRegion.TextSpan);
             Assert.Equal(hintSpan, outliningRegion.HintSpan);
@@ -33,7 +33,8 @@ public void TestToStringWithHintSpan()
             var bannerText = "Foo";
             var autoCollapse = true;
 
-            var outliningRegion = new OutliningSpan(span, hintSpan, bannerText, autoCollapse);
+            var outliningRegion = new BlockSpan(true, span, hintSpan, 
+                bannerText: bannerText, autoCollapse: autoCollapse);
 
             Assert.Equal("{Span=[0..1), HintSpan=[2..3), BannerText=\"Foo\", AutoCollapse=True, IsDefaultCollapsed=False}", outliningRegion.ToString());
         }
@@ -45,9 +46,10 @@ public void TestToStringWithoutHintSpan()
             var bannerText = "Foo";
             var autoCollapse = true;
 
-            var outliningRegion = new OutliningSpan(span, bannerText, autoCollapse);
+            var outliningRegion = new BlockSpan(true, span, 
+                bannerText: bannerText, autoCollapse: autoCollapse);
 
             Assert.Equal("{Span=[0..1), BannerText=\"Foo\", AutoCollapse=True, IsDefaultCollapsed=False}", outliningRegion.ToString());
         }
     }
-}
+}
\ No newline at end of file

src/EditorFeatures/Test/Outlining/OutliningTaggerTests.cs

@@ -2,17 +2,12 @@
 
 using System.Collections.Generic;
 using System.Linq;
-using System.Threading;
 using System.Threading.Tasks;
-using Microsoft.CodeAnalysis.Editor;
-using Microsoft.CodeAnalysis.Editor.Implementation.Outlining;
-using Microsoft.CodeAnalysis.Editor.Shared.Extensions;
+using Microsoft.CodeAnalysis.Editor.Implementation.Structure;
 using Microsoft.CodeAnalysis.Editor.Shared.Utilities;
 using Microsoft.CodeAnalysis.Editor.Tagging;
 using Microsoft.CodeAnalysis.Editor.UnitTests.Workspaces;
 using Microsoft.CodeAnalysis.Shared.TestHooks;
-using Microsoft.CodeAnalysis.Text;
-using Microsoft.VisualStudio.Text;
 using Microsoft.VisualStudio.Text.Editor;
 using Microsoft.VisualStudio.Text.Projection;
 using Microsoft.VisualStudio.Text.Tagging;
@@ -128,7 +123,7 @@ private static async Task<List<IOutliningRegionTag>> GetTagsFromWorkspaceAsync(T
             var editorService = workspace.GetService<IEditorOptionsFactoryService>();
             var projectionService = workspace.GetService<IProjectionBufferFactoryService>();
 
-            var provider = new VisualStudio14OutliningTaggerProvider(
+            var provider = new VisualStudio14StructureTaggerProvider(
                 workspace.ExportProvider.GetExportedValue<IForegroundNotificationService>(),
                 textService, editorService, projectionService,
                 AggregateAsynchronousOperationListener.EmptyListeners);

src/EditorFeatures/Test/Tagging/AsynchronousTaggerTests.cs

@@ -5,19 +5,16 @@
 using System.Linq;
 using System.Threading;
 using System.Threading.Tasks;
-using Microsoft.CodeAnalysis.Editor.Implementation.Outlining;
-using Microsoft.CodeAnalysis.Editor.Shared.Options;
+using Microsoft.CodeAnalysis.Editor.Implementation.Structure;
 using Microsoft.CodeAnalysis.Editor.Shared.Tagging;
 using Microsoft.CodeAnalysis.Editor.Tagging;
 using Microsoft.CodeAnalysis.Editor.UnitTests.Workspaces;
-using Microsoft.CodeAnalysis.Options;
 using Microsoft.CodeAnalysis.Shared.TestHooks;
 using Microsoft.CodeAnalysis.Text.Shared.Extensions;
 using Microsoft.VisualStudio.Text;
 using Microsoft.VisualStudio.Text.Editor;
 using Microsoft.VisualStudio.Text.Projection;
 using Microsoft.VisualStudio.Text.Tagging;
-using Moq;
 using Roslyn.Test.Utilities;
 using Roslyn.Utilities;
 using Xunit;
@@ -98,7 +95,7 @@ public async Task TestSynchronousOutlining()
             {
                 WpfTestCase.RequireWpfFact($"{nameof(AsynchronousTaggerTests)}.{nameof(TestSynchronousOutlining)} creates asynchronous taggers");
 
-                var tagProvider = new VisualStudio14OutliningTaggerProvider(
+                var tagProvider = new VisualStudio14StructureTaggerProvider(
                     workspace.GetService<IForegroundNotificationService>(),
                     workspace.GetService<ITextEditorFactoryService>(),
                     workspace.GetService<IEditorOptionsFactoryService>(),

src/EditorFeatures/VisualBasic/BasicEditorFeatures.vbproj

@@ -165,38 +165,6 @@
     <Compile Include="NavigationBar\GenerateFinalizerItem.vb" />
     <Compile Include="NavigationBar\GenerateMethodItem.vb" />
     <Compile Include="NavigationBar\VisualBasicNavigationBarItemService.vb" />
-    <Compile Include="Outlining\Outliners\AccessorDeclarationOutliner.vb" />
-    <Compile Include="Outlining\Outliners\CompilationUnitOutliner.vb" />
-    <Compile Include="Outlining\Outliners\ConstructorDeclarationOutliner.vb" />
-    <Compile Include="Outlining\Outliners\DelegateDeclarationOutliner.vb" />
-    <Compile Include="Outlining\Outliners\DisabledTextTriviaOutliner.vb" />
-    <Compile Include="Outlining\Outliners\DocumentationCommentOutliner.vb" />
-    <Compile Include="Outlining\Outliners\EnumDeclarationOutliner.vb" />
-    <Compile Include="Outlining\Outliners\EventDeclarationOutliner.vb" />
-    <Compile Include="Outlining\Outliners\ExternalMethodDeclarationOutliner.vb" />
-    <Compile Include="Outlining\Outliners\FieldDeclarationOutliner.vb" />
-    <Compile Include="Outlining\Outliners\MetadataAsSource\AbstractMetadataAsSourceOutliner.vb" />
-    <Compile Include="Outlining\Outliners\MetadataAsSource\ConstructorDeclarationOutliner.vb" />
-    <Compile Include="Outlining\Outliners\MetadataAsSource\DelegateDeclarationOutliner.vb" />
-    <Compile Include="Outlining\Outliners\MetadataAsSource\EnumDeclarationOutliner.vb" />
-    <Compile Include="Outlining\Outliners\MetadataAsSource\EnumMemberDeclarationOutliner.vb" />
-    <Compile Include="Outlining\Outliners\MetadataAsSource\EventDeclarationOutliner.vb" />
-    <Compile Include="Outlining\Outliners\MetadataAsSource\FieldDeclarationOutliner.vb" />
-    <Compile Include="Outlining\Outliners\MetadataAsSource\MethodDeclarationOutliner.vb" />
-    <Compile Include="Outlining\Outliners\MetadataAsSource\OperatorDeclarationOutliner.vb" />
-    <Compile Include="Outlining\Outliners\MetadataAsSource\PropertyDeclarationOutliner.vb" />
-    <Compile Include="Outlining\Outliners\MetadataAsSource\RegionDirectiveOutliner.vb" />
-    <Compile Include="Outlining\Outliners\MetadataAsSource\TypeDeclarationOutliner.vb" />
-    <Compile Include="Outlining\Outliners\MethodDeclarationOutliner.vb" />
-    <Compile Include="Outlining\Outliners\MultilineLambdaOutliner.vb" />
-    <Compile Include="Outlining\Outliners\NamespaceDeclarationOutliner.vb" />
-    <Compile Include="Outlining\Outliners\OperatorDeclarationOutliner.vb" />
-    <Compile Include="Outlining\Outliners\PropertyDeclarationOutliner.vb" />
-    <Compile Include="Outlining\Outliners\RegionDirectiveOutliner.vb" />
-    <Compile Include="Outlining\Outliners\TypeDeclarationOutliner.vb" />
-    <Compile Include="Outlining\Outliners\XmlExpressionOutliner.vb" />
-    <Compile Include="Outlining\VisualBasicOutliningHelpers.vb" />
-    <Compile Include="Outlining\VisualBasicOutliningService.vb" />
     <Compile Include="QuickInfo\SemanticQuickInfoProvider.vb" />
     <Compile Include="ReferenceHighlighting\ReferenceHighlightingAdditionalReferenceProvider.vb" />
     <Compile Include="RenameTracking\BasicRenameTrackingLanguageHeuristicsService.vb" />
@@ -259,4 +227,4 @@
     <PublicAPI Include="PublicAPI.Unshipped.txt" />
   </ItemGroup>
   <Import Project="..\..\..\build\Targets\VSL.Imports.targets" />
-</Project>
+</Project>
\ No newline at end of file

src/EditorFeatures/VisualBasicTest/Outlining/AccessorDeclarationOutlinerTests.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 Microsoft.CodeAnalysis.Editor.Implementation.Outlining
-Imports Microsoft.CodeAnalysis.Editor.VisualBasic.Outlining
+Imports Microsoft.CodeAnalysis.Structure
+Imports Microsoft.CodeAnalysis.VisualBasic.Structure
 Imports Microsoft.CodeAnalysis.VisualBasic.Syntax
 
 Namespace Microsoft.CodeAnalysis.Editor.VisualBasic.UnitTests.Outlining
     Public Class AccessorDeclarationOutlinerTests
         Inherits AbstractVisualBasicSyntaxNodeOutlinerTests(Of AccessorStatementSyntax)
 
