Sync with vs-editor-core@0b543734

27 files changed, 940 insertions, 7 deletions

diff --git a/Directory.Build.props b/Directory.Build.props
index 5f55836..c7c4cbb 100644
--- a/Directory.Build.props
+++ b/Directory.Build.props
@@ -19,7 +19,7 @@
   </PropertyGroup>
 
   <PropertyGroup>
-    <NuGetVersionRoslyn>3.2.0-beta4-19324-01</NuGetVersionRoslyn>
+    <NuGetVersionRoslyn>3.2.0-beta4-19359-03</NuGetVersionRoslyn>
     <NuGetVersionVSEditor Condition="$(NuGetVersionVSEditor) == ''">16.0.379-g4a55b0e4f2</NuGetVersionVSEditor>
   </PropertyGroup>
 
diff --git a/src/Editor/Imaging/Def/Catalogs/LightBulbImageCatalog.cs b/src/Editor/Imaging/Def/Catalogs/LightBulbImageCatalog.cs
new file mode 100644
index 0000000..09b0f47
--- /dev/null
+++ b/src/Editor/Imaging/Def/Catalogs/LightBulbImageCatalog.cs
@@ -0,0 +1,26 @@
+//
+//  Copyright (c) Microsoft Corporation. All rights reserved.
+//  Licensed under the MIT License. See License.txt in the project root for license information.
+//
+
+using System;
+
+using Microsoft.VisualStudio.Core.Imaging;
+
+namespace Microsoft.VisualStudio.Language.Intellisense
+{
+    public static class LightBulbImageCatalog
+    {
+        public static readonly Guid CatalogId = new Guid("f09c8ce2-d515-4226-a430-dec104c81f05");
+
+        public static object GetImage(this IImageService imageService, LightBulbImageId imageId, ImageTags imageTags = default)
+            => imageService.GetImage(new ImageDescription(new ImageId(CatalogId, (int)imageId), 16, imageTags));
+    }
+
+    public enum LightBulbImageId
+    {
+        OnlyActions = 1,
+        Fixes,
+        ErrorFixes,
+    }
+}
diff --git a/src/Editor/Imaging/Def/Catalogs/OverviewMarginCatalog.cs b/src/Editor/Imaging/Def/Catalogs/OverviewMarginCatalog.cs
new file mode 100644
index 0000000..c177e17
--- /dev/null
+++ b/src/Editor/Imaging/Def/Catalogs/OverviewMarginCatalog.cs
@@ -0,0 +1,29 @@
+//
+//  Copyright (c) Microsoft Corporation. All rights reserved.
+//  Licensed under the MIT License. See License.txt in the project root for license information.
+//
+
+using System;
+
+using Microsoft.VisualStudio.Core.Imaging;
+
+namespace Microsoft.VisualStudio.Text.OverviewMargin
+{
+    public static class OverviewMarginCatalog
+    {
+        public static readonly Guid CatalogId = new Guid("47efec21-fd36-445d-99a4-238f66ab764c");
+
+        public static object GetImage(this IImageService imageService, OverviewMarginImageId imageId, ImageTags imageTags = default)
+        	=> imageService.GetImage(new ImageDescription(new ImageId(CatalogId, (int)imageId), 16, imageTags));
+    }
+
+    public enum OverviewMarginImageId
+    {
+        Busy = 1,
+        Ok,
+        Warning,
+        Error,
+        Suggestion,
+        Hide
+    }
+}
diff --git a/src/Editor/Imaging/Def/Catalogs/SignatureHelpImageCatalog.cs b/src/Editor/Imaging/Def/Catalogs/SignatureHelpImageCatalog.cs
new file mode 100644
index 0000000..857b0fd
--- /dev/null
+++ b/src/Editor/Imaging/Def/Catalogs/SignatureHelpImageCatalog.cs
@@ -0,0 +1,25 @@
+//
+//  Copyright (c) Microsoft Corporation. All rights reserved.
+//  Licensed under the MIT License. See License.txt in the project root for license information.
+//
+
+using System;
+
+using Microsoft.VisualStudio.Core.Imaging;
+
+namespace Microsoft.VisualStudio.Language.Intellisense
+{
+    public static class SignatureHelpImageCatalog
+    {
+        public static readonly Guid CatalogId = new Guid("95fdedcb-dc13-48a8-8165-ed1fff877d9a");
+
+        public static object GetImage(this IImageService imageService, SignatureHelpImageId imageId)
+            => imageService.GetImage(new ImageDescription(new ImageId(CatalogId, (int)imageId), 16, ImageTags.Template)) as object;
+    }
+
+    public enum SignatureHelpImageId
+    {
+        PreviousSignatureButton = 1,
+        NextSignatureButton
+    }
+}
diff --git a/src/Editor/Core/Def/IImageService.cs b/src/Editor/Imaging/Def/IImageService.cs
index 9ae87a0..cecb445 100644
--- a/src/Editor/Core/Def/IImageService.cs
+++ b/src/Editor/Imaging/Def/IImageService.cs
@@ -2,6 +2,7 @@
 //  Copyright (c) Microsoft Corporation. All rights reserved.
 //  Licensed under the MIT License. See License.txt in the project root for license information.
 //
+
 namespace Microsoft.VisualStudio.Core.Imaging
 {
     public interface IImageService
@@ -24,4 +25,4 @@ namespace Microsoft.VisualStudio.Core.Imaging
             ImageTags tags = ImageTags.None)
             => imageService.GetImage(new ImageDescription(id, size, tags));
     }
-}
\ No newline at end of file
+}
diff --git a/src/Editor/Core/Def/ImageDescription.cs b/src/Editor/Imaging/Def/ImageDescription.cs
index 1ec4c7e..33f89b3 100644
--- a/src/Editor/Core/Def/ImageDescription.cs
+++ b/src/Editor/Imaging/Def/ImageDescription.cs
@@ -1,4 +1,9 @@
-using System;
+//
+//  Copyright (c) Microsoft Corporation. All rights reserved.
+//  Licensed under the MIT License. See License.txt in the project root for license information.
