Updated AST & mcs.

ICSharpCode.NRefactory.Tests/CSharp/Parser/ParseUtil.cs

@@ -13,38 +13,38 @@ namespace ICSharpCode.NRefactory.CSharp.Parser
 	/// </summary>
 	public class ParseUtilCSharp
 	{
-		public static T ParseGlobal<T>(string code, bool expectErrors = false) where T : INode
+		public static T ParseGlobal<T>(string code, bool expectErrors = false) where T : DomNode
 		{
 			CSharpParser parser = new CSharpParser();
 			CompilationUnit cu = parser.Parse(new StringReader(code));
 			
 			Assert.AreEqual(expectErrors, parser.HasErrors, "HasErrors");
 			
-			INode node = cu.Children.Single();
+			DomNode node = cu.Children.Single();
 			Type type = typeof(T);
 			Assert.IsTrue(type.IsAssignableFrom(node.GetType()), String.Format("Parsed node was {0} instead of {1} ({2})", node.GetType(), type, node));
 			return (T)node;
 		}
 		
-		public static T ParseStatement<T>(string stmt, bool expectErrors = false) where T : INode
+		public static T ParseStatement<T>(string stmt, bool expectErrors = false) where T : DomNode
 		{
 			CSharpParser parser = new CSharpParser();
 			var statements = parser.ParseStatements(new StringReader(stmt));
 			
 			Assert.AreEqual(expectErrors, parser.HasErrors, "HasErrors");
 			
-			INode statement = statements.Single();
+			DomNode statement = statements.Single();
 			Type type = typeof(T);
 			Assert.IsTrue(type.IsAssignableFrom(statement.GetType()), String.Format("Parsed statement was {0} instead of {1} ({2})", statement.GetType(), type, statement));
 			return (T)statement;
 		}
 		
-		public static T ParseExpression<T>(string expr, bool expectErrors = false) where T : INode
+		public static T ParseExpression<T>(string expr, bool expectErrors = false) where T : DomNode
 		{
 			if (expectErrors) Assert.Ignore("errors not yet implemented");
 			
 			CSharpParser parser = new CSharpParser();
-			INode parsedExpression = parser.ParseExpression(new StringReader(expr));
+			DomNode parsedExpression = parser.ParseExpression(new StringReader(expr));
 			
 			Assert.AreEqual(expectErrors, parser.HasErrors, "HasErrors");
 			

ICSharpCode.NRefactory.Tests/CSharp/Resolver/ResolverTestBase.cs

@@ -175,11 +175,11 @@ namespace ICSharpCode.NRefactory.CSharp.Resolver
 			return (T)rr;
 		}
 		
-		sealed class FindNodeVisitor : AbstractDomVisitor<object, object>
+		sealed class FindNodeVisitor : DomVisitor<object, object>
 		{
 			readonly DomLocation start;
 			readonly DomLocation end;
-			public INode ResultNode;
+			public DomNode ResultNode;
 			
 			public FindNodeVisitor(DomLocation start, DomLocation end)
 			{
@@ -187,7 +187,7 @@ namespace ICSharpCode.NRefactory.CSharp.Resolver
 				this.end = end;
 			}
 			
-			protected override object VisitChildren(INode node, object data)
+			protected override object VisitChildren(DomNode node, object data)
 			{
 				if (node.StartLocation == start && node.EndLocation == end) {
 					if (ResultNode != null)

ICSharpCode.NRefactory/CSharp/Dom/CSharpModifierToken.cs

@@ -1,4 +1,4 @@
-// 
+// 
 // CSharpModifierToken.cs
 //  
 // Author:
@@ -46,7 +46,7 @@ namespace ICSharpCode.NRefactory.CSharp
 		static CSharpModifierToken ()
 		{
 			lengthTable[Modifiers.New] = "new".Length;
-			lengthTable[Modifiers.Public] = "public".Length;
+			lengthTable[Modifiers.Public] = "new".Length;
 			lengthTable[Modifiers.Protected] = "protected".Length;
 			lengthTable[Modifiers.Private] = "private".Length;
 			lengthTable[Modifiers.Internal] = "internal".Length;
@@ -61,6 +61,7 @@ namespace ICSharpCode.NRefactory.CSharp
 			lengthTable[Modifiers.Extern] = "extern".Length;
 			lengthTable[Modifiers.Volatile] = "volatile".Length;
 			lengthTable[Modifiers.Unsafe] = "unsafe".Length;
+			lengthTable[Modifiers.Override] = "override".Length; 
 		}
 		
 		public CSharpModifierToken (DomLocation location, Modifiers modifier) : base (location, 0)

ICSharpCode.NRefactory/CSharp/Dom/CSharpTokenNode.cs

@@ -24,11 +24,36 @@
 // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 // THE SOFTWARE.
 using System;
-using ICSharpCode.NRefactory.TypeSystem;
 namespace ICSharpCode.NRefactory.CSharp
 {
-	public class CSharpTokenNode : AbstractNode
+	public class CSharpTokenNode : DomNode
 	{
+		public static new readonly CSharpTokenNode Null = new NullCSharpTokenNode ();
+		class NullCSharpTokenNode : CSharpTokenNode
+		{
+			public override bool IsNull {
+				get {
+					return true;
+				}
+			}
+			
+			public NullCSharpTokenNode () : base (DomLocation.Empty, 0)
+			{
+			}
+			
+			public override S AcceptVisitor<T, S> (DomVisitor<T, S> visitor, T data)
+			{
+				return default (S);
+			}
+		}
+		
+		
+		public override NodeType NodeType {
+			get {
+				return NodeType.Token;
+			}
+		}
+		
 		DomLocation startLocation;
 		public override DomLocation StartLocation {
 			get {
@@ -49,7 +74,7 @@ namespace ICSharpCode.NRefactory.CSharp
 			this.tokenLength = tokenLength;
 		}
 		
-		public override S AcceptVisitor<T, S> (IDomVisitor<T, S> visitor, T data)
+		public override S AcceptVisitor<T, S> (DomVisitor<T, S> visitor, T data)
 		{
 			return default (S);
 		}

ICSharpCode.NRefactory/CSharp/Dom/CompilationUnit.cs

@@ -24,16 +24,74 @@
 // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 // THE SOFTWARE.
 using System;
+using System.Collections.Generic;
 
 namespace ICSharpCode.NRefactory.CSharp
 {
-	public class CompilationUnit : AbstractNode 
+	public class CompilationUnit : DomNode 
 	{
+		public override NodeType NodeType {
+			get {
+				return NodeType.Unknown;
+			}
+		}
+		
 		public CompilationUnit ()
 		{
 		}
 		
-		public override S AcceptVisitor<T, S> (IDomVisitor<T, S> visitor, T data)
+		public DomNode GetNodeAt (int line, int column)
+		{
+			return GetNodeAt (new DomLocation (line, column));
+		}
+		
+		public DomNode GetNodeAt (DomLocation location)
+		{
+			DomNode node = this;
+			while (node.FirstChild != null) {
+				var child = node.FirstChild;
+				while (child != null) {
+					if (child.StartLocation <= location && location < child.EndLocation) {
+						node = child;
+						break;
+					}
+					child = child.NextSibling;
+				}
+				// found no better child node - therefore the parent is the right one.
+				if (child == null)
+					break;
+			}
+			return node;
+		}
+		
+		public IEnumerable<DomNode> GetNodesBetween (int startLine, int startColumn, int endLine, int endColumn)
+		{
+			return GetNodesBetween (new DomLocation (startLine, startColumn), new DomLocation (endLine, endColumn));
+		}
+		
+		public IEnumerable<DomNode> GetNodesBetween (DomLocation start, DomLocation end)
+		{
+			DomNode node = this;
+			while (node != null) {
+				DomNode next;
+				if (start <= node.StartLocation && node.EndLocation < end) {
+					yield return node;
+					next = node.NextSibling;
+				} else {
+					if (node.EndLocation < start) {
+						next = node.NextSibling; 
+					} else {
+						next = node.FirstChild;
+					}
+				}
+				
+				if (next != null && next.StartLocation > end)
+					yield break;
+				node = next;
+			}
+		}
+		
+		public override S AcceptVisitor<T, S> (DomVisitor<T, S> visitor, T data)
 		{
 			return visitor.VisitCompilationUnit (this, data);
 		}

ICSharpCode.NRefactory/CSharp/Dom/ComposedType.cs

@@ -27,15 +27,22 @@ using System;
 using System.Collections.Generic;
 using System.Linq;
 
+
 namespace ICSharpCode.NRefactory.CSharp
 {
-	public class ComposedType : AbstractNode
+	public class ComposedType : DomNode
 	{
 		public const int NullableRole  = 100;
 		public const int PointerRole   = 101;
 		public const int ArraySpecRole = 102;
 		
-		public INode BaseType {
+		public override NodeType NodeType {
+			get {
+				return NodeType.Unknown;
+			}
+		}
+		
+		public DomNode BaseType {
 			get {
 				return GetChildByRole (Roles.ReturnType);
 			}
@@ -45,13 +52,18 @@ namespace ICSharpCode.NRefactory.CSharp
 			get { return GetChildrenByRole (ArraySpecRole).Cast<ArraySpecifier> () ?? new ArraySpecifier[0]; }
 		}
 		
-		public override S AcceptVisitor<T, S> (IDomVisitor<T, S> visitor, T data)
+		public override S AcceptVisitor<T, S> (DomVisitor<T, S> visitor, T data)
 		{
 			return visitor.VisitComposedType (this, data);
 		}
 		
-		public class ArraySpecifier : AbstractNode
+		public class ArraySpecifier : DomNode
 		{
+			public override NodeType NodeType {
+				get {
+					return NodeType.Unknown;
+				}
+			}
 			
 			public CSharpTokenNode LBracket {
 				get { return (CSharpTokenNode)GetChildByRole (Roles.LBracket); }
@@ -62,7 +74,7 @@ namespace ICSharpCode.NRefactory.CSharp
 			}
 		
 			
-			public override S AcceptVisitor<T, S> (IDomVisitor<T, S> visitor, T data)
+			public override S AcceptVisitor<T, S> (DomVisitor<T, S> visitor, T data)
 			{
 				return default (S);
 			}