-        Friend Overrides Function CreateOutliner() As AbstractSyntaxOutliner
+        Friend Overrides Function CreateOutliner() As AbstractSyntaxStructureProvider
             Return New AccessorDeclarationOutliner()
         End Function
 
@@ -302,4 +302,4 @@ EndClass
         End Function
 
     End Class
-End Namespace
+End Namespace
\ No newline at end of file

src/EditorFeatures/VisualBasicTest/Outlining/CommentTests.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 Microsoft.CodeAnalysis.Editor.Implementation.Outlining
 Imports Microsoft.CodeAnalysis.Editor.UnitTests.Outlining
-Imports Microsoft.CodeAnalysis.Editor.VisualBasic.Outlining
+Imports Microsoft.CodeAnalysis.Structure
+Imports Microsoft.CodeAnalysis.VisualBasic.Structure
 
 Namespace Microsoft.CodeAnalysis.Editor.VisualBasic.UnitTests.Outlining
     Public Class CommentTests
@@ -14,7 +14,7 @@ Namespace Microsoft.CodeAnalysis.Editor.VisualBasic.UnitTests.Outlining
             End Get
         End Property
 
-        Friend Overrides Async Function GetRegionsAsync(document As Document, position As Integer) As Task(Of OutliningSpan())
+        Friend Overrides Async Function GetRegionsAsync(document As Document, position As Integer) As Task(Of BlockSpan())
             Dim root = Await document.GetSyntaxRootAsync()
             Dim trivia = root.FindTrivia(position, findInsideTrivia:=True)
 
@@ -25,7 +25,7 @@ Namespace Microsoft.CodeAnalysis.Editor.VisualBasic.UnitTests.Outlining
             ElseIf token.TrailingTrivia.Contains(trivia) Then
                 Return CreateCommentsRegions(token.TrailingTrivia).ToArray()
             Else
-                Return Contract.FailWithReturn(Of OutliningSpan())()
+                Return Contract.FailWithReturn(Of BlockSpan())()
             End If
         End Function
 
@@ -84,6 +84,5 @@ End Class
             Await VerifyRegionsAsync(code,
                 Region("span", "' Hello ...", autoCollapse:=True))
         End Function
-
     End Class
-End Namespace
+End Namespace
\ No newline at end of file

src/EditorFeatures/VisualBasicTest/Outlining/CompilationUnitOutlinerTests.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 Microsoft.CodeAnalysis.Editor.Implementation.Outlining
-Imports Microsoft.CodeAnalysis.Editor.VisualBasic.Outlining
+Imports Microsoft.CodeAnalysis.Structure
+Imports Microsoft.CodeAnalysis.VisualBasic.Structure
 Imports Microsoft.CodeAnalysis.VisualBasic.Syntax
 
 Namespace Microsoft.CodeAnalysis.Editor.VisualBasic.UnitTests.Outlining
@@ -9,7 +9,7 @@ Namespace Microsoft.CodeAnalysis.Editor.VisualBasic.UnitTests.Outlining
     Public Class CompilationUnitOutlinerTests
         Inherits AbstractVisualBasicSyntaxNodeOutlinerTests(Of CompilationUnitSyntax)
 
-        Friend Overrides Function CreateOutliner() As AbstractSyntaxOutliner
+        Friend Overrides Function CreateOutliner() As AbstractSyntaxStructureProvider
             Return New CompilationUnitOutliner()
         End Function
 
@@ -71,6 +71,5 @@ Imports System.Linq|}
                 Region("span2", "Imports ...", autoCollapse:=True),
                 Region("span3", "' Bottom ...", autoCollapse:=True))
         End Function
-
     End Class
-End Namespace
+End Namespace
\ No newline at end of file

src/EditorFeatures/VisualBasicTest/Outlining/ConstructorDeclarationOutlinerTests.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 Microsoft.CodeAnalysis.Editor.Implementation.Outlining
-Imports Microsoft.CodeAnalysis.Editor.VisualBasic.Outlining
+Imports Microsoft.CodeAnalysis.Structure
+Imports Microsoft.CodeAnalysis.VisualBasic.Structure
 Imports Microsoft.CodeAnalysis.VisualBasic.Syntax
 
 Namespace Microsoft.CodeAnalysis.Editor.VisualBasic.UnitTests.Outlining
     Public Class ConstructorDeclarationOutlinerTests
         Inherits AbstractVisualBasicSyntaxNodeOutlinerTests(Of SubNewStatementSyntax)
 
-        Friend Overrides Function CreateOutliner() As AbstractSyntaxOutliner
+        Friend Overrides Function CreateOutliner() As AbstractSyntaxStructureProvider
             Return New ConstructorDeclarationOutliner()
         End Function
 
@@ -74,6 +74,5 @@ End Class
                 Region("span1", "' My ...", autoCollapse:=True),
                 Region("span2", "Sub New() ...", autoCollapse:=True))
         End Function
-
     End Class
-End Namespace
+End Namespace
\ No newline at end of file

src/EditorFeatures/VisualBasicTest/Outlining/DelegateDeclarationOutlinerTests.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 Microsoft.CodeAnalysis.Editor.Implementation.Outlining
-Imports Microsoft.CodeAnalysis.Editor.VisualBasic.Outlining
+Imports Microsoft.CodeAnalysis.Structure
+Imports Microsoft.CodeAnalysis.VisualBasic.Structure
 Imports Microsoft.CodeAnalysis.VisualBasic.Syntax
 
 Namespace Microsoft.CodeAnalysis.Editor.VisualBasic.UnitTests.Outlining
     Public Class DelegateDeclarationOutlinerTests
         Inherits AbstractVisualBasicSyntaxNodeOutlinerTests(Of DelegateStatementSyntax)
 
-        Friend Overrides Function CreateOutliner() As AbstractSyntaxOutliner
+        Friend Overrides Function CreateOutliner() As AbstractSyntaxStructureProvider
             Return New DelegateDeclarationOutliner()
         End Function
 
@@ -22,6 +22,5 @@ Delegate Sub $$Foo()
             Await VerifyRegionsAsync(code,
                 Region("span", "' Hello ...", autoCollapse:=True))
         End Function
-
     End Class
-End Namespace
+End Namespace
\ No newline at end of file

src/EditorFeatures/VisualBasicTest/Outlining/DisabledCodeOutlinerTests.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 Microsoft.CodeAnalysis.Editor.Implementation.Outlining
-Imports Microsoft.CodeAnalysis.Editor.VisualBasic.Outlining
+Imports Microsoft.CodeAnalysis.Structure
+Imports Microsoft.CodeAnalysis.VisualBasic.Structure
 
 Namespace Microsoft.CodeAnalysis.Editor.VisualBasic.UnitTests.Outlining
     Public Class DisabledCodeOutlinerTests
         Inherits AbstractVisualBasicSyntaxTriviaOutlinerTests
 
-        Friend Overrides Function CreateOutliner() As AbstractSyntaxOutliner
+        Friend Overrides Function CreateOutliner() As AbstractSyntaxStructureProvider
             Return New DisabledTextTriviaOutliner()
         End Function
 
@@ -51,6 +51,5 @@ Blah|}
             Await VerifyRegionsAsync(code,
                 Region("span", VisualBasicOutliningHelpers.Ellipsis, autoCollapse:=True))
         End Function
-
     End Class
-End Namespace
+End Namespace
\ No newline at end of file

src/EditorFeatures/VisualBasicTest/Outlining/DocumentationCommentOutlinerTests.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 Microsoft.CodeAnalysis.Editor.Implementation.Outlining
-Imports Microsoft.CodeAnalysis.Editor.VisualBasic.Outlining
+Imports Microsoft.CodeAnalysis.Structure
+Imports Microsoft.CodeAnalysis.VisualBasic.Structure
 Imports Microsoft.CodeAnalysis.VisualBasic.Syntax
 
 Namespace Microsoft.CodeAnalysis.Editor.VisualBasic.UnitTests.Outlining
     Public Class DocumentationCommentOutlinerTests
         Inherits AbstractVisualBasicSyntaxNodeOutlinerTests(Of DocumentationCommentTriviaSyntax)
 
-        Friend Overrides Function CreateOutliner() As AbstractSyntaxOutliner
+        Friend Overrides Function CreateOutliner() As AbstractSyntaxStructureProvider
             Return New DocumentationCommentOutliner()
         End Function
 
@@ -154,4 +154,4 @@ End Class
                 Region("span", "''' <summary> Summary with SeeClass , SeeAlsoClass , Nothing , T , t , and not-supported .", autoCollapse:=True))
         End Function
     End Class
-End Namespace
+End Namespace
\ No newline at end of file

src/EditorFeatures/VisualBasicTest/Outlining/EnumDeclarationOutlinerTests.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 Microsoft.CodeAnalysis.Editor.Implementation.Outlining
-Imports Microsoft.CodeAnalysis.Editor.VisualBasic.Outlining
+Imports Microsoft.CodeAnalysis.Structure
+Imports Microsoft.CodeAnalysis.VisualBasic.Structure
 Imports Microsoft.CodeAnalysis.VisualBasic.Syntax
 
 Namespace Microsoft.CodeAnalysis.Editor.VisualBasic.UnitTests.Outlining
     Public Class EnumDeclarationOutlinerTests
         Inherits AbstractVisualBasicSyntaxNodeOutlinerTests(Of EnumStatementSyntax)
 
-        Friend Overrides Function CreateOutliner() As AbstractSyntaxOutliner
+        Friend Overrides Function CreateOutliner() As AbstractSyntaxStructureProvider
             Return New EnumDeclarationOutliner()
         End Function
 