+//
+
+using System;
 
 namespace Microsoft.VisualStudio.Core.Imaging
 {
@@ -66,4 +71,4 @@ namespace Microsoft.VisualStudio.Core.Imaging
         public static bool operator !=(ImageDescription left, ImageDescription right)
             => !(left == right);
     }
-}
\ No newline at end of file
+}
diff --git a/src/Editor/Core/Def/ImageTags.cs b/src/Editor/Imaging/Def/ImageTags.cs
index 814d7c1..6e2163d 100644
--- a/src/Editor/Core/Def/ImageTags.cs
+++ b/src/Editor/Imaging/Def/ImageTags.cs
@@ -1,3 +1,8 @@
+//
+//  Copyright (c) Microsoft Corporation. All rights reserved.
+//  Licensed under the MIT License. See License.txt in the project root for license information.
+//
+
 using System;
 
 namespace Microsoft.VisualStudio.Core.Imaging
@@ -14,4 +19,4 @@ namespace Microsoft.VisualStudio.Core.Imaging
         Selected = 1 << 5,
         Template = 1 << 6
     }
-}
\ No newline at end of file
+}
diff --git a/src/Editor/Imaging/Def/Imaging.csproj b/src/Editor/Imaging/Def/Imaging.csproj
new file mode 100644
index 0000000..06606e4
--- /dev/null
+++ b/src/Editor/Imaging/Def/Imaging.csproj
@@ -0,0 +1,17 @@
+<?xml version="1.0" encoding="utf-8"?>
+<Project Sdk="Microsoft.NET.Sdk">
+  <PropertyGroup>
+    <AssemblyName>Microsoft.VisualStudio.Editor.Imaging</AssemblyName>
+    <RootNamespace>Microsoft.VisualStudio.Imaging</RootNamespace>
+    <PushToPublicFeed>true</PushToPublicFeed>
+    <NoWarn>649;436;$(NoWarn)</NoWarn>
+    <AssemblyAttributeClsCompliant>true</AssemblyAttributeClsCompliant>
+    <LocalizationEnabled>false</LocalizationEnabled>
+    <InsertNuget>true</InsertNuget>
+    <IncludeInOptProf>true</IncludeInOptProf>
+    <TargetFramework>$(TargetFramework)</TargetFramework>
+  </PropertyGroup>
+  <ItemGroup>
+    <ProjectReference Include="..\..\Core\Def\CoreUtility.csproj" />
+  </ItemGroup>
+</Project>
diff --git a/src/Editor/Language/Def/Intellisense/Snippet/CodeSnippet.cs b/src/Editor/Language/Def/Intellisense/Snippet/CodeSnippet.cs
new file mode 100644
index 0000000..e5f0fa1
--- /dev/null
+++ b/src/Editor/Language/Def/Intellisense/Snippet/CodeSnippet.cs
@@ -0,0 +1,123 @@
+//
+//  Copyright (c) Microsoft Corporation. All rights reserved.
+//  Licensed under the MIT License. See License.txt in the project root for license information.
+//
+
+using System.Collections.Generic;
+using System.Linq;
+using System.Xml;
+using System.Xml.Linq;
+
+namespace Microsoft.VisualStudio.Text.Editor.Expansion
+{
+    public class CodeSnippet
+    {
+        public string Title { get; set; }
+        public string Shortcut { get; set; }
+        public string Description { get; set; }
+        public string Author { get; set; }
+        public List<string> SnippetTypes { get; set; }
+        public string Code { get; set; }
+        public List<ExpansionField> Fields { get; set; }
+        public string FilePath { get; set; }
+        public string Language { get; set; }
+        public XElement Snippet { get; set; }
+
+        public CodeSnippet()
+        {
+
+        }
+
+        public CodeSnippet(XElement codeSnippetElement, string filePath)
+        {
+            this.FilePath = filePath;
+            this.Fields = new List<ExpansionField>();
+            this.SnippetTypes = new List<string>();
+
+            var header = codeSnippetElement.Element(GetXName("Header"));
+            this.Title = GetElementInnerText(header, "Title");
+            this.Shortcut = GetElementInnerText(header, "Shortcut") ?? ""; // https://github.com/dotnet/roslyn/pull/31738
+            this.Description = GetElementInnerText(header, "Description");
+            this.Author = GetElementInnerText(header, "Author");
+            var snippetTypes = header.Element(GetXName("SnippetTypes"));
+            if (snippetTypes != null)
+            {
+                var snippetTypeElements = snippetTypes.Elements();
+                foreach (var snippetType in snippetTypeElements)
+                {
+                    SnippetTypes.Add(snippetType.Value);
+                }
+            }
+
+            Snippet = codeSnippetElement.Element(GetXName("Snippet"));
+            var declarations = Snippet.Element(GetXName("Declarations"));
+            ReadDeclarations(declarations);
+            var code = Snippet.Element(GetXName("Code"));
+            this.Code = code.Value.Replace("\n", "\r\n");
+            this.Language = code.Attribute("Language").Value;
+        }
+
+        private void ReadDeclarations(XElement declarations)
+        {
+            if (declarations == null)
+            {
+                return;
+            }
+
+            foreach (var declarationElement in declarations.Elements())
+            {
+                var defaultAttribute = declarationElement.Attribute("Default");
+                var editableAttribute = declarationElement.Attribute("Editable");
+                this.Fields.Add(new ExpansionField
+                {
+                    ID = GetElementInnerText(declarationElement, "ID"),
+                    ToolTip = GetElementInnerText(declarationElement, "ToolTip"),
+                    Default = GetElementInnerText(declarationElement, "Default") ?? " ",
+                    Function = GetElementInnerText(declarationElement, "Function"),
+                    IsDefault = defaultAttribute != null && defaultAttribute.Value == "true",
+                    Editable = editableAttribute == null || editableAttribute.Value == "true" || editableAttribute.Value == "1"
+                });
+            }
+        }
+
+        private static string GetElementInnerText(XElement element, string subElementName)
+        {
+            var subElement = element.Element(GetXName(subElementName));
+            if (subElement == null)
+            {
+                return null;
+            }
+
+            return subElement.Value;
+        }
+
+        public static IEnumerable<CodeSnippet> ReadSnippetsFromFile(string filePath)
+        {
+            try
+            {
+                XDocument document = XDocument.Load(filePath);
+                var codeSnippetsElement = document.Root;
+                IEnumerable<XElement> codeSnippetElements = null;
+                if (codeSnippetsElement.Name.LocalName == "CodeSnippets")
+                {
+                    codeSnippetElements = codeSnippetsElement.Elements(GetXName("CodeSnippet"));
+                }
+                else
+                {
+                    codeSnippetElements = new[] { codeSnippetsElement };
+                }
+
+                return codeSnippetElements.Select(element => new CodeSnippet(element, filePath));
+            }
+            catch (XmlException)
+            {
+                return Enumerable.Empty<CodeSnippet>();
+            }
+        }
+
+        private static XName GetXName(string localName)
+        {
+            return XName.Get(localName, "http://schemas.microsoft.com/VisualStudio/2005/CodeSnippet");
+        }
+    }
+}
diff --git a/src/Editor/Language/Def/Intellisense/Snippet/ExpansionField.cs b/src/Editor/Language/Def/Intellisense/Snippet/ExpansionField.cs
new file mode 100644
index 0000000..9bdef92
--- /dev/null
+++ b/src/Editor/Language/Def/Intellisense/Snippet/ExpansionField.cs
@@ -0,0 +1,75 @@
+//
+//  Copyright (c) Microsoft Corporation. All rights reserved.