ICSharpCode.NRefactory/CSharp/Dom/DomNode.cs

@@ -1,5 +1,5 @@
-// 
-// AbstractNode.cs
+// 
+// AstNode.cs
 //  
 // Author:
 //       Mike Krüger <mkrueger@novell.com>
@@ -29,56 +29,42 @@ using System.Collections.Generic;
 
 namespace ICSharpCode.NRefactory.CSharp
 {
-	public abstract class AbstractNode : INode
+	public abstract class DomNode
 	{
-		public static class Roles
+		public static readonly DomNode Null = new NullAstNode ();
+		class NullAstNode : DomNode
 		{
-			// some pre defined constants for common roles
-			public const int Identifier    = 1;
-			public const int Keyword   = 2;
-			public const int Argument  = 3;
-			public const int Attribute = 4;
-			public const int ReturnType = 5;
-			public const int Modifier  = 6;
-			public const int Body       = 7;
-			public const int Initializer = 8;
-			public const int Condition = 9;
-			public const int EmbeddedStatement = 10;
-			public const int Iterator = 11;
-			public const int Expression = 12;
-			public const int Statement = 13;
-			public const int TargetExpression = 14;
-			public const int Member = 15;
-			
-			// some pre defined constants for most used punctuation 
-			
-			public const int LPar = 50; // (
-			public const int RPar = 51; // )
-			
-			public const int LBrace = 52; // {
-			public const int RBrace = 53; // }
-			
-			public const int LBracket = 54; // [
-			public const int RBracket = 55; // ]
-			
-			public const int LChevron = 56; // <
-			public const int RChevron = 57; // >
-			
-			public const int Dot = 58; // ,
-			public const int Comma = 59; // ,
-			public const int Colon = 60; // :
-			public const int Semicolon = 61; // ;
-			public const int QuestionMark = 62; // ?
+			public override NodeType NodeType {
+				get {
+					return NodeType.Unknown;
+				}
+			}
 			
-			public const int Assign = 63; // =
+			public override bool IsNull {
+				get {
+					return true;
+				}
+			}
 			
-			public const int TypeArgument = 64;
-			public const int Constraint = 65;
+			public override S AcceptVisitor<T, S> (DomVisitor<T, S> visitor, T data)
+			{
+				return default (S);
+			}
+		}
+		
+		public abstract NodeType NodeType {
+			get;
+		}
+		
+		public virtual bool IsNull {
+			get {
+				return false;
+			}
 		}
 		
 		public virtual DomLocation StartLocation {
 			get { 
-				INode child = (INode)FirstChild;
+				var child = FirstChild;
 				if (child == null)
 					return DomLocation.Empty;
 				return child.StartLocation;
@@ -87,14 +73,14 @@ namespace ICSharpCode.NRefactory.CSharp
 		
 		public virtual DomLocation EndLocation {
 			get { 
-				INode child = (INode)LastChild;
+				var child = LastChild;
 				if (child == null)
 					return DomLocation.Empty;
 				return child.EndLocation;
 			}
 		}
 		
-		public INode Parent {
+		public DomNode Parent {
 			get;
 			set;
 		}
@@ -104,29 +90,29 @@ namespace ICSharpCode.NRefactory.CSharp
 			set;
 		}
 		
-		public INode NextSibling {
+		public DomNode NextSibling {
 			get;
 			set;
 		}
 		
-		public INode PrevSibling {
+		public DomNode PrevSibling {
 			get;
 			set;
 		}
 		
-		public INode FirstChild {
+		public DomNode FirstChild {
 			get;
 			set;
 		}
 		
-		public INode LastChild {
+		public DomNode LastChild {
 			get;
 			set;
 		}
 		
-		public IEnumerable<INode> Children {
+		public IEnumerable<DomNode> Children {
 			get {
-				INode cur = FirstChild;
+				var cur = FirstChild;
 				while (cur != null) {
 					yield return cur;
 					cur = cur.NextSibling;
@@ -134,29 +120,31 @@ namespace ICSharpCode.NRefactory.CSharp
 			}
 		}
 		
-		public INode GetChildByRole (int role)
+		public DomNode GetChildByRole (int role)
 		{
-			AbstractNode cur = (AbstractNode)FirstChild;
+			var cur = FirstChild;
 			while (cur != null) {
 				if (cur.Role == role)
 					return cur;
-				cur = (AbstractNode)cur.NextSibling;
+				cur = cur.NextSibling;
 			}
 			return null;
 		}
 		
-		public IEnumerable<INode> GetChildrenByRole (int role)
+		public IEnumerable<DomNode> GetChildrenByRole (int role)
 		{
-			AbstractNode cur = (AbstractNode)FirstChild;
+			var cur = FirstChild;
 			while (cur != null) {
 				if (cur.Role == role)
 					yield return cur;
-				cur = (AbstractNode)cur.NextSibling;
+				cur = cur.NextSibling;
 			}
 		}
 		
-		public void AddChild (INode child)
+		public void AddChild (DomNode child)
 		{
+			if (child == null)
+				return;
 			child.Parent = this;
 			if (FirstChild == null) {
 				LastChild = FirstChild = child;
@@ -167,15 +155,20 @@ namespace ICSharpCode.NRefactory.CSharp
 			}
 		}
 		
-		public void AddChild (INode child, int role)
+		public void AddChild (DomNode child, int role)
 		{
+			if (child == null)
+				return;
 			child.Role = role;
 			AddChild (child);
 		}
 		
-		public void InsertChildBefore (INode nextSibling, INode child, int role)
+		public void InsertChildBefore (DomNode nextSibling, DomNode child, int role)
 		{
-			if (nextSibling == null) {
+			if (child == null)
+				return;
+			
+			if (FirstChild == null || nextSibling == null) {
 				AddChild (child, role);
 				return;
 			}
@@ -187,16 +180,55 @@ namespace ICSharpCode.NRefactory.CSharp
 			if (nextSibling.PrevSibling != null) {
 				child.PrevSibling = nextSibling.PrevSibling;
 				nextSibling.PrevSibling.NextSibling = child;
-			} else if (this.FirstChild == nextSibling) {
-				this.FirstChild = child;
 			}
 			nextSibling.PrevSibling = child;
 		}
 		
-		public virtual S AcceptVisitor<T, S> (IDomVisitor<T, S> visitor, T data)
+		public abstract S AcceptVisitor<T, S> (DomVisitor<T, S> visitor, T data);
+		
+		public static class Roles
 		{
-			return default(S);
+			// some pre defined constants for common roles
+			public const int Identifier    = 1;
+			public const int Keyword   = 2;
+			public const int Argument  = 3;
+			public const int Attribute = 4;
+			public const int ReturnType = 5;
+			public const int Modifier  = 6;
+			public const int Body       = 7;
+			public const int Initializer = 8;
+			public const int Condition = 9;
+			public const int EmbeddedStatement = 10;
+			public const int Iterator = 11;
+			public const int Expression = 12;
+			public const int Statement = 13;
+			public const int TargetExpression = 14;
+			public const int Member = 15;
+			
+			// some pre defined constants for most used punctuation 
+			
+			public const int LPar = 50; // (
+			public const int RPar = 51; // )
+			
+			public const int LBrace = 52; // {
+			public const int RBrace = 53; // }
+			
+			public const int LBracket = 54; // [
+			public const int RBracket = 55; // ]
+			
+			public const int LChevron = 56; // <
+			public const int RChevron = 57; // >
+			
+			public const int Dot = 58; // ,
+			public const int Comma = 59; // ,
+			public const int Colon = 60; // :
+			public const int Semicolon = 61; // ;
+			public const int QuestionMark = 62; // ?
+			
+			public const int Assign = 63; // =
+			
+			public const int TypeArgument = 64;
+			public const int Constraint = 65;
 		}
-		
 	}
 }

ICSharpCode.NRefactory/CSharp/Dom/DomVisitor.cs

@@ -1,5 +1,5 @@
-// 
-// IDomVisitor.cs
+// 
+// DomVisitor.cs
 //  
 // Author:
 //       Mike Krüger <mkrueger@novell.com>
@@ -28,11 +28,11 @@ using System;
 
 namespace ICSharpCode.NRefactory.CSharp
 {
-	public abstract class AbstractDomVisitor<T, S> : IDomVisitor<T, S>
+	public abstract class DomVisitor<T, S>
 	{
-		protected virtual S VisitChildren (INode node, T data)
+		protected virtual S VisitChildren (DomNode node, T data)
 		{
-			INode child = node.FirstChild;
+			var child = node.FirstChild;
 			while (child != null) {
 				child.AcceptVisitor (this, data);
 				child = child.NextSibling;
@@ -55,6 +55,11 @@ namespace ICSharpCode.NRefactory.CSharp
 			return default (S);
 		}
 		
+		public virtual S VisitComposedType (ComposedType composedType, T data)
+		{
+			return default (S);
+		}
+		
 		public virtual S VisitAttribute (Attribute attribute, T data) 
 		{
 			return VisitChildren (attribute, data);
@@ -77,7 +82,15 @@ namespace ICSharpCode.NRefactory.CSharp
 		
 		public virtual S VisitTypeDeclaration (TypeDeclaration typeDeclaration, T data) 
 		{
-			return VisitChildren (typeDeclaration, data);
+			foreach (var node in typeDeclaration.GetChildrenByRole (TypeDeclaration.Roles.Member)) {
+				node.AcceptVisitor (this, data);
+			}
+			return default (S);
+		}
+		
+		public virtual S VisitEnumDeclaration (EnumDeclaration enumDeclaration, T data) 
+		{
+			return VisitChildren (enumDeclaration, data);
 		}
 		
 		public virtual S VisitEnumMemberDeclaration (EnumMemberDeclaration enumMemberDeclaration, T data) 
@@ -345,6 +358,11 @@ namespace ICSharpCode.NRefactory.CSharp
 			return VisitChildren (invocationExpression, data);
 		}
 		
+		public virtual S VisitDirectionExpression (DirectionExpression directionExpression, T data)
+		{
+			return VisitChildren (directionExpression, data);
+		}
+		
 		public virtual S VisitMemberReferenceExpression (MemberReferenceExpression memberReferenceExpression, T data) 
 		{
 			return VisitChildren (memberReferenceExpression, data);
@@ -360,7 +378,7 @@ namespace ICSharpCode.NRefactory.CSharp
 			return VisitChildren (objectCreateExpression, data);
 		}
 		
-		public virtual S VisitArrayObjectCreateExpression (ArrayObjectCreateExpression arrayObjectCreateExpression, T data) 
+		public virtual S VisitArrayCreateExpression (ArrayCreateExpression arrayObjectCreateExpression, T data) 
 		{
 			return VisitChildren (arrayObjectCreateExpression, data);
 		}
@@ -470,14 +488,9 @@ namespace ICSharpCode.NRefactory.CSharp
 			return VisitChildren (argListExpression, data);
 		}
 		
-		public virtual S VisitComposedType (ComposedType composedType, T data)
+		public S VisitArrayInitializerExpression (ArrayInitializerExpression arrayInitializerExpression, T data)
 		{
-			return VisitChildren (composedType, data);
-		}
-		
-		public virtual S VisitDirectionExpression (DirectionExpression directionExpression, T data)
-		{
-			return VisitChildren (directionExpression, data);
+			return VisitChildren (arrayInitializerExpression, data);
 		}
 	}
 }

ICSharpCode.NRefactory/CSharp/Dom/Expressions/AnonymousMethodExpression.cs

@@ -1,4 +1,4 @@
-// 
+// 
 // AnonymousMethodExpression.cs
 //  
 // Author:
@@ -30,32 +30,42 @@ using System.Collections.Generic;
 
 namespace ICSharpCode.NRefactory.CSharp
 {
-	public class AnonymousMethodExpression : AbstractNode
+	public class AnonymousMethodExpression : DomNode
 	{
-		public IEnumerable<ParameterDeclaration> Arguments { 
+		public override NodeType NodeType {
 			get {
-				return base.GetChildrenByRole (Roles.Argument).Cast <ParameterDeclaration>();
+				return NodeType.Expression;
 			}
 		}
 		
