Fixed NullReferenceException when opening C# file without opening a solution.

src/AddIns/DisplayBindings/AvalonEdit.AddIn/Src/QuickClassBrowser.cs

@@ -242,28 +242,21 @@ namespace ICSharpCode.AvalonEdit.AddIn
 			IUnresolvedTypeDefinition selectedClass = item != null ? item.Entity as IUnresolvedTypeDefinition : null;
 			memberItems = new List<EntityItem>();
 			if (selectedClass != null) {
-				var project = ProjectService.OpenSolution.FindProjectContainingFile(FileName.Create(selectedClass.ParsedFile.FileName));
-				if (project != null) {
-					ICompilation c = ParserService.GetCompilation(project);
-					// HACK: Resolving an IUnresolvedTypeDefinition currently does strange things in NR5 if the unresolved typedef
-					// is not part of the compilation (e.g. replaced with newer version), so we need this hack to ensure we
-					// use it only as a type name:
-					var typeRef = ReflectionHelper.ParseReflectionName(selectedClass.ReflectionName);
-					var context = new SimpleTypeResolveContext(c.MainAssembly);
-					ITypeDefinition compoundClass = typeRef.Resolve(context).GetDefinition();
-					if (compoundClass != null) {
-						var ambience = project.GetAmbience();
-						foreach (var member in compoundClass.Members) {
-							if (member.IsSynthetic)
-								continue;
-							bool isInSamePart = string.Equals(member.UnresolvedMember.ParsedFile.FileName, selectedClass.ParsedFile.FileName, StringComparison.OrdinalIgnoreCase);
-							memberItems.Add(new EntityItem(member, ambience) { IsInSamePart = isInSamePart });
-						}
-						memberItems.Sort();
-						if (jumpOnSelectionChange) {
-							AnalyticsMonitorService.TrackFeature(GetType(), "JumpToClass");
-							JumpTo(item, selectedClass.Region);
-						}
+				ICompilation compilation = ParserService.GetCompilationForFile(FileName.Create(selectedClass.ParsedFile.FileName));
+				var context = new SimpleTypeResolveContext(compilation.MainAssembly);
+				ITypeDefinition compoundClass = selectedClass.Resolve(context).GetDefinition();
+				if (compoundClass != null) {
+					var ambience = compilation.GetAmbience();
+					foreach (var member in compoundClass.Members) {
+						if (member.IsSynthetic)
+							continue;
+						bool isInSamePart = string.Equals(member.UnresolvedMember.ParsedFile.FileName, selectedClass.ParsedFile.FileName, StringComparison.OrdinalIgnoreCase);
+						memberItems.Add(new EntityItem(member, ambience) { IsInSamePart = isInSamePart });
+					}
+					memberItems.Sort();
+					if (jumpOnSelectionChange) {
+						AnalyticsMonitorService.TrackFeature(GetType(), "JumpToClass");
+						JumpTo(item, selectedClass.Region);
 					}
 				}
 			}

src/Main/Base/Project/Src/Services/ParserService/ParserService.cs

@@ -48,7 +48,8 @@ namespace ICSharpCode.SharpDevelop.Parser
 		/// </summary>
 		public static ICompilation GetCompilationForFile(FileName fileName)
 		{
-			return GetCurrentSolutionSnapshot().GetCompilation(ProjectService.OpenSolution.FindProjectContainingFile(fileName));
+			Solution solution = ProjectService.OpenSolution;
+			return GetCurrentSolutionSnapshot().GetCompilation(solution != null ? solution.FindProjectContainingFile(fileName) : null);
 		}
 		
 		/// <summary>
@@ -65,23 +66,6 @@ namespace ICSharpCode.SharpDevelop.Parser
 		{
 			return project.ProjectContent;
 		}
-		
-		/// <summary>
-		/// Gets the project that owns the specified project content.
-		/// Returns null for referenced assemblies.
-		/// </summary>
-		public static IProject GetProject(IProjectContent projectContent)
-		{
-			if (projectContent == null)
-				return null;
-			if (ProjectService.OpenSolution != null) {
-				foreach (var project in ProjectService.OpenSolution.Projects) {
-					if (project.ProjectContent == projectContent)
-						return project;
-				}
-			}
-			return null;
-		}
 		#endregion
 		
 		#region Initialization + ParserThread

src/Main/Base/Project/Src/Services/ParserService/SharpDevelopSolutionSnapshot.cs

@@ -35,7 +35,7 @@ namespace ICSharpCode.SharpDevelop.Parser
 		public IProjectContent GetProjectContent(IProject project)
 		{
 			if (project == null)
-				throw new ArgumentNullException("project");
+				return null;
 			IProjectContent pc;
 			if (projectContentSnapshots.TryGetValue(project, out pc))
 				return pc;
@@ -43,6 +43,17 @@ namespace ICSharpCode.SharpDevelop.Parser
 				return null;
 		}
 		
+		public IProject GetProject(IProjectContent projectContent)
+		{
+			if (projectContent == null)
+				return null;
+			foreach (var pair in projectContentSnapshots) {
+				if (pair.Value == projectContent)
+					return pair.Key;
+			}
+			return null;
+		}
+		
 		public ICompilation GetCompilation(IProject project)
 		{
 			IProjectContent pc;

src/Main/Base/Project/Src/Util/ExtensionMethods.cs

@@ -127,6 +127,21 @@ namespace ICSharpCode.SharpDevelop
 			return ICSharpCode.NRefactory.Utils.TreeTraversal.PreOrder(input, recursion);
 		}
 		
+		/// <summary>
+		/// Gets the project for which the specified compilation was created.
+		/// Returns null if the compilation was not created using the SharpDevelop project system.
+		/// </summary>
+		public static IProject GetProject(this ICompilation compilation)
+		{
+			if (compilation == null)
+				throw new ArgumentNullException("compilation");
+			var snapshot = compilation.SolutionSnapshot as SharpDevelopSolutionSnapshot;
+			if (snapshot != null)
+				return snapshot.GetProject(compilation.MainAssembly.UnresolvedAssembly as IProjectContent);
+			else
+				return null;
+		}
+		
 		/// <summary>
 		/// Creates an array containing a part of the array (similar to string.Substring).
 		/// </summary>
@@ -549,12 +564,12 @@ namespace ICSharpCode.SharpDevelop
 		}
 		
 		/// <summary>
-		/// Gets the ambience for the specified project content.
+		/// Gets the ambience for the specified compilation.
 		/// Never returns null.
 		/// </summary>
-		public static IAmbience GetAmbience(this IProjectContent pc)
+		public static IAmbience GetAmbience(this ICompilation compilation)
 		{
-			IProject p = ParserService.GetProject(pc);
+			IProject p = compilation.GetProject();
 			if (p != null)
 				return p.GetAmbience();
 			else