+//  Licensed under the MIT License. See License.txt in the project root for license information.
+//
+
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using System.Xml.Linq;
+
+namespace Microsoft.VisualStudio.Text.Editor.Expansion
+{
+    public class ExpansionField
+    {
+        public string ID { get; set; }
+        public string ToolTip { get; set; }
+        public string Default { get; set; }
+        public string Function { get; set; }
+
+        private List<int> offsets = new List<int>();
+
+        public int GetOffsetCount()
+        {
+            return offsets.Count;
+        }
+
+        public void AddOffset(int offset)
+        {
+            offsets.Add(offset);
+        }
+
+        public int GetOffset(int index)
+        {
+            return offsets[index];
+        }
+
+        public string GetDefault()
+        {
+            return Default;
+        }
+
+        public int GetLength()
+        {
+            return Default.Length;
+        }
+
+        public bool IsEditable()
+        {
+            return Editable;
+        }
+
+        public XElement GetFunctionXML()
+        {
+            return new XElement(XName.Get("ExpansionField"))
+            {
+                Value = Function
+            };
+        }
+
+        public bool UsesFunction()
+        {
+            return Function != null;
+        }
+
+        public bool IsDefault { get; set; }
+        public bool Editable { get; set; }
+
+        public string GetName()
+        {
+            return ID;
+        }
+    }
+}
diff --git a/src/Editor/Language/Def/Intellisense/Snippet/ExpansionTemplate.cs b/src/Editor/Language/Def/Intellisense/Snippet/ExpansionTemplate.cs
new file mode 100644
index 0000000..356d2bd
--- /dev/null
+++ b/src/Editor/Language/Def/Intellisense/Snippet/ExpansionTemplate.cs
@@ -0,0 +1,148 @@
+//
+//  Copyright (c) Microsoft Corporation. All rights reserved.
+//  Licensed under the MIT License. See License.txt in the project root for license information.
+//
+
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Text.RegularExpressions;
+using System.Threading.Tasks;
+
+namespace Microsoft.VisualStudio.Text.Editor.Expansion
+{
+    public class ExpansionTemplate
+    {
+        private string snippetFullText;
+        private readonly List<ExpansionField> tokens = new List<ExpansionField>();
+        private int selectedOffset;
+        private int editOffset;
+        private string snippetFirst;
+        private string snippetLast;
+
+        public CodeSnippet Snippet { get; set; }
+
+        public ExpansionTemplate(string filePath)
+            :this(CodeSnippet.ReadSnippetsFromFile(filePath).First())
+        {
+            
+        }
+
+        public ExpansionTemplate(CodeSnippet snippet)
+        {
+            Snippet = snippet;
+            Parse();
+        }
+
+        private void Parse()
+        {
+            foreach (var field in Snippet.Fields)
+            {
+                tokens.Add(field);
+            }
+
+            var matches = Regex.Matches(Snippet.Code, @"\$(\w+)\$");
+
+            var total = new StringBuilder();
+            int index = 0;
+            int indexCorrection = 0;
+            foreach (Match match in matches)
+            {
+                string fieldName = match.Groups[1].Value;
+                string substitution = GetDefaultValue(fieldName) ?? "";
+                if (match.Index > index)
+                {
+                    total.Append(Snippet.Code.Substring(index, match.Index - index));
+                }
+
+                AddToken(total.Length, fieldName);
+                total.Append(substitution);
+
+                index = match.Index + match.Length;
+                indexCorrection += substitution.Length;
+            }
+
+            if (index <= Snippet.Code.Length - 1)
+            {
+                total.Append(Snippet.Code.Substring(index, Snippet.Code.Length - index));
+            }
+
+            this.snippetFullText = total.ToString();
+            this.snippetFirst = snippetFullText.Substring(0, selectedOffset);
+            this.snippetLast = snippetFullText.Substring(selectedOffset, snippetFullText.Length - selectedOffset);
+        }
+
+        private string GetDefaultValue(string fieldName)
+        {
+            ExpansionField field = FindField(fieldName);
+            if (field == null)
+            {
+                return null;
+            }
+
+            return field.Default;
+        }
+
+        private void AddToken(int position, string fieldName)
+        {
+            ExpansionField field = FindField(fieldName);
+            if (field != null)
+            {
+                field.AddOffset(position);
+            }
+            else if (fieldName == "selected")
+            {
+                this.selectedOffset = position;
+            }
+            else if (fieldName == "end")
+            {
+                this.editOffset = position;
+            }
+        }
+
+        private ExpansionField FindField(string fieldName)
+        {
+            return tokens.FirstOrDefault(t => t.ID == fieldName);
+        }
+
+        public string GetCodeSnippet()
+        {
+            return snippetFullText;
+        }
+
+        public int GetSelectedOffset()
+        {
+            return selectedOffset;
+        }
+
+        public int GetEditOffset()
+        {
+            return editOffset;
+        }
+
+        public string GetCodeSnippet(bool all, bool first)
+        {
+            if (all)
+            {
+                return snippetFullText;
+            }
+            else if (first)
+            {
+                return snippetFirst;
+            }
+            else
+            {
+                return snippetLast;
+            }
+        }
+
+        public IEnumerable<ExpansionField> Fields
+        {
+            get
+            {
+                return tokens;
+            }
+        }
+    }
+}
diff --git a/src/Editor/Language/Def/Intellisense/Snippet/IExpansionClient.cs b/src/Editor/Language/Def/Intellisense/Snippet/IExpansionClient.cs
new file mode 100644
index 0000000..f04d13c
--- /dev/null
+++ b/src/Editor/Language/Def/Intellisense/Snippet/IExpansionClient.cs
@@ -0,0 +1,24 @@
+//
+//  Copyright (c) Microsoft Corporation. All rights reserved.
