Add "IUsingScope" to allow representing the nesting of usings in namespaces in SharpDevelop.Dom.

git-svn-id: svn://svn.sharpdevelop.net/sharpdevelop/branches/3.0@3675 1ccf3a8d-04fe-1044-b7c0-cef0b8235c61

src/AddIns/BackendBindings/Boo/BooBinding/Project/Src/CodeCompletion/ConvertVisitor.cs

@@ -137,7 +137,7 @@ namespace Grunwald.BooBinding.CodeCompletion
 				u.Usings.Add(p.Namespace);
 			else
 				u.AddAlias(p.Alias.Name, new GetClassReturnType(_cu.ProjectContent, p.Namespace, 0));
-			_cu.Usings.Add(u);
+			_cu.UsingScope.Usings.Add(u);
 		}
 		
 		private IClass OuterClass {
@@ -504,6 +504,12 @@ namespace Grunwald.BooBinding.CodeCompletion
 			OuterClass.Properties.Add(property);
 			property.UserData = node;
 		}
+		
+		public override void OnNamespaceDeclaration(Boo.Lang.Compiler.Ast.NamespaceDeclaration node)
+		{
+			_cu.UsingScope = new DefaultUsingScope { NamespaceName = node.Name };
+			base.OnNamespaceDeclaration(node);
+		}
 	}
 }
 

src/AddIns/BackendBindings/Python/PythonBinding/Project/Src/PythonAstWalker.cs

@@ -108,7 +108,7 @@ namespace ICSharpCode.PythonBinding
 				Console.WriteLine("Name: " + name.MakeString());
 				newUsing.Usings.Add(name.MakeString());
 			}
-			compilationUnit.Usings.Add(newUsing);
+			compilationUnit.UsingScope.Usings.Add(newUsing);
 			return false;
 		}
 				

src/AddIns/BackendBindings/Python/PythonBinding/Project/Src/PythonResolver.cs

@@ -287,7 +287,7 @@ namespace ICSharpCode.PythonBinding
 			if (typeName != null) {
 				IClass resolvedClass = GetClass(typeName);
 				if (resolvedClass != null) {
-					DefaultClass dummyClass = new DefaultClass(null, "Global");
+					DefaultClass dummyClass = new DefaultClass(DefaultCompilationUnit.DummyCompilationUnit, "Global");
 					DefaultMethod dummyMethod = new DefaultMethod(dummyClass, String.Empty);
 					DefaultField.LocalVariableField field = new DefaultField.LocalVariableField(resolvedClass.DefaultReturnType, expression, DomRegion.Empty, dummyClass);
 					return new LocalResolveResult(dummyMethod, field);

src/AddIns/BackendBindings/Python/PythonBinding/Test/Parsing/ParseImportTestFixture.cs

@@ -38,13 +38,13 @@ namespace PythonBinding.Tests.Parsing
 		[Test]
 		public void OneUsing()
 		{
-			Assert.AreEqual(1, compilationUnit.Usings.Count);
+			Assert.AreEqual(1, compilationUnit.UsingScope.Usings.Count);
 		}
 		
 		[Test]
 		public void UsingSystem()
 		{
-			Assert.AreEqual("System", compilationUnit.Usings[0].Usings[0]);
+			Assert.AreEqual("System", compilationUnit.UsingScope.Usings[0].Usings[0]);
 		}
 	}
 }

src/AddIns/BackendBindings/Python/PythonBinding/Test/Resolver/NamespaceContentsAddedToCtrlSpaceTestFixture.cs

@@ -44,7 +44,7 @@ namespace PythonBinding.Tests.Resolver
 			// Add usings.
 			DefaultUsing newUsing = new DefaultUsing(cu.ProjectContent);
 			newUsing.Usings.Add("MyNamespace");
-			cu.Usings.Add(newUsing);
+			cu.UsingScope.Usings.Add(newUsing);
 
 			results = resolver.CtrlSpace(0, "".Length, parseInfo, "", ExpressionContext.Default);
 		}

src/AddIns/Misc/CodeAnalysis/Src/SuppressMessageCommand.cs

@@ -141,11 +141,20 @@ namespace ICSharpCode.CodeAnalysis
 		{
 			if (CheckImports(cu.ProjectContent.DefaultImports))
 				return true;
-			foreach (IUsing u in cu.Usings) {
+			return CheckImports(cu.UsingScope);
+		}
+		
+		static bool CheckImports(IUsingScope scope)
+		{
+			foreach (IUsing u in scope.Usings) {
 				if (CheckImports(u)) {
 					return true;
 				}
 			}
+			foreach (IUsingScope childscope in scope.ChildScopes) {
+				if (CheckImports(childscope))
+					return true;
+			}
 			return false;
 		}
 		

