Refactor Solution decompilation to use Language instead of AssemblyTreeNode.

ICSharpCode.Decompiler/CSharp/WholeProjectDecompiler.cs

@@ -35,6 +35,7 @@ using System.Reflection.Metadata;
 using static ICSharpCode.Decompiler.Metadata.DotNetCorePathFinderExtensions;
 using static ICSharpCode.Decompiler.Metadata.MetadataExtensions;
 using ICSharpCode.Decompiler.Metadata;
+using ICSharpCode.Decompiler.Solution;
 
 namespace ICSharpCode.Decompiler.CSharp
 {

ICSharpCode.Decompiler/ICSharpCode.Decompiler.csproj

@@ -61,7 +61,9 @@
     <Compile Include="CSharp\CSharpLanguageVersion.cs" />
     <Compile Include="CSharp\RequiredNamespaceCollector.cs" />
     <Compile Include="CSharp\SequencePointBuilder.cs" />
-    <Compile Include="CSharp\SolutionCreator.cs" />
+    <Compile Include="Solution\ProjectId.cs" />
+    <Compile Include="Solution\ProjectItem.cs" />
+    <Compile Include="Solution\SolutionCreator.cs" />
     <Compile Include="CSharp\Syntax\AstNode.cs" />
     <Compile Include="CSharp\Syntax\AstNodeCollection.cs" />
     <Compile Include="CSharp\Syntax\AstType.cs" />

ICSharpCode.Decompiler/Solution/ProjectId.cs

@@ -0,0 +1,56 @@
+// Copyright (c) 2019 AlphaSierraPapa for the SharpDevelop Team
+// 
+// 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;
+
+namespace ICSharpCode.Decompiler.Solution
+{
+	/// <summary>
+	/// A container class that holds platform and GUID information about a Visual Studio project.
+	/// </summary>
+	public class ProjectId
+	{
+		/// <summary>
+		/// Initializes a new instance of the <see cref="ProjectId"/> class.
+		/// </summary>
+		/// <param name="projectPlatform">The project platform.</param>
+		/// <param name="projectGuid">The project GUID.</param>
+		/// 
+		/// <exception cref="ArgumentException">Thrown when <paramref name="projectFile"/> 
+		/// or <paramref name="projectPlatform"/> is null or empty.</exception>
+		public ProjectId(string projectPlatform, Guid projectGuid)
+		{
+			if (string.IsNullOrWhiteSpace(projectPlatform)) {
+				throw new ArgumentException("The platform cannot be null or empty.", nameof(projectPlatform));
+			}
+
+			Guid = projectGuid;
+			PlatformName = projectPlatform;
+		}
+
+		/// <summary>
+		/// Gets the GUID of this project.
+		/// </summary>
+		public Guid Guid { get; }
+
+		/// <summary>
+		/// Gets the platform name of this project. Only single platform per project is supported.
+		/// </summary>
+		public string PlatformName { get; }
+	}
+}

ICSharpCode.Decompiler/Solution/ProjectItem.cs

@@ -0,0 +1,55 @@
+// Copyright (c) 2019 AlphaSierraPapa for the SharpDevelop Team
+// 
+// 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.IO;
+
+namespace ICSharpCode.Decompiler.Solution
+{
+	/// <summary>
+	/// A container class that holds information about a Visual Studio project.
+	/// </summary>
+	public sealed class ProjectItem : ProjectId
+	{
+		/// <summary>
+		/// Initializes a new instance of the <see cref="ProjectItem"/> class.
+		/// </summary>
+		/// <param name="projectFile">The full path of the project file.</param>
+		/// <param name="projectPlatform">The project platform.</param>
+		/// <param name="projectGuid">The project GUID.</param>
+		/// 
+		/// <exception cref="ArgumentException">Thrown when <paramref name="projectFile"/> 
+		/// or <paramref name="projectPlatform"/> is null or empty.</exception>
+		public ProjectItem(string projectFile, string projectPlatform, Guid projectGuid)
+			: base(projectPlatform, projectGuid)
+		{
+			ProjectName = Path.GetFileNameWithoutExtension(projectFile);
+			FilePath = projectFile;
+		}
+
+		/// <summary>
+		/// Gets the name of the project.
+		/// </summary>
+		public string ProjectName { get; }
+
+		/// <summary>
+		/// Gets the full path to the project file.
+		/// </summary>
+		public string FilePath { get; }
+	}
+}

ICSharpCode.Decompiler/Solution/SolutionCreator.cs

@@ -1,4 +1,4 @@
-// Copyright (c) 2016 Daniel Grunwald
+// Copyright (c) 2019 AlphaSierraPapa for the SharpDevelop Team
 // 
 // 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
@@ -22,74 +22,8 @@ using System.IO;
 using System.Linq;
 using System.Xml.Linq;
 