-		public IEnumerable<ParameterDeclaration> Parameters { 
-			// TODO: Arguments or Parameters ???
+		// used to make a difference between delegate {} and delegate () {} 
+		public bool HasParameterList {
 			get {
-				return this.Arguments;
+				return GetChildByRole (Roles.LPar) != null;
 			}
 		}
 		
-		public bool HasParameterList {
-			get { return GetChildByRole (Roles.LPar) != null; }
+		public CSharpTokenNode LPar {
+			get { return (CSharpTokenNode)GetChildByRole (Roles.LPar) ?? CSharpTokenNode.Null; }
+		}
+		
+		public CSharpTokenNode RPar {
+			get { return (CSharpTokenNode)GetChildByRole (Roles.RPar) ?? CSharpTokenNode.Null; }
+		}
+		
+		public IEnumerable<ParameterDeclaration> Parameters { 
+			get {
+				return base.GetChildrenByRole (Roles.Argument).Cast <ParameterDeclaration> ();
+			}
 		}
 		
 		public BlockStatement Body {
 			get {
-				return (BlockStatement)GetChildByRole (Roles.Body);
+				return (BlockStatement)GetChildByRole (Roles.Body) ?? BlockStatement.Null;
 			}
 		}
 		
-		public override S AcceptVisitor<T, S> (IDomVisitor<T, S> visitor, T data)
+		public override S AcceptVisitor<T, S> (DomVisitor<T, S> visitor, T data)
 		{
 			return visitor.VisitAnonymousMethodExpression (this, data);
 		}

ICSharpCode.NRefactory/CSharp/Dom/Expressions/ArgListExpression.cs

@@ -24,7 +24,6 @@
 // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 // THE SOFTWARE.
 
-using ICSharpCode.NRefactory.TypeSystem;
 using System;
 using System.Collections.Generic;
 using System.Linq;
@@ -34,30 +33,36 @@ namespace ICSharpCode.NRefactory.CSharp
 	/// <summary>
 	/// Represents the undocumented __arglist keyword.
 	/// </summary>
-	public class ArgListExpression : AbstractNode
+	public class ArgListExpression : DomNode
 	{
+		public override NodeType NodeType {
+			get {
+				return NodeType.Expression;
+			}
+		}
+
 		public bool IsAccess { // access is __arglist, otherwise it's __arlist (a1, a2, ..., an)
 			get;
 			set;
 		}
 		
 		public CSharpTokenNode Keyword {
-			get { return (CSharpTokenNode)GetChildByRole (Roles.Keyword); }
+			get { return (CSharpTokenNode)GetChildByRole (Roles.Keyword) ?? CSharpTokenNode.Null; }
 		}
 		
 		public CSharpTokenNode LPar {
-			get { return (CSharpTokenNode)GetChildByRole (Roles.LPar); }
+			get { return (CSharpTokenNode)GetChildByRole (Roles.LPar) ?? CSharpTokenNode.Null; }
 		}
 		
 		public CSharpTokenNode RPar {
-			get { return (CSharpTokenNode)GetChildByRole (Roles.RPar); }
+			get { return (CSharpTokenNode)GetChildByRole (Roles.RPar) ?? CSharpTokenNode.Null; }
 		}
 		
-		public IEnumerable<INode> Arguments {
-			get { return GetChildrenByRole (Roles.Argument).Cast<INode> (); }
+		public IEnumerable<DomNode> Arguments {
+			get { return GetChildrenByRole (Roles.Argument); }
 		}
 		
-		public override S AcceptVisitor<T, S> (IDomVisitor<T, S> visitor, T data)
+		public override S AcceptVisitor<T, S> (DomVisitor<T, S> visitor, T data)
 		{
 			return visitor.VisitArgListExpression (this, data);
 		}

ICSharpCode.NRefactory/CSharp/Dom/Expressions/ArrayCreateExpression.cs

@@ -25,19 +25,25 @@
 // THE SOFTWARE.
 
 using System;
-using ICSharpCode.NRefactory.TypeSystem;
 using System.Collections.Generic;
+
 namespace ICSharpCode.NRefactory.CSharp
 {
-	public class ArrayObjectCreateExpression : ObjectCreateExpression
+	public class ArrayCreateExpression : ObjectCreateExpression
 	{
+		public override NodeType NodeType {
+			get {
+				return NodeType.Expression;
+			}
+		}
+
 		public CSharpTokenNode Rank {
-			get { return (CSharpTokenNode)GetChildByRole (Roles.RPar); }
+			get { return (CSharpTokenNode)GetChildByRole (Roles.RPar) ?? CSharpTokenNode.Null; }
 		}
 		
-		public override S AcceptVisitor<T, S> (IDomVisitor<T, S> visitor, T data)
+		public override S AcceptVisitor<T, S> (DomVisitor<T, S> visitor, T data)
 		{
-			return visitor.VisitArrayObjectCreateExpression (this, data);
+			return visitor.VisitArrayCreateExpression (this, data);
 		}
 	}
 }

ICSharpCode.NRefactory/CSharp/Dom/Expressions/ArrayInitializerExpression.cs

@@ -0,0 +1,45 @@
+// 
+// ArrayInitializerExpression.cs
+//  
+// Author:
+//       Mike Krüger <mkrueger@novell.com>
+// 
+// Copyright (c) 2010 Novell, Inc (http://www.novell.com)
+// 
+// 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.NRefactory.CSharp
+{ 
+	public class ArrayInitializerExpression : DomNode
+	{
+		public override NodeType NodeType {
+			get {
+				return NodeType.Expression;
+			}
+		}
+		
+		
+		public override S AcceptVisitor<T, S> (DomVisitor<T, S> visitor, T data)
+		{
+			return visitor.VisitArrayInitializerExpression (this, data);
+		}
+	}
+}
+

ICSharpCode.NRefactory/CSharp/Dom/Expressions/AsExpression.cs

@@ -24,21 +24,26 @@
 // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 // THE SOFTWARE.
 using System;
-using ICSharpCode.NRefactory.TypeSystem;
 
 namespace ICSharpCode.NRefactory.CSharp
 {
-	public class AsExpression : AbstractNode
+	public class AsExpression : DomNode
 	{
+		public override NodeType NodeType {
+			get {
+				return NodeType.Expression;
+			}
+		}
+
 		public FullTypeName TypeReference {
-			get { return (FullTypeName)GetChildByRole (Roles.ReturnType); }
+			get { return (FullTypeName)GetChildByRole (Roles.ReturnType) ?? FullTypeName.Null; }
 		}
 		
-		public INode Expression {
-			get { return GetChildByRole (Roles.Expression); }
+		public DomNode Expression {
+			get { return GetChildByRole (Roles.Expression) ?? DomNode.Null; }
 		}
 		
-		public override S AcceptVisitor<T, S> (IDomVisitor<T, S> visitor, T data)
+		public override S AcceptVisitor<T, S> (DomVisitor<T, S> visitor, T data)
 		{
 			return visitor.VisitAsExpression (this, data);
 		}

ICSharpCode.NRefactory/CSharp/Dom/Expressions/AssignmentExpression.cs

@@ -1,4 +1,4 @@
-// 
+// 
 // AssignmentExpression.cs
 //  
 // Author:
@@ -25,12 +25,17 @@
 // THE SOFTWARE.
 
 using System;
-using ICSharpCode.NRefactory.TypeSystem;
 
 namespace ICSharpCode.NRefactory.CSharp
 {
-	public class AssignmentExpression : AbstractNode
+	public class AssignmentExpression : DomNode
 	{
+		public override NodeType NodeType {
+			get {
+				return NodeType.Expression;
+			}
+		}
+
 		public const int LeftExpressionRole = 100;
 		public const int RightExpressionRole = 101;
 		public const int OperatorRole = 102;
@@ -40,20 +45,20 @@ namespace ICSharpCode.NRefactory.CSharp
 			set;
 		}
 		
-		public INode Left {
-			get { return GetChildByRole (LeftExpressionRole); }
+		public DomNode Left {
+			get { return GetChildByRole (LeftExpressionRole) ?? DomNode.Null; }
 		}
 		
-		public INode Right {
-			get { return GetChildByRole (RightExpressionRole); }
+		public DomNode Right {
+			get { return GetChildByRole (RightExpressionRole) ?? DomNode.Null; }
 		}
 		
 		public CSharpTokenNode Operator {
-			get { return (CSharpTokenNode)GetChildByRole (OperatorRole); }
+			get { return (CSharpTokenNode)GetChildByRole (OperatorRole) ?? CSharpTokenNode.Null; }
 		}
 	
 		
-		public override S AcceptVisitor<T, S> (IDomVisitor<T, S> visitor, T data)
+		public override S AcceptVisitor<T, S> (DomVisitor<T, S> visitor, T data)
 		{
 			return visitor.VisitAssignmentExpression (this, data);
 		}
@@ -75,12 +80,12 @@ namespace ICSharpCode.NRefactory.CSharp
 		/// <summary>left %= right</summary>
 		Modulus,
 		
-		/// <summary>left &lt;&lt;= right</summary>
+		/// <summary>left <<= right</summary>
 		ShiftLeft,
 		/// <summary>left >>= right</summary>
 		ShiftRight,
 		
-		/// <summary>left &amp;= right</summary>
+		/// <summary>left &= right</summary>
 		BitwiseAnd,
 		/// <summary>left |= right</summary>
 		BitwiseOr,

ICSharpCode.NRefactory/CSharp/Dom/Expressions/BaseReferenceExpression.cs

@@ -25,12 +25,17 @@
 // THE SOFTWARE.
 
 using System;
-using ICSharpCode.NRefactory.TypeSystem;
 
 namespace ICSharpCode.NRefactory.CSharp
 {
-	public class BaseReferenceExpression : AbstractNode
+	public class BaseReferenceExpression : DomNode
 	{
+		public override NodeType NodeType {
+			get {
+				return NodeType.Expression;
+			}
+		}
+
 		public DomLocation Location {
 			get;
 			set;
@@ -47,7 +52,7 @@ namespace ICSharpCode.NRefactory.CSharp
 			}
 		}
 		
-		public override S AcceptVisitor<T, S> (IDomVisitor<T, S> visitor, T data)
+		public override S AcceptVisitor<T, S> (DomVisitor<T, S> visitor, T data)
 		{
 			return visitor.VisitBaseReferenceExpression (this, data);
 		}

ICSharpCode.NRefactory/CSharp/Dom/Expressions/BinaryOperatorExpression.cs

@@ -1,4 +1,4 @@
-// 
+// 
 // BinaryOperatorExpression.cs
 //  
 // Author:
@@ -25,39 +25,39 @@
 // THE SOFTWARE.
 
 using System;
-using ICSharpCode.NRefactory.TypeSystem;
 
 namespace ICSharpCode.NRefactory.CSharp
 {
-	public class BinaryOperatorExpression : AbstractNode
+	public class BinaryOperatorExpression : DomNode
 	{
 		public const int LeftExpressionRole = 100;
 		public const int RightExpressionRole = 101;
 		public const int OperatorRole = 102;
 		