@@ -50,6 +50,5 @@ End Enum|} ' Foo
                 Region("span1", "Enum E1 ...", autoCollapse:=True),
                 Region("span2", "' Hello ...", autoCollapse:=True))
         End Function
-
     End Class
-End Namespace
+End Namespace
\ No newline at end of file

src/EditorFeatures/VisualBasicTest/Outlining/EventDeclarationOutlinerTests.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 Microsoft.CodeAnalysis.Editor.Implementation.Outlining
-Imports Microsoft.CodeAnalysis.Editor.VisualBasic.Outlining
+Imports Microsoft.CodeAnalysis.Structure
+Imports Microsoft.CodeAnalysis.VisualBasic.Structure
 Imports Microsoft.CodeAnalysis.VisualBasic.Syntax
 
 Namespace Microsoft.CodeAnalysis.Editor.VisualBasic.UnitTests.Outlining
     Public Class EventDeclarationOutlinerTests
         Inherits AbstractVisualBasicSyntaxNodeOutlinerTests(Of EventStatementSyntax)
 
-        Friend Overrides Function CreateOutliner() As AbstractSyntaxOutliner
+        Friend Overrides Function CreateOutliner() As AbstractSyntaxStructureProvider
             Return New EventDeclarationOutliner()
         End Function
 
@@ -96,6 +96,5 @@ End Class
                 Region("span1", "' My ...", autoCollapse:=True),
                 Region("span2", "Custom Event eventName As EventHandler ...", autoCollapse:=True))
         End Function
-
     End Class
-End Namespace
+End Namespace
\ No newline at end of file

src/EditorFeatures/VisualBasicTest/Outlining/ExternalMethodDeclarationOutlinerTests.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 Microsoft.CodeAnalysis.Editor.Implementation.Outlining
-Imports Microsoft.CodeAnalysis.Editor.VisualBasic.Outlining
+Imports Microsoft.CodeAnalysis.Structure
+Imports Microsoft.CodeAnalysis.VisualBasic.Structure
 Imports Microsoft.CodeAnalysis.VisualBasic.Syntax
 
 Namespace Microsoft.CodeAnalysis.Editor.VisualBasic.UnitTests.Outlining
     Public Class ExternalMethodDeclarationOutlinerTests
         Inherits AbstractVisualBasicSyntaxNodeOutlinerTests(Of DeclareStatementSyntax)
 
-        Friend Overrides Function CreateOutliner() As AbstractSyntaxOutliner
+        Friend Overrides Function CreateOutliner() As AbstractSyntaxStructureProvider
             Return New ExternalMethodDeclarationOutliner()
         End Function
 
@@ -26,4 +26,4 @@ End Class
                 Region("span", "' Hello ...", autoCollapse:=True))
         End Function
     End Class
-End Namespace
+End Namespace
\ No newline at end of file

src/EditorFeatures/VisualBasicTest/Outlining/FieldDeclarationOutlinerTests.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 Microsoft.CodeAnalysis.Editor.Implementation.Outlining
-Imports Microsoft.CodeAnalysis.Editor.VisualBasic.Outlining
+Imports Microsoft.CodeAnalysis.Structure
+Imports Microsoft.CodeAnalysis.VisualBasic.Structure
 Imports Microsoft.CodeAnalysis.VisualBasic.Syntax
 
 Namespace Microsoft.CodeAnalysis.Editor.VisualBasic.UnitTests.Outlining
     Public Class FieldDeclarationOutlinerTests
         Inherits AbstractVisualBasicSyntaxNodeOutlinerTests(Of FieldDeclarationSyntax)
 
-        Friend Overrides Function CreateOutliner() As AbstractSyntaxOutliner
+        Friend Overrides Function CreateOutliner() As AbstractSyntaxStructureProvider
             Return New FieldDeclarationOutliner()
         End Function
 
@@ -25,6 +25,5 @@ End Class
             Await VerifyRegionsAsync(code,
                 Region("span", "' Hello ...", autoCollapse:=True))
         End Function
-
     End Class
-End Namespace
+End Namespace
\ No newline at end of file

src/EditorFeatures/VisualBasicTest/Outlining/MetadataAsSource/ConstructorDeclarationOutlinerTests.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 Microsoft.CodeAnalysis.Editor.Implementation.Outlining
-Imports Microsoft.CodeAnalysis.Editor.VisualBasic.Outlining
+Imports Microsoft.CodeAnalysis.Structure
+Imports Microsoft.CodeAnalysis.VisualBasic.Structure
 Imports Microsoft.CodeAnalysis.VisualBasic.Syntax
-Imports MaSOutliners = Microsoft.CodeAnalysis.Editor.VisualBasic.Outlining.MetadataAsSource
+Imports MaSOutliners = Microsoft.CodeAnalysis.VisualBasic.Structure.MetadataAsSource
 
 Namespace Microsoft.CodeAnalysis.Editor.VisualBasic.UnitTests.Outlining.MetadataAsSource
     Public Class ConstructorDeclarationOutlinerTests
@@ -15,7 +15,7 @@ Namespace Microsoft.CodeAnalysis.Editor.VisualBasic.UnitTests.Outlining.Metadata
             End Get
         End Property
 
-        Friend Overrides Function CreateOutliner() As AbstractSyntaxOutliner
+        Friend Overrides Function CreateOutliner() As AbstractSyntaxStructureProvider
             Return New MaSOutliners.ConstructorDeclarationOutliner()
         End Function
 
@@ -78,7 +78,5 @@ End Class
             Await VerifyRegionsAsync(code,
                 Region("collapse", "hint", VisualBasicOutliningHelpers.Ellipsis, autoCollapse:=True))
         End Function
-
     End Class
-End Namespace
-
+End Namespace
\ No newline at end of file

src/EditorFeatures/VisualBasicTest/Outlining/MetadataAsSource/DelegateDeclarationOutlinerTests.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 Microsoft.CodeAnalysis.Editor.Implementation.Outlining
-Imports Microsoft.CodeAnalysis.Editor.VisualBasic.Outlining
+Imports Microsoft.CodeAnalysis.Structure
+Imports Microsoft.CodeAnalysis.VisualBasic.Structure
 Imports Microsoft.CodeAnalysis.VisualBasic.Syntax
-Imports MaSOutliners = Microsoft.CodeAnalysis.Editor.VisualBasic.Outlining.MetadataAsSource
+Imports MaSOutliners = Microsoft.CodeAnalysis.VisualBasic.Structure.MetadataAsSource
 
 Namespace Microsoft.CodeAnalysis.Editor.VisualBasic.UnitTests.Outlining.MetadataAsSource
     Public Class DelegateDeclarationOutlinerTests
@@ -15,7 +15,7 @@ Namespace Microsoft.CodeAnalysis.Editor.VisualBasic.UnitTests.Outlining.Metadata
             End Get
         End Property
 
-        Friend Overrides Function CreateOutliner() As AbstractSyntaxOutliner
+        Friend Overrides Function CreateOutliner() As AbstractSyntaxStructureProvider
             Return New MaSOutliners.DelegateDeclarationOutliner()
         End Function
 
@@ -66,6 +66,5 @@ Delegate Sub $$Bar()
             Await VerifyRegionsAsync(code,
                 Region("collapse", "hint", VisualBasicOutliningHelpers.Ellipsis, autoCollapse:=True))
         End Function
-
     End Class
-End Namespace
+End Namespace
\ No newline at end of file

src/EditorFeatures/VisualBasicTest/Outlining/MetadataAsSource/EnumDeclarationOutlinerTests.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 Microsoft.CodeAnalysis.Editor.VisualBasic.Outlining
+Imports Microsoft.CodeAnalysis.Structure
+Imports Microsoft.CodeAnalysis.VisualBasic.Structure
 Imports Microsoft.CodeAnalysis.VisualBasic.Syntax
-Imports Microsoft.CodeAnalysis.Editor.Implementation.Outlining
-Imports MaSOutliners = Microsoft.CodeAnalysis.Editor.VisualBasic.Outlining.MetadataAsSource
+Imports MaSOutliners = Microsoft.CodeAnalysis.VisualBasic.Structure.MetadataAsSource
 
 Namespace Microsoft.CodeAnalysis.Editor.VisualBasic.UnitTests.Outlining.MetadataAsSource
     Public Class EnumDeclarationOutlinerTests
@@ -15,7 +15,7 @@ Namespace Microsoft.CodeAnalysis.Editor.VisualBasic.UnitTests.Outlining.Metadata
             End Get
         End Property
 
-        Friend Overrides Function CreateOutliner() As AbstractSyntaxOutliner
+        Friend Overrides Function CreateOutliner() As AbstractSyntaxStructureProvider
             Return New MaSOutliners.EnumDeclarationOutliner()
         End Function
 
@@ -76,6 +76,5 @@ End Enum
             Await VerifyRegionsAsync(code,
                 Region("collapse", "hint", VisualBasicOutliningHelpers.Ellipsis, autoCollapse:=True))
         End Function
-
     End Class
-End Namespace
+End Namespace
\ No newline at end of file

src/EditorFeatures/VisualBasicTest/Outlining/MetadataAsSource/EnumMemberDeclarationOutlinerTests.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 Microsoft.CodeAnalysis.Editor.Implementation.Outlining
-Imports Microsoft.CodeAnalysis.Editor.VisualBasic.Outlining
+Imports Microsoft.CodeAnalysis.Structure
+Imports Microsoft.CodeAnalysis.VisualBasic.Structure
 Imports Microsoft.CodeAnalysis.VisualBasic.Syntax
-Imports MaSOutliners = Microsoft.CodeAnalysis.Editor.VisualBasic.Outlining.MetadataAsSource
+Imports MaSOutliners = Microsoft.CodeAnalysis.VisualBasic.Structure.MetadataAsSource
 
 Namespace Microsoft.CodeAnalysis.Editor.VisualBasic.UnitTests.Outlining.MetadataAsSource
     Public Class EnumMemberDeclarationOutlinerTests
@@ -15,7 +15,7 @@ Namespace Microsoft.CodeAnalysis.Editor.VisualBasic.UnitTests.Outlining.Metadata
             End Get
         End Property
 