src/AddIns/Misc/UnitTesting/Test/Utils/MockClass.cs

@@ -127,6 +127,12 @@ namespace UnitTesting.Tests.Utils
 			}
 		}
 		
+		public IUsingScope UsingScope {
+			get {
+				throw new NotImplementedException();
+			}
+		}
+		
 		public DomRegion BodyRegion {
 			get {
 				throw new NotImplementedException();

src/Main/Base/Project/Src/Services/RefactoringService/NamespaceRefactoringService.cs

@@ -46,7 +46,7 @@ namespace ICSharpCode.SharpDevelop.Refactoring
 			if (info == null) return;
 			ICompilationUnit cu = info.MostRecentCompilationUnit;
 			
-			List<IUsing> newUsings = new List<IUsing>(cu.Usings);
+			List<IUsing> newUsings = new List<IUsing>(cu.UsingScope.Usings);
 			if (sort) {
 				newUsings.Sort(CompareUsings);
 			}
@@ -72,7 +72,7 @@ namespace ICSharpCode.SharpDevelop.Refactoring
 				PutEmptyLineAfterLastSystemNamespace(newUsings);
 			}
 			
-			cu.ProjectContent.Language.CodeGenerator.ReplaceUsings(new TextEditorDocument(document), cu.Usings, newUsings);
+			cu.ProjectContent.Language.CodeGenerator.ReplaceUsings(new TextEditorDocument(document), cu.UsingScope.Usings, newUsings);
 		}
 		
 		static void PutEmptyLineAfterLastSystemNamespace(List<IUsing> newUsings)
@@ -98,7 +98,7 @@ namespace ICSharpCode.SharpDevelop.Refactoring
 			IUsing newUsingDecl = new DefaultUsing(cu.ProjectContent);
 			newUsingDecl.Usings.Add(newNamespace);
 			
-			List<IUsing> newUsings = new List<IUsing>(cu.Usings);
+			List<IUsing> newUsings = new List<IUsing>(cu.UsingScope.Usings);
 			if (sortExistingUsings) {
 				newUsings.Sort(CompareUsings);
 			}
@@ -118,7 +118,7 @@ namespace ICSharpCode.SharpDevelop.Refactoring
 			if (sortExistingUsings) {
 				PutEmptyLineAfterLastSystemNamespace(newUsings);
 			}
-			cu.ProjectContent.Language.CodeGenerator.ReplaceUsings(new TextEditorDocument(document), cu.Usings, newUsings);
+			cu.ProjectContent.Language.CodeGenerator.ReplaceUsings(new TextEditorDocument(document), cu.UsingScope.Usings, newUsings);
 		}
 	}
 }

src/Main/Base/Test/MemberLookupHelperTests.cs

@@ -89,8 +89,8 @@ namespace ICSharpCode.SharpDevelop.Tests
 			DefaultProjectContent dpc = new DefaultProjectContent();
 			dpc.ReferencedContents.Add(msc);
 			DefaultCompilationUnit cu = new DefaultCompilationUnit(dpc);
-			cu.Usings.Add(new DefaultUsing(dpc, new DomRegion(1,1, 5,5)));
-			cu.Usings[0].Usings.Add("System.Collections.Generic");
+			cu.UsingScope.Usings.Add(new DefaultUsing(dpc, new DomRegion(1,1, 5,5)));
+			cu.UsingScope.Usings[0].Usings.Add("System.Collections.Generic");
 			
 			DefaultClass listDerivingClass = new DefaultClass(cu, "DerivesFromList");
 			cu.Classes.Add(listDerivingClass);
@@ -108,8 +108,8 @@ namespace ICSharpCode.SharpDevelop.Tests
 			DefaultProjectContent dpc = new DefaultProjectContent();
 			dpc.ReferencedContents.Add(msc);
 			DefaultCompilationUnit cu = new DefaultCompilationUnit(dpc);
-			cu.Usings.Add(new DefaultUsing(dpc, new DomRegion(1,1, 5,5)));
-			cu.Usings[0].Usings.Add("System.Collections.Generic");
+			cu.UsingScope.Usings.Add(new DefaultUsing(dpc, new DomRegion(1,1, 5,5)));
+			cu.UsingScope.Usings[0].Usings.Add("System.Collections.Generic");
 			