-namespace ICSharpCode.Decompiler.CSharp
+namespace ICSharpCode.Decompiler.Solution
 {
-	/// <summary>
-	/// A container class that holds information about a Visual Studio project.
-	/// </summary>
-	public sealed class ProjectItem : ProjectId
-	{
-		/// <summary>
-		/// Initializes a new instance of the <see cref="ProjectItem"/> class.
-		/// </summary>
-		/// <param name="projectFile">The full path of the project file.</param>
-		/// <param name="projectPlatform">The project platform.</param>
-		/// <param name="projectGuid">The project GUID.</param>
-		/// 
-		/// <exception cref="ArgumentException">Thrown when <paramref name="projectFile"/> 
-		/// or <paramref name="projectPlatform"/> is null or empty.</exception>
-		public ProjectItem(string projectFile, string projectPlatform, Guid projectGuid)
-			: base(projectPlatform, projectGuid)
-		{
-			ProjectName = Path.GetFileNameWithoutExtension(projectFile);
-			FilePath = projectFile;
-		}
-
-		/// <summary>
-		/// Gets the name of the project.
-		/// </summary>
-		public string ProjectName { get; }
-
-		/// <summary>
-		/// Gets the full path to the project file.
-		/// </summary>
-		public string FilePath { get; }
-	}
-
-	/// <summary>
-	/// A container class that holds platform and GUID information about a Visual Studio project.
-	/// </summary>
-	public class ProjectId
-	{
-		/// <summary>
-		/// Initializes a new instance of the <see cref="ProjectId"/> class.
-		/// </summary>
-		/// <param name="projectPlatform">The project platform.</param>
-		/// <param name="projectGuid">The project GUID.</param>
-		/// 
-		/// <exception cref="ArgumentException">Thrown when <paramref name="projectFile"/> 
-		/// or <paramref name="projectPlatform"/> is null or empty.</exception>
-		public ProjectId(string projectPlatform, Guid projectGuid)
-		{
-			if (string.IsNullOrWhiteSpace(projectPlatform)) {
-				throw new ArgumentException("The platform cannot be null or empty.", nameof(projectPlatform));
-			}
-
-			Guid = projectGuid;
-			PlatformName = projectPlatform;
-		}
-
-		/// <summary>
-		/// Gets the GUID of this project.
-		/// </summary>
-		public Guid Guid { get; }
-
-		/// <summary>
-		/// Gets the platform name of this project. Only single platform per project is supported.
-		/// </summary>
-		public string PlatformName { get; }
-	}
-
 	/// <summary>
 	/// A helper class that can write a Visual Studio Solution file for the provided projects.
 	/// </summary>

ILSpy/Languages/CSharpLanguage.cs

@@ -34,6 +34,7 @@ using ICSharpCode.Decompiler.CSharp.Syntax;
 using ICSharpCode.Decompiler.CSharp.Transforms;
 using ICSharpCode.Decompiler.Metadata;
 using ICSharpCode.Decompiler.Output;
+using ICSharpCode.Decompiler.Solution;
 using ICSharpCode.Decompiler.TypeSystem;
 using ICSharpCode.Decompiler.Util;
 using ICSharpCode.ILSpy.TreeNodes;
@@ -343,7 +344,7 @@ namespace ICSharpCode.ILSpy
 			}
 		}
 
-		public override object DecompileAssembly(LoadedAssembly assembly, ITextOutput output, DecompilationOptions options)
+		public override ProjectId DecompileAssembly(LoadedAssembly assembly, ITextOutput output, DecompilationOptions options)
 		{
 			var module = assembly.GetPEFileOrNull();
 			if (options.FullDecompilation && options.SaveAsProjectDirectory != null) {
@@ -389,7 +390,7 @@ namespace ICSharpCode.ILSpy
 					}
 					if (metadata.IsAssembly) {
 						var asm = metadata.GetAssemblyDefinition();
-						if (asm.HashAlgorithm != System.Reflection.AssemblyHashAlgorithm.None)
+						if (asm.HashAlgorithm != AssemblyHashAlgorithm.None)
 							output.WriteLine("// Hash algorithm: " + asm.HashAlgorithm.ToString().ToUpper());
 						if (!asm.PublicKey.IsNil) {
 							output.Write("// Public key: ");
@@ -415,8 +416,7 @@ namespace ICSharpCode.ILSpy
 					}
 					WriteCode(output, options.DecompilerSettings, st, decompiler.TypeSystem);
 				}
-
-				return true;
+				return null;
 			}
 		}
 

ILSpy/Languages/ILLanguage.cs

@@ -27,6 +27,8 @@ using System.Reflection.Metadata.Ecma335;
 using System.Linq;
 using ICSharpCode.Decompiler.Metadata;
 using ICSharpCode.Decompiler.TypeSystem;
+using ICSharpCode.Decompiler.Util;
+using ICSharpCode.Decompiler.Solution;
 
 namespace ICSharpCode.ILSpy
 {
@@ -150,7 +152,7 @@ namespace ICSharpCode.ILSpy
 			dis.DisassembleNamespace(nameSpace, module, types.Select(t => (TypeDefinitionHandle)t.MetadataToken));
 		}
 		