-        Friend Overrides Function CreateOutliner() As AbstractSyntaxOutliner
+        Friend Overrides Function CreateOutliner() As AbstractSyntaxStructureProvider
             Return New MaSOutliners.EnumMemberDeclarationOutliner()
         End Function
 
@@ -60,6 +60,5 @@ End Enum
             Await VerifyRegionsAsync(code,
                 Region("collapse", "hint", VisualBasicOutliningHelpers.Ellipsis, autoCollapse:=True))
         End Function
-
     End Class
-End Namespace
+End Namespace
\ No newline at end of file

src/EditorFeatures/VisualBasicTest/Outlining/MetadataAsSource/EventDeclarationOutlinerTests.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 Microsoft.CodeAnalysis.Editor.Implementation.Outlining
-Imports Microsoft.CodeAnalysis.Editor.VisualBasic.Outlining
+Imports Microsoft.CodeAnalysis.Structure
+Imports Microsoft.CodeAnalysis.VisualBasic.Structure
 Imports Microsoft.CodeAnalysis.VisualBasic.Syntax
-Imports MaSOutliners = Microsoft.CodeAnalysis.Editor.VisualBasic.Outlining.MetadataAsSource
+Imports MaSOutliners = Microsoft.CodeAnalysis.VisualBasic.Structure.MetadataAsSource
 
 Namespace Microsoft.CodeAnalysis.Editor.VisualBasic.UnitTests.Outlining.MetadataAsSource
     Public Class EventDeclarationOutlinerTests
@@ -15,7 +15,7 @@ Namespace Microsoft.CodeAnalysis.Editor.VisualBasic.UnitTests.Outlining.Metadata
             End Get
         End Property
 
-        Friend Overrides Function CreateOutliner() As AbstractSyntaxOutliner
+        Friend Overrides Function CreateOutliner() As AbstractSyntaxStructureProvider
             Return New MaSOutliners.EventDeclarationOutliner()
         End Function
 
@@ -72,6 +72,5 @@ End Class
             Await VerifyRegionsAsync(code,
                 Region("collapse", "hint", VisualBasicOutliningHelpers.Ellipsis, autoCollapse:=True))
         End Function
-
     End Class
-End Namespace
+End Namespace
\ No newline at end of file

src/EditorFeatures/VisualBasicTest/Outlining/MetadataAsSource/FieldDeclarationOutlinerTests.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 Microsoft.CodeAnalysis.Editor.Implementation.Outlining
-Imports Microsoft.CodeAnalysis.Editor.VisualBasic.Outlining
+Imports Microsoft.CodeAnalysis.Structure
+Imports Microsoft.CodeAnalysis.VisualBasic.Structure
 Imports Microsoft.CodeAnalysis.VisualBasic.Syntax
-Imports MaSOutliners = Microsoft.CodeAnalysis.Editor.VisualBasic.Outlining.MetadataAsSource
+Imports MaSOutliners = Microsoft.CodeAnalysis.VisualBasic.Structure.MetadataAsSource
 
 Namespace Microsoft.CodeAnalysis.Editor.VisualBasic.UnitTests.Outlining.MetadataAsSource
     Public Class FieldDeclarationOutlinerTests
@@ -15,7 +15,7 @@ Namespace Microsoft.CodeAnalysis.Editor.VisualBasic.UnitTests.Outlining.Metadata
             End Get
         End Property
 
-        Friend Overrides Function CreateOutliner() As AbstractSyntaxOutliner
+        Friend Overrides Function CreateOutliner() As AbstractSyntaxStructureProvider
             Return New MaSOutliners.FieldDeclarationOutliner()
         End Function
 
@@ -58,4 +58,4 @@ End Class
                 Region("collapse", "hint", VisualBasicOutliningHelpers.Ellipsis, autoCollapse:=True))
         End Function
     End Class
-End Namespace
+End Namespace
\ No newline at end of file

src/EditorFeatures/VisualBasicTest/Outlining/MetadataAsSource/InvalidIdentifierTests.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.Threading
-Imports Microsoft.CodeAnalysis.Editor.Implementation.Outlining
 Imports Microsoft.CodeAnalysis.Editor.UnitTests.Outlining
+Imports Microsoft.CodeAnalysis.Structure
 
 Namespace Microsoft.CodeAnalysis.Editor.VisualBasic.UnitTests.Outlining.MetadataAsSource
     ''' <summary>
@@ -24,10 +24,11 @@ Namespace Microsoft.CodeAnalysis.Editor.VisualBasic.UnitTests.Outlining.Metadata
             End Get
         End Property
 
-        Friend Overrides Async Function GetRegionsAsync(document As Document, position As Integer) As Task(Of OutliningSpan())
-            Dim outliningService = document.Project.LanguageServices.GetService(Of IOutliningService)()
+        Friend Overrides Async Function GetRegionsAsync(document As Document, position As Integer) As Task(Of BlockSpan())
+            Dim outliningService = document.Project.LanguageServices.GetService(Of BlockStructureService)()
 
-            Return (Await outliningService.GetOutliningSpansAsync(document, CancellationToken.None)) _
+            Return (Await outliningService.GetBlockStructureAsync(document, CancellationToken.None)) _
+                .Spans _
                 .WhereNotNull() _
                 .ToArray()
         End Function

src/EditorFeatures/VisualBasicTest/Outlining/MetadataAsSource/MethodDeclarationOutlinerTests.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 Microsoft.CodeAnalysis.Editor.Implementation.Outlining
-Imports Microsoft.CodeAnalysis.Editor.VisualBasic.Outlining
+Imports Microsoft.CodeAnalysis.Structure
+Imports Microsoft.CodeAnalysis.VisualBasic.Structure
 Imports Microsoft.CodeAnalysis.VisualBasic.Syntax
-Imports MaSOutliners = Microsoft.CodeAnalysis.Editor.VisualBasic.Outlining.MetadataAsSource
+Imports MaSOutliners = Microsoft.CodeAnalysis.VisualBasic.Structure.MetadataAsSource
 
 Namespace Microsoft.CodeAnalysis.Editor.VisualBasic.UnitTests.Outlining.MetadataAsSource
     Public Class MethodDeclarationOutlinerTests
@@ -15,7 +15,7 @@ Namespace Microsoft.CodeAnalysis.Editor.VisualBasic.UnitTests.Outlining.Metadata
             End Get
         End Property
 
-        Friend Overrides Function CreateOutliner() As AbstractSyntaxOutliner
+        Friend Overrides Function CreateOutliner() As AbstractSyntaxStructureProvider
             Return New MaSOutliners.MethodDeclarationOutliner()
         End Function
 
@@ -76,6 +76,5 @@ End Class
             Await VerifyRegionsAsync(code,
                 Region("collapse", "hint", VisualBasicOutliningHelpers.Ellipsis, autoCollapse:=True))
         End Function
-
     End Class
-End Namespace
+End Namespace
\ No newline at end of file

src/EditorFeatures/VisualBasicTest/Outlining/MetadataAsSource/OperatorDeclarationOutlinerTests.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 Microsoft.CodeAnalysis.Editor.Implementation.Outlining
-Imports Microsoft.CodeAnalysis.Editor.VisualBasic.Outlining
+Imports Microsoft.CodeAnalysis.Structure
+Imports Microsoft.CodeAnalysis.VisualBasic.Structure
 Imports Microsoft.CodeAnalysis.VisualBasic.Syntax
-Imports MaSOutliners = Microsoft.CodeAnalysis.Editor.VisualBasic.Outlining.MetadataAsSource
+Imports MaSOutliners = Microsoft.CodeAnalysis.VisualBasic.Structure.MetadataAsSource
 
 Namespace Microsoft.CodeAnalysis.Editor.VisualBasic.UnitTests.Outlining.MetadataAsSource
     Public Class OperatorDeclarationOutlinerTests
@@ -15,7 +15,7 @@ Namespace Microsoft.CodeAnalysis.Editor.VisualBasic.UnitTests.Outlining.Metadata
             End Get
         End Property
 
-        Friend Overrides Function CreateOutliner() As AbstractSyntaxOutliner
+        Friend Overrides Function CreateOutliner() As AbstractSyntaxStructureProvider
             Return New MaSOutliners.OperatorDeclarationOutliner()
         End Function
 
@@ -72,6 +72,5 @@ End Class
             Await VerifyRegionsAsync(code,
                 Region("collapse", "hint", VisualBasicOutliningHelpers.Ellipsis, autoCollapse:=True))
         End Function
-
     End Class
-End Namespace
+End Namespace
\ No newline at end of file

src/EditorFeatures/VisualBasicTest/Outlining/MetadataAsSource/PropertyDeclarationOutlinerTests.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 Microsoft.CodeAnalysis.Editor.Implementation.Outlining
-Imports Microsoft.CodeAnalysis.Editor.VisualBasic.Outlining
+Imports Microsoft.CodeAnalysis.Structure
+Imports Microsoft.CodeAnalysis.VisualBasic.Structure
 Imports Microsoft.CodeAnalysis.VisualBasic.Syntax
-Imports MaSOutliners = Microsoft.CodeAnalysis.Editor.VisualBasic.Outlining.MetadataAsSource
+Imports MaSOutliners = Microsoft.CodeAnalysis.VisualBasic.Structure.MetadataAsSource
 
 Namespace Microsoft.CodeAnalysis.Editor.VisualBasic.UnitTests.Outlining.MetadataAsSource
     Public Class PropertyDeclarationOutlinerTests
@@ -15,7 +15,7 @@ Namespace Microsoft.CodeAnalysis.Editor.VisualBasic.UnitTests.Outlining.Metadata
             End Get
         End Property
 