 			DefaultClass listDerivingClass = new DefaultClass(cu, "DerivesFromList");
 			cu.Classes.Add(listDerivingClass);

src/Main/Base/Test/SearchClassTests.cs

@@ -25,9 +25,9 @@ namespace ICSharpCode.SharpDevelop.Tests
 			pc.Language = language;
 			DefaultCompilationUnit cu = new DefaultCompilationUnit(pc);
 			if (language == LanguageProperties.VBNet)
-				cu.Usings.Add(CreateUsing(pc, "syStEm"));
+				cu.UsingScope.Usings.Add(CreateUsing(pc, "syStEm"));
 			else
-				cu.Usings.Add(CreateUsing(pc, "System"));
+				cu.UsingScope.Usings.Add(CreateUsing(pc, "System"));
 			return cu;
 		}
 		
@@ -168,7 +168,7 @@ namespace ICSharpCode.SharpDevelop.Tests
 			ICompilationUnit cu = Prepare(LanguageProperties.CSharp);
 			cu.ProjectContent.ReferencedContents.Add(ref1.ProjectContent);
 			cu.ProjectContent.ReferencedContents.Add(ref2.ProjectContent);
-			cu.Usings.Add(new DefaultUsing(cu.ProjectContent) { Usings = { "NS1", "NS2" } });
+			cu.UsingScope.Usings.Add(new DefaultUsing(cu.ProjectContent) { Usings = { "NS1", "NS2" } });
 			
 			SearchTypeResult r = cu.ProjectContent.SearchType(new SearchTypeRequest("ClassName", 0, null, cu, 1, 1));
 			Assert.AreEqual(ModifierEnum.Public, r.Result.GetUnderlyingClass().Modifiers);

src/Main/Base/Test/SearchGenericClassTests.cs

@@ -29,7 +29,7 @@ namespace ICSharpCode.SharpDevelop.Tests
 			pc.Language = language;
 			DefaultCompilationUnit cu = new DefaultCompilationUnit(pc);
 			if (usingMode == 1) {
-				cu.Usings.Add(CreateUsing(pc, "syStEm.coLLectIons"));
+				cu.UsingScope.Usings.Add(CreateUsing(pc, "syStEm.coLLectIons"));
 				pc.DefaultImports = new DefaultUsing(pc);
 				pc.DefaultImports.Usings.Add("syStEm");
 				pc.DefaultImports.Usings.Add("syStEm.coLLEctionS.GeNeRic");
@@ -39,9 +39,9 @@ namespace ICSharpCode.SharpDevelop.Tests
 				pc.DefaultImports.Usings.Add("syStEm.coLLEctioNs");
 				pc.DefaultImports.Usings.Add("syStEm.coLLEctionS.GeNeRic");
 			} else { // usingMode == 0
-				cu.Usings.Add(CreateUsing(pc, "System"));
-				cu.Usings.Add(CreateUsing(pc, "System.Collections"));
-				cu.Usings.Add(CreateUsing(pc, "System.Collections.Generic"));
+				cu.UsingScope.Usings.Add(CreateUsing(pc, "System"));
+				cu.UsingScope.Usings.Add(CreateUsing(pc, "System.Collections"));
+				cu.UsingScope.Usings.Add(CreateUsing(pc, "System.Collections.Generic"));
 			}
 			return cu;
 		}

src/Main/Base/Test/Utils/MockClass.cs

@@ -61,6 +61,12 @@ namespace ICSharpCode.SharpDevelop.Tests.Utils
 			}
 		}
 		
+		public IUsingScope UsingScope {
+			get {
+				throw new NotImplementedException();
+			}
+		}
+		
 		public DomRegion Region {
 			get {
 				throw new NotImplementedException();

src/Main/ICSharpCode.SharpDevelop.Dom/Project/ICSharpCode.SharpDevelop.Dom.csproj