-		public override object DecompileAssembly(LoadedAssembly assembly, ITextOutput output, DecompilationOptions options)
+		public override ProjectId DecompileAssembly(LoadedAssembly assembly, ITextOutput output, DecompilationOptions options)
 		{
 			output.WriteLine("// " + assembly.FileName);
 			output.WriteLine();
@@ -174,8 +176,7 @@ namespace ICSharpCode.ILSpy
 					dis.WriteModuleContents(module);
 				}
 			}
-
-			return true;
+			return null;
 		}
 	}
 }

ILSpy/Languages/Language.cs

@@ -23,6 +23,7 @@ using System.Reflection.PortableExecutable;
 using System.Text;
 using ICSharpCode.Decompiler;
 using ICSharpCode.Decompiler.Metadata;
+using ICSharpCode.Decompiler.Solution;
 using ICSharpCode.Decompiler.TypeSystem;
 using ICSharpCode.Decompiler.TypeSystem.Implementation;
 using ICSharpCode.Decompiler.Util;
@@ -131,11 +132,11 @@ namespace ICSharpCode.ILSpy
 			WriteCommentLine(output, nameSpace);
 		}
 
-		public virtual object DecompileAssembly(LoadedAssembly assembly, ITextOutput output, DecompilationOptions options)
+		public virtual ProjectId DecompileAssembly(LoadedAssembly assembly, ITextOutput output, DecompilationOptions options)
 		{
 			WriteCommentLine(output, assembly.FileName);
 			var asm = assembly.GetPEFileOrNull();
-			if (asm == null) return false;
+			if (asm == null) return null;
 			var metadata = asm.Metadata;
 			if (metadata.IsAssembly) {
 				var name = metadata.GetAssemblyDefinition();
@@ -147,8 +148,7 @@ namespace ICSharpCode.ILSpy
 			} else {
 				WriteCommentLine(output, metadata.GetString(metadata.GetModuleDefinition().Name));
 			}
-
-			return true;
+			return null;
 		}
 
 		public virtual void WriteCommentLine(ITextOutput output, string comment)

ILSpy/MainWindow.xaml.cs

@@ -914,27 +914,78 @@ namespace ICSharpCode.ILSpy
 		void SaveCommandExecuted(object sender, ExecutedRoutedEventArgs e)
 		{
 			var selectedNodes = SelectedNodes.ToList();
-			if (selectedNodes.Count > 1) {
-				var assemblyNodes = selectedNodes
-					.OfType<AssemblyTreeNode>()
-					.Where(n => n.Language is CSharpLanguage)
-					.ToList();
-
-				if (assemblyNodes.Count == selectedNodes.Count) {
-					var initialPath = Path.GetDirectoryName(assemblyNodes[0].LoadedAssembly.FileName);
-					var selectedPath = SolutionWriter.SelectSolutionFile(initialPath);
+			if (selectedNodes.Count == 1) {
+				// if there's only one treenode selected
+				// we will invoke the custom Save logic
+				if (selectedNodes[0].Save(TextView))
+					return;
+			} else if (selectedNodes.All(n => n is AssemblyTreeNode)) {
+				var initialPath = Path.GetDirectoryName(((AssemblyTreeNode)selectedNodes[0]).LoadedAssembly.FileName);
+				var selectedPath = SelectSolutionFile(initialPath);
 
 				if (!string.IsNullOrEmpty(selectedPath)) {
-						SolutionWriter.CreateSolution(TextView, selectedPath, assemblyNodes);
+					var assemblies = selectedNodes.OfType<AssemblyTreeNode>()
+						.Select(n => n.LoadedAssembly)
+						.Where(a => a != null).ToArray();
+					SolutionWriter.CreateSolution(TextView, selectedPath, CurrentLanguage, assemblies);
 				}
 				return;
 			}
-			}
 
-			if (selectedNodes.Count != 1 || !selectedNodes[0].Save(TextView)) {
+			// Fallback: if nobody was able to handle the request, use default behavior.
+			// try to save all nodes to disk.
 			var options = new DecompilationOptions() { FullDecompilation = true };
 			TextView.SaveToDisk(CurrentLanguage, selectedNodes, options);
 		}
+
+		/// <summary>
+		/// Shows a File Selection dialog where the user can select the target file for the solution.
+		/// </summary>
+		/// <param name="path">The initial path to show in the dialog. If not specified, the 'Documents' directory
+		/// will be used.</param>
+		/// 
+		/// <returns>The full path of the selected target file, or <c>null</c> if the user canceled.</returns>
+		string SelectSolutionFile(string path)
+		{
+			const string SolutionExtension = ".sln";
+			const string DefaultSolutionName = "Solution";
+
+			if (string.IsNullOrWhiteSpace(path)) {
+				path = Environment.GetFolderPath(Environment.SpecialFolder.MyDocuments);
+			}
+
+			SaveFileDialog dlg = new SaveFileDialog();
+			dlg.InitialDirectory = path;
+			dlg.FileName = Path.Combine(path, DefaultSolutionName + SolutionExtension);
+			dlg.Filter = "Visual Studio Solution file|*" + SolutionExtension;
+
+			bool targetInvalid;
+			do {
+				if (dlg.ShowDialog() != true) {
+					return null;
+				}
+
+				string selectedPath = Path.GetDirectoryName(dlg.FileName);
+				try {
+					targetInvalid = Directory.EnumerateFileSystemEntries(selectedPath).Any();
+				} catch (Exception e) when (e is IOException || e is UnauthorizedAccessException || e is System.Security.SecurityException) {
+					MessageBox.Show(
+						"The directory cannot be accessed. Please ensure it exists and you have sufficient rights to access it.",
+						"Solution directory not accessible",
+						MessageBoxButton.OK, MessageBoxImage.Error);
+					targetInvalid = true;
+					continue;
+				}
+
+				if (targetInvalid) {
+					MessageBox.Show(
+						"The directory is not empty. Please select an empty directory.",
+						"Solution directory not empty",
+						MessageBoxButton.OK, MessageBoxImage.Warning);
+				}
+			} while (targetInvalid);
+
+			return dlg.FileName;
 		}
 