-        Friend Overrides Function CreateOutliner() As AbstractSyntaxOutliner
+        Friend Overrides Function CreateOutliner() As AbstractSyntaxStructureProvider
             Return New MaSOutliners.PropertyDeclarationOutliner()
         End Function
 
@@ -72,6 +72,5 @@ End Class
             Await VerifyRegionsAsync(code,
                 Region("collapse", "hint", VisualBasicOutliningHelpers.Ellipsis, autoCollapse:=True))
         End Function
-
     End Class
-End Namespace
+End Namespace
\ No newline at end of file

src/EditorFeatures/VisualBasicTest/Outlining/MetadataAsSource/RegionDirectiveOutlinerTests.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 Microsoft.CodeAnalysis.Editor.Implementation.Outlining
+Imports Microsoft.CodeAnalysis.Structure
 Imports Microsoft.CodeAnalysis.VisualBasic.Syntax
-Imports MaSOutliners = Microsoft.CodeAnalysis.Editor.VisualBasic.Outlining.MetadataAsSource
+Imports MaSOutliners = Microsoft.CodeAnalysis.VisualBasic.Structure.MetadataAsSource
 
 Namespace Microsoft.CodeAnalysis.Editor.VisualBasic.UnitTests.Outlining.MetadataAsSource
     Public Class RegionDirectiveOutlinerTests
@@ -14,7 +14,7 @@ Namespace Microsoft.CodeAnalysis.Editor.VisualBasic.UnitTests.Outlining.Metadata
             End Get
         End Property
 
-        Friend Overrides Function CreateOutliner() As AbstractSyntaxOutliner
+        Friend Overrides Function CreateOutliner() As AbstractSyntaxStructureProvider
             Return New MaSOutliners.RegionDirectiveOutliner()
         End Function
 
@@ -39,6 +39,5 @@ Namespace Microsoft.CodeAnalysis.Editor.VisualBasic.UnitTests.Outlining.Metadata
             Await VerifyRegionsAsync(code,
                 Region("span", "#Region", autoCollapse:=True, isDefaultCollapsed:=False))
         End Function
-
     End Class
-End Namespace
+End Namespace
\ No newline at end of file

src/EditorFeatures/VisualBasicTest/Outlining/MetadataAsSource/TypeDeclarationOutlinerTests.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 Microsoft.CodeAnalysis.Editor.Implementation.Outlining
-Imports Microsoft.CodeAnalysis.Editor.VisualBasic.Outlining
+Imports Microsoft.CodeAnalysis.Structure
+Imports Microsoft.CodeAnalysis.VisualBasic.Structure
 Imports Microsoft.CodeAnalysis.VisualBasic.Syntax
-Imports MaSOutliners = Microsoft.CodeAnalysis.Editor.VisualBasic.Outlining.MetadataAsSource
+Imports MaSOutliners = Microsoft.CodeAnalysis.VisualBasic.Structure.MetadataAsSource
 
 Namespace Microsoft.CodeAnalysis.Editor.VisualBasic.UnitTests.Outlining.MetadataAsSource
     Public Class TypeDeclarationOutlinerTests
@@ -15,7 +15,7 @@ Namespace Microsoft.CodeAnalysis.Editor.VisualBasic.UnitTests.Outlining.Metadata
             End Get
         End Property
 
-        Friend Overrides Function CreateOutliner() As AbstractSyntaxOutliner
+        Friend Overrides Function CreateOutliner() As AbstractSyntaxStructureProvider
             Return New MaSOutliners.TypeDeclarationOutliner()
         End Function
 
@@ -68,6 +68,5 @@ End Class
             Await VerifyRegionsAsync(code,
                 Region("collapse", "hint", VisualBasicOutliningHelpers.Ellipsis, autoCollapse:=True))
         End Function
-
     End Class
-End Namespace
+End Namespace
\ No newline at end of file

src/EditorFeatures/VisualBasicTest/Outlining/MethodDeclarationOutlinerTests.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 Microsoft.CodeAnalysis.Editor.Implementation.Outlining
-Imports Microsoft.CodeAnalysis.Editor.VisualBasic.Outlining
+Imports Microsoft.CodeAnalysis.Structure
+Imports Microsoft.CodeAnalysis.VisualBasic.Structure
 Imports Microsoft.CodeAnalysis.VisualBasic.Syntax
 
 Namespace Microsoft.CodeAnalysis.Editor.VisualBasic.UnitTests.Outlining
     Public Class MethodDeclarationOutlinerTests
         Inherits AbstractVisualBasicSyntaxNodeOutlinerTests(Of MethodStatementSyntax)
 
-        Friend Overrides Function CreateOutliner() As AbstractSyntaxOutliner
+        Friend Overrides Function CreateOutliner() As AbstractSyntaxStructureProvider
             Return New MethodDeclarationOutliner()
         End Function
 
@@ -174,6 +174,5 @@ End Class
             Await VerifyRegionsAsync(code,
                 Region("span", "Public Function myFunction(myFunc1 As Func(Of System.String, System.String, System.String), myFunc2 As Func(Of System.String, System.String, System.String)) ...", autoCollapse:=True))
         End Function
-
     End Class
-End Namespace
+End Namespace
\ No newline at end of file

src/EditorFeatures/VisualBasicTest/Outlining/MultilineLambdaOutlinerTests.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 Microsoft.CodeAnalysis.Editor.Implementation.Outlining
-Imports Microsoft.CodeAnalysis.Editor.VisualBasic.Outlining
+Imports Microsoft.CodeAnalysis.Structure
+Imports Microsoft.CodeAnalysis.VisualBasic.Structure
 Imports Microsoft.CodeAnalysis.VisualBasic.Syntax
 
 Namespace Microsoft.CodeAnalysis.Editor.VisualBasic.UnitTests.Outlining
     Public Class MultilineLambdaOutlinerTests
         Inherits AbstractVisualBasicSyntaxNodeOutlinerTests(Of MultiLineLambdaExpressionSyntax)
 
-        Friend Overrides Function CreateOutliner() As AbstractSyntaxOutliner
+        Friend Overrides Function CreateOutliner() As AbstractSyntaxStructureProvider
             Return New MultilineLambdaOutliner()
         End Function
 
@@ -84,6 +84,5 @@ End Class
             Await VerifyRegionsAsync(code,
                 Region("span", "Function(x) As Integer ...", autoCollapse:=False))
         End Function
-
     End Class
-End Namespace
+End Namespace
\ No newline at end of file

src/EditorFeatures/VisualBasicTest/Outlining/NamespaceDeclarationOutlinerTests.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 Microsoft.CodeAnalysis.Editor.Implementation.Outlining
-Imports Microsoft.CodeAnalysis.Editor.VisualBasic.Outlining
+Imports Microsoft.CodeAnalysis.Structure
+Imports Microsoft.CodeAnalysis.VisualBasic.Structure
 Imports Microsoft.CodeAnalysis.VisualBasic.Syntax
 
 Namespace Microsoft.CodeAnalysis.Editor.VisualBasic.UnitTests.Outlining
     Public Class NamespaceDeclarationOutlinerTests
         Inherits AbstractVisualBasicSyntaxNodeOutlinerTests(Of NamespaceStatementSyntax)
 
-        Friend Overrides Function CreateOutliner() As AbstractSyntaxOutliner
+        Friend Overrides Function CreateOutliner() As AbstractSyntaxStructureProvider
             Return New NamespaceDeclarationOutliner()
         End Function
 
@@ -50,6 +50,5 @@ End Namespace|}
                 Region("span1", "Namespace N1 ...", autoCollapse:=False),
                 Region("span2", "' My ...", autoCollapse:=True))
         End Function
-
     End Class
-End Namespace
+End Namespace
\ No newline at end of file

src/EditorFeatures/VisualBasicTest/Outlining/OperatorDeclarationOutlinerTests.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 Microsoft.CodeAnalysis.Editor.Implementation.Outlining
-Imports Microsoft.CodeAnalysis.Editor.VisualBasic.Outlining
+Imports Microsoft.CodeAnalysis.Structure
+Imports Microsoft.CodeAnalysis.VisualBasic.Structure
 Imports Microsoft.CodeAnalysis.VisualBasic.Syntax
 
 Namespace Microsoft.CodeAnalysis.Editor.VisualBasic.UnitTests.Outlining
     Public Class OperatorDeclarationOutlinerTests
         Inherits AbstractVisualBasicSyntaxNodeOutlinerTests(Of OperatorStatementSyntax)
 
-        Friend Overrides Function CreateOutliner() As AbstractSyntaxOutliner
+        Friend Overrides Function CreateOutliner() As AbstractSyntaxStructureProvider
             Return New OperatorDeclarationOutliner()
         End Function
 
@@ -40,6 +40,5 @@ End Class
                 Region("span1", "' Hello ...", autoCollapse:=True),
                 Region("span2", "Public Shared Widening Operator CType(b As Base) As Integer ...", autoCollapse:=True))
         End Function
-
     End Class
-End Namespace
+End Namespace
\ No newline at end of file

src/EditorFeatures/VisualBasicTest/Outlining/OverallOutliningTests.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.Threading
-Imports Microsoft.CodeAnalysis.Editor.Implementation.Outlining
 Imports Microsoft.CodeAnalysis.Editor.UnitTests.Outlining
+Imports Microsoft.CodeAnalysis.Structure
 
 Namespace Microsoft.CodeAnalysis.Editor.VisualBasic.UnitTests.Outlining
     Public Class OverallOutliningTests
@@ -14,10 +14,11 @@ Namespace Microsoft.CodeAnalysis.Editor.VisualBasic.UnitTests.Outlining
             End Get
         End Property
 