+//  Licensed under the MIT License. See License.txt in the project root for license information.
+//
+
+using System;
+using System.Xml.Linq;
+
+namespace Microsoft.VisualStudio.Text.Editor.Expansion
+{
+    public interface IExpansionClient
+    {
+        IExpansionFunction GetExpansionFunction(XElement xmlFunctionNode, string fieldName);
+        void FormatSpan(SnapshotSpan span);
+
+        void EndExpansion();
+
+        void OnBeforeInsertion(IExpansionSession session);
+        void OnAfterInsertion(IExpansionSession session);
+
+        void PositionCaretForEditing(ITextView textView, SnapshotPoint point);
+        void OnItemChosen(string tittle, string path);
+    }
+}
diff --git a/src/Editor/Language/Def/Intellisense/Snippet/IExpansionFunction.cs b/src/Editor/Language/Def/Intellisense/Snippet/IExpansionFunction.cs
new file mode 100644
index 0000000..af945a5
--- /dev/null
+++ b/src/Editor/Language/Def/Intellisense/Snippet/IExpansionFunction.cs
@@ -0,0 +1,30 @@
+//
+//  Copyright (c) Microsoft Corporation. All rights reserved.
+//  Licensed under the MIT License. See License.txt in the project root for license information.
+//
+
+namespace Microsoft.VisualStudio.Text.Editor.Expansion
+{
+    public enum ExpansionFunctionType
+    {
+        List,
+        Value
+    };
+
+    public interface IExpansionFunction
+    {
+        void GetDefaultValue(out string value, out bool hasDefaultValue);
+
+        void GetCurrentValue(out string value, out bool hasCurrentValue);
+
+        bool FieldChanged(string fieldName);
+
+        ExpansionFunctionType GetFunctionType();
+
+        int GetListCount();
+
+        string GetListText(int index);
+
+        void ReleaseFunction();
+    }
+}
diff --git a/src/Editor/Language/Def/Intellisense/Snippet/IExpansionManager.cs b/src/Editor/Language/Def/Intellisense/Snippet/IExpansionManager.cs
new file mode 100644
index 0000000..077b20b
--- /dev/null
+++ b/src/Editor/Language/Def/Intellisense/Snippet/IExpansionManager.cs
@@ -0,0 +1,18 @@
+//
+//  Copyright (c) Microsoft Corporation. All rights reserved.
+//  Licensed under the MIT License. See License.txt in the project root for license information.
+//
+
+using System;
+using System.Collections.Generic;
+using Microsoft.VisualStudio.Utilities;
+
+namespace Microsoft.VisualStudio.Text.Editor.Expansion
+{
+	public interface IExpansionManager
+	{
+        IEnumerable<ExpansionTemplate> EnumerateExpansions(IContentType contentType, bool shortcutOnly, string[] snippetTypes, bool includeNullType, bool includeDuplicates);
+		ExpansionTemplate GetTemplateByName(IExpansionClient expansionClient, IContentType contentType, string name, string filePath, ITextView textView, SnapshotSpan span, bool showDisambiguationUI);
+		ExpansionTemplate GetTemplateByShortcut(IExpansionClient expansionClient, string shortcut, IContentType contentType, ITextView textView, SnapshotSpan span, bool showDisambiguationUI);
+	}
+}
diff --git a/src/Editor/Language/Def/Intellisense/Snippet/IExpansionService.cs b/src/Editor/Language/Def/Intellisense/Snippet/IExpansionService.cs
new file mode 100644
index 0000000..193edf5
--- /dev/null
+++ b/src/Editor/Language/Def/Intellisense/Snippet/IExpansionService.cs
@@ -0,0 +1,18 @@
+//
+//  Copyright (c) Microsoft Corporation. All rights reserved.
+//  Licensed under the MIT License. See License.txt in the project root for license information.
+//
+
+using System;
+using System.Threading;
+using Microsoft.VisualStudio.Utilities;
+
+namespace Microsoft.VisualStudio.Text.Editor.Expansion
+{
+    public interface IExpansionService
+    {
+        IExpansionSession InsertExpansion(SnapshotSpan triggerSpan, IExpansionClient expansionClient, IContentType contentType, CancellationToken cancellationToken = default);
+        IExpansionSession InsertNamedExpansion(string title, string pszPath, SnapshotSpan triggerSpan, IExpansionClient expansionClient, IContentType contentType, bool showDisambiguationUI);
+        void InvokeInsertionUI(IExpansionClient expansionClient, IContentType contentType, string[] types, bool includeNullType, string[] kinds, bool includeNullKind, string prefixText, string completionChar);
+    }
+}
diff --git a/src/Editor/Language/Def/Intellisense/Snippet/IExpansionServiceProvider.cs b/src/Editor/Language/Def/Intellisense/Snippet/IExpansionServiceProvider.cs
new file mode 100644
index 0000000..cead20d
--- /dev/null
+++ b/src/Editor/Language/Def/Intellisense/Snippet/IExpansionServiceProvider.cs
@@ -0,0 +1,12 @@
+//
+//  Copyright (c) Microsoft Corporation. All rights reserved.
+//  Licensed under the MIT License. See License.txt in the project root for license information.
+//
+
+namespace Microsoft.VisualStudio.Text.Editor.Expansion
+{
+    public interface IExpansionServiceProvider
+    {
+        IExpansionService GetExpansionService(ITextView textView);
+    }
+}
diff --git a/src/Editor/Language/Def/Intellisense/Snippet/IExpansionSession.cs b/src/Editor/Language/Def/Intellisense/Snippet/IExpansionSession.cs
new file mode 100644
index 0000000..9845f93
--- /dev/null
+++ b/src/Editor/Language/Def/Intellisense/Snippet/IExpansionSession.cs
@@ -0,0 +1,25 @@
+//
+//  Copyright (c) Microsoft Corporation. All rights reserved.
+//  Licensed under the MIT License. See License.txt in the project root for license information.