 		public void RefreshDecompiledView()

ILSpy/SolutionWriter.cs

@@ -22,15 +22,12 @@ using System.Collections.Generic;
 using System.Diagnostics;
 using System.IO;
 using System.Linq;
-using System.Security;
 using System.Threading;
 using System.Threading.Tasks;
-using System.Windows;
 using ICSharpCode.Decompiler;
-using ICSharpCode.Decompiler.CSharp;
+using ICSharpCode.Decompiler.Solution;
+using ICSharpCode.Decompiler.Util;
 using ICSharpCode.ILSpy.TextView;
-using ICSharpCode.ILSpy.TreeNodes;
-using Microsoft.Win32;
 
 namespace ICSharpCode.ILSpy
 {
@@ -38,73 +35,23 @@ namespace ICSharpCode.ILSpy
 	/// An utility class that creates a Visual Studio solution containing projects for the
 	/// decompiled assemblies.
 	/// </summary>
-	internal static class SolutionWriter
+	internal class SolutionWriter
 	{
-		private const string SolutionExtension = ".sln";
-		private const string DefaultSolutionName = "Solution";
-
-		/// <summary>
-		/// Shows a File Selection dialog where the user can select the target file for the solution.
-		/// </summary>
-		/// <param name="path">The initial path to show in the dialog. If not specified, the 'Documents' directory
-		/// will be used.</param>
-		/// 
-		/// <returns>The full path of the selected target file, or <c>null</c> if the user canceled.</returns>
-		public static string SelectSolutionFile(string path)
-		{
-			if (string.IsNullOrWhiteSpace(path)) {
-				path = Environment.GetFolderPath(Environment.SpecialFolder.MyDocuments);
-			}
-
-			SaveFileDialog dlg = new SaveFileDialog();
-			dlg.InitialDirectory = path;
-			dlg.FileName = Path.Combine(path, DefaultSolutionName + SolutionExtension);
-			dlg.Filter = "Visual Studio Solution file|*" + SolutionExtension;
-
-			bool targetInvalid;
-			do {
-				if (dlg.ShowDialog() != true) {
-					return null;
-				}
-
-				string selectedPath = Path.GetDirectoryName(dlg.FileName);
-				try {
-					targetInvalid = Directory.EnumerateFileSystemEntries(selectedPath).Any();
-				} catch (Exception e) when (e is IOException || e is UnauthorizedAccessException || e is SecurityException) {
-					MessageBox.Show(
-						"The directory cannot be accessed. Please ensure it exists and you have sufficient rights to access it.",
-						"Solution directory not accessible",
-						MessageBoxButton.OK, MessageBoxImage.Error);
-					targetInvalid = true;
-					continue;
-				}
-				
-				if (targetInvalid) {
-					MessageBox.Show(
-						"The directory is not empty. Please select an empty directory.",
-						"Solution directory not empty",
-						MessageBoxButton.OK, MessageBoxImage.Warning);
-				}
-			} while (targetInvalid);
-
-			return dlg.FileName;
-		}
-
 		/// <summary>
 		/// Creates a Visual Studio solution that contains projects with decompiled code
-		/// of the specified <paramref name="assemblyNodes"/>. The solution file will be saved
+		/// of the specified <paramref name="assemblies"/>. The solution file will be saved
 		/// to the <paramref name="solutionFilePath"/>. The directory of this file must either
 		/// be empty or not exist.
 		/// </summary>
 		/// <param name="textView">A reference to the <see cref="DecompilerTextView"/> instance.</param>
 		/// <param name="solutionFilePath">The target file path of the solution file.</param>
-		/// <param name="assemblyNodes">The assembly nodes to decompile.</param>
+		/// <param name="assemblies">The assembly nodes to decompile.</param>
 		/// 
 		/// <exception cref="ArgumentException">Thrown when <paramref name="solutionFilePath"/> is null,
 		/// an empty or a whitespace string.</exception>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="textView"/>> or
-		/// <paramref name="assemblyNodes"/> is null.</exception>
-		public static void CreateSolution(DecompilerTextView textView, string solutionFilePath, IEnumerable<AssemblyTreeNode> assemblyNodes)
+		/// <paramref name="assemblies"/> is null.</exception>
+		public static void CreateSolution(DecompilerTextView textView, string solutionFilePath, Language language, IEnumerable<LoadedAssembly> assemblies)
 		{
 			if (textView == null) {
 				throw new ArgumentNullException(nameof(textView));
@@ -114,29 +61,37 @@ namespace ICSharpCode.ILSpy
 				throw new ArgumentException("The solution file path cannot be null or empty.", nameof(solutionFilePath));
 			}
 