+		public override NodeType NodeType {
+			get {
+				return NodeType.Expression;
+			}
+		}
+
 		public BinaryOperatorType BinaryOperatorType {
 			get;
 			set;
 		}
 		
-		[ObsoleteAttribute]
-		public BinaryOperatorType Op {
-			get { return this.BinaryOperatorType; }
-		}
-		
 		public CSharpTokenNode Operator {
-			get { return (CSharpTokenNode)GetChildByRole (OperatorRole); }
+			get { return (CSharpTokenNode)GetChildByRole (OperatorRole) ?? CSharpTokenNode.Null; }
 		}
 		
-		public INode Left {
-			get { return GetChildByRole (LeftExpressionRole); }
+		public DomNode Left {
+			get { return GetChildByRole (LeftExpressionRole) ?? DomNode.Null; }
 		}
 		
-		public INode Right {
-			get { return GetChildByRole (RightExpressionRole); }
+		public DomNode Right {
+			get { return GetChildByRole (RightExpressionRole) ?? DomNode.Null; }
 		}
 		
-		public override S AcceptVisitor<T, S> (IDomVisitor<T, S> visitor, T data)
+		public override S AcceptVisitor<T, S> (DomVisitor<T, S> visitor, T data)
 		{
 			return visitor.VisitBinaryOperatorExpression (this, data);
 		}

ICSharpCode.NRefactory/CSharp/Dom/Expressions/CastExpression.cs

@@ -25,29 +25,34 @@
 // THE SOFTWARE.
 
 using System;
-using ICSharpCode.NRefactory.TypeSystem;
 
 namespace ICSharpCode.NRefactory.CSharp
 {
-	public class CastExpression : AbstractNode
+	public class CastExpression : DomNode
 	{
-		public INode CastTo {
-			get { return (INode)GetChildByRole (Roles.ReturnType); }
+		public override NodeType NodeType {
+			get {
+				return NodeType.Expression;
+			}
+		}
+
+		public DomNode CastTo {
+			get { return GetChildByRole (Roles.ReturnType) ?? DomNode.Null; }
 		}
 		
-		public INode Expression {
-			get { return GetChildByRole (Roles.Expression); }
+		public DomNode Expression {
+			get { return GetChildByRole (Roles.Expression) ?? DomNode.Null; }
 		}
 		
 		public CSharpTokenNode LPar {
-			get { return (CSharpTokenNode)GetChildByRole (Roles.LPar); }
+			get { return (CSharpTokenNode)GetChildByRole (Roles.LPar) ?? CSharpTokenNode.Null; }
 		}
 		
 		public CSharpTokenNode RPar {
-			get { return (CSharpTokenNode)GetChildByRole (Roles.RPar); }
+			get { return (CSharpTokenNode)GetChildByRole (Roles.RPar) ?? CSharpTokenNode.Null; }
 		}
 		
-		public override S AcceptVisitor<T, S> (IDomVisitor<T, S> visitor, T data)
+		public override S AcceptVisitor<T, S> (DomVisitor<T, S> visitor, T data)
 		{
 			return visitor.VisitCastExpression (this, data);
 		}

ICSharpCode.NRefactory/CSharp/Dom/Expressions/CheckedExpression.cs

@@ -25,25 +25,30 @@
 // THE SOFTWARE.
 
 using System;
-using ICSharpCode.NRefactory.TypeSystem;
 
 namespace ICSharpCode.NRefactory.CSharp
 {
-	public class CheckedExpression : AbstractNode
+	public class CheckedExpression : DomNode
 	{
-		public INode Expression {
-			get { return GetChildByRole (Roles.Expression); }
+		public override NodeType NodeType {
+			get {
+				return NodeType.Expression;
+			}
+		}
+
+		public DomNode Expression {
+			get { return GetChildByRole (Roles.Expression) ?? DomNode.Null; }
 		}
 		
 		public CSharpTokenNode LPar {
-			get { return (CSharpTokenNode)GetChildByRole (Roles.LPar); }
+			get { return (CSharpTokenNode)GetChildByRole (Roles.LPar) ?? CSharpTokenNode.Null; }
 		}
 		
 		public CSharpTokenNode RPar {
-			get { return (CSharpTokenNode)GetChildByRole (Roles.RPar); }
+			get { return (CSharpTokenNode)GetChildByRole (Roles.RPar) ?? CSharpTokenNode.Null; }
 		}
 		
-		public override S AcceptVisitor<T, S> (IDomVisitor<T, S> visitor, T data)
+		public override S AcceptVisitor<T, S> (DomVisitor<T, S> visitor, T data)
 		{
 			return visitor.VisitCheckedExpression (this, data);
 		}

ICSharpCode.NRefactory/CSharp/Dom/Expressions/ConditionalExpression.cs

@@ -25,39 +25,44 @@
 // THE SOFTWARE.
 
 using System;
-using ICSharpCode.NRefactory.TypeSystem;
 
 namespace ICSharpCode.NRefactory.CSharp
 {
 	/// <summary>
 	/// cond ? true : false
 	/// </summary>
-	public class ConditionalExpression : AbstractNode
+	public class ConditionalExpression : DomNode
 	{
 		public const int TrueExpressionRole = 100;
 		public const int FalseExpressionRole = 101;
 		
-		public INode TrueExpression {
-			get { return GetChildByRole (TrueExpressionRole); }
+		public override NodeType NodeType {
+			get {
+				return NodeType.Expression;
+			}
+		}
+
+		public DomNode TrueExpression {
+			get { return GetChildByRole (TrueExpressionRole) ?? DomNode.Null; }
 		}
 		
-		public INode FalseExpression {
-			get { return GetChildByRole (FalseExpressionRole); }
+		public DomNode FalseExpression {
+			get { return GetChildByRole (FalseExpressionRole) ?? DomNode.Null; }
 		}
 
-		public INode Condition {
-			get { return GetChildByRole (Roles.Condition); }
+		public DomNode Condition {
+			get { return GetChildByRole (Roles.Condition) ?? DomNode.Null; }
 		}
 		
 		public CSharpTokenNode QuestionMark {
-			get { return (CSharpTokenNode)GetChildByRole (Roles.QuestionMark); }
+			get { return (CSharpTokenNode)GetChildByRole (Roles.QuestionMark) ?? CSharpTokenNode.Null; }
 		}
 		
 		public CSharpTokenNode Colon {
-			get { return (CSharpTokenNode)GetChildByRole (Roles.Colon); }
+			get { return (CSharpTokenNode)GetChildByRole (Roles.Colon) ?? CSharpTokenNode.Null; }
 		}
 		
-		public override S AcceptVisitor<T, S> (IDomVisitor<T, S> visitor, T data)
+		public override S AcceptVisitor<T, S> (DomVisitor<T, S> visitor, T data)
 		{
 			return visitor.VisitConditionalExpression (this, data);
 		}

ICSharpCode.NRefactory/CSharp/Dom/Expressions/DefaultValueExpression.cs

@@ -27,13 +27,19 @@ using System;
 
 namespace ICSharpCode.NRefactory.CSharp
 {
-	public class DefaultValueExpression : AbstractNode
+	public class DefaultValueExpression : DomNode
 	{
+		public override NodeType NodeType {
+			get {
+				return NodeType.Expression;
+			}
+		}
+
 		public FullTypeName TypeReference {
-			get { return (FullTypeName)GetChildByRole (Roles.ReturnType); }
+			get { return (FullTypeName)GetChildByRole (Roles.ReturnType) ?? FullTypeName.Null; }
 		}
 		
-		public override S AcceptVisitor<T, S> (IDomVisitor<T, S> visitor, T data)
+		public override S AcceptVisitor<T, S> (DomVisitor<T, S> visitor, T data)
 		{
 			return visitor.VisitDefaultValueExpression (this, data);
 		}

ICSharpCode.NRefactory/CSharp/Dom/Expressions/DirectionExpression.cs

@@ -35,8 +35,14 @@ namespace ICSharpCode.NRefactory.CSharp
 		Ref
 	}
 	
-	public class DirectionExpression  : AbstractNode
-	{	
+	public class DirectionExpression  : DomNode
+	{
+		public override NodeType NodeType {
+			get {
+				return NodeType.Expression;
+			}
+		}
+		
 		public FieldDirection FieldDirection {
 			get;
 			set;
@@ -44,14 +50,14 @@ namespace ICSharpCode.NRefactory.CSharp
 		
 		
 		public CSharpTokenNode Keyword {
-			get { return (CSharpTokenNode)GetChildByRole (Roles.Keyword); }
+			get { return (CSharpTokenNode)GetChildByRole (Roles.Keyword) ?? CSharpTokenNode.Null; }
 		}
 		
-		public INode Expression {
-			get { return GetChildByRole (Roles.Expression); }
+		public DomNode Expression {
+			get { return GetChildByRole (Roles.Expression) ?? DomNode.Null; }
 		}
 		
-		public override S AcceptVisitor<T, S> (IDomVisitor<T, S> visitor, T data)
+		public override S AcceptVisitor<T, S> (DomVisitor<T, S> visitor, T data)
 		{
 			return visitor.VisitDirectionExpression (this, data);
 		}

ICSharpCode.NRefactory/CSharp/Dom/Expressions/IdentifierExpression.cs

@@ -1,4 +1,4 @@
-// 
+// 
 // IdentifierExpression.cs
 //  
 // Author:
@@ -25,26 +25,31 @@
 // THE SOFTWARE.
 
 using System;
-using ICSharpCode.NRefactory.TypeSystem;
 
 namespace ICSharpCode.NRefactory.CSharp
 {
-	public class IdentifierExpression : AbstractNode
+	public class IdentifierExpression : DomNode
 	{
-		public Identifier IdentifierToken {
+		public override NodeType NodeType {
+			get {
+				return NodeType.Expression;
+			}
+		}
+		
+		public  Identifier IdentifierToken {
 			get {
-				return (Identifier)GetChildByRole (Roles.Identifier);
+				return (Identifier)GetChildByRole (Roles.Identifier) ?? ICSharpCode.NRefactory.CSharp.Identifier.Null;
 			}
 		}
 		
 		public string Identifier {
 			get {
 				Identifier i = this.IdentifierToken;
-				return i != null ? i.Name : null;
+				return !i.IsNull ? i.Name : null;
 			}
 		}
 		
-		public override S AcceptVisitor<T, S> (IDomVisitor<T, S> visitor, T data)
+		public override S AcceptVisitor<T, S> (DomVisitor<T, S> visitor, T data)
 		{
 			return visitor.VisitIdentifierExpression (this, data);
 		}