-        Friend Overrides Async Function GetRegionsAsync(document As Document, position As Integer) As Task(Of OutliningSpan())
-            Dim outliningService = document.Project.LanguageServices.GetService(Of IOutliningService)()
+        Friend Overrides Async Function GetRegionsAsync(document As Document, position As Integer) As Task(Of BlockSpan())
+            Dim outliningService = document.Project.LanguageServices.GetService(Of BlockStructureService)()
 
-            Return (Await outliningService.GetOutliningSpansAsync(document, CancellationToken.None)) _
+            Return (Await outliningService.GetBlockStructureAsync(document, CancellationToken.None)) _
+                .Spans _
                 .WhereNotNull() _
                 .ToArray()
         End Function
@@ -36,6 +37,5 @@ End Class|}
                 Region("span1", "Class C ...", autoCollapse:=False),
                 Region("span2", "Something", autoCollapse:=False, isDefaultCollapsed:=True))
         End Function
-
     End Class
-End Namespace
+End Namespace
\ No newline at end of file

src/EditorFeatures/VisualBasicTest/Outlining/PropertyDeclarationOutlinerTests.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 Microsoft.CodeAnalysis.Editor.Implementation.Outlining
-Imports Microsoft.CodeAnalysis.Editor.VisualBasic.Outlining
+Imports Microsoft.CodeAnalysis.Structure
+Imports Microsoft.CodeAnalysis.VisualBasic.Structure
 Imports Microsoft.CodeAnalysis.VisualBasic.Syntax
 
 Namespace Microsoft.CodeAnalysis.Editor.VisualBasic.UnitTests.Outlining
     Public Class PropertyDeclarationOutlinerTests
         Inherits AbstractVisualBasicSyntaxNodeOutlinerTests(Of PropertyStatementSyntax)
 
-        Friend Overrides Function CreateOutliner() As AbstractSyntaxOutliner
+        Friend Overrides Function CreateOutliner() As AbstractSyntaxStructureProvider
             Return New PropertyDeclarationOutliner()
         End Function
 
@@ -42,6 +42,5 @@ End Class
             Await VerifyRegionsAsync(code,
                 Region("span", "WriteOnly Property P1 As Integer ...", autoCollapse:=True))
         End Function
-
     End Class
-End Namespace
+End Namespace
\ No newline at end of file

src/EditorFeatures/VisualBasicTest/Outlining/RegionDirectiveOutlinerTests.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 Microsoft.CodeAnalysis.Editor.Implementation.Outlining
-Imports Microsoft.CodeAnalysis.Editor.VisualBasic.Outlining
+Imports Microsoft.CodeAnalysis.Structure
+Imports Microsoft.CodeAnalysis.VisualBasic.Structure
 Imports Microsoft.CodeAnalysis.VisualBasic.Syntax
 
 Namespace Microsoft.CodeAnalysis.Editor.VisualBasic.UnitTests.Outlining
     Public Class RegionDirectiveOutlinerTests
         Inherits AbstractVisualBasicSyntaxNodeOutlinerTests(Of RegionDirectiveTriviaSyntax)
 
-        Friend Overrides Function CreateOutliner() As AbstractSyntaxOutliner
+        Friend Overrides Function CreateOutliner() As AbstractSyntaxStructureProvider
             Return New RegionDirectiveOutliner()
         End Function
 
@@ -67,4 +67,4 @@ End Class
                 Region("span", "#Region", autoCollapse:=False, isDefaultCollapsed:=True))
         End Function
     End Class
-End Namespace
+End Namespace
\ No newline at end of file

src/EditorFeatures/VisualBasicTest/Outlining/TypeDeclarationOutlinerTests.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 Microsoft.CodeAnalysis.Editor.Implementation.Outlining
-Imports Microsoft.CodeAnalysis.Editor.VisualBasic.Outlining
+Imports Microsoft.CodeAnalysis.Structure
+Imports Microsoft.CodeAnalysis.VisualBasic.Structure
 Imports Microsoft.CodeAnalysis.VisualBasic.Syntax
 
 Namespace Microsoft.CodeAnalysis.Editor.VisualBasic.UnitTests.Outlining
     Public Class TypeDeclarationOutlinerTests
         Inherits AbstractVisualBasicSyntaxNodeOutlinerTests(Of TypeStatementSyntax)
 
-        Friend Overrides Function CreateOutliner() As AbstractSyntaxOutliner
+        Friend Overrides Function CreateOutliner() As AbstractSyntaxStructureProvider
             Return New TypeDeclarationOutliner()
         End Function
 
@@ -178,6 +178,5 @@ End Structure|}
                 Region("span1", "Structure S1 ...", autoCollapse:=False),
                 Region("span2", "' Hello ...", autoCollapse:=True))
         End Function
-
     End Class
-End Namespace
+End Namespace
\ No newline at end of file

src/EditorFeatures/VisualBasicTest/Outlining/XmlExpressionOutlinerTests.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 Microsoft.CodeAnalysis.Editor.Implementation.Outlining
-Imports Microsoft.CodeAnalysis.Editor.VisualBasic.Outlining
+Imports Microsoft.CodeAnalysis.Structure
+Imports Microsoft.CodeAnalysis.VisualBasic.Structure
 Imports Microsoft.CodeAnalysis.VisualBasic.Syntax
 
 Namespace Microsoft.CodeAnalysis.Editor.VisualBasic.UnitTests.Outlining
     Public Class XmlDocumentOutlinerTests
         Inherits AbstractVisualBasicSyntaxNodeOutlinerTests(Of XmlNodeSyntax)
 
-        Friend Overrides Function CreateOutliner() As AbstractSyntaxOutliner
+        Friend Overrides Function CreateOutliner() As AbstractSyntaxStructureProvider
             Return New XmlExpressionOutliner()
         End Function
 
@@ -134,6 +134,5 @@ End Class
 
             Await VerifyNoRegionsAsync(code)
         End Function
-
     End Class
-End Namespace
+End Namespace
\ No newline at end of file

src/Features/CSharp/Portable/CSharpFeatures.csproj

@@ -352,6 +352,47 @@
     <Compile Include="Organizing\Organizers\OperatorDeclarationOrganizer.cs" />
     <Compile Include="Organizing\Organizers\PropertyDeclarationOrganizer.cs" />
     <Compile Include="Organizing\Organizers\StructDeclarationOrganizer.cs" />
+    <Compile Include="Structure\CSharpBlockStructureProvider.cs" />
+    <Compile Include="Structure\CSharpOutliningHelpers.cs" />
+    <Compile Include="Structure\CSharpBlockStructureService.cs" />
+    <Compile Include="Structure\Outliners\AccessorDeclarationOutliner.cs" />
+    <Compile Include="Structure\Outliners\AnonymousMethodExpressionOutliner.cs" />
+    <Compile Include="Structure\Outliners\CompilationUnitOutliner.cs" />
+    <Compile Include="Structure\Outliners\ConstructorDeclarationOutliner.cs" />
+    <Compile Include="Structure\Outliners\ConversionOperatorDeclarationOutliner.cs" />
+    <Compile Include="Structure\Outliners\DelegateDeclarationOutliner.cs" />
+    <Compile Include="Structure\Outliners\DestructorDeclarationOutliner.cs" />
+    <Compile Include="Structure\Outliners\DisabledTextTriviaOutliner.cs" />
+    <Compile Include="Structure\Outliners\DocumentationCommentOutliner.cs" />
+    <Compile Include="Structure\Outliners\EnumDeclarationOutliner.cs" />
+    <Compile Include="Structure\Outliners\EventDeclarationOutliner.cs" />
+    <Compile Include="Structure\Outliners\EventFieldDeclarationOutliner.cs" />
+    <Compile Include="Structure\Outliners\FieldDeclarationOutliner.cs" />
+    <Compile Include="Structure\Outliners\IndexerDeclarationOutliner.cs" />
+    <Compile Include="Structure\Outliners\MetadataAsSource\AbstractMetadataAsSourceOutliner.cs" />
+    <Compile Include="Structure\Outliners\MetadataAsSource\ConstructorDeclarationOutliner.cs" />
+    <Compile Include="Structure\Outliners\MetadataAsSource\ConversionOperatorDeclarationOutliner.cs" />
+    <Compile Include="Structure\Outliners\MetadataAsSource\DelegateDeclarationOutliner.cs" />
+    <Compile Include="Structure\Outliners\MetadataAsSource\DestructorDeclarationOutliner.cs" />
+    <Compile Include="Structure\Outliners\MetadataAsSource\EnumDeclarationOutliner.cs" />
+    <Compile Include="Structure\Outliners\MetadataAsSource\EnumMemberDeclarationOutliner.cs" />
+    <Compile Include="Structure\Outliners\MetadataAsSource\EventDeclarationOutliner.cs" />
+    <Compile Include="Structure\Outliners\MetadataAsSource\EventFieldDeclarationOutliner.cs" />
+    <Compile Include="Structure\Outliners\MetadataAsSource\FieldDeclarationOutliner.cs" />
+    <Compile Include="Structure\Outliners\MetadataAsSource\IndexerDeclarationOutliner.cs" />
+    <Compile Include="Structure\Outliners\MetadataAsSource\MethodDeclarationOutliner.cs" />
+    <Compile Include="Structure\Outliners\MetadataAsSource\OperatorDeclarationOutliner.cs" />
+    <Compile Include="Structure\Outliners\MetadataAsSource\PropertyDeclarationOutliner.cs" />
+    <Compile Include="Structure\Outliners\MetadataAsSource\RegionDirectiveOutliner.cs" />
+    <Compile Include="Structure\Outliners\MetadataAsSource\TypeDeclarationOutliner.cs" />
+    <Compile Include="Structure\Outliners\MethodDeclarationOutliner.cs" />
+    <Compile Include="Structure\Outliners\NamespaceDeclarationOutliner.cs" />
+    <Compile Include="Structure\Outliners\OperatorDeclarationOutliner.cs" />
+    <Compile Include="Structure\Outliners\ParenthesizedLambdaExpressionOutliner.cs" />
+    <Compile Include="Structure\Outliners\PropertyDeclarationOutliner.cs" />
+    <Compile Include="Structure\Outliners\RegionDirectiveOutliner.cs" />
+    <Compile Include="Structure\Outliners\SimpleLambdaExpressionOutliner.cs" />
+    <Compile Include="Structure\Outliners\TypeDeclarationOutliner.cs" />
     <Compile Include="RemoveUnnecessaryImports\CSharpRemoveUnnecessaryImportsService.cs" />
     <Compile Include="RemoveUnnecessaryImports\CSharpRemoveUnnecessaryImportsService.Rewriter.cs" />
     <Compile Include="ReplaceMethodWithProperty\CSharpReplaceMethodWithPropertyService.cs" />
@@ -390,4 +431,4 @@
   </ItemGroup>
   <Import Project="..\..\..\Compilers\CSharp\CSharpAnalyzerDriver\CSharpAnalyzerDriver.projitems" Label="Shared" />
   <Import Project="..\..\..\..\build\Targets\VSL.Imports.targets" />
-</Project>
+</Project>
\ No newline at end of file