-			if (assemblyNodes == null) {
-				throw new ArgumentNullException(nameof(assemblyNodes));
+			if (assemblies == null) {
+				throw new ArgumentNullException(nameof(assemblies));
 			}
 
+			var writer = new SolutionWriter(solutionFilePath);
+
 			textView
-				.RunWithCancellation(ct => CreateSolution(solutionFilePath, assemblyNodes, ct))
+				.RunWithCancellation(ct => writer.CreateSolution(assemblies, language, ct))
 				.Then(output => textView.ShowText(output))
 				.HandleExceptions();
 		}
 
-		private static async Task<AvalonEditTextOutput> CreateSolution(
-			string solutionFilePath,
-			IEnumerable<AssemblyTreeNode> assemblyNodes,
-			CancellationToken ct)
+		readonly string solutionFilePath;
+		readonly string solutionDirectory;
+		readonly ConcurrentBag<ProjectItem> projects;
+		readonly ConcurrentBag<string> statusOutput;
+
+		SolutionWriter(string solutionFilePath)
 		{
-			var solutionDirectory = Path.GetDirectoryName(solutionFilePath);
-			var statusOutput = new ConcurrentBag<string>();
-			var projects = new ConcurrentBag<ProjectItem>();
+			this.solutionFilePath = solutionFilePath;
+			solutionDirectory = Path.GetDirectoryName(solutionFilePath);
+			statusOutput = new ConcurrentBag<string>();
+			projects = new ConcurrentBag<ProjectItem>();
+		}
 
+		async Task<AvalonEditTextOutput> CreateSolution(IEnumerable<LoadedAssembly> assemblies, Language language, CancellationToken ct)
+		{
 			var result = new AvalonEditTextOutput();
 
 			var duplicates = new HashSet<string>();
-			if (assemblyNodes.Any(n => !duplicates.Add(n.LoadedAssembly.ShortName))) {
+			if (assemblies.Any(asm => !duplicates.Add(asm.ShortName))) {
 				result.WriteLine("Duplicate assembly names selected, cannot generate a solution.");
 				return result;
 			}
@@ -144,7 +99,7 @@ namespace ICSharpCode.ILSpy
 			Stopwatch stopwatch = Stopwatch.StartNew();
 
 			try {
-				await Task.Run(() => Parallel.ForEach(assemblyNodes, n => WriteProject(n, solutionDirectory, statusOutput, projects, ct)))
+				await Task.Run(() => Parallel.ForEach(assemblies, n => WriteProject(n, language, solutionDirectory, ct)))
 					.ConfigureAwait(false);
 
 				await Task.Run(() => SolutionCreator.WriteSolutionFile(solutionFilePath, projects))
@@ -172,13 +127,13 @@ namespace ICSharpCode.ILSpy
 
 			if (statusOutput.Count == 0) {
 				result.WriteLine("Successfully decompiled the following assemblies into Visual Studio projects:");
-				foreach (var item in assemblyNodes.Select(n => n.Text.ToString())) {
+				foreach (var item in assemblies.Select(n => n.Text.ToString())) {
 					result.WriteLine(item);
 				}
 
 				result.WriteLine();
 
-				if (assemblyNodes.Count() == projects.Count) {
+				if (assemblies.Count() == projects.Count) {
 					result.WriteLine("Created the Visual Studio Solution file.");
 				}
 
@@ -191,17 +146,10 @@ namespace ICSharpCode.ILSpy
 			return result;
 		}
 
-		private static void WriteProject(
-			AssemblyTreeNode assemblyNode,
-			string targetDirectory,
-			ConcurrentBag<string> statusOutput,
-			ConcurrentBag<ProjectItem> targetContainer,
-			CancellationToken ct)
+		void WriteProject(LoadedAssembly loadedAssembly, Language language, string targetDirectory, CancellationToken ct)
 		{
-			var loadedAssembly = assemblyNode.LoadedAssembly;
-
 			targetDirectory = Path.Combine(targetDirectory, loadedAssembly.ShortName);
-			string projectFileName = Path.Combine(targetDirectory, loadedAssembly.ShortName + assemblyNode.Language.ProjectFileExtension);
+			string projectFileName = Path.Combine(targetDirectory, loadedAssembly.ShortName + language.ProjectFileExtension);
 
 			if (!Directory.Exists(targetDirectory)) {
 				try {
@@ -218,17 +166,15 @@ namespace ICSharpCode.ILSpy
 					var options = new DecompilationOptions() {
 						FullDecompilation = true,
 						CancellationToken = ct,
-					SaveAsProjectDirectory = targetDirectory };
+						SaveAsProjectDirectory = targetDirectory
+					};
 