@@ -88,6 +88,7 @@
     <Compile Include="Src\Implementations\DefaultReturnType.cs" />
     <Compile Include="Src\Implementations\DefaultTypeParameter.cs" />
     <Compile Include="Src\Implementations\DefaultUsing.cs" />
+    <Compile Include="Src\Implementations\DefaultUsingScope.cs" />
     <Compile Include="Src\Implementations\ElementReturnType.cs" />
     <Compile Include="Src\Implementations\GenericReturnType.cs" />
     <Compile Include="Src\Implementations\GetClassReturnType.cs" />
@@ -102,6 +103,7 @@
     <Compile Include="Src\Interfaces\ExplicitInterfaceImplementation.cs" />
     <Compile Include="Src\Interfaces\IDomProgressMonitor.cs" />
     <Compile Include="Src\Interfaces\IFreezable.cs" />
+    <Compile Include="Src\Interfaces\IUsingScope.cs" />
     <Compile Include="Src\LazyList.cs" />
     <Compile Include="Src\NRefactoryResolver\CodeSnippetConverter.cs" />
     <Compile Include="Src\NRefactoryResolver\CSharpToVBNetConvertVisitor.cs" />

src/Main/ICSharpCode.SharpDevelop.Dom/Project/Src/CtrlSpaceResolveHelper.cs

@@ -84,7 +84,7 @@ namespace ICSharpCode.SharpDevelop.Dom
 		{
 			IProjectContent projectContent = cu.ProjectContent;
 			projectContent.AddNamespaceContents(result, "", projectContent.Language, true);
-			foreach (IUsing u in cu.Usings) {
+			foreach (IUsing u in cu.GetAllUsings()) {
 				AddUsing(result, u, projectContent);
 			}
 			AddUsing(result, projectContent.DefaultImports, projectContent);

src/Main/ICSharpCode.SharpDevelop.Dom/Project/Src/ExtensionMethods.cs

@@ -8,6 +8,7 @@
 using System;
 using System.Collections;
 using System.Collections.Generic;
+using System.Linq;
 
 namespace ICSharpCode.SharpDevelop.Dom
 {
@@ -27,5 +28,33 @@ namespace ICSharpCode.SharpDevelop.Dom
 			foreach (T o in elements)
 				list.Add(o);
 		}
+		
+		public static IEnumerable<T> Flatten<T>(this IEnumerable<T> input, Func<T, IEnumerable<T>> recursion)
+		{
+			Stack<IEnumerator<T>> stack = new Stack<IEnumerator<T>>();
+			try {
+				stack.Push(input.GetEnumerator());
+				while (stack.Count > 0) {
+					while (stack.Peek().MoveNext()) {
+						T element = stack.Peek().Current;
+						yield return element;
+						IEnumerable<T> children = recursion(element);
+						if (children != null) {
+							stack.Push(children.GetEnumerator());
+						}
+					}
+					stack.Pop();
+				}
+			} finally {
+				while (stack.Count > 0) {
+					stack.Pop().Dispose();
+				}
+			}
+		}
+		
+		public static IEnumerable<IUsing> GetAllUsings(this ICompilationUnit cu)
+		{
+			return (new[]{cu.UsingScope}).Flatten(s=>s.ChildScopes).SelectMany(s=>s.Usings);
+		}
 	}
 }

src/Main/ICSharpCode.SharpDevelop.Dom/Project/Src/Implementations/AbstractEntity.cs

@@ -18,9 +18,9 @@ namespace ICSharpCode.SharpDevelop.Dom
 		
 		IClass declaringType;
 		
-		string fullyQualifiedName = null;
-		string name               = null;
-		string nspace             = null;
+		string fullyQualifiedName;
+		string name;
+		string nspace;
 		
 		public AbstractEntity(IClass declaringType)
 		{
@@ -29,11 +29,10 @@ namespace ICSharpCode.SharpDevelop.Dom
 		
 		public AbstractEntity(IClass declaringType, string name)
 		{
-			if (declaringType == null)
-				throw new ArgumentNullException("declaringType");
 			this.declaringType = declaringType;
 			this.name = name;
-			nspace = declaringType.FullyQualifiedName;
+			if (declaringType != null)
+				nspace = declaringType.FullyQualifiedName;
 			
 			// lazy-computing the fully qualified name for class members saves ~7 MB RAM (when loading the SharpDevelop solution).
 			//fullyQualifiedName = nspace + '.' + name;

src/Main/ICSharpCode.SharpDevelop.Dom/Project/Src/Implementations/DefaultClass.cs

