[TextEditor] Implemented code lens subsystem & show references lenses.master-codelens

It's the rosyln code lens service driving the first code lens.

11 files changed, 455 insertions, 0 deletions

diff --git a/main/src/addins/CSharpBinding/CSharpBinding.addin.xml b/main/src/addins/CSharpBinding/CSharpBinding.addin.xml
index 75a1ce00fa..139cb9b8ea 100644
--- a/main/src/addins/CSharpBinding/CSharpBinding.addin.xml
+++ b/main/src/addins/CSharpBinding/CSharpBinding.addin.xml
@@ -343,4 +343,9 @@
 	<Extension path = "/MonoDevelop/Ide/AutoInsertBracketHandler">
 		<Class class="MonoDevelop.CSharp.Features.AutoInsertBracket.CSharpAutoInsertBracketHandler" insertbefore="Default"/>
 	</Extension>
+
+	<Extension path = "/MonoDevelop/Ide/CodeLensProvider">
+		<CodeLens class="MonoDevelop.CSharp.Refactoring.CSharpCodeLensProvider" mimeType="text/x-csharp"/>
+	</Extension>
+	
 </ExtensionModel>
diff --git a/main/src/addins/CSharpBinding/CSharpBinding.csproj b/main/src/addins/CSharpBinding/CSharpBinding.csproj
index 2a2746c11d..1adfa743db 100644
--- a/main/src/addins/CSharpBinding/CSharpBinding.csproj
+++ b/main/src/addins/CSharpBinding/CSharpBinding.csproj
@@ -424,6 +424,7 @@
     <Compile Include="MonoDevelop.CSharp.Features\GotoDefinition\GotoDefinitionHelpers.cs" />
     <Compile Include="MonoDevelop.CSharp.Features\GotoDefinition\GotoDefinitionService.cs" />
     <Compile Include="Util\PortingExtensions.cs" />
+    <Compile Include="MonoDevelop.CSharp.Refactoring\CSharpCodeLensProvider.cs" />
   </ItemGroup>
   <ItemGroup>
     <None Include="Makefile.am" />
diff --git a/main/src/addins/CSharpBinding/MonoDevelop.CSharp.Refactoring/CSharpCodeLensProvider.cs b/main/src/addins/CSharpBinding/MonoDevelop.CSharp.Refactoring/CSharpCodeLensProvider.cs
new file mode 100644
index 0000000000..0c820ff72f
--- /dev/null
+++ b/main/src/addins/CSharpBinding/MonoDevelop.CSharp.Refactoring/CSharpCodeLensProvider.cs
@@ -0,0 +1,131 @@
+//
+// CSharpCodeLensProvider.cs
+//
+// Author:
+//       Mike Krüger <mikkrg@microsoft.com>
+//
+// Copyright (c) 2017 Microsoft Corporation
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+using System;
+using System.Collections.Generic;
+using System.Threading;
+using System.Threading.Tasks;
+using MonoDevelop.Ide.Editor;
+using MonoDevelop.Ide.Editor.Extension;
+using MonoDevelop.Ide.TypeSystem;
+using Microsoft.CodeAnalysis.CodeLens;
+using Microsoft.CodeAnalysis;
+using System.Linq;
+using Xwt;
+using Cairo;
+using MonoDevelop.Ide.Editor.Highlighting;
+using MonoDevelop.Components;
+using MonoDevelop.Core;
+using MonoDevelop.Ide.Fonts;
+
+namespace MonoDevelop.CSharp.Refactoring
+{
+	class CSharpCodeLens : CodeLens
+	{
+		readonly ICodeLensDisplayInfoService displayService;
+		readonly ICodeLensReferencesService referencesService;
+		readonly ISymbol symbol;
+		readonly SyntaxNode displayNode;
+		readonly Solution solution;
+		readonly DocumentId id;
+
+		public override Core.Text.TextSegment CodeLensSpan {
+			get {
+				return new Core.Text.TextSegment (displayNode.Span.Start, displayNode.Span.Length);
+			}
+		}
+
+		public CSharpCodeLens (Solution solution, DocumentId id, ICodeLensDisplayInfoService displayService, ICodeLensReferencesService referencesService, ISymbol symbol, SyntaxNode displayNode)
+		{
+			this.id = id;
+			this.solution = solution;