+//
+
+using System;
+using System.Xml.Linq;
+
+namespace Microsoft.VisualStudio.Text.Editor.Expansion
+{
+    public interface IExpansionSession
+    {
+        void EndCurrentExpansion(bool leaveCaret);
+        bool GoToNextExpansionField(bool commitIfLast);
+        bool GoToPreviousExpansionField();
+        string GetFieldValue(string fieldName);
+        void SetFieldDefault(string fieldName, string newValue);
+        SnapshotSpan GetFieldSpan(string fieldName);
+        XElement GetHeaderNode();
+        XElement GetDeclarationNode();
+        XElement GetSnippetNode();
+        SnapshotSpan GetSnippetSpan();
+        SnapshotSpan EndSpan { get; set; }
+    }
+}
diff --git a/src/Editor/Language/Def/Language/AssemblyInfo.cs b/src/Editor/Language/Def/Language/AssemblyInfo.cs
index cb9fc3b..b9002d7 100644
--- a/src/Editor/Language/Def/Language/AssemblyInfo.cs
+++ b/src/Editor/Language/Def/Language/AssemblyInfo.cs
@@ -18,6 +18,7 @@ using System.Security.Permissions;
 [assembly: InternalsVisibleTo("Microsoft.VisualStudio.Editor.Implementation, PublicKey=" + ThisAssembly.PublicKey)]
 [assembly: InternalsVisibleTo("Microsoft.VisualStudio.CodeLens.Service, PublicKey=" + ThisAssembly.PublicKey)]
 [assembly: InternalsVisibleTo("Microsoft.VisualStudio.UI.Text.Cocoa.View.Implementation, PublicKey=" + ThisAssembly.PublicKey)]
+[assembly: InternalsVisibleTo("Microsoft.VisualStudio.Platform.VSEditor, PublicKey=" + ThisAssembly.PublicKey)]
 
 // InternalsVisibleTo for VS for Mac implementation assembly:
 [assembly: InternalsVisibleTo("Microsoft.VisualStudio.Text.Implementation, PublicKey=0024000004800000940000000602000000240000525341310004000001000100e57febc1f220077550a65e338d3d15d7cbd189cf4f62f7c3829dcb2f8441a6c40631d172e3deb4dc0bb7237b44ec9daeb9bd7d72c3d64c4f52b968795443cb58bc341583c29440345b8c35f72f6a31aecb2903376136f8fc35779bb422eb643f8668fa6605c697bff927e3bb10745328ff878bd1b7e42bbcb839f04baa8460bd")]
diff --git a/src/Editor/Language/Util/LanguageUtil/AssemblyInfo.cs b/src/Editor/Language/Util/LanguageUtil/AssemblyInfo.cs
index 2f4ea70..3821eb8 100644
--- a/src/Editor/Language/Util/LanguageUtil/AssemblyInfo.cs
+++ b/src/Editor/Language/Util/LanguageUtil/AssemblyInfo.cs
@@ -11,6 +11,7 @@ using System.Runtime.ConstrainedExecution;
 [assembly: InternalsVisibleTo("Microsoft.VisualStudio.Language.Intellisense.UnitTestHelper, PublicKey=" + ThisAssembly.PublicKey)]
 [assembly: InternalsVisibleTo("Microsoft.VisualStudio.Language.Intellisense.UnitTests, PublicKey=" + ThisAssembly.PublicKey)]
 [assembly: InternalsVisibleTo("Microsoft.VisualStudio.UI.Text.Cocoa.View.Implementation, PublicKey=" + ThisAssembly.PublicKey)]
+[assembly: InternalsVisibleTo("Microsoft.VisualStudio.Platform.VSEditor, PublicKey=" + ThisAssembly.PublicKey)]
 
 // General Information about an assembly is controlled through the following
 // set of attributes. Change these attribute values to modify the information
diff --git a/src/Editor/Text/Def/TextUI/AssemblyInfo.cs b/src/Editor/Text/Def/TextUI/AssemblyInfo.cs
index f26bbe9..e404e66 100644
--- a/src/Editor/Text/Def/TextUI/AssemblyInfo.cs
+++ b/src/Editor/Text/Def/TextUI/AssemblyInfo.cs
@@ -15,13 +15,14 @@ using System.Security.Permissions;
 [assembly: InternalsVisibleTo("Microsoft.VisualStudio.UI.Text.Commanding.Implementation, PublicKey=" + ThisAssembly.PublicKey)]
 [assembly: InternalsVisibleTo("Microsoft.VisualStudio.UI.Text.Commanding.Implementation.UnitTests, PublicKey=" + ThisAssembly.PublicKey)]
 [assembly: InternalsVisibleTo("Microsoft.VisualStudio.Text.UI.Utilities, PublicKey=" + ThisAssembly.PublicKey)]
+[assembly: InternalsVisibleTo("Microsoft.VisualStudio.Platform.VSEditor, PublicKey=" + ThisAssembly.PublicKey)]
 
 // InternalsVisibleTo for VS for Mac implementation assembly:
 [assembly: InternalsVisibleTo("Microsoft.VisualStudio.Text.Implementation, PublicKey=0024000004800000940000000602000000240000525341310004000001000100e57febc1f220077550a65e338d3d15d7cbd189cf4f62f7c3829dcb2f8441a6c40631d172e3deb4dc0bb7237b44ec9daeb9bd7d72c3d64c4f52b968795443cb58bc341583c29440345b8c35f72f6a31aecb2903376136f8fc35779bb422eb643f8668fa6605c697bff927e3bb10745328ff878bd1b7e42bbcb839f04baa8460bd")]
 [assembly: InternalsVisibleTo("Microsoft.VisualStudio.UI.Text.Cocoa.View.Implementation, PublicKey=" + ThisAssembly.PublicKey)]
 
 //
-// General Information about an assembly is controlled through the following 
+// General Information about an assembly is controlled through the following
 // set of attributes. Change these attribute values to modify the information
 // associated with an assembly.