@@ -26,6 +26,7 @@ namespace ICSharpCode.SharpDevelop.Dom
 		IList<IMethod>   methods;
 		IList<IEvent>    events;
 		IList<ITypeParameter> typeParameters;
+		IUsingScope usingScope;
 		
 		protected override void FreezeInternal()
 		{
@@ -119,23 +120,47 @@ namespace ICSharpCode.SharpDevelop.Dom
 			}
 		}
 		
+		/// <summary>
+		/// Gets the using scope of contains this class.
+		/// </summary>
+		public IUsingScope UsingScope {
+			get { return usingScope; }
+			set {
+				if (value == null)
+					throw new ArgumentNullException("UsingScope");
+				CheckBeforeMutation();
+				usingScope = value;
+			}
+		}
+		
 		public DefaultClass(ICompilationUnit compilationUnit, string fullyQualifiedName) : base(null)
 		{
+			if (compilationUnit == null)
+				throw new ArgumentNullException("compilationUnit");
+			if (fullyQualifiedName == null)
+				throw new ArgumentNullException("fullyQualifiedName");
 			this.compilationUnit = compilationUnit;
 			this.FullyQualifiedName = fullyQualifiedName;
+			this.UsingScope = compilationUnit.UsingScope;
 		}
 		
 		public DefaultClass(ICompilationUnit compilationUnit, IClass declaringType) : base(declaringType)
 		{
+			if (compilationUnit == null)
+				throw new ArgumentNullException("compilationUnit");
 			this.compilationUnit = compilationUnit;
+			this.UsingScope = compilationUnit.UsingScope;
 		}
 		
 		public DefaultClass(ICompilationUnit compilationUnit, ClassType classType, ModifierEnum modifiers, DomRegion region, IClass declaringType) : base(declaringType)
 		{
+			if (compilationUnit == null)
+				throw new ArgumentNullException("compilationUnit");
 			this.compilationUnit = compilationUnit;
 			this.region = region;
 			this.classType = classType;
 			Modifiers = modifiers;
+			this.UsingScope = compilationUnit.UsingScope;
 		}
 		
 		// fields must be volatile to ensure that the optimizer doesn't reorder accesses to it

src/Main/ICSharpCode.SharpDevelop.Dom/Project/Src/Implementations/DefaultCompilationUnit.cs

@@ -21,7 +21,7 @@ namespace ICSharpCode.SharpDevelop.Dom
 			return this;
 		}
 		
-		IList<IUsing> usings  = new List<IUsing>();
+		IUsingScope usingScope = new DefaultUsingScope();
 		IList<IClass> classes = new List<IClass>();
 		IList<IAttribute> attributes = new List<IAttribute>();
 		IList<FoldingRegion> foldingRegions = new List<FoldingRegion>();
@@ -30,11 +30,11 @@ namespace ICSharpCode.SharpDevelop.Dom
 		protected override void FreezeInternal()
 		{
 			// Deep Freeze: freeze lists and their contents
-			usings = FreezeList(usings);
 			classes = FreezeList(classes);
 			attributes = FreezeList(attributes);
 			foldingRegions = FreezeList(foldingRegions);
 			tagComments = FreezeList(tagComments);
+			usingScope.Freeze();
 			
 			base.FreezeInternal();
 		}
@@ -85,9 +85,13 @@ namespace ICSharpCode.SharpDevelop.Dom
 			}
 		}
 		
-		public virtual IList<IUsing> Usings {
-			get {
-				return usings;
+		public virtual IUsingScope UsingScope {
+			get { return usingScope; }
+			set {
+				if (value == null)
+					throw new ArgumentNullException("UsingScope");
+				CheckBeforeMutation();
+				usingScope = value;
 			}
 		}
 

src/Main/ICSharpCode.SharpDevelop.Dom/Project/Src/Implementations/DefaultUsingScope.cs