+			this.displayService = displayService;
+			this.referencesService = referencesService;
+			this.symbol = symbol;
+			this.displayNode = displayNode;
+		}
+
+		Size size;
+		ReferenceCount count;
+		public override Size Size => size;
+
+		public async Task Update (CancellationToken token)
+		{
+			count = await referencesService.GetReferenceCountAsync (solution, id, displayNode, 1000, token);
+		}
+
+		public override void Draw (CodeLansDrawingParameters drawingParameters)
+		{
+			var p = drawingParameters as GtkCodeLansDrawingParameters;
+			if (count == null || p == null)
+				return;
+			p.Context.Save ();
+			var theme = p.Editor.Options.GetEditorTheme ();
+			theme.TryGetColor (EditorThemeColors.FoldLine, out Components.HslColor color);
+			p.Context.SetSourceColor (color);
+			p.Context.Translate (p.X, p.Y);
+			p.Layout.FontDescription = FontService.SansFont;
+			string text;
+			if (count.IsCapped) {
+				text = GettextCatalog.GetString (">{0} references", count.Count);
+			} else {
+				text = GettextCatalog.GetString ("{0} references", count.Count);
+			}
+			p.Layout.SetMarkup ("<span size='small'>" + text + "</span>");
+			p.Context.ShowLayout (p.Layout);
+			p.Context.Restore ();
+			p.Layout.GetPixelSize (out int pw, out int ph);
+			size = new Size (pw, ph);
+		}
+	}
+
+	class CSharpCodeLensProvider : CodeLensProvider
+	{
+		public override async Task<IEnumerable<CodeLens>> GetLenses (TextEditor editor, DocumentContext ctx, CancellationToken token)
+		{
+			var languageService = ctx.RoslynWorkspace.Services.GetLanguageServices (LanguageNames.CSharp);
+			if (languageService == null)
+				return Enumerable.Empty<CodeLens> ();
+			var displayService = languageService.GetService<ICodeLensDisplayInfoService> ();
+			var referencesService = ctx.RoslynWorkspace.Services.GetService<ICodeLensReferencesService> ();
+			if (displayService == null || referencesService == null)
+				return Enumerable.Empty<CodeLens> ();
+			var model = await ctx.AnalysisDocument.GetSemanticModelAsync (token).ConfigureAwait (false);
+			var root = await model.SyntaxTree.GetRootAsync (token).ConfigureAwait (false);
+			var result = new List<CodeLens> ();
+			foreach (var node in model.SyntaxTree.GetRoot ().DescendantNodesAndSelf ()) {
+				var symbol = model.GetDeclaredSymbol (node);
+				if (symbol == null || symbol.Kind == SymbolKind.Namespace)
+					continue;
+				var displayNode = displayService.GetDisplayNode (node);
+				var newLens = new CSharpCodeLens (ctx.AnalysisDocument.Project.Solution, ctx.AnalysisDocument.Id, displayService, referencesService, symbol, displayNode);
+				await newLens.Update (token);
+				result.Add (newLens);
+			}
+
+			return result;
+		}
+	}
+}
diff --git a/main/src/addins/MonoDevelop.SourceEditor2/MonoDevelop.SourceEditor.csproj b/main/src/addins/MonoDevelop.SourceEditor2/MonoDevelop.SourceEditor.csproj
index 5f8755a9d5..2dd9437c9b 100644
--- a/main/src/addins/MonoDevelop.SourceEditor2/MonoDevelop.SourceEditor.csproj
+++ b/main/src/addins/MonoDevelop.SourceEditor2/MonoDevelop.SourceEditor.csproj
@@ -284,6 +284,7 @@
     <Compile Include="Mono.TextEditor.Theatrics\SmartScrolledWindow.cs" />
     <Compile Include="Mono.TextEditor.Theatrics\Stage.cs" />
     <None Include="packages.config" />
+    <Compile Include="MonoDevelop.SourceEditor\TextMarker\CodeLensMarker.cs" />