 //
diff --git a/src/Editor/Text/Def/TextUICocoa/AssemblyInfo.cs b/src/Editor/Text/Def/TextUICocoa/AssemblyInfo.cs
index e65861e..15fc302 100644
--- a/src/Editor/Text/Def/TextUICocoa/AssemblyInfo.cs
+++ b/src/Editor/Text/Def/TextUICocoa/AssemblyInfo.cs
@@ -7,4 +7,5 @@
 
 using System.Runtime.CompilerServices;
 
-[assembly: InternalsVisibleTo("Microsoft.VisualStudio.UI.Text.Cocoa.View.Implementation, PublicKey=" + ThisAssembly.PublicKey)]
\ No newline at end of file
+[assembly: InternalsVisibleTo("Microsoft.VisualStudio.UI.Text.Cocoa.View.Implementation, PublicKey=" + ThisAssembly.PublicKey)]
+[assembly: InternalsVisibleTo("Microsoft.VisualStudio.Platform.VSEditor, PublicKey=" + ThisAssembly.PublicKey)]
diff --git a/src/Editor/Text/Def/TextUICocoa/Classification/ClassificationExtensions.cs b/src/Editor/Text/Def/TextUICocoa/Classification/ClassificationExtensions.cs
new file mode 100644
index 0000000..78ce7a2
--- /dev/null
+++ b/src/Editor/Text/Def/TextUICocoa/Classification/ClassificationExtensions.cs
@@ -0,0 +1,99 @@
+//
+//  Copyright (c) Microsoft Corporation. All rights reserved.
+//  Licensed under the MIT License. See License.txt in the project root for license information.
+//
+
+using System;
+using System.Windows;
+
+using AppKit;
+
+namespace Microsoft.VisualStudio.Text.Classification
+{
+    using static ClassificationFormatDefinition;
+
+    public static class ClassificationExtensions
+    {
+        internal const string FontRenderingScaleId = "FontRenderingScale";
+
+        public static void UpdateFont(
+            this ResourceDictionary resourceDictionary,
+            NSFont font)
+        {
+            if (font == null)
+                throw new ArgumentNullException(nameof(font));
+
+            resourceDictionary[TypefaceId] = font.FontDescriptor.FontDescriptorWithSize(0);
+            resourceDictionary[FontRenderingSizeId] = (double)font.PointSize;
+        }
+
+        public static NSFont GetFont(
+            this ResourceDictionary resourceDictionary,
+            bool respectScale = true)
+        {
+            NSFontDescriptor fontDescriptor = null;
+            nfloat fontSize = 0;
+
+            switch (resourceDictionary[TypefaceId])
+            {
+                case NSFontDescriptor fd:
+                    fontDescriptor = fd;
+                    break;
+                case NSFont rdFont:
+                    fontDescriptor = rdFont.FontDescriptor;
+                    fontSize = rdFont.PointSize;
+                    break;
+                case string fontName:
+                    fontDescriptor = NSFontWorkarounds
+                        .FromFontName(fontName, 0)
+                        .FontDescriptor;
+                    break;
+            }
+
+            switch (resourceDictionary[FontRenderingSizeId])
+            {
+                case double d:
+                    fontSize = (nfloat)d;
+                    break;
+                case float f:
+                    fontSize = f;
+                    break;
+                case nfloat nf:
+                    fontSize = nf;
+                    break;
+                case int i:
+                    fontSize = i;
+                    break;
+            }
+
+            if (fontSize <= 0)
+                fontSize = NSFont.SystemFontSize;
+
+            if (respectScale && resourceDictionary[FontRenderingScaleId] is double scale)
+                fontSize *= (nfloat)scale;
+
+            var font = fontDescriptor == null
+                ? NSFontWorkarounds.UserFixedPitchFontOfSize(fontSize)
+                : NSFontWorkarounds.FromDescriptor(fontDescriptor, fontSize);
+
+            NSFontTraitMask convertFontTraits = 0;
+
+            if (resourceDictionary.Contains(IsBoldId) &&
+                resourceDictionary[IsBoldId] is bool isBold &&
+                isBold)
+                convertFontTraits |= NSFontTraitMask.Bold;
+
+            if (resourceDictionary.Contains(IsItalicId) &&
+                resourceDictionary[IsItalicId] is bool isItalic &&
+                isItalic)
+                convertFontTraits |= NSFontTraitMask.Italic;
+
+            if (convertFontTraits != 0)
+                font = NSFontManager.SharedFontManager.ConvertFontWorkaround(
+                    font,
+                    convertFontTraits);
+
+            return font;
+        }
+    }
+}
\ No newline at end of file
diff --git a/src/Editor/Text/Def/TextUICocoa/Editor/ICocoaTextViewExtensions.cs b/src/Editor/Text/Def/TextUICocoa/Editor/ICocoaTextViewExtensions.cs
new file mode 100644
index 0000000..3f0d46c
--- /dev/null
+++ b/src/Editor/Text/Def/TextUICocoa/Editor/ICocoaTextViewExtensions.cs
@@ -0,0 +1,64 @@
+//
+//  Copyright (c) Microsoft Corporation. All rights reserved.
+//  Licensed under the MIT License. See License.txt in the project root for license information.
+//
+
+using System;
+using System.Linq;
+
+using AppKit;
+using CoreGraphics;
+
+using Microsoft.VisualStudio.Text.Formatting;
+
+namespace Microsoft.VisualStudio.Text.Editor
+{
+    public static class ICocoaTextViewExtensions
+    {
+        public static CGPoint GetViewRelativeMousePosition(this ICocoaTextView textView, NSEvent theEvent)
+            => textView.VisualElement.ConvertPointFromView(theEvent.LocationInWindow, null);
+
+        public static void MoveCaretToPosition(this ICocoaTextView textView, NSEvent theEvent)
+        {
+            var mousePosition = GetViewRelativeMousePosition(textView, theEvent);
+
+            mousePosition.X += (nfloat)textView.ViewportLeft;
+            mousePosition.Y += (nfloat)textView.ViewportTop;
+
+            // Set the caret at the closest mouse location (if there is no selection surrounding the clicked location)
+            ITextViewLine textViewLine = textView.TextViewLines.GetTextViewLineContainingYCoordinate(mousePosition.Y);
+            if (textViewLine != null)
+            {
+                VirtualSnapshotPoint clickedBufferPosition = textViewLine.GetInsertionBufferPositionFromXCoordinate(mousePosition.X);
+
+                // What we're trying to determine is: if the caret were to be placed by this
+                // click, would it still be inside the current selection?