ICSharpCode.NRefactory/CSharp/Dom/Expressions/IndexerExpression.cs

@@ -26,34 +26,39 @@
 
 using System;
 using System.Linq;
-using ICSharpCode.NRefactory.TypeSystem;
 using System.Collections.Generic;
 
 namespace ICSharpCode.NRefactory.CSharp
 {
-	public class IndexerExpression : AbstractNode
+	public class IndexerExpression : DomNode
 	{
-		public INode Target {
-			get { return (INode)GetChildByRole (Roles.TargetExpression); }
+		public override NodeType NodeType {
+			get {
+				return NodeType.Expression;
+			}
+		}
+
+		public DomNode Target {
+			get { return GetChildByRole (Roles.TargetExpression); }
 		}
 		
 		public CSharpTokenNode LBracket {
 			get {
-				return (CSharpTokenNode)GetChildByRole (Roles.LBracket);
+				return (CSharpTokenNode)GetChildByRole (Roles.LBracket) ?? CSharpTokenNode.Null;
 			}
 		}
 		
 		public CSharpTokenNode RBracket {
 			get {
-				return (CSharpTokenNode)GetChildByRole (Roles.RBracket);
+				return (CSharpTokenNode)GetChildByRole (Roles.RBracket) ?? CSharpTokenNode.Null;
 			}
 		}
 		
-		public IEnumerable<INode> Arguments {
+		public IEnumerable<DomNode> Arguments {
 			get { return GetChildrenByRole (Roles.Argument); }
 		}
 		
-		public override S AcceptVisitor<T, S> (IDomVisitor<T, S> visitor, T data)
+		public override S AcceptVisitor<T, S> (DomVisitor<T, S> visitor, T data)
 		{
 			return visitor.VisitIndexerExpression (this, data);
 		}

ICSharpCode.NRefactory/CSharp/Dom/Expressions/InvocationExpression.cs

@@ -26,30 +26,36 @@
 
 using System;
 using System.Linq;
-using ICSharpCode.NRefactory.TypeSystem;
+
 using System.Collections.Generic;
 
 namespace ICSharpCode.NRefactory.CSharp
 {
-	public class InvocationExpression : AbstractNode
+	public class InvocationExpression : DomNode
 	{
-		public INode Target {
-			get { return GetChildByRole (Roles.TargetExpression); }
+		public override NodeType NodeType {
+			get {
+				return NodeType.Expression;
+			}
+		}
+
+		public DomNode Target {
+			get { return GetChildByRole (Roles.TargetExpression) ?? DomNode.Null; }
 		}
 		
-		public IEnumerable<INode> Arguments {
-			get { return GetChildrenByRole (Roles.Argument).Cast<INode> (); }
+		public IEnumerable<DomNode> Arguments {
+			get { return GetChildrenByRole (Roles.Argument); }
 		}
 		
 		public CSharpTokenNode LPar {
-			get { return (CSharpTokenNode)GetChildByRole (Roles.LPar); }
+			get { return (CSharpTokenNode)GetChildByRole (Roles.LPar) ?? CSharpTokenNode.Null; }
 		}
 		
 		public CSharpTokenNode RPar {
-			get { return (CSharpTokenNode)GetChildByRole (Roles.RPar); }
+			get { return (CSharpTokenNode)GetChildByRole (Roles.RPar) ?? CSharpTokenNode.Null; }
 		}
 		
-		public override S AcceptVisitor<T, S> (IDomVisitor<T, S> visitor, T data)
+		public override S AcceptVisitor<T, S> (DomVisitor<T, S> visitor, T data)
 		{
 			return visitor.VisitInvocationExpression (this, data);
 		}

ICSharpCode.NRefactory/CSharp/Dom/Expressions/IsExpression.cs

@@ -1,4 +1,4 @@
-// 
+// 
 // TypeOfIsExpression.cs
 //  
 // Author:
@@ -24,21 +24,26 @@
 // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 // THE SOFTWARE.
 using System;
-using ICSharpCode.NRefactory.TypeSystem;
 
 namespace ICSharpCode.NRefactory.CSharp
 {
-	public class IsExpression : AbstractNode
+	public class IsExpression : DomNode
 	{
-		public INode TypeReference {
-			get { return GetChildByRole (Roles.ReturnType); }
+		public override NodeType NodeType {
+			get {
+				return NodeType.Expression;
+			}
+		}
+
+		public FullTypeName TypeReference {
+			get { return (FullTypeName)GetChildByRole (Roles.ReturnType) ?? FullTypeName.Null; }
 		}
 		
-		public INode Expression {
-			get { return GetChildByRole (Roles.Expression); }
+		public DomNode Expression {
+			get { return GetChildByRole (Roles.Expression) ?? DomNode.Null; }
 		}
 		
-		public override S AcceptVisitor<T, S> (IDomVisitor<T, S> visitor, T data)
+		public override S AcceptVisitor<T, S> (DomVisitor<T, S> visitor, T data)
 		{
 			return visitor.VisitIsExpression (this, data);
 		}

ICSharpCode.NRefactory/CSharp/Dom/Expressions/LambdaExpression.cs

@@ -1,4 +1,4 @@
-// 
+// 
 // LambdaExpression.cs
 //  
 // Author:
@@ -29,9 +29,15 @@ using System.Collections.Generic;
 
 namespace ICSharpCode.NRefactory.CSharp
 {
-	public class LambdaExpression : AbstractNode
+	public class LambdaExpression : DomNode
 	{
-		public IEnumerable<ParameterDeclaration> Arguments { 
+		public override NodeType NodeType {
+			get {
+				return NodeType.Expression;
+			}
+		}
+
+		public IEnumerable<ParameterDeclaration> Parameters { 
 			get {
 				return base.GetChildrenByRole (Roles.Argument).Cast <ParameterDeclaration>();
 			}
@@ -39,23 +45,23 @@ namespace ICSharpCode.NRefactory.CSharp
 		
 		public BlockStatement Body {
 			get {
-				return (BlockStatement)GetChildByRole (Roles.Body);
+				return (BlockStatement)GetChildByRole (Roles.Body) ?? BlockStatement.Null;
 			}
 		}
 		
 		public CSharpTokenNode Arrow {
-			get { return (CSharpTokenNode)GetChildByRole (Roles.Assign); }
+			get { return (CSharpTokenNode)GetChildByRole (Roles.Assign) ?? CSharpTokenNode.Null; }
 		}
 		
 		public CSharpTokenNode LPar {
-			get { return (CSharpTokenNode)GetChildByRole (Roles.LPar); }
+			get { return (CSharpTokenNode)GetChildByRole (Roles.LPar) ?? CSharpTokenNode.Null; }
 		}
 		
 		public CSharpTokenNode RPar {
-			get { return (CSharpTokenNode)GetChildByRole (Roles.RPar); }
+			get { return (CSharpTokenNode)GetChildByRole (Roles.RPar) ?? CSharpTokenNode.Null; }
 		}
 		
-		public override S AcceptVisitor<T, S> (IDomVisitor<T, S> visitor, T data)
+		public override S AcceptVisitor<T, S> (DomVisitor<T, S> visitor, T data)
 		{
 			return visitor.VisitLambdaExpression (this, data);
 		}

ICSharpCode.NRefactory/CSharp/Dom/Expressions/MemberReferenceExpression.cs

@@ -1,4 +1,4 @@
-// 
+// 
 // MemberReferenceExpression.cs
 //  
 // Author:
@@ -26,34 +26,39 @@
 
 using System;
 using System.Linq;
-using ICSharpCode.NRefactory.TypeSystem;
 using System.Collections.Generic;
 
 namespace ICSharpCode.NRefactory.CSharp
 {
-	public class MemberReferenceExpression : AbstractNode
+	public class MemberReferenceExpression : DomNode
 	{
-		public INode Target {
-			get { return GetChildByRole (Roles.TargetExpression); }
+		public override NodeType NodeType {
+			get {
+				return NodeType.Expression;
+			}
+		}
+
+		public DomNode Target {
+			get { return GetChildByRole (Roles.TargetExpression) ?? DomNode.Null; }
 		}
 		
 		public Identifier Identifier {
 			get {
-				return (Identifier)GetChildByRole (Roles.Identifier);
+				return (Identifier)GetChildByRole (Roles.Identifier) ?? Identifier.Null;
 			}
 		}
-		
+
 		public string MemberName {
 			get {
 				return this.Identifier.Name;
 			}
 		}
 		
-		public IEnumerable<INode> TypeArguments {
-			get { return GetChildrenByRole (Roles.TypeArgument).Cast<INode> (); }
+		public IEnumerable<DomNode> TypeArguments {
+			get { return GetChildrenByRole (Roles.TypeArgument); }
 		}
 		
-		public override S AcceptVisitor<T, S> (IDomVisitor<T, S> visitor, T data)
+		public override S AcceptVisitor<T, S> (DomVisitor<T, S> visitor, T data)
 		{
 			return visitor.VisitMemberReferenceExpression (this, data);
 		}

ICSharpCode.NRefactory/CSharp/Dom/Expressions/NullReferenceExpression.cs

@@ -25,13 +25,18 @@
 // THE SOFTWARE.
 
 using System;
-using ICSharpCode.NRefactory.TypeSystem;
 
 namespace ICSharpCode.NRefactory.CSharp
 {
-	public class NullReferenceExpression : AbstractNode
+	public class NullReferenceExpression : DomNode
 	{
-		public override S AcceptVisitor<T, S> (IDomVisitor<T, S> visitor, T data)
+		public override NodeType NodeType {
+			get {
+				return NodeType.Expression;
+			}
+		}
+
+		public override S AcceptVisitor<T, S> (DomVisitor<T, S> visitor, T data)
 		{
 			return visitor.VisitNullReferenceExpression (this, data);
 		}

ICSharpCode.NRefactory/CSharp/Dom/Expressions/ObjectCreateExpression.cs

@@ -25,30 +25,35 @@
 // THE SOFTWARE.
 
 using System;
-using ICSharpCode.NRefactory.TypeSystem;
 using System.Collections.Generic;
 
 namespace ICSharpCode.NRefactory.CSharp
 {
-	public class ObjectCreateExpression : AbstractNode
+	public class ObjectCreateExpression : DomNode
 	{
-		public INode Type {
-			get { return (INode)GetChildByRole (Roles.ReturnType); }
+		public override NodeType NodeType {
+			get {
+				return NodeType.Expression;
+			}
+		}
+
+		public DomNode Type {
+			get { return GetChildByRole (Roles.ReturnType) ?? DomNode.Null; }
 		}
 		
 		public CSharpTokenNode LPar {
-			get { return (CSharpTokenNode)GetChildByRole (Roles.LPar); }
+			get { return (CSharpTokenNode)GetChildByRole (Roles.LPar) ?? CSharpTokenNode.Null; }
 		}
 		
 		public CSharpTokenNode RPar {
-			get { return (CSharpTokenNode)GetChildByRole (Roles.RPar); }
+			get { return (CSharpTokenNode)GetChildByRole (Roles.RPar) ?? CSharpTokenNode.Null; }
 		}
 		
-		public IEnumerable<INode> Arguments {
+		public IEnumerable<DomNode> Arguments {
 			get { return GetChildrenByRole (Roles.Argument); }
 		}
 		
-		public override S AcceptVisitor<T, S> (IDomVisitor<T, S> visitor, T data)
+		public override S AcceptVisitor<T, S> (DomVisitor<T, S> visitor, T data)
 		{
 			return visitor.VisitObjectCreateExpression (this, data);
 		}