   </ItemGroup>
   <ItemGroup>
     <EmbeddedResource Include="gtk-gui\gui.stetic">
diff --git a/main/src/addins/MonoDevelop.SourceEditor2/MonoDevelop.SourceEditor/SourceEditorView.cs b/main/src/addins/MonoDevelop.SourceEditor2/MonoDevelop.SourceEditor/SourceEditorView.cs
index 91db517e37..5955135c60 100644
--- a/main/src/addins/MonoDevelop.SourceEditor2/MonoDevelop.SourceEditor/SourceEditorView.cs
+++ b/main/src/addins/MonoDevelop.SourceEditor2/MonoDevelop.SourceEditor/SourceEditorView.cs
@@ -3496,6 +3496,11 @@ namespace MonoDevelop.SourceEditor
 			return new MessageBubbleTextMarker (messageBubbleCache);
 		}
 
+		ICodeLensMarker ITextMarkerFactory.CreateCodeLensMarker (TextEditor editor)
+		{
+			return new CodeLensMarker ();
+		}
+
 		IGenericTextSegmentMarker ITextMarkerFactory.CreateGenericTextSegmentMarker (MonoDevelop.Ide.Editor.TextEditor editor, TextSegmentMarkerEffect effect, int offset, int length)
 		{
 			switch (effect) {
diff --git a/main/src/addins/MonoDevelop.SourceEditor2/MonoDevelop.SourceEditor/TextMarker/CodeLensMarker.cs b/main/src/addins/MonoDevelop.SourceEditor2/MonoDevelop.SourceEditor/TextMarker/CodeLensMarker.cs
new file mode 100644
index 0000000000..a77afdd9e1
--- /dev/null
+++ b/main/src/addins/MonoDevelop.SourceEditor2/MonoDevelop.SourceEditor/TextMarker/CodeLensMarker.cs
@@ -0,0 +1,93 @@
+//
+// CodeLensMarker.cs
+//
+// Author:
+//       Mike Krüger <mikkrg@microsoft.com>
+//
+// Copyright (c) 2017 Microsoft Corporation
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+using System;
+using System.Linq;
+using Mono.TextEditor;
+using Mono.TextEditor.Highlighting;
+using MonoDevelop.SourceEditor.Wrappers;
+using MonoDevelop.Components;
+using MonoDevelop.Debugger;
+using MonoDevelop.Ide.Editor;
+using Xwt.Drawing;
+using System.Collections.Generic;
+using MonoDevelop.Ide.Editor.Highlighting;
+using MonoDevelop.Ide.Editor.Extension;
+
+namespace MonoDevelop.SourceEditor
+{
+	class CodeLensMarker : TextLineMarker, IExtendingTextLineMarker, ICodeLensMarker
+	{
+		public bool IsSpaceAbove => true;
+
+		public IDocumentLine Line => LineSegment;
+
+		public void Draw(MonoTextEditor editor, Cairo.Context g, int lineNr, Cairo.Rectangle lineArea)
+		{
+			double x = lineArea.X;
+			double y = lineArea.Y - editor.LineHeight;
+			var line = editor.GetLine (lineNr);
+			if (line == null)
+				return;
+			var lineLayout = editor.TextViewMargin.GetLayout (line);
+			if (lineLayout == null)
+				return;
+			var indent = line.GetIndentation (editor.Document);
+			lineLayout.GetCursorPos (indent.Length, out Pango.Rectangle strong_pos, out Pango.Rectangle weak_pos);
+			x += strong_pos.X / Pango.Scale.PangoScale;
+			using (var layout = new Pango.Layout (editor.PangoContext)) {
+				foreach (var codeLens in codeLenses) {
+					var param = new GtkCodeLansDrawingParameters (Ide.IdeApp.Workbench.ActiveDocument.Editor, lineNr, new Xwt.Rectangle (lineArea.X, lineArea.Y, lineArea.Width, lineArea.Height), x, y, layout, g);
+					codeLens.Draw (param);
+					x += codeLens.Size.Width + 4;
+				}
+			}
+			if (lineLayout.IsUncached)
+				lineLayout.Dispose ();
+		}
+
+		public double GetLineHeight(MonoTextEditor editor) => editor.LineHeight * 2;
+
+		#region ICodeLensMarker implementation
+		readonly List<CodeLens> codeLenses = new List<CodeLens>();
+
+		public int CodeLensCount => codeLenses.Count;