-					if (assemblyNode.Decompile(assemblyNode.Language, projectFileOutput, options) is ProjectId projectInfo) {
-						targetContainer.Add(new ProjectItem(projectFileName, projectInfo.PlatformName, projectInfo.Guid));
-					}
-				}
+					var projectInfo = language.DecompileAssembly(loadedAssembly, projectFileOutput, options);
+					if (projectInfo != null) {
+						projects.Add(new ProjectItem(projectFileName, projectInfo.PlatformName, projectInfo.Guid));
 					}
-			catch (OperationCanceledException) {
-				throw;
 				}
-			catch (Exception e) {
+			} catch (Exception e) when (!(e is OperationCanceledException)) {
 				statusOutput.Add($"Failed to decompile the assembly '{loadedAssembly.FileName}':{Environment.NewLine}{e}");
 			}
 		}

ILSpy/TreeNodes/AssemblyListTreeNode.cs

@@ -141,7 +141,7 @@ namespace ICSharpCode.ILSpy.TreeNodes
 
 		public Action<SharpTreeNode> Select = delegate { };
 
-		public override object Decompile(Language language, ITextOutput output, DecompilationOptions options)
+		public override void Decompile(Language language, ITextOutput output, DecompilationOptions options)
 		{
 			language.WriteCommentLine(output, "List: " + assemblyList.ListName);
 			output.WriteLine();
@@ -150,8 +150,6 @@ namespace ICSharpCode.ILSpy.TreeNodes
 				output.WriteLine();
 				asm.Decompile(language, output, options);
 			}
-
-			return true;
 		}
 
 		#region Find*Node

ILSpy/TreeNodes/AssemblyReferenceTreeNode.cs

@@ -79,7 +79,7 @@ namespace ICSharpCode.ILSpy.TreeNodes
 			}
 		}
 		
-		public override object Decompile(Language language, ITextOutput output, DecompilationOptions options)
+		public override void Decompile(Language language, ITextOutput output, DecompilationOptions options)
 		{
 			var loaded = parentAssembly.LoadedAssembly.LoadedAssemblyReferencesInfo.TryGetInfo(r.FullName, out var info);
 			if (r.IsWindowsRuntime) {
@@ -98,8 +98,6 @@ namespace ICSharpCode.ILSpy.TreeNodes
 				output.Unindent();
 				output.WriteLine();
 			}
-
-			return true;
 		}
 	}
 }

ILSpy/TreeNodes/AssemblyTreeNode.cs

@@ -240,7 +240,7 @@ namespace ICSharpCode.ILSpy.TreeNodes
 				return FilterResult.Recurse;
 		}
 
-		public override object Decompile(Language language, ITextOutput output, DecompilationOptions options)
+		public override void Decompile(Language language, ITextOutput output, DecompilationOptions options)
 		{
 			void HandleException(Exception ex, string message)
 			{
@@ -259,21 +259,21 @@ namespace ICSharpCode.ILSpy.TreeNodes
 				switch (ex.InnerException) {
 					case BadImageFormatException badImage:
 						HandleException(badImage, "This file does not contain a managed assembly.");
-						return null;
+						return;
 					case FileNotFoundException fileNotFound:
 						HandleException(fileNotFound, "The file was not found.");
-						return null;
+						return;
 					case DirectoryNotFoundException dirNotFound:
 						HandleException(dirNotFound, "The directory was not found.");
-						return null;
+						return;
 					case PEFileNotSupportedException notSupported:
 						HandleException(notSupported, notSupported.Message);
-						return null;
+						return;
 					default:
 						throw;
 				}
 			}
-			return language.DecompileAssembly(LoadedAssembly, output, options);
+			language.DecompileAssembly(LoadedAssembly, output, options);
 		}
 
 		public override bool Save(DecompilerTextView textView)

ILSpy/TreeNodes/BaseTypesEntryNode.cs

@@ -97,10 +97,9 @@ namespace ICSharpCode.ILSpy.TreeNodes
 			return false;
 		}
 
-		public override object Decompile(Language language, ITextOutput output, DecompilationOptions options)
+		public override void Decompile(Language language, ITextOutput output, DecompilationOptions options)
 		{
 			language.WriteCommentLine(output, language.TypeToString(type, includeNamespace: true));
-			return true;
 		}
 
 		IEntity IMemberTreeNode.Member {

ILSpy/TreeNodes/BaseTypesTreeNode.cs

@@ -69,14 +69,12 @@ namespace ICSharpCode.ILSpy.TreeNodes
 			}
 		}
 
-		public override object Decompile(Language language, ITextOutput output, DecompilationOptions options)
+		public override void Decompile(Language language, ITextOutput output, DecompilationOptions options)
 		{
 			App.Current.Dispatcher.Invoke(DispatcherPriority.Normal, new Action(EnsureLazyChildren));
 			foreach (ILSpyTreeNode child in this.Children) {
 				child.Decompile(language, output, options);
 			}
-
-			return true;
 		}
 	}
 }

ILSpy/TreeNodes/DerivedTypesEntryNode.cs

@@ -90,10 +90,9 @@ namespace ICSharpCode.ILSpy.TreeNodes
 			e.Handled = BaseTypesEntryNode.ActivateItem(this, type);
 		}
 