src/EditorFeatures/CSharp/Outlining/CSharpOutliningService.cs → src/Features/CSharp/Portable/Structure/CSharpBlockStructureProvider.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.
+// 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;
 using System.Collections.Immutable;
-using System.Composition;
-using Microsoft.CodeAnalysis.CSharp;
 using Microsoft.CodeAnalysis.CSharp.Syntax;
-using Microsoft.CodeAnalysis.Editor.Implementation.Outlining;
-using Microsoft.CodeAnalysis.Host.Mef;
-using Roslyn.Utilities;
+using Microsoft.CodeAnalysis.Structure;
 
-namespace Microsoft.CodeAnalysis.Editor.CSharp.Outlining
+namespace Microsoft.CodeAnalysis.CSharp.Structure
 {
-    [ExportLanguageService(typeof(IOutliningService), LanguageNames.CSharp), Shared]
-    internal class CSharpOutliningService : AbstractOutliningService
+    internal class CSharpBlockStructureProvider : AbstractBlockStructureProvider
     {
-        private static readonly ImmutableDictionary<Type, ImmutableArray<AbstractSyntaxOutliner>> s_defaultNodeOutlinerMap = CreateDefaultNodeOutlinerMap();
-        private static readonly ImmutableDictionary<int, ImmutableArray<AbstractSyntaxOutliner>> s_defaultTriviaOutlinerMap = CreateDefaultTriviaOutlinerMap();
+        private static readonly ImmutableDictionary<Type, ImmutableArray<AbstractSyntaxStructureProvider>> s_defaultNodeOutlinerMap = CreateDefaultNodeOutlinerMap();
+        private static readonly ImmutableDictionary<int, ImmutableArray<AbstractSyntaxStructureProvider>> s_defaultTriviaOutlinerMap = CreateDefaultTriviaOutlinerMap();
 
-        private static ImmutableDictionary<Type, ImmutableArray<AbstractSyntaxOutliner>> CreateDefaultNodeOutlinerMap()
+        private static ImmutableDictionary<Type, ImmutableArray<AbstractSyntaxStructureProvider>> CreateDefaultNodeOutlinerMap()
         {
-            var builder = ImmutableDictionary.CreateBuilder<Type, ImmutableArray<AbstractSyntaxOutliner>>();
+            var builder = ImmutableDictionary.CreateBuilder<Type, ImmutableArray<AbstractSyntaxStructureProvider>>();
 
             builder.Add<AccessorDeclarationSyntax, AccessorDeclarationOutliner>();
             builder.Add<AnonymousMethodExpressionSyntax, AnonymousMethodExpressionOutliner>();
@@ -49,18 +44,18 @@ internal class CSharpOutliningService : AbstractOutliningService
             return builder.ToImmutable();
         }
 
-        private static ImmutableDictionary<int, ImmutableArray<AbstractSyntaxOutliner>> CreateDefaultTriviaOutlinerMap()
+        private static ImmutableDictionary<int, ImmutableArray<AbstractSyntaxStructureProvider>> CreateDefaultTriviaOutlinerMap()
         {
-            var builder = ImmutableDictionary.CreateBuilder<int, ImmutableArray<AbstractSyntaxOutliner>>();
+            var builder = ImmutableDictionary.CreateBuilder<int, ImmutableArray<AbstractSyntaxStructureProvider>>();
 
-            builder.Add((int)SyntaxKind.DisabledTextTrivia, ImmutableArray.Create<AbstractSyntaxOutliner>(new DisabledTextTriviaOutliner()));
+            builder.Add((int)SyntaxKind.DisabledTextTrivia, ImmutableArray.Create<AbstractSyntaxStructureProvider>(new DisabledTextTriviaOutliner()));
 
             return builder.ToImmutable();
         }
 
-        private CSharpOutliningService()
+        internal CSharpBlockStructureProvider()
             : base(s_defaultNodeOutlinerMap, s_defaultTriviaOutlinerMap)
         {
         }
     }
-}
+}
\ No newline at end of file

src/Features/CSharp/Portable/Structure/CSharpBlockStructureService.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 System.Composition;
+using Microsoft.CodeAnalysis.Host;
+using Microsoft.CodeAnalysis.Host.Mef;
+using Microsoft.CodeAnalysis.Structure;
+
+namespace Microsoft.CodeAnalysis.CSharp.Structure
+{
+    [ExportLanguageServiceFactory(typeof(BlockStructureService), LanguageNames.CSharp), Shared]
+    internal class CSharpBlockStructureServiceFactory : ILanguageServiceFactory
+    {
+        public ILanguageService CreateLanguageService(HostLanguageServices languageServices)
+        {
+            return new CSharpBlockStructureService(languageServices.WorkspaceServices.Workspace);
+        }
+    }
+
+    [ExportLanguageService(typeof(BlockStructureService), LanguageNames.CSharp), Shared]
+    internal class CSharpBlockStructureService : BlockStructureServiceWithProviders
+    {
+        public CSharpBlockStructureService(Workspace workspace) : base(workspace)
+        {
+        }
+
+        protected override ImmutableArray<BlockStructureProvider> GetBuiltInProviders()
+        {
+            return ImmutableArray.Create<BlockStructureProvider>(
+                new CSharpBlockStructureProvider());
+        }
+
+        public override string Language => LanguageNames.CSharp;
+    }
+}
\ No newline at end of file

src/EditorFeatures/CSharp/Outlining/CSharpOutliningHelpers.cs → src/Features/CSharp/Portable/Structure/CSharpOutliningHelpers.cs

@@ -2,16 +2,17 @@
 
 using System;
 using System.Collections.Generic;
+using System.Collections.Immutable;
 using System.Linq;
 using Microsoft.CodeAnalysis.CSharp;
 using Microsoft.CodeAnalysis.CSharp.Extensions;
 using Microsoft.CodeAnalysis.CSharp.Syntax;
-using Microsoft.CodeAnalysis.Editor.Implementation.Outlining;
 using Microsoft.CodeAnalysis.Shared.Extensions;
+using Microsoft.CodeAnalysis.Structure;
 using Microsoft.CodeAnalysis.Text;
 using Roslyn.Utilities;
 
-namespace Microsoft.CodeAnalysis.Editor.CSharp.Outlining
+namespace Microsoft.CodeAnalysis.CSharp.Structure
 {
     internal static class CSharpOutliningHelpers
     {
@@ -133,26 +134,28 @@ private static string GetCommentBannerText(SyntaxTrivia comment)
             }
         }
 
-        private static OutliningSpan CreateCommentRegion(SyntaxTrivia startComment, SyntaxTrivia endComment)
+        private static BlockSpan CreateCommentRegion(SyntaxTrivia startComment, SyntaxTrivia endComment)
         {
             var span = TextSpan.FromBounds(startComment.SpanStart, endComment.Span.End);
 
-            return new OutliningSpan(
-                span,
+            return new BlockSpan(
+                isCollapsible: true,
+                textSpan: span,
                 hintSpan: span,
                 bannerText: GetCommentBannerText(startComment),
                 autoCollapse: true);
         }
 
         // For testing purposes
-        internal static IEnumerable<OutliningSpan> CreateCommentRegions(SyntaxTriviaList triviaList)
+        internal static ImmutableArray<BlockSpan> CreateCommentRegions(SyntaxTriviaList triviaList)
         {
-            var result = new List<OutliningSpan>();
+            var result = ImmutableArray.CreateBuilder<BlockSpan>();
             CollectCommentRegions(triviaList, result);
-            return result;
+            return result.ToImmutable();
         }
 
-        public static void CollectCommentRegions(SyntaxTriviaList triviaList, List<OutliningSpan> spans)
+        public static void CollectCommentRegions(
+            SyntaxTriviaList triviaList, ImmutableArray<BlockSpan>.Builder spans)
         {
             if (triviaList.Count > 0)
             {
@@ -199,7 +202,8 @@ public static void CollectCommentRegions(SyntaxTriviaList triviaList, List<Outli
             }
         }
 
-        public static void CollectCommentRegions(SyntaxNode node, List<OutliningSpan> spans)
+        public static void CollectCommentRegions(
+            SyntaxNode node, ImmutableArray<BlockSpan>.Builder spans)
         {
             if (node == null)
             {
@@ -211,17 +215,22 @@ public static void CollectCommentRegions(SyntaxNode node, List<OutliningSpan> sp
             CollectCommentRegions(triviaList, spans);
         }
 
-        private static OutliningSpan CreateRegion(TextSpan textSpan, string bannerText, bool autoCollapse)
+        private static BlockSpan CreateRegion(TextSpan textSpan, string bannerText, bool autoCollapse)
         {
             return CreateRegion(textSpan, textSpan, bannerText, autoCollapse);
         }
 