+
+		public void AddLens(CodeLens lens)
+		{
+			if (lens == null)
+				throw new ArgumentNullException(nameof(lens));
+			codeLenses.Add(lens);
+		}
+
+		public void RemoveLens(CodeLens lens)
+		{
+			if (lens == null)
+				throw new ArgumentNullException(nameof(lens));
+			codeLenses.Remove(lens);
+		}
+		#endregion
+	}
+}
diff --git a/main/src/core/MonoDevelop.Ide/ExtensionModel/MonoDevelop.Ide.addin.xml b/main/src/core/MonoDevelop.Ide/ExtensionModel/MonoDevelop.Ide.addin.xml
index b716716444..617f97a492 100644
--- a/main/src/core/MonoDevelop.Ide/ExtensionModel/MonoDevelop.Ide.addin.xml
+++ b/main/src/core/MonoDevelop.Ide/ExtensionModel/MonoDevelop.Ide.addin.xml
@@ -238,6 +238,10 @@
 		<ExtensionNode name = "Assembly" type = "MonoDevelop.Core.AddIns.AssemblyExtensionNode" />
 	</ExtensionPoint>
 
+	<ExtensionPoint path = "/MonoDevelop/Ide/CodeLensProvider" name = "Code lens provider">
+		<Description>Algorithm for providing code lenses in a file.</Description>
+		<ExtensionNode name="CodeLens" type="MonoDevelop.Ide.Extensions.MimeTypeExtensionNode"/>
+	</ExtensionPoint>
   <!-- Extensions -->
 	
 	<Extension path = "/MonoDevelop/Core/Applications">
@@ -320,6 +324,7 @@
 		<Class class = "MonoDevelop.Ide.Editor.TextMate.TextMateFoldingTextEditorExtension" />
 		<Class class = "MonoDevelop.Ide.Editor.TextMate.TextMateIndentationTextEditorExtension" />
 		<Class class = "MonoDevelop.Ide.Editor.TextMate.TextMateCompletionTextEditorExtension" />
+		<Class class = "MonoDevelop.Ide.Editor.Extension.CodeLensTextEditorExtension" />
 		<Class id="FinalStep" class = "MonoDevelop.Ide.Editor.Extension.TextEditorExtensionMarker" />
 	</Extension>
 	
diff --git a/main/src/core/MonoDevelop.Ide/MonoDevelop.Ide.Editor.Extension/CodeLensTextEditorExtension.cs b/main/src/core/MonoDevelop.Ide/MonoDevelop.Ide.Editor.Extension/CodeLensTextEditorExtension.cs
new file mode 100644
index 0000000000..113071f296
--- /dev/null
+++ b/main/src/core/MonoDevelop.Ide/MonoDevelop.Ide.Editor.Extension/CodeLensTextEditorExtension.cs
@@ -0,0 +1,204 @@
+//
+// AbstractCodeLensExtension.cs
+//
+// Author:
+//       Mike Krüger <mikkrg@microsoft.com>
+//
+// Copyright (c) 2017 Microsoft Corporation
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+using System;
+using MonoDevelop.Ide.Gui.Content;
+using System.Collections.Generic;
+using System.Linq;
+using MonoDevelop.Ide.FindInFiles;
+using System.Threading;
+using System.Threading.Tasks;
+using MonoDevelop.Core;
+using System.Diagnostics.CodeAnalysis;
+using MonoDevelop.Ide.Editor;
+using MonoDevelop.Core.Text;
+using System.Collections.Immutable;
+using Mono.Addins;
+using MonoDevelop.Ide.Extensions;
+using MonoDevelop.Ide.TypeSystem;
+using Cairo;
+
+namespace MonoDevelop.Ide.Editor.Extension
+{
+	public sealed class GtkCodeLansDrawingParameters : CodeLansDrawingParameters
+	{
+		public Pango.Layout Layout { get; private set; }
+		public Context Context { get; private set; }
+
+		public GtkCodeLansDrawingParameters (TextEditor editor, int lineNr, Xwt.Rectangle lineArea, double x, double y, Pango.Layout layout, Context context) : base (editor, lineNr, lineArea, x, y)
+		{
+			Layout = layout;
+			Context = context;
+		}
+	}
+
+	public abstract class CodeLansDrawingParameters
+	{
+		public TextEditor Editor { get; private set; }
+		public int LineNr { get; private set; }