ICSharpCode.NRefactory/CSharp/Dom/Expressions/ParenthesizedExpression.cs

@@ -25,25 +25,30 @@
 // THE SOFTWARE.
 
 using System;
-using ICSharpCode.NRefactory.TypeSystem;
 
 namespace ICSharpCode.NRefactory.CSharp
 {
-	public class ParenthesizedExpression : AbstractNode
+	public class ParenthesizedExpression : DomNode
 	{
-		public INode Expression {
-			get { return GetChildByRole (Roles.Expression); }
+		public override NodeType NodeType {
+			get {
+				return NodeType.Expression;
+			}
+		}
+
+		public DomNode Expression {
+			get { return GetChildByRole (Roles.Expression) ?? DomNode.Null; }
 		}
 		
 		public CSharpTokenNode LPar {
-			get { return (CSharpTokenNode)GetChildByRole (Roles.LPar); }
+			get { return (CSharpTokenNode)GetChildByRole (Roles.LPar) ?? CSharpTokenNode.Null; }
 		}
 		
 		public CSharpTokenNode RPar {
-			get { return (CSharpTokenNode)GetChildByRole (Roles.RPar); }
+			get { return (CSharpTokenNode)GetChildByRole (Roles.RPar) ?? CSharpTokenNode.Null; }
 		}
 		
-		public override S AcceptVisitor<T, S> (IDomVisitor<T, S> visitor, T data)
+		public override S AcceptVisitor<T, S> (DomVisitor<T, S> visitor, T data)
 		{
 			return visitor.VisitParenthesizedExpression (this, data);
 		}

ICSharpCode.NRefactory/CSharp/Dom/Expressions/PointerReferenceExpression.cs

@@ -26,7 +26,6 @@
 
 using System;
 using System.Linq;
-using ICSharpCode.NRefactory.TypeSystem;
 using System.Collections.Generic;
 
 namespace ICSharpCode.NRefactory.CSharp
@@ -36,8 +35,14 @@ namespace ICSharpCode.NRefactory.CSharp
 	/// </summary>
 	public class PointerReferenceExpression : MemberReferenceExpression
 	{
-		public INode Expression {
-			get { return GetChildByRole (Roles.TargetExpression); }
+		public override NodeType NodeType {
+			get {
+				return NodeType.Expression;
+			}
+		}
+
+		public DomNode Expression {
+			get { return GetChildByRole (Roles.TargetExpression) ?? DomNode.Null; }
 		}
 		
 		public string Dim {
@@ -45,7 +50,7 @@ namespace ICSharpCode.NRefactory.CSharp
 			set;
 		}
 		
-		public override S AcceptVisitor<T, S> (IDomVisitor<T, S> visitor, T data)
+		public override S AcceptVisitor<T, S> (DomVisitor<T, S> visitor, T data)
 		{
 			return visitor.VisitPointerReferenceExpression (this, data);
 		}

ICSharpCode.NRefactory/CSharp/Dom/Expressions/PrimitiveExpression.cs

@@ -25,12 +25,17 @@
 // THE SOFTWARE.
 
 using System;
-using ICSharpCode.NRefactory.TypeSystem;
 
 namespace ICSharpCode.NRefactory.CSharp
 {
-	public class PrimitiveExpression : AbstractNode
+	public class PrimitiveExpression : DomNode
 	{
+		public override NodeType NodeType {
+			get {
+				return NodeType.Expression;
+			}
+		}
+
 		DomLocation startLocation;
 		public override DomLocation StartLocation {
 			get {
@@ -58,7 +63,7 @@ namespace ICSharpCode.NRefactory.CSharp
 		}
 		
 		
-		public override S AcceptVisitor<T, S> (IDomVisitor<T, S> visitor, T data)
+		public override S AcceptVisitor<T, S> (DomVisitor<T, S> visitor, T data)
 		{
 			return visitor.VisitPrimitiveExpression (this, data);
 		}

ICSharpCode.NRefactory/CSharp/Dom/Expressions/QueryExpression.cs

@@ -27,18 +27,23 @@
 using System;
 using System.Linq;
 using System.Collections.Generic;
-using ICSharpCode.NRefactory.TypeSystem;
 
 namespace ICSharpCode.NRefactory.CSharp
 {
-	public class QueryExpressionFromClause : AbstractNode
+	public class QueryExpressionFromClause : DomNode
 	{
 		public const int FromKeywordRole = 100;
 		public const int InKeywordRole = 101;
 		
-		public INode Type {
+		public override NodeType NodeType {
 			get {
-				return (INode)GetChildByRole (Roles.ReturnType);
+				return NodeType.Expression;
+			}
+		}
+
+		public DomNode Type {
+			get {
+				return GetChildByRole (Roles.ReturnType) ?? DomNode.Null;
 			}
 		}
 		
@@ -50,15 +55,15 @@ namespace ICSharpCode.NRefactory.CSharp
 		
 		public Identifier QueryIdentifier {
 			get {
-				return (Identifier)GetChildByRole (Roles.Identifier);
+				return (Identifier)GetChildByRole (Roles.Identifier) ?? ICSharpCode.NRefactory.CSharp.Identifier.Null;
 			}
 		}
 		
-		public INode Expression {
-			get { return GetChildByRole (Roles.Expression); }
+		public DomNode Expression {
+			get { return GetChildByRole (Roles.Expression) ?? DomNode.Null; }
 		}
 		
-		public override S AcceptVisitor<T, S> (IDomVisitor<T, S> visitor, T data)
+		public override S AcceptVisitor<T, S> (DomVisitor<T, S> visitor, T data)
 		{
 			return visitor.VisitQueryExpressionFromClause (this, data);
 		}
@@ -93,13 +98,13 @@ namespace ICSharpCode.NRefactory.CSharp
 		}
 		
 		
-		public INode OnExpression {
+		public DomNode OnExpression {
 			get {
 				return GetChildByRole (OnExpressionRole);
 			}
 		}
 		
-		public INode EqualsExpression {
+		public DomNode EqualsExpression {
 			get {
 				return GetChildByRole (EqualsExpressionRole);
 			}
@@ -117,21 +122,26 @@ namespace ICSharpCode.NRefactory.CSharp
 			}
 		}
 		
-		public INode InExpression {
+		public DomNode InExpression {
 			get {
-				return (INode)GetChildByRole (Roles.Expression);
+				return GetChildByRole (Roles.Expression);
 			}
 		}
-
 		
-		public override S AcceptVisitor<T, S> (IDomVisitor<T, S> visitor, T data)
+		public override S AcceptVisitor<T, S> (DomVisitor<T, S> visitor, T data)
 		{
 			return visitor.VisitQueryExpressionJoinClause (this, data);
 		}
 	}
 	
-	public class QueryExpressionGroupClause : AbstractNode
+	public class QueryExpressionGroupClause : DomNode
 	{
+		public override NodeType NodeType {
+			get {
+				return NodeType.Unknown;
+			}
+		}
+		
 		public const int ProjectionExpressionRole = 100;
 		public const int GroupByExpressionRole    = 101;
 		
@@ -146,26 +156,32 @@ namespace ICSharpCode.NRefactory.CSharp
 			get { return (CSharpTokenNode)GetChildByRole (ByKeywordRole); }
 		}
 		
-		public INode Projection {
+		public DomNode Projection {
 			get {
 				return GetChildByRole (ProjectionExpressionRole);
 			}
 		}
 		
-		public INode GroupBy {
+		public DomNode GroupBy {
 			get {
 				return GetChildByRole (GroupByExpressionRole);
 			}
 		}
 		
-		public override S AcceptVisitor<T, S> (IDomVisitor<T, S> visitor, T data)
+		public override S AcceptVisitor<T, S> (DomVisitor<T, S> visitor, T data)
 		{
 			return visitor.VisitQueryExpressionGroupClause (this, data);
 		}
 	}
 	
-	public class QueryExpressionLetClause : AbstractNode 
+	public class QueryExpressionLetClause : DomNode 
 	{
+		public override NodeType NodeType {
+			get {
+				return NodeType.Unknown;
+			}
+		}
+		
 		public string Identifier {
 			get {
 				return QueryIdentifier.Name;
@@ -178,7 +194,7 @@ namespace ICSharpCode.NRefactory.CSharp
 			}
 		}
 		
-		public INode Expression {
+		public DomNode Expression {
 			get {
 				return GetChildByRole (Roles.Expression);
 			}
@@ -188,28 +204,34 @@ namespace ICSharpCode.NRefactory.CSharp
 			get { return (CSharpTokenNode)GetChildByRole (Roles.Keyword); }
 		}
 		
-		public INode Assign {
+		public DomNode Assign {
 			get {
-				return (INode)GetChildByRole (Roles.Assign);
+				return GetChildByRole (Roles.Assign);
 			}
 		}
 		
-		public override S AcceptVisitor<T, S> (IDomVisitor<T, S> visitor, T data)
+		public override S AcceptVisitor<T, S> (DomVisitor<T, S> visitor, T data)
 		{
 			return visitor.VisitQueryExpressionLetClause (this, data);
 		}
 	}
 	
-	public class QueryExpressionOrderClause : AbstractNode
+	public class QueryExpressionOrderClause : DomNode
 	{
 		public const int OrderingRole = 100;
 		
+		public override NodeType NodeType {
+			get {
+				return NodeType.Unknown;
+			}
+		}
+		
 		public bool OrderAscending {
 			get;
 			set;
 		}
 		
-		public INode Expression {
+		public DomNode Expression {
 			get {
 				return GetChildByRole (Roles.Expression);
 			}
@@ -219,27 +241,32 @@ namespace ICSharpCode.NRefactory.CSharp
 			get { return (CSharpTokenNode)GetChildByRole (Roles.Keyword); }
 		}
 		
-		
-		public override S AcceptVisitor<T, S> (IDomVisitor<T, S> visitor, T data)
+		public override S AcceptVisitor<T, S> (DomVisitor<T, S> visitor, T data)
 		{
 			return visitor.VisitQueryExpressionOrderClause (this, data);
 		}
 	}
 	
-	public class QueryExpressionOrdering : AbstractNode
+	public class QueryExpressionOrdering : DomNode
 	{
+		public override NodeType NodeType {
+			get {
+				return NodeType.Unknown;
+			}
+		}
+		
 		public QueryExpressionOrderingDirection Direction {
 			get;
 			set;
 		}
 		
-		public INode Criteria {
+		public DomNode Criteria {
 			get {
 				return GetChildByRole (Roles.Expression);
 			}
 		}
 		
-		public override S AcceptVisitor<T, S> (IDomVisitor<T, S> visitor, T data)
+		public override S AcceptVisitor<T, S> (DomVisitor<T, S> visitor, T data)
 		{
 			return visitor.VisitQueryExpressionOrdering (this, data);
 		}
@@ -252,40 +279,53 @@ namespace ICSharpCode.NRefactory.CSharp
 		Descending
 	}
 	