-		public override object Decompile(Language language, ITextOutput output, DecompilationOptions options)
+		public override void Decompile(Language language, ITextOutput output, DecompilationOptions options)
 		{
 			language.WriteCommentLine(output, language.TypeToString(type, includeNamespace: true));
-			return true;
 		}
 
 		IEntity IMemberTreeNode.Member => type;

ILSpy/TreeNodes/DerivedTypesTreeNode.cs

@@ -92,10 +92,9 @@ namespace ICSharpCode.ILSpy.TreeNodes
 			return typeRef.GetFullTypeName(referenceMetadata) == typeDef.GetFullTypeName(definitionMetadata);
 		}
 
-		public override object Decompile(Language language, ITextOutput output, DecompilationOptions options)
+		public override void Decompile(Language language, ITextOutput output, DecompilationOptions options)
 		{
 			threading.Decompile(language, output, options, EnsureLazyChildren);
-			return true;
 		}
 	}
 }

ILSpy/TreeNodes/EventTreeNode.cs

@@ -67,10 +67,9 @@ namespace ICSharpCode.ILSpy.TreeNodes
 				return FilterResult.Hidden;
 		}
 		
-		public override object Decompile(Language language, ITextOutput output, DecompilationOptions options)
+		public override void Decompile(Language language, ITextOutput output, DecompilationOptions options)
 		{
 			language.DecompileEvent(EventDefinition, output, options);
-			return true;
 		}
 		
 		public override bool IsPublicAPI {

ILSpy/TreeNodes/FieldTreeNode.cs

@@ -68,10 +68,9 @@ namespace ICSharpCode.ILSpy.TreeNodes
 				return FilterResult.Hidden;
 		}
 
-		public override object Decompile(Language language, ITextOutput output, DecompilationOptions options)
+		public override void Decompile(Language language, ITextOutput output, DecompilationOptions options)
 		{
 			language.DecompileField(FieldDefinition, output, options);
-			return true;
 		}
 		
 		public override bool IsPublicAPI {

ILSpy/TreeNodes/ILSpyTreeNode.cs

@@ -57,7 +57,7 @@ namespace ICSharpCode.ILSpy.TreeNodes
 				return FilterResult.Hidden;
 		}
 
-		public abstract object Decompile(Language language, ITextOutput output, DecompilationOptions options);
+		public abstract void Decompile(Language language, ITextOutput output, DecompilationOptions options);
 
 		/// <summary>
 		/// Used to implement special view logic for some items.

ILSpy/TreeNodes/MethodTreeNode.cs

@@ -83,10 +83,9 @@ namespace ICSharpCode.ILSpy.TreeNodes
 			}
 		}
 
-		public override object Decompile(Language language, ITextOutput output, DecompilationOptions options)
+		public override void Decompile(Language language, ITextOutput output, DecompilationOptions options)
 		{
 			language.DecompileMethod(MethodDefinition, output, options);
-			return true;
 		}
 
 		public override FilterResult Filter(FilterSettings settings)

ILSpy/TreeNodes/ModuleReferenceTreeNode.cs

@@ -72,11 +72,10 @@ namespace ICSharpCode.ILSpy.TreeNodes
 			}
 		}
 
-		public override object Decompile(Language language, ITextOutput output, DecompilationOptions options)
+		public override void Decompile(Language language, ITextOutput output, DecompilationOptions options)
 		{
 			language.WriteCommentLine(output, moduleName);
 			language.WriteCommentLine(output, containsMetadata ? "contains metadata" : "contains no metadata");
-			return true;
 		}
 	}
 }

ILSpy/TreeNodes/NamespaceTreeNode.cs

@@ -56,10 +56,9 @@ namespace ICSharpCode.ILSpy.TreeNodes
 				return FilterResult.Recurse;
 		}
 		
-		public override object Decompile(Language language, ITextOutput output, DecompilationOptions options)
+		public override void Decompile(Language language, ITextOutput output, DecompilationOptions options)
 		{
 			language.DecompileNamespace(name, this.Children.OfType<TypeTreeNode>().Select(t => t.TypeDefinition), output, options);
-			return true;
 		}
 	}
 }

ILSpy/TreeNodes/PropertyTreeNode.cs

@@ -74,10 +74,9 @@ namespace ICSharpCode.ILSpy.TreeNodes
 				return FilterResult.Hidden;
 		}
 
-		public override object Decompile(Language language, ITextOutput output, DecompilationOptions options)
+		public override void Decompile(Language language, ITextOutput output, DecompilationOptions options)
 		{
 			language.DecompileProperty(PropertyDefinition, output, options);
-			return true;
 		}
 
 		public override bool IsPublicAPI {

ILSpy/TreeNodes/ReferenceFolderTreeNode.cs

@@ -62,7 +62,7 @@ namespace ICSharpCode.ILSpy.TreeNodes
 				this.Children.Add(new ModuleReferenceTreeNode(parentAssembly, r, metadata));
 		}
 		