+		public Xwt.Rectangle LineArea { get; private set; }
+
+		public double X { get; private set; }
+		public double Y { get; private set; }
+
+		public CodeLansDrawingParameters (TextEditor editor, int lineNr, Xwt.Rectangle lineArea, double x, double y)
+		{
+			Editor = editor;
+			LineNr = lineNr;
+			LineArea = lineArea;
+			X = x;
+			Y = y;
+		}
+	}
+
+	public abstract class CodeLens
+	{
+		public abstract TextSegment CodeLensSpan { get; }
+
+		public abstract void Draw (CodeLansDrawingParameters drawingParameters);
+
+		public abstract Xwt.Size Size { get; }
+	}
+
+	public abstract class CodeLensProvider
+	{
+		internal string MimeType { get; set; }
+
+		public abstract Task<IEnumerable<CodeLens>> GetLenses (TextEditor editor, DocumentContext ctx, CancellationToken token);
+	}
+
+	class CodeLensTextEditorExtension : TextEditorExtension
+	{
+		CancellationTokenSource src = new CancellationTokenSource ();
+		bool isDisposed;
+		static List<CodeLensProvider> codeLensProviders = new List<CodeLensProvider> ();
+
+		static CodeLensTextEditorExtension ()
+		{
+			AddinManager.AddExtensionNodeHandler ("/MonoDevelop/Ide/CodeLensProvider", delegate (object sender, ExtensionNodeEventArgs args) {
+				var node = (MimeTypeExtensionNode)args.ExtensionNode;
+				switch (args.Change) {
+				case ExtensionChange.Add:
+					var matcher = (CodeLensProvider)node.CreateInstance ();
+					matcher.MimeType = node.MimeType;
+					codeLensProviders.Add (matcher);
+					break;
+				case ExtensionChange.Remove:
+					var toRemove = codeLensProviders.FirstOrDefault (m => m.MimeType == node.MimeType);
+					if (toRemove != null)
+						codeLensProviders.Remove (toRemove);
+					break;
+				}
+			});
+		}
+
+		protected override void Initialize ()
+		{
+			DocumentContext.DocumentParsed += DocumentContext_DocumentParsed;
+		}
+
+		public override void Dispose ()
+		{
+			if (isDisposed)
+				return;
+			isDisposed = true;
+			CancelDocumentParsedUpdate ();
+			DocumentContext.DocumentParsed -= DocumentContext_DocumentParsed;
+			base.Dispose ();
+		}
+
+		void CancelDocumentParsedUpdate ()
+		{
+			src.Cancel ();
+			src = new CancellationTokenSource ();
+		}
+
+		void DocumentContext_DocumentParsed (object sender, EventArgs e)
+		{
+			CancelDocumentParsedUpdate ();
+			var token = src.Token;
+			var parsedDocument = DocumentContext.ParsedDocument;
+			if (!isDisposed)
+				UpdateLenses (token);
+		}
+
+		List<ICodeLensMarker> codeLensMarkers = new List<ICodeLensMarker> ();
+		struct CodeLensCacheItem
+		{
+			public ICodeLensMarker Marker { get; set; }
+			public CodeLens Lens { get; set; }
+
+			public CodeLensCacheItem (ICodeLensMarker marker, CodeLens lens)
+			{
+				Marker = marker;
+				Lens = lens;
+			}
+		}
+
+		Dictionary<CodeLensProvider, List<CodeLensCacheItem>> lensCache = new Dictionary<CodeLensProvider, List<CodeLensCacheItem>> ();
+
+		async void UpdateLenses (CancellationToken token = default (CancellationToken))
+		{
+			foreach (var provider in codeLensProviders) {
+				var lenses = await provider.GetLenses (Editor, DocumentContext, token).ConfigureAwait (false);
+				await Runtime.RunInMainThread (delegate {
+					if (lensCache.TryGetValue (provider, out List<CodeLensCacheItem> cache)) {
+						lensCache.Remove (provider);
+						foreach (var item in cache)