+
+                bool insideSelection;
+
+                // If neither virtual space is enabled nor the selection mode is box, check the non-virtual buffer point
+                if (!(textView.Options.GetOptionValue(DefaultTextViewOptions.UseVirtualSpaceId) || (textView.Selection.Mode == TextSelectionMode.Box)))
+                {
+                    SnapshotPoint nonVirtualPoint = clickedBufferPosition.Position;
+                    insideSelection = textView.Selection.SelectedSpans.Any(selectionSpan => selectionSpan.Contains(nonVirtualPoint));
+                }
+                else
+                {
+                    insideSelection = textView.Selection.VirtualSelectedSpans.Any(selectionSpan => selectionSpan.Contains(clickedBufferPosition));
+                }
+
+                // If this is outside of the selection, move the caret.
+                if (!insideSelection)
+                {
+                    textView.Caret.MoveTo(textViewLine, mousePosition.X);
+                    textView.Selection.Clear();
+                    textView.Caret.EnsureVisible();
+                }
+            }
+            else
+            {
+                textView.Caret.MoveTo(new SnapshotPoint(textView.TextSnapshot, textView.TextSnapshot.Length));
+            }
+        }
+    }
+}
diff --git a/src/Editor/Text/Def/TextUICocoa/NSFontExtensions.cs b/src/Editor/Text/Def/TextUICocoa/NSFontExtensions.cs
new file mode 100644
index 0000000..98489e9
--- /dev/null
+++ b/src/Editor/Text/Def/TextUICocoa/NSFontExtensions.cs
@@ -0,0 +1,179 @@
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// Licensed under the MIT License.
+
+using System;
+using System.Runtime.InteropServices;
+
+using Foundation;
+using ObjCRuntime;
+
+namespace AppKit
+{
+    public static class NSFontWorkarounds
+    {
+        [DllImport(Constants.ObjectiveCLibrary, EntryPoint = "objc_msgSend")]
+        static extern IntPtr IntPtr_objc_msgSend_IntPtr_nfloat(IntPtr receiver, IntPtr selector, IntPtr arg1, nfloat arg2);
+
+        [DllImport(Constants.ObjectiveCLibrary, EntryPoint = "objc_msgSend")]
+        static extern IntPtr IntPtr_objc_msgSend_IntPtr_nuint_nint_nfloat(IntPtr receiver, IntPtr selector, IntPtr arg1, nuint arg2, nint arg3, nfloat arg4);
+
+        [DllImport(Constants.ObjectiveCLibrary, EntryPoint = "objc_msgSend")]
+        static extern IntPtr IntPtr_objc_msgSend_nfloat(IntPtr receiver, IntPtr selector, nfloat arg1);
+
+        [DllImport(Constants.ObjectiveCLibrary, EntryPoint = "objc_msgSend")]
+        static extern IntPtr IntPtr_objc_msgSend_IntPtr_nuint(IntPtr receiver, IntPtr selector, IntPtr arg1, nuint arg2);
+
+        [DllImport(Constants.ObjectiveCLibrary, EntryPoint = "objc_msgSend")]
+        static extern bool bool_objc_msgSend_IntPtr(IntPtr receiver, IntPtr selector, IntPtr arg1);
+
+        static readonly IntPtr sel_respondsToSelector_ = Selector.GetHandle("respondsToSelector:");
+
+        static bool RespondsToSelector(IntPtr receiver, IntPtr selector)
+            => bool_objc_msgSend_IntPtr(receiver, sel_respondsToSelector_, selector);
+
+        static readonly IntPtr classPtrNSFont = Class.GetHandle("NSFont");
+
+        static readonly IntPtr selFontWithName_Size = Selector.GetHandle("fontWithName:size:");
+
+        /// <summary>
+        /// Workaround for https://github.com/xamarin/xamarin-macios/pull/5423
+        /// </summary>
+        public static NSFont FromFontName(string fontName, nfloat fontSize)
+        {
+            var fontNamePtr = NSString.CreateNative(fontName);
+
+            try
+            {
+                return WrappedNSFont.Wrap(IntPtr_objc_msgSend_IntPtr_nfloat(
+                    classPtrNSFont,
+                    selFontWithName_Size,
+                    fontNamePtr,
+                    fontSize));
+            }
+            finally
+            {
+                NSString.ReleaseNative(fontNamePtr);
+            }
+        }
+
+        static readonly IntPtr selUserFixedPitchFontOfSize = Selector.GetHandle("userFixedPitchFontOfSize:");
+
+        public static NSFont UserFixedPitchFontOfSize(nfloat fontSize)
+            => WrappedNSFont.Wrap(IntPtr_objc_msgSend_nfloat(
+                classPtrNSFont,
+                selUserFixedPitchFontOfSize,
+                fontSize));
+
+        static readonly IntPtr selUserFontOfSize = Selector.GetHandle("userFontOfSize:");
+
+        public static NSFont UserFontOfSize(nfloat fontSize)
+            => WrappedNSFont.Wrap(IntPtr_objc_msgSend_nfloat(
+                classPtrNSFont,
+                selUserFontOfSize,
+                fontSize));
+
+        static readonly IntPtr sel_systemFontOfSize_ = Selector.GetHandle("systemFontOfSize:");
+
+        public static NSFont SystemFontOfSize(nfloat fontSize)
+            => WrappedNSFont.Wrap(IntPtr_objc_msgSend_nfloat(
+                classPtrNSFont,
+                sel_systemFontOfSize_,
+                fontSize));
+
+        static readonly IntPtr sel__lightSystemFontOfSize_ = Selector.GetHandle("_lightSystemFontOfSize:");
+        static readonly IntPtr sel_lightSystemFontOfSize_ = Selector.GetHandle("lightSystemFontOfSize:");
+
+        public static NSFont LightSystemFontOfSize(nfloat fontSize)
+        {
+            IntPtr selectorHandle;
+
+            if (RespondsToSelector(classPtrNSFont, sel__lightSystemFontOfSize_))
+                // _lightSystemFontOfSize: is AppKit internal as of 10.14 but is used by Spotlight and Xcode
+                selectorHandle = sel__lightSystemFontOfSize_;
+            else if (RespondsToSelector(classPtrNSFont, sel_lightSystemFontOfSize_))
+                // lightSystemFontOfSize: does not exist, but may in a future macOS... try it next