@@ -0,0 +1,70 @@
+// <file>
+//     <copyright see="prj:///doc/copyright.txt"/>
+//     <license see="prj:///doc/license.txt"/>
+//     <author name="Daniel Grunwald"/>
+//     <version>$Revision$</version>
+// </file>
+
+using System;
+using System.Collections.Generic;
+
+namespace ICSharpCode.SharpDevelop.Dom
+{
+	public class DefaultUsingScope : AbstractFreezable, IUsingScope
+	{
+		DomRegion region;
+		IUsingScope parent;
+		IList<IUsing> usings;
+		IList<IUsingScope> childScopes;
+		string namespaceName = "";
+		
+		protected override void FreezeInternal()
+		{
+			base.FreezeInternal();
+			usings = FreezeList(usings);
+			childScopes = FreezeList(childScopes);
+		}
+		
+		public DomRegion Region {
+			get { return region; }
+			set {
+				CheckBeforeMutation();
+				region = value;
+			}
+		}
+		
+		public IUsingScope Parent {
+			get { return parent; }
+			set {
+				CheckBeforeMutation();
+				parent = value;
+			}
+		}
+		
+		public virtual IList<IUsing> Usings {
+			get {
+				if (usings == null)
+					usings = new List<IUsing>();
+				return usings;
+			}
+		}
+		
+		public virtual IList<IUsingScope> ChildScopes {
+			get {
+				if (childScopes == null)
+					childScopes = new List<IUsingScope>();
+				return childScopes;
+			}
+		}
+		
+		public string NamespaceName {
+			get { return namespaceName; }
+			set {
+				if (value == null)
+					throw new ArgumentNullException("NamespaceName");
+				CheckBeforeMutation();
+				namespaceName = value;
+			}
+		}
+	}
+}

src/Main/ICSharpCode.SharpDevelop.Dom/Project/Src/Interfaces/IClass.cs

@@ -43,6 +43,13 @@ namespace ICSharpCode.SharpDevelop.Dom
 			get;
 		}
 		
+		/// <summary>
+		/// Gets the using scope of contains this class.
+		/// </summary>
+		IUsingScope UsingScope {
+			get;
+		}
+		
 		IList<IReturnType> BaseTypes {
 			get;
 		}

src/Main/ICSharpCode.SharpDevelop.Dom/Project/Src/Interfaces/ICompilationUnit.cs

@@ -30,7 +30,11 @@ namespace ICSharpCode.SharpDevelop.Dom
 			get;
 		}
 		
-		IList<IUsing> Usings {
+		/// <summary>
+		/// Gets the main using scope of the compilation unit.
+		/// That scope usually represents the root namespace.
+		/// </summary>
+		IUsingScope UsingScope {
 			get;
 		}
 		

src/Main/ICSharpCode.SharpDevelop.Dom/Project/Src/Interfaces/IUsingScope.cs

@@ -0,0 +1,46 @@
+// <file>
+//     <copyright see="prj:///doc/copyright.txt"/>
+//     <license see="prj:///doc/license.txt"/>
+//     <author name="Daniel Grunwald"/>
+//     <version>$Revision$</version>
+// </file>
+
+using System;
+using System.Collections.Generic;
+
+namespace ICSharpCode.SharpDevelop.Dom
+{
+	/// <summary>
+	/// A scope that can contain using declarations.
+	/// In C#, every file is a using scope, and every "namespace" declaration inside
+	/// the file is a nested using scope.
+	/// </summary>
+	public interface IUsingScope : IFreezable
+	{
+		/// <summary>
+		/// Gets the region of the using scope.
+		/// </summary>
+		DomRegion Region { get; }
+		
+		/// <summary>
+		/// Gets the parent scope.
+		/// Returns null if this is a root scope.
+		/// </summary>
+		IUsingScope Parent { get; }
+		
+		/// <summary>
+		/// Gets the usings in this using scope.
+		/// </summary>
+		IList<IUsing> Usings { get; }
+		
+		/// <summary>
+		/// Gets the list of child scopes. Child scopes usually represent "namespace" declarations.
+		/// </summary>
+		IList<IUsingScope> ChildScopes { get; }
+		
+		/// <summary>
+		/// Gets the name of the namespace represented by the using scope.
+		/// </summary>
+		string NamespaceName { get; }
+	}
+}

src/Main/ICSharpCode.SharpDevelop.Dom/Project/Src/NRefactoryResolver/NRefactoryASTConvertVisitor.cs

@@ -19,8 +19,8 @@ namespace ICSharpCode.SharpDevelop.Dom.NRefactoryResolver
 {
 	public class NRefactoryASTConvertVisitor : AbstractAstVisitor
 	{
-		ICompilationUnit cu;
-		Stack<string> currentNamespace = new Stack<string>();
+		DefaultCompilationUnit cu;
+		DefaultUsingScope currentNamespace;
 		Stack<DefaultClass> currentClass = new Stack<DefaultClass>();
 		public string VBRootNamespace { get; set; }
 		