-	public class QueryExpressionSelectClause : AbstractNode 
+	public class QueryExpressionSelectClause : DomNode 
 	{
+		public override NodeType NodeType {
+			get {
+				return NodeType.Unknown;
+			}
+		}
+		
 		public CSharpTokenNode SelectKeyword {
 			get { return (CSharpTokenNode)GetChildByRole (Roles.Keyword); }
 		}
 		
-		public INode Projection {
+		public DomNode Projection {
 			get {
-				return (INode)GetChildByRole (Roles.Expression);
+				return GetChildByRole (Roles.Expression);
 			}
 		}
 		
-		public override S AcceptVisitor<T, S> (IDomVisitor<T, S> visitor, T data)
+		public override S AcceptVisitor<T, S> (DomVisitor<T, S> visitor, T data)
 		{
 			return visitor.VisitQueryExpressionSelectClause (this, data);
 		}
 	}
 	
-	public class QueryExpressionWhereClause : AbstractNode 
+	public class QueryExpressionWhereClause : DomNode 
 	{
+		public override NodeType NodeType {
+			get {
+				return NodeType.Unknown;
+			}
+		}
+		
 		public CSharpTokenNode WhereKeyword {
 			get { return (CSharpTokenNode)GetChildByRole (Roles.Keyword); }
 		}
 		
-		public INode Condition {
+		public DomNode Condition {
 			get {
-				return (INode)GetChildByRole (Roles.Condition);
+				return GetChildByRole (Roles.Condition);
 			}
 		}
 		
-		public override S AcceptVisitor<T, S> (IDomVisitor<T, S> visitor, T data)
+		public override S AcceptVisitor<T, S> (DomVisitor<T, S> visitor, T data)
 		{
 			return visitor.VisitQueryExpressionWhereClause (this, data);
 		}
+		
 	}
 	
 }

ICSharpCode.NRefactory/CSharp/Dom/Expressions/SizeOfExpression.cs

@@ -24,27 +24,32 @@
 // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 // THE SOFTWARE.
 using System;
-using ICSharpCode.NRefactory.TypeSystem;
 
 namespace ICSharpCode.NRefactory.CSharp
 {
-	public class SizeOfExpression : AbstractNode
+	public class SizeOfExpression : DomNode
 	{
+		public override NodeType NodeType {
+			get {
+				return NodeType.Expression;
+			}
+		}
+
 		public FullTypeName Type {
 			get {
-				return (FullTypeName)GetChildByRole (Roles.ReturnType);
+				return (FullTypeName)GetChildByRole (Roles.ReturnType) ?? FullTypeName.Null;
 			}
 		}
 		
 		public CSharpTokenNode LPar {
-			get { return (CSharpTokenNode)GetChildByRole (Roles.LPar); }
+			get { return (CSharpTokenNode)GetChildByRole (Roles.LPar) ?? CSharpTokenNode.Null; }
 		}
 		
 		public CSharpTokenNode RPar {
-			get { return (CSharpTokenNode)GetChildByRole (Roles.RPar); }
+			get { return (CSharpTokenNode)GetChildByRole (Roles.RPar) ?? CSharpTokenNode.Null; }
 		}
 		
-		public override S AcceptVisitor<T, S> (IDomVisitor<T, S> visitor, T data)
+		public override S AcceptVisitor<T, S> (DomVisitor<T, S> visitor, T data)
 		{
 			return visitor.VisitSizeOfExpression (this, data);
 		}

ICSharpCode.NRefactory/CSharp/Dom/Expressions/StackAllocExpression.cs

@@ -25,43 +25,48 @@
 // THE SOFTWARE.
 
 using System;
-using ICSharpCode.NRefactory.TypeSystem;
 
 namespace ICSharpCode.NRefactory.CSharp
 {
-	public class StackAllocExpression : AbstractNode
+	public class StackAllocExpression : DomNode
 	{
 		public const int StackAllocKeywordRole = 100;
 		
+		public override NodeType NodeType {
+			get {
+				return NodeType.Expression;
+			}
+		}
+
 		public FullTypeName Type {
 			get {
-				return (FullTypeName)GetChildByRole (Roles.ReturnType);
+				return (FullTypeName)GetChildByRole (Roles.ReturnType) ?? FullTypeName.Null;
 			}
 		}
 		
-		public INode CountExpression {
-			get { return (INode)GetChildByRole (Roles.Expression); }
+		public DomNode CountExpression {
+			get { return GetChildByRole (Roles.Expression) ?? DomNode.Null; }
 		}
 		
 		public CSharpTokenNode StackAllocKeyword {
 			get {
-				return (CSharpTokenNode)GetChildByRole (StackAllocKeywordRole);
+				return (CSharpTokenNode)GetChildByRole (StackAllocKeywordRole) ?? CSharpTokenNode.Null;
 			}
 		}
 		
 		public CSharpTokenNode LBracket {
 			get {
-				return (CSharpTokenNode)GetChildByRole (Roles.LBracket);
+				return (CSharpTokenNode)GetChildByRole (Roles.LBracket) ?? CSharpTokenNode.Null;
 			}
 		}
 		
 		public CSharpTokenNode RBracket {
 			get {
-				return (CSharpTokenNode)GetChildByRole (Roles.RBracket);
+				return (CSharpTokenNode)GetChildByRole (Roles.RBracket) ?? CSharpTokenNode.Null;
 			}
 		}
 		
-		public override S AcceptVisitor<T, S> (IDomVisitor<T, S> visitor, T data)
+		public override S AcceptVisitor<T, S> (DomVisitor<T, S> visitor, T data)
 		{
 			return visitor.VisitStackAllocExpression (this, data);
 		}

ICSharpCode.NRefactory/CSharp/Dom/Expressions/ThisReferenceExpression.cs

@@ -25,17 +25,22 @@
 // THE SOFTWARE.
 
 using System;
-using ICSharpCode.NRefactory.TypeSystem;
 
 namespace ICSharpCode.NRefactory.CSharp
 {
-	public class ThisReferenceExpression : AbstractNode
+	public class ThisReferenceExpression : DomNode
 	{
 		public DomLocation Location {
 			get;
 			set;
 		}
 		
+		public override NodeType NodeType {
+			get {
+				return NodeType.Expression;
+			}
+		}
+
 		public override DomLocation StartLocation {
 			get {
 				return Location;
@@ -48,7 +53,7 @@ namespace ICSharpCode.NRefactory.CSharp
 		}
 
 
-		public override S AcceptVisitor<T, S> (IDomVisitor<T, S> visitor, T data)
+		public override S AcceptVisitor<T, S> (DomVisitor<T, S> visitor, T data)
 		{
 			return visitor.VisitThisReferenceExpression (this, data);
 		}

ICSharpCode.NRefactory/CSharp/Dom/Expressions/TypeOfExpression.cs

@@ -25,27 +25,32 @@
 // THE SOFTWARE.
 
 using System;
-using ICSharpCode.NRefactory.TypeSystem;
 
 namespace ICSharpCode.NRefactory.CSharp
 {
-	public class TypeOfExpression : AbstractNode
+	public class TypeOfExpression : DomNode
 	{
+		public override NodeType NodeType {
+			get {
+				return NodeType.Expression;
+			}
+		}
+
 		public FullTypeName Type {
 			get {
-				return (FullTypeName)GetChildByRole (Roles.ReturnType);
+				return (FullTypeName)GetChildByRole (Roles.ReturnType) ?? FullTypeName.Null;
 			}
 		}
 		
 		public CSharpTokenNode LPar {
-			get { return (CSharpTokenNode)GetChildByRole (Roles.LPar); }
+			get { return (CSharpTokenNode)GetChildByRole (Roles.LPar) ?? CSharpTokenNode.Null; }
 		}
 		
 		public CSharpTokenNode RPar {
-			get { return (CSharpTokenNode)GetChildByRole (Roles.RPar); }
+			get { return (CSharpTokenNode)GetChildByRole (Roles.RPar) ?? CSharpTokenNode.Null; }
 		}
 		
-		public override S AcceptVisitor<T, S> (IDomVisitor<T, S> visitor, T data)
+		public override S AcceptVisitor<T, S> (DomVisitor<T, S> visitor, T data)
 		{
 			return visitor.VisitTypeOfExpression (this, data);
 		}

ICSharpCode.NRefactory/CSharp/Dom/Expressions/UnaryOperatorExpression.cs

@@ -1,4 +1,4 @@
-// 
+// 
 // UnaryOperatorExpression.cs
 //  
 // Author:
@@ -25,24 +25,29 @@
 // THE SOFTWARE.
 
 using System;
-using ICSharpCode.NRefactory.TypeSystem;
 
 namespace ICSharpCode.NRefactory.CSharp
 {
-	public class UnaryOperatorExpression : AbstractNode
+	public class UnaryOperatorExpression : DomNode
 	{
 		public const int Operator = 100;
 		
+		public override NodeType NodeType {
+			get {
+				return NodeType.Expression;
+			}
+		}
+
 		public UnaryOperatorType UnaryOperatorType {
 			get;
 			set;
 		}
 		
-		public INode Expression {
-			get { return GetChildByRole (Roles.Expression); }
+		public DomNode Expression {
+			get { return GetChildByRole (Roles.Expression) ?? DomNode.Null; }
 		}
 		
-		public override S AcceptVisitor<T, S> (IDomVisitor<T, S> visitor, T data)
+		public override S AcceptVisitor<T, S> (DomVisitor<T, S> visitor, T data)
 		{
 			return visitor.VisitUnaryOperatorExpression (this, data);
 		}
@@ -68,7 +73,7 @@ namespace ICSharpCode.NRefactory.CSharp
 		PostDecrement,
 		/// <summary>Dereferencing (*a)</summary>
 		Dereference,
-		/// <summary>Get address (&amp;a)</summary>
+		/// <summary>Get address (&a)</summary>
 		AddressOf
 	}
 	

ICSharpCode.NRefactory/CSharp/Dom/Expressions/UncheckedExpression.cs

@@ -25,24 +25,30 @@
 // THE SOFTWARE.
 
 using System;
-using ICSharpCode.NRefactory.TypeSystem;
 
 namespace ICSharpCode.NRefactory.CSharp
 {
-	public class UncheckedExpression : AbstractNode
+	public class UncheckedExpression : DomNode
 	{
-		public INode Expression {
-			get { return GetChildByRole (Roles.Expression); }
+		public override NodeType NodeType {
+			get {
+				return NodeType.Expression;
+			}
+		}
+
+		public DomNode Expression {
+			get { return GetChildByRole (Roles.Expression) ?? DomNode.Null; }
 		}
 		
 		public CSharpTokenNode LPar {
-			get { return (CSharpTokenNode)GetChildByRole (Roles.LPar); }
+			get { return (CSharpTokenNode)GetChildByRole (Roles.LPar) ?? CSharpTokenNode.Null; }
 		}
 		
 		public CSharpTokenNode RPar {
-			get { return (CSharpTokenNode)GetChildByRole (Roles.RPar); }
+			get { return (CSharpTokenNode)GetChildByRole (Roles.RPar) ?? CSharpTokenNode.Null; }
 		}
-		public override S AcceptVisitor<T, S> (IDomVisitor<T, S> visitor, T data)
+		
+		public override S AcceptVisitor<T, S> (DomVisitor<T, S> visitor, T data)
 		{
 			return visitor.VisitUncheckedExpression (this, data);
 		}