+							item.Marker.RemoveLens (item.Lens);
+					}
+
+					var newCache = new List<CodeLensCacheItem> ();
+					foreach (var lens in lenses) {
+						var line = Editor.GetLineByOffset (lens.CodeLensSpan.Offset);
+						var codeLensMarker = Editor.GetLineMarkers (line).OfType<ICodeLensMarker> ().FirstOrDefault ();
+						if (codeLensMarker == null) {
+							codeLensMarker = Editor.TextMarkerFactory.CreateCodeLensMarker (Editor);
+							Editor.AddMarker (line, codeLensMarker);
+							codeLensMarkers.Add (codeLensMarker);
+						}
+						codeLensMarker.AddLens (lens);
+						newCache.Add (new CodeLensCacheItem (codeLensMarker, lens));
+					}
+					lensCache.Add (provider, newCache);
+				});
+			}
+
+			await Runtime.RunInMainThread (delegate {
+				RemoveUnusedCodeLensMarkers ();
+			});
+		}
+
+		void RemoveUnusedCodeLensMarkers ()
+		{
+			foreach (var marker in codeLensMarkers.ToArray ()) {
+				if (marker.CodeLensCount == 0) {
+					Editor.RemoveMarker (marker);
+					codeLensMarkers.Remove (marker);
+				}
+			}
+		}
+	}
+}
\ No newline at end of file
diff --git a/main/src/core/MonoDevelop.Ide/MonoDevelop.Ide.Editor/ITextLineMarker.cs b/main/src/core/MonoDevelop.Ide/MonoDevelop.Ide.Editor/ITextLineMarker.cs
index 982033e951..34a51d5efe 100644
--- a/main/src/core/MonoDevelop.Ide/MonoDevelop.Ide.Editor/ITextLineMarker.cs
+++ b/main/src/core/MonoDevelop.Ide/MonoDevelop.Ide.Editor/ITextLineMarker.cs
@@ -77,4 +77,12 @@ namespace MonoDevelop.Ide.Editor
 
 		void AddTask (MonoDevelop.Ide.Tasks.TaskListEntry task);
 	}
+
+	public interface ICodeLensMarker : ITextLineMarker
+	{
+		int CodeLensCount { get; }
+
+		void AddLens (MonoDevelop.Ide.Editor.Extension.CodeLens lens);
+		void RemoveLens (MonoDevelop.Ide.Editor.Extension.CodeLens lens);
+	}
 }
\ No newline at end of file
diff --git a/main/src/core/MonoDevelop.Ide/MonoDevelop.Ide.Editor/InternalExtensionAPI/ITextMarkerFactory.cs b/main/src/core/MonoDevelop.Ide/MonoDevelop.Ide.Editor/InternalExtensionAPI/ITextMarkerFactory.cs
index 95900bc1d4..1581b639a4 100644
--- a/main/src/core/MonoDevelop.Ide/MonoDevelop.Ide.Editor/InternalExtensionAPI/ITextMarkerFactory.cs
+++ b/main/src/core/MonoDevelop.Ide/MonoDevelop.Ide.Editor/InternalExtensionAPI/ITextMarkerFactory.cs
@@ -44,6 +44,7 @@ namespace MonoDevelop.Ide.Editor
 		ITextLineMarker CreateAsmLineMarker (TextEditor editor);
 		IUnitTestMarker CreateUnitTestMarker (TextEditor editor, UnitTestMarkerHost host, UnitTestLocation unitTestLocation);
 		IMessageBubbleLineMarker CreateMessageBubbleLineMarker (TextEditor editor);
+		ICodeLensMarker CreateCodeLensMarker (TextEditor editor);
 		#endregion
 
 		#region Segment marker
diff --git a/main/src/core/MonoDevelop.Ide/MonoDevelop.Ide.csproj b/main/src/core/MonoDevelop.Ide/MonoDevelop.Ide.csproj
index 9a8a810544..a7e558474b 100644
--- a/main/src/core/MonoDevelop.Ide/MonoDevelop.Ide.csproj
+++ b/main/src/core/MonoDevelop.Ide/MonoDevelop.Ide.csproj
@@ -9460,6 +9460,7 @@
     <Compile Include="MonoDevelop.Ide.Projects\LanguageCellRenderer.cs" />
     <Compile Include="MonoDevelop.Components\RestartPanel.cs" />
     <Compile Include="MonoDevelop.Ide.Gui.OptionPanels\DotNetCompileTargetSelector.cs" />
+    <Compile Include="MonoDevelop.Ide.Editor.Extension\CodeLensTextEditorExtension.cs" />
   </ItemGroup>
   <ItemGroup>
     <None Include="Makefile.am" />