@@ -181,13 +181,12 @@ namespace ICSharpCode.SharpDevelop.Dom.NRefactoryResolver
 			if (compilationUnit == null) {
 				return null;
 			}
+			currentNamespace = new DefaultUsingScope();
 			if (!string.IsNullOrEmpty(VBRootNamespace)) {
-				currentNamespace.Push(VBRootNamespace);
-				compilationUnit.AcceptChildren(this, data);
-				currentNamespace.Pop();
-			} else {
-				compilationUnit.AcceptChildren(this, data);
+				currentNamespace.NamespaceName = VBRootNamespace;
 			}
+			cu.UsingScope = currentNamespace;
+			compilationUnit.AcceptChildren(this, data);
 			return cu;
 		}
 		
@@ -197,7 +196,7 @@ namespace ICSharpCode.SharpDevelop.Dom.NRefactoryResolver
 			foreach (AST.Using u in usingDeclaration.Usings) {
 				u.AcceptVisitor(this, us);
 			}
-			cu.Usings.Add(us);
+			currentNamespace.Usings.Add(us);
 			return data;
 		}
 		
@@ -313,18 +312,24 @@ namespace ICSharpCode.SharpDevelop.Dom.NRefactoryResolver
 			return null;
 		}
 		
+		string PrependCurrentNamespace(string name)
+		{
+			if (string.IsNullOrEmpty(currentNamespace.NamespaceName))
+				return name;
+			else
+				return currentNamespace.NamespaceName + "." + name;
+		}
+		
 		public override object VisitNamespaceDeclaration(AST.NamespaceDeclaration namespaceDeclaration, object data)
 		{
-			string name;
-			if (currentNamespace.Count == 0) {
-				name = namespaceDeclaration.Name;
-			} else {
-				name = currentNamespace.Peek() + '.' + namespaceDeclaration.Name;
-			}
-			
-			currentNamespace.Push(name);
+			DefaultUsingScope oldNamespace = currentNamespace;
+			currentNamespace = new DefaultUsingScope {
+				Parent = oldNamespace,
+				NamespaceName = PrependCurrentNamespace(namespaceDeclaration.Name),
+			};
+			oldNamespace.ChildScopes.Add(currentNamespace);
 			object ret = namespaceDeclaration.AcceptChildren(this, data);
-			currentNamespace.Pop();
+			currentNamespace = oldNamespace;
 			return ret;
 		}
 		
@@ -364,13 +369,10 @@ namespace ICSharpCode.SharpDevelop.Dom.NRefactoryResolver
 				cur.InnerClasses.Add(c);
 				c.FullyQualifiedName = cur.FullyQualifiedName + '.' + typeDeclaration.Name;
 			} else {
-				if (currentNamespace.Count == 0) {
-					c.FullyQualifiedName = typeDeclaration.Name;
-				} else {
-					c.FullyQualifiedName = currentNamespace.Peek() + '.' + typeDeclaration.Name;
-				}
+				c.FullyQualifiedName = PrependCurrentNamespace(typeDeclaration.Name);
 				cu.Classes.Add(c);
 			}
+			c.UsingScope = currentNamespace;
 			currentClass.Push(c);
 			
 			ConvertTemplates(typeDeclaration.Templates, c); // resolve constrains in context of the class
@@ -468,13 +470,10 @@ namespace ICSharpCode.SharpDevelop.Dom.NRefactoryResolver
 				cur.InnerClasses.Add(c);
 				c.FullyQualifiedName = cur.FullyQualifiedName + '.' + name;
 			} else {
-				if (currentNamespace.Count == 0) {
-					c.FullyQualifiedName = name;
-				} else {
-					c.FullyQualifiedName = currentNamespace.Peek() + '.' + name;
-				}
+				c.FullyQualifiedName = PrependCurrentNamespace(name);
 				cu.Classes.Add(c);
 			}
+			c.UsingScope = currentNamespace;
 			currentClass.Push(c); // necessary for CreateReturnType
 			ConvertTemplates(templates, c);
 			

src/Main/ICSharpCode.SharpDevelop.Dom/Project/Src/NRefactoryResolver/NRefactoryResolver.cs