-        private static OutliningSpan CreateRegion(TextSpan textSpan, TextSpan hintSpan, string bannerText, bool autoCollapse)
+        private static BlockSpan CreateRegion(TextSpan textSpan, TextSpan hintSpan, string bannerText, bool autoCollapse)
         {
-            return new OutliningSpan(textSpan, hintSpan, bannerText, autoCollapse);
+            return new BlockSpan(
+                isCollapsible: true,
+                textSpan: textSpan,
+                hintSpan: hintSpan,
+                bannerText: bannerText,
+                autoCollapse: autoCollapse);
         }
 
-        public static OutliningSpan CreateRegion(SyntaxNode node, string bannerText, bool autoCollapse)
+        public static BlockSpan CreateRegion(SyntaxNode node, string bannerText, bool autoCollapse)
         {
             return CreateRegion(
                 node.Span,
@@ -229,7 +238,7 @@ public static OutliningSpan CreateRegion(SyntaxNode node, string bannerText, boo
                 autoCollapse);
         }
 
-        public static OutliningSpan CreateRegion(SyntaxNode node, SyntaxToken syntaxToken, string bannerText, bool autoCollapse)
+        public static BlockSpan CreateRegion(SyntaxNode node, SyntaxToken syntaxToken, string bannerText, bool autoCollapse)
         {
             return CreateRegion(
                 node,
@@ -239,7 +248,7 @@ public static OutliningSpan CreateRegion(SyntaxNode node, SyntaxToken syntaxToke
                 autoCollapse);
         }
 
-        public static OutliningSpan CreateRegion(SyntaxNode node, SyntaxToken startToken, int endPos, string bannerText, bool autoCollapse)
+        public static BlockSpan CreateRegion(SyntaxNode node, SyntaxToken startToken, int endPos, string bannerText, bool autoCollapse)
         {
             // If the SyntaxToken is actually missing, don't attempt to create an outlining region.
             if (startToken.IsMissing)
@@ -261,7 +270,7 @@ public static OutliningSpan CreateRegion(SyntaxNode node, SyntaxToken startToken
                 autoCollapse);
         }
 
-        public static OutliningSpan CreateRegion(SyntaxNode node, SyntaxToken startToken, SyntaxToken endToken, string bannerText, bool autoCollapse)
+        public static BlockSpan CreateRegion(SyntaxNode node, SyntaxToken startToken, SyntaxToken endToken, string bannerText, bool autoCollapse)
         {
             return CreateRegion(
                 node,
@@ -271,7 +280,7 @@ public static OutliningSpan CreateRegion(SyntaxNode node, SyntaxToken startToken
                 autoCollapse);
         }
 
-        public static OutliningSpan CreateRegion(SyntaxNode node, bool autoCollapse)
+        public static BlockSpan CreateRegion(SyntaxNode node, bool autoCollapse)
         {
             return CreateRegion(
                 node,
@@ -281,7 +290,7 @@ public static OutliningSpan CreateRegion(SyntaxNode node, bool autoCollapse)
 
         // Adds everything after 'syntaxToken' up to and including the end 
         // of node as a region.  The snippet to display is just "..."
-        public static OutliningSpan CreateRegion(SyntaxNode node, SyntaxToken syntaxToken, bool autoCollapse)
+        public static BlockSpan CreateRegion(SyntaxNode node, SyntaxToken syntaxToken, bool autoCollapse)
         {
             return CreateRegion(
                 node, syntaxToken,
@@ -291,7 +300,7 @@ public static OutliningSpan CreateRegion(SyntaxNode node, SyntaxToken syntaxToke
 
         // Adds everything after 'syntaxToken' up to and including the end 
         // of node as a region.  The snippet to display is just "..."
-        public static OutliningSpan CreateRegion(SyntaxNode node, SyntaxToken startToken, SyntaxToken endToken, bool autoCollapse)
+        public static BlockSpan CreateRegion(SyntaxNode node, SyntaxToken startToken, SyntaxToken endToken, bool autoCollapse)
         {
             return CreateRegion(
                 node, startToken, endToken,
@@ -302,7 +311,7 @@ public static OutliningSpan CreateRegion(SyntaxNode node, SyntaxToken startToken
         // Adds the span surrounding the syntax list as a region.  The
         // snippet shown is the text from the first line of the first 
         // node in the list.
-        public static OutliningSpan CreateRegion(IEnumerable<SyntaxNode> syntaxList, bool autoCollapse)
+        public static BlockSpan CreateRegion(IEnumerable<SyntaxNode> syntaxList, bool autoCollapse)
         {
             if (syntaxList.IsEmpty())
             {

src/EditorFeatures/CSharp/Outlining/Outliners/AccessorDeclarationOutliner.cs → src/Features/CSharp/Portable/Structure/Outliners/AccessorDeclarationOutliner.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.Generic;
+using System.Collections.Immutable;
 using System.Threading;
 using Microsoft.CodeAnalysis.CSharp.Syntax;
-using Microsoft.CodeAnalysis.Editor.Implementation.Outlining;
+using Microsoft.CodeAnalysis.Structure;
 
-namespace Microsoft.CodeAnalysis.Editor.CSharp.Outlining
+namespace Microsoft.CodeAnalysis.CSharp.Structure
 {
-    internal class AccessorDeclarationOutliner : AbstractSyntaxNodeOutliner<AccessorDeclarationSyntax>
+    internal class AccessorDeclarationOutliner : AbstractSyntaxNodeStructureProvider<AccessorDeclarationSyntax>
     {
-        protected override void CollectOutliningSpans(
+        protected override void CollectBlockSpans(
             AccessorDeclarationSyntax accessorDeclaration,
-            List<OutliningSpan> spans,
+            ImmutableArray<BlockSpan>.Builder spans,
             CancellationToken cancellationToken)
         {
             CSharpOutliningHelpers.CollectCommentRegions(accessorDeclaration, spans);

src/EditorFeatures/CSharp/Outlining/Outliners/AnonymousMethodExpressionOutliner.cs → src/Features/CSharp/Portable/Structure/Outliners/AnonymousMethodExpressionOutliner.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.Generic;
+using System.Collections.Immutable;
 using System.Threading;
-using Microsoft.CodeAnalysis.CSharp;
 using Microsoft.CodeAnalysis.CSharp.Syntax;
-using Microsoft.CodeAnalysis.Editor.Implementation.Outlining;
+using Microsoft.CodeAnalysis.Structure;
 
-namespace Microsoft.CodeAnalysis.Editor.CSharp.Outlining
+namespace Microsoft.CodeAnalysis.CSharp.Structure
 {
-    internal class AnonymousMethodExpressionOutliner : AbstractSyntaxNodeOutliner<AnonymousMethodExpressionSyntax>
+    internal class AnonymousMethodExpressionOutliner : AbstractSyntaxNodeStructureProvider<AnonymousMethodExpressionSyntax>
     {
-        protected override void CollectOutliningSpans(
+        protected override void CollectBlockSpans(
             AnonymousMethodExpressionSyntax anonymousMethod,
-            List<OutliningSpan> spans,
+            ImmutableArray<BlockSpan>.Builder spans,
             CancellationToken cancellationToken)
         {
             // fault tolerance

src/EditorFeatures/CSharp/Outlining/Outliners/CompilationUnitOutliner.cs → src/Features/CSharp/Portable/Structure/Outliners/CompilationUnitOutliner.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.Generic;
+using System.Collections.Immutable;
 using System.Threading;
 using Microsoft.CodeAnalysis.CSharp.Syntax;
-using Microsoft.CodeAnalysis.Editor.Implementation.Outlining;
+using Microsoft.CodeAnalysis.Structure;
 
-namespace Microsoft.CodeAnalysis.Editor.CSharp.Outlining
+namespace Microsoft.CodeAnalysis.CSharp.Structure
 {
-    internal class CompilationUnitOutliner : AbstractSyntaxNodeOutliner<CompilationUnitSyntax>
+    internal class CompilationUnitOutliner : AbstractSyntaxNodeStructureProvider<CompilationUnitSyntax>
     {
-        protected override void CollectOutliningSpans(
+        protected override void CollectBlockSpans(
             CompilationUnitSyntax compilationUnit,
-            List<OutliningSpan> spans,
+            ImmutableArray<BlockSpan>.Builder spans,
             CancellationToken cancellationToken)
         {
             CSharpOutliningHelpers.CollectCommentRegions(compilationUnit, spans);

src/EditorFeatures/CSharp/Outlining/Outliners/ConstructorDeclarationOutliner.cs → src/Features/CSharp/Portable/Structure/Outliners/ConstructorDeclarationOutliner.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.Generic;
+using System.Collections.Immutable;
 using System.Threading;
 using Microsoft.CodeAnalysis.CSharp.Syntax;
-using Microsoft.CodeAnalysis.Editor.Implementation.Outlining;
+using Microsoft.CodeAnalysis.Structure;
 
-namespace Microsoft.CodeAnalysis.Editor.CSharp.Outlining
+namespace Microsoft.CodeAnalysis.CSharp.Structure
 {
-    internal class ConstructorDeclarationOutliner : AbstractSyntaxNodeOutliner<ConstructorDeclarationSyntax>
+    internal class ConstructorDeclarationOutliner : AbstractSyntaxNodeStructureProvider<ConstructorDeclarationSyntax>
     {
-        protected override void CollectOutliningSpans(
+        protected override void CollectBlockSpans(
             ConstructorDeclarationSyntax constructorDeclaration,
-            List<OutliningSpan> spans,
+            ImmutableArray<BlockSpan>.Builder spans,
             CancellationToken cancellationToken)
         {
             CSharpOutliningHelpers.CollectCommentRegions(constructorDeclaration, spans);