+                selectorHandle = sel_lightSystemFontOfSize_;
+            else
+                // systemFontOfSize: has always existed, fall back to it
+                selectorHandle = sel_systemFontOfSize_;
+
+            return WrappedNSFont.Wrap(IntPtr_objc_msgSend_nfloat(
+                classPtrNSFont,
+                selectorHandle,
+                fontSize));
+        }
+
+        static readonly IntPtr selToolTipsFontOfSize = Selector.GetHandle("toolTipsFontOfSize:");
+
+        public static NSFont ToolTipsFontOfSize(nfloat fontSize)
+            => WrappedNSFont.Wrap(IntPtr_objc_msgSend_nfloat(
+                classPtrNSFont,
+                selToolTipsFontOfSize,
+                fontSize));
+
+        static readonly IntPtr selFontWithDescriptor_Size = Selector.GetHandle("fontWithDescriptor:size:");
+
+        public static NSFont FromDescriptor(NSFontDescriptor fontDescriptor, nfloat fontSize)
+            => WrappedNSFont.Wrap(IntPtr_objc_msgSend_IntPtr_nfloat(
+                classPtrNSFont,
+                selFontWithDescriptor_Size,
+                (fontDescriptor ?? throw new ArgumentNullException(nameof(fontDescriptor))).Handle,
+                fontSize));
+
+        static readonly IntPtr selFontWithFamily_traits_weight_size_ = Selector.GetHandle("fontWithFamily:traits:weight:size:");
+
+        public static NSFont FontWithFamilyWorkaround(
+            this NSFontManager fontManager,
+            string family,
+            NSFontTraitMask traits,
+            nint weight,
+            nfloat size)
+        {
+            if (family == null)
+                throw new ArgumentNullException(nameof(family));
+
+            var familyPtr = NSString.CreateNative(family);
+            try
+            {
+                return WrappedNSFont.Wrap(IntPtr_objc_msgSend_IntPtr_nuint_nint_nfloat(
+                    fontManager.Handle,
+                    selFontWithFamily_traits_weight_size_,
+                    familyPtr,
+                    (nuint)(ulong)traits,
+                    weight,
+                    size));
+            } finally
+            {
+                NSString.ReleaseNative(familyPtr);
+            }
+        }
+
+        static readonly IntPtr selConvertFont_toHaveTrait_ = Selector.GetHandle("convertFont:toHaveTrait:");
+
+        public static NSFont ConvertFontWorkaround(
+            this NSFontManager fontManager,
+            NSFont font,
+            NSFontTraitMask trait)
+        {
+            if (font == null)
+                throw new ArgumentNullException(nameof(font));
+
+            return WrappedNSFont.Wrap(
+                IntPtr_objc_msgSend_IntPtr_nuint(
+                    fontManager.Handle,
+                    selConvertFont_toHaveTrait_,
+                    font.Handle,
+                    (nuint)(ulong)trait));
+        }
+
+        sealed class WrappedNSFont : NSFont
+        {
+            public static NSFont Wrap(IntPtr handle)
+                => handle == IntPtr.Zero ? null : new WrappedNSFont(handle);
+
+            WrappedNSFont(IntPtr handle) : base(handle)
+            {
+            }
+        }
+    }
+}
\ No newline at end of file
diff --git a/src/Editor/Text/Def/TextUICocoa/TextUICocoa.csproj b/src/Editor/Text/Def/TextUICocoa/TextUICocoa.csproj
index a93e997..920cc6b 100644
--- a/src/Editor/Text/Def/TextUICocoa/TextUICocoa.csproj
+++ b/src/Editor/Text/Def/TextUICocoa/TextUICocoa.csproj
@@ -4,8 +4,12 @@
     <TargetFramework>$(TargetFramework)</TargetFramework>
   </PropertyGroup>
   <ItemGroup>
+    <Reference Include="PresentationFramework" />
+  </ItemGroup>
+  <ItemGroup>
     <ProjectReference Include="..\TextData\TextData.csproj" />
     <ProjectReference Include="..\TextUI\TextUI.csproj" />
+    <ProjectReference Include="..\TextUIWpf\TextUIWpf.csproj" />
   </ItemGroup>
   <ItemGroup>
     <PackageReference Include="Microsoft.VisualStudio.Composition" />
diff --git a/src/Editor/Text/Util/TextDataUtil/AssemblyInfo.cs b/src/Editor/Text/Util/TextDataUtil/AssemblyInfo.cs
index ea93b49..ccc6bf1 100644
--- a/src/Editor/Text/Util/TextDataUtil/AssemblyInfo.cs
+++ b/src/Editor/Text/Util/TextDataUtil/AssemblyInfo.cs
@@ -72,6 +72,7 @@ using System.Runtime.ConstrainedExecution;
 [assembly: InternalsVisibleTo("Microsoft.VisualStudio.UI.Text.Commanding.Implementation.UnitTests, PublicKey=" + ThisAssembly.PublicKey)]
 [assembly: InternalsVisibleTo("Microsoft.VisualStudio.Text.MultiSelection.Implementation.UI.UnitTests, PublicKey=" + ThisAssembly.PublicKey)]
 [assembly: InternalsVisibleTo("Microsoft.VisualStudio.UI.Text.Cocoa.View.Implementation, PublicKey=" + ThisAssembly.PublicKey)]
+[assembly: InternalsVisibleTo("Microsoft.VisualStudio.Platform.VSEditor, PublicKey=" + ThisAssembly.PublicKey)]
 //
 // General Information about an assembly is controlled through the following
 // set of attributes. Change these attribute values to modify the information
diff --git a/src/Editor/Text/Util/TextUIUtil/AssemblyInfo.cs b/src/Editor/Text/Util/TextUIUtil/AssemblyInfo.cs
index 4567dde..c5cbe95 100644
--- a/src/Editor/Text/Util/TextUIUtil/AssemblyInfo.cs
+++ b/src/Editor/Text/Util/TextUIUtil/AssemblyInfo.cs
@@ -30,6 +30,7 @@ using System.Security.Permissions;
 [assembly: InternalsVisibleTo("Microsoft.VisualStudio.Text.Editor.PrintingService.Implementation, PublicKey=" + ThisAssembly.PublicKey)]
 [assembly: InternalsVisibleTo("EditorTestApp, PublicKey=" + ThisAssembly.PublicKey)]
 [assembly: InternalsVisibleTo("Microsoft.VisualStudio.UI.Text.Cocoa.View.Implementation, PublicKey=" + ThisAssembly.PublicKey)]
+[assembly: InternalsVisibleTo("Microsoft.VisualStudio.Platform.VSEditor, PublicKey=" + ThisAssembly.PublicKey)]
 
 //
 // General Information about an assembly is controlled through the following