-		public override object Decompile(Language language, ITextOutput output, DecompilationOptions options)
+		public override void Decompile(Language language, ITextOutput output, DecompilationOptions options)
 		{
 			language.WriteCommentLine(output, $"Detected Target-Framework-Id: {parentAssembly.LoadedAssembly.GetTargetFrameworkIdAsync().Result}");
 			App.Current.Dispatcher.Invoke(DispatcherPriority.Normal, new Action(EnsureLazyChildren));
@@ -86,7 +86,6 @@ namespace ICSharpCode.ILSpy.TreeNodes
 				output.Unindent();
 				output.WriteLine();
 			}
-			return true;
 		}
 	}
 }

ILSpy/TreeNodes/ResourceListTreeNode.cs

@@ -64,15 +64,13 @@ namespace ICSharpCode.ILSpy.TreeNodes
 				return FilterResult.Recurse;
 		}
 		
-		public override object Decompile(Language language, ITextOutput output, DecompilationOptions options)
+		public override void Decompile(Language language, ITextOutput output, DecompilationOptions options)
 		{
 			App.Current.Dispatcher.Invoke(DispatcherPriority.Normal, new Action(EnsureLazyChildren));
 			foreach (ILSpyTreeNode child in this.Children) {
 				child.Decompile(language, output, options);
 				output.WriteLine();
 			}
-
-			return true;
 		}
 	}
 }

ILSpy/TreeNodes/ResourceNodes/ImageListResourceEntryNode.cs

@@ -75,10 +75,9 @@ namespace ICSharpCode.ILSpy.TreeNodes
 		}
 
 
-		public override object Decompile(Language language, ITextOutput output, DecompilationOptions options)
+		public override void Decompile(Language language, ITextOutput output, DecompilationOptions options)
 		{
 			EnsureLazyChildren();
-			return true;
 		}
 	}
 }

ILSpy/TreeNodes/ResourceNodes/ResourceEntryNode.cs

@@ -73,10 +73,9 @@ namespace ICSharpCode.ILSpy.TreeNodes
 			return result;
 		}
 
-		public override object Decompile(Language language, ITextOutput output, DecompilationOptions options)
+		public override void Decompile(Language language, ITextOutput output, DecompilationOptions options)
 		{
 			language.WriteCommentLine(output, string.Format("{0} = {1}", key, data));
-			return true;
 		}
 
 		public override bool Save(DecompilerTextView textView)

ILSpy/TreeNodes/ResourceNodes/ResourceTreeNode.cs

@@ -67,7 +67,7 @@ namespace ICSharpCode.ILSpy.TreeNodes
 				return FilterResult.Hidden;
 		}
 		
-		public override object Decompile(Language language, ITextOutput output, DecompilationOptions options)
+		public override void Decompile(Language language, ITextOutput output, DecompilationOptions options)
 		{
 			language.WriteCommentLine(output, string.Format("{0} ({1}, {2})", r.Name, r.ResourceType, r.Attributes));
 			
@@ -76,8 +76,6 @@ namespace ICSharpCode.ILSpy.TreeNodes
 				smartOutput.AddButton(Images.Save, Resources.Save, delegate { Save(MainWindow.Instance.TextView); });
 				output.WriteLine();
 			}
-
-			return true;
 		}
 		
 		public override bool View(DecompilerTextView textView)

ILSpy/TreeNodes/ResourceNodes/ResourcesFileTreeNode.cs

@@ -141,7 +141,7 @@ namespace ICSharpCode.ILSpy.TreeNodes
 			return true;
 		}
 
-		public override object Decompile(Language language, ITextOutput output, DecompilationOptions options)
+		public override void Decompile(Language language, ITextOutput output, DecompilationOptions options)
 		{
 			EnsureLazyChildren();
 			base.Decompile(language, output, options);
@@ -168,8 +168,6 @@ namespace ICSharpCode.ILSpy.TreeNodes
 				}
 				output.WriteLine();
 			}
-
-			return true;
 		}
 
 		internal class SerializedObjectRepresentation

ILSpy/TreeNodes/ThreadingSupport.cs

@@ -128,9 +128,8 @@ namespace ICSharpCode.ILSpy.TreeNodes
 				return FilterResult.Match;
 			}
 			
-			public override object Decompile(Language language, ITextOutput output, DecompilationOptions options)
+			public override void Decompile(Language language, ITextOutput output, DecompilationOptions options)
 			{
-				return false;
 			}
 		}
 		
@@ -152,9 +151,8 @@ namespace ICSharpCode.ILSpy.TreeNodes
 				return FilterResult.Match;
 			}
 			
-			public override object Decompile(Language language, ITextOutput output, DecompilationOptions options)
+			public override void Decompile(Language language, ITextOutput output, DecompilationOptions options)
 			{
-				return false;
 			}
 		}
 

ILSpy/TreeNodes/TypeTreeNode.cs

@@ -103,10 +103,9 @@ namespace ICSharpCode.ILSpy.TreeNodes
 
 		public override bool CanExpandRecursively => true;
 
-		public override object Decompile(Language language, ITextOutput output, DecompilationOptions options)
+		public override void Decompile(Language language, ITextOutput output, DecompilationOptions options)
 		{
 			language.DecompileType(TypeDefinition, output, options);
-			return true;
 		}
 
 		public override object Icon => GetIcon(TypeDefinition);