ICSharpCode.NRefactory/CSharp/Dom/FullTypeName.cs

@@ -24,25 +24,45 @@
 // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 // THE SOFTWARE.
 using System;
-using ICSharpCode.NRefactory.TypeSystem;
 using System.Collections.Generic;
 using System.Linq;
 
 namespace ICSharpCode.NRefactory.CSharp
 {
-	public class FullTypeName : AbstractNode
+	public class FullTypeName : DomNode
 	{
+		public static readonly new FullTypeName Null = new NullFullTypeName ();
+		class NullFullTypeName : FullTypeName
+		{
+			public override bool IsNull {
+				get {
+					return true;
+				}
+			}
+			
+			public override S AcceptVisitor<T, S> (DomVisitor<T, S> visitor, T data)
+			{
+				return default (S);
+			}
+		}
+		
+		public override NodeType NodeType {
+			get {
+				return NodeType.Unknown;
+			}
+		}
+		
 		public Identifier Identifier {
 			get {
 				return (Identifier)GetChildByRole (Roles.Identifier);
 			}
 		}
 			
-		public IEnumerable<INode> TypeArguments {
-			get { return GetChildrenByRole (Roles.TypeArgument).Cast<INode> (); }
+		public IEnumerable<DomNode> TypeArguments {
+			get { return GetChildrenByRole (Roles.TypeArgument) ?? new DomNode[0]; }
 		}
 		
-		public override S AcceptVisitor<T, S> (IDomVisitor<T, S> visitor, T data)
+		public override S AcceptVisitor<T, S> (DomVisitor<T, S> visitor, T data)
 		{
 			return visitor.VisitFullTypeName (this, data);
 		}

ICSharpCode.NRefactory/CSharp/Dom/GeneralScope/Attribute.cs

@@ -26,13 +26,18 @@
 
 using System;
 using System.Linq;
-using ICSharpCode.NRefactory.TypeSystem;
 using System.Collections.Generic;
 
 namespace ICSharpCode.NRefactory.CSharp
 {
-	public class Attribute : AbstractNode
+	public class Attribute : DomNode
 	{
+		public override NodeType NodeType {
+			get {
+				return NodeType.Unknown;
+			}
+		}
+
 		public string Name {
 			get {
 				return NameIdentifier.QualifiedName;
@@ -46,13 +51,13 @@ namespace ICSharpCode.NRefactory.CSharp
 		}
 		
 		// Todo: Arguments should not be nodes, instead it should be expressions, change when it's implemented.
-		public IEnumerable<INode> Arguments { 
+		public IEnumerable<DomNode> Arguments { 
 			get {
-				return base.GetChildrenByRole (Roles.Argument).Cast <INode>();
+				return base.GetChildrenByRole (Roles.Argument);
 			}
 		}
 
-		public override S AcceptVisitor<T, S> (IDomVisitor<T, S> visitor, T data)
+		public override S AcceptVisitor<T, S> (DomVisitor<T, S> visitor, T data)
 		{
 			return visitor.VisitAttribute (this, data);
 		}

ICSharpCode.NRefactory/CSharp/Dom/GeneralScope/AttributeSection.cs

@@ -1,4 +1,4 @@
-// 
+// 
 // AttributeSection.cs
 //  
 // Author:
@@ -26,29 +26,34 @@
 
 using System;
 using System.Linq;
-using ICSharpCode.NRefactory.TypeSystem;
 using System.Collections.Generic;
 
 namespace ICSharpCode.NRefactory.CSharp
 {
-	public class AttributeSection : AbstractNode
+	public class AttributeSection : DomNode
 	{
 		const int TargetRole = 101;
 		
+		public override NodeType NodeType {
+			get {
+				return NodeType.Unknown;
+			}
+		}
+		
 		public AttributeTarget AttributeTarget {
 			get;
 			set;
 		}
 
 		public Identifier TargetIdentifier {
-			get { return (Identifier)GetChildByRole (TargetRole); }
+			get { return (Identifier)GetChildByRole (TargetRole) ?? Identifier.Null; }
 		}
 
 		public IEnumerable<Attribute> Attributes {
 			get { return base.GetChildrenByRole (Roles.Attribute).Cast<Attribute> (); }
 		}
 
-		public override S AcceptVisitor<T, S> (IDomVisitor<T, S> visitor, T data)
+		public override S AcceptVisitor<T, S> (DomVisitor<T, S> visitor, T data)
 		{
 			return visitor.VisitAttributeSection (this, data);
 		}

ICSharpCode.NRefactory/CSharp/Dom/GeneralScope/Constraint.cs

@@ -26,30 +26,36 @@
 
 using System;
 using System.Linq;
-using ICSharpCode.NRefactory.TypeSystem;
 using System.Collections.Generic;
 
 namespace ICSharpCode.NRefactory.CSharp
 {
-	public class Constraint : AbstractNode
+	public class Constraint : DomNode
 	{
+		
+		public override NodeType NodeType {
+			get {
+				return NodeType.Unknown;
+			}
+		}
+		
 		public CSharpTokenNode WhereKeyword {
-			get { return (CSharpTokenNode)GetChildByRole (Roles.Keyword); }
+			get { return (CSharpTokenNode)GetChildByRole (Roles.Keyword) ?? CSharpTokenNode.Null; }
 		}
 		
 		public Identifier TypeParameter {
-			get { return (Identifier)GetChildByRole (Roles.Identifier); }
+			get { return (Identifier)GetChildByRole (Roles.Identifier) ?? Identifier.Null; }
 		}
 		
 		public CSharpTokenNode Colon {
-			get { return (CSharpTokenNode)GetChildByRole (Roles.Colon); }
+			get { return (CSharpTokenNode)GetChildByRole (Roles.Colon) ?? CSharpTokenNode.Null; }
 		}
 		
-		public IEnumerable<INode> TypeArguments {
-			get { return GetChildrenByRole (Roles.TypeArgument).Cast<INode> (); }
+		public IEnumerable<DomNode> TypeParameters {
+			get { return GetChildrenByRole (Roles.TypeArgument); }
 		}
 		
-		public override S AcceptVisitor<T, S> (IDomVisitor<T, S> visitor, T data)
+		public override S AcceptVisitor<T, S> (DomVisitor<T, S> visitor, T data)
 		{
 			return visitor.VisitConstraint (this, data);
 		}

ICSharpCode.NRefactory/CSharp/Dom/GeneralScope/DelegateDeclaration.cs

@@ -1,4 +1,4 @@
-// 
+// 
 // DelegateDeclaration.cs
 //  
 // Author:
@@ -26,13 +26,18 @@
 
 using System;
 using System.Linq;
-using ICSharpCode.NRefactory.TypeSystem;
 using System.Collections.Generic;
 
 namespace ICSharpCode.NRefactory.CSharp
 {
 	public class DelegateDeclaration : AbstractMemberBase
 	{
+		public override NodeType NodeType {
+			get {
+				return NodeType.Type;
+			}
+		}
+		
 		public string Name {
 			get {
 				return NameIdentifier.Name;
@@ -41,28 +46,37 @@ namespace ICSharpCode.NRefactory.CSharp
 		
 		public Identifier NameIdentifier {
 			get {
-				return (Identifier)GetChildByRole (Roles.Identifier);
+				return (Identifier)GetChildByRole (Roles.Identifier) ?? Identifier.Null;
 			}
 		}
 		
-		public INode ReturnType {
+		public DomNode ReturnType {
 			get {
-				return (INode)GetChildByRole (Roles.ReturnType);
+				return GetChildByRole (Roles.ReturnType) ?? DomNode.Null;
 			}
 		}
 		
-		// TODO: call this Parameters or Arguments?
-		public IEnumerable<ParameterDeclaration> Parameters {
-			get { return this.Arguments; }
+		public IEnumerable<ParameterDeclaration> Parameters { 
+			get {
+				return base.GetChildrenByRole (Roles.Argument).Cast <ParameterDeclaration> ();
+			}
+		}
+		
+		public CSharpTokenNode LPar {
+			get { return (CSharpTokenNode)GetChildByRole (Roles.LPar) ?? CSharpTokenNode.Null; }
+		}
+		
+		public CSharpTokenNode RPar {
+			get { return (CSharpTokenNode)GetChildByRole (Roles.RPar) ?? CSharpTokenNode.Null; }
 		}
 		
-		public IEnumerable<ParameterDeclaration> Arguments { 
+		public IEnumerable<AttributeSection> Attributes { 
 			get {
-				return base.GetChildrenByRole (Roles.Argument).Cast <ParameterDeclaration>();
+				return base.GetChildrenByRole (Roles.Attribute).Cast <AttributeSection>();
 			}
 		}
 		
-		public override S AcceptVisitor<T, S> (IDomVisitor<T, S> visitor, T data)
+		public override S AcceptVisitor<T, S> (DomVisitor<T, S> visitor, T data)
 		{
 			return visitor.VisitDelegateDeclaration (this, data);
 		}

ICSharpCode.NRefactory/CSharp/Dom/GeneralScope/EnumDeclaration.cs

@@ -1,4 +1,4 @@
-// 
+// 
 // EnumDeclaration.cs
 //  
 // Author:
@@ -26,13 +26,53 @@
 
 using System;
 using System.Linq;
-using ICSharpCode.NRefactory.TypeSystem;
 using System.Collections.Generic;
+using ICSharpCode.NRefactory.TypeSystem;
 
 namespace ICSharpCode.NRefactory.CSharp
 {
-	public class EnumMemberDeclaration : AbstractMemberBase
+	public class EnumDeclaration : TypeDeclaration
+	{
+		public override NodeType NodeType {
+			get {
+				return NodeType.Type;
+			}
+		}
+		
+		const int EnumMemberDeclarationRole = 100;
+		
+		public IEnumerable<EnumMemberDeclaration> Members { 
+			get {
+				return base.GetChildrenByRole (EnumMemberDeclarationRole).Cast <EnumMemberDeclaration>();
+			}
+		}
+		
+		public override ClassType ClassType {
+			get {
+				return ClassType.Enum;
+			}
+		}
+		
+		public override S AcceptVisitor<T, S> (DomVisitor<T, S> visitor, T data)
+		{
+			return visitor.VisitEnumDeclaration (this, data);
+		}
+	}
+	
+	public class EnumMemberDeclaration : DomNode
 	{
+		public override NodeType NodeType {
+			get {
+				return NodeType.Member;
+			}
+		}
+		
+		public IEnumerable<AttributeSection> Attributes { 
+			get {
+				return base.GetChildrenByRole (Roles.Attribute).Cast <AttributeSection>();
+			}
+		}
+		
 		public string Name {
 			get {
 				return NameIdentifier.Name;
@@ -41,17 +81,17 @@ namespace ICSharpCode.NRefactory.CSharp
 		