@@ -205,7 +205,7 @@ namespace ICSharpCode.SharpDevelop.Dom.NRefactoryResolver
 				} else if ("global".Equals(expression, StringComparison.InvariantCultureIgnoreCase)) {
 					return new NamespaceResolveResult(null, null, "");
 				}
-			// array
+				// array
 			} else if (language == NR.SupportedLanguage.CSharp && expressionResult.Context.IsTypeContext && !expressionResult.Context.IsObjectCreation) {
 				expr = ParseTypeReference(expression);
 			}
@@ -596,16 +596,19 @@ namespace ICSharpCode.SharpDevelop.Dom.NRefactoryResolver
 			}
 			
 			if (languageProperties.CanImportClasses) {
-				foreach (IUsing @using in cu.Usings) {
-					foreach (string import in @using.Usings) {
-						IClass c = GetClass(import, 0);
-						if (c != null) {
-							ResolveResult rr = ResolveMember(c.DefaultReturnType, identifier,
-							                                 identifierExpression.TypeArguments,
-							                                 IsInvoked(identifierExpression),
-							                                 false, null);
-							if (rr != null && rr.IsValid)
-								return rr;
+				IUsingScope scope = callingClass != null ? callingClass.UsingScope : cu.UsingScope;
+				for (; scope != null; scope = scope.Parent) {
+					foreach (IUsing @using in scope.Usings) {
+						foreach (string import in @using.Usings) {
+							IClass c = GetClass(import, 0);
+							if (c != null) {
+								ResolveResult rr = ResolveMember(c.DefaultReturnType, identifier,
+								                                 identifierExpression.TypeArguments,
+								                                 IsInvoked(identifierExpression),
+								                                 false, null);
+								if (rr != null && rr.IsValid)
+									return rr;
+							}
 						}
 					}
 				}

src/Main/ICSharpCode.SharpDevelop.Dom/Project/Src/ProjectContent/DefaultProjectContent.cs

@@ -238,7 +238,7 @@ namespace ICSharpCode.SharpDevelop.Dom
 		/// </summary>
 		private class GenericClassContainer : DefaultClass
 		{
-			public GenericClassContainer(string fullyQualifiedName) : base(null, fullyQualifiedName) {}
+			public GenericClassContainer(string fullyQualifiedName) : base(DefaultCompilationUnit.DummyCompilationUnit, fullyQualifiedName) {}
 			
 			IClass[] realClasses = new IClass[4];
 			
@@ -744,7 +744,7 @@ namespace ICSharpCode.SharpDevelop.Dom
 				return null;
 			}
 			
-			foreach (IUsing u in unit.Usings) {
+			foreach (IUsing u in unit.GetAllUsings()) {
 				if (u != null) {
 					string nameSpace = u.SearchNamespace(name);
 					if (nameSpace != null) {
@@ -854,7 +854,7 @@ namespace ICSharpCode.SharpDevelop.Dom
 			}
 			if (request.CurrentCompilationUnit != null) {
 				// Combine name with usings
-				foreach (IUsing u in request.CurrentCompilationUnit.Usings) {
+				foreach (IUsing u in request.CurrentCompilationUnit.GetAllUsings()) {
 					if (u != null) {
 						foreach (IReturnType r in u.SearchType(name, request.TypeParameterCount)) {
 							if (MatchesRequest(ref request, r)) {

src/Main/ICSharpCode.SharpDevelop.Dom/Project/Src/Refactoring/NRefactoryRefactoringProvider.cs

@@ -8,6 +8,7 @@
 using System;
 using System.Collections.Generic;
 using System.IO;
+using System.Linq;
 using System.Text;
 
 using ICSharpCode.NRefactory.Ast;
@@ -510,7 +511,8 @@ namespace ICSharpCode.SharpDevelop.Dom.Refactoring
 				if (tr.ExtensionMethod != null) {
 					// the invocation of an extension method can implicitly use a using
 					StringComparer nameComparer = cu.ProjectContent.Language.NameComparer;
-					foreach (IUsing import in cu.Usings) {
+					// go through all usings in all nested child scopes
+					foreach (IUsing import in cu.GetAllUsings()) {
 						foreach (string i in import.Usings) {
 							if (nameComparer.Equals(tr.ExtensionMethod.DeclaringType.Namespace, i)) {
 								usedUsings.Add(import);
@@ -528,7 +530,7 @@ namespace ICSharpCode.SharpDevelop.Dom.Refactoring
 			}
 			
 			List<IUsing> unusedUsings = new List<IUsing>();
-			foreach (IUsing import in cu.Usings) {
+			foreach (IUsing import in cu.GetAllUsings()) {
 				if (!usedUsings.Contains(import)) {
 					if (import.HasAliases) {
 						foreach (string key in import.Aliases.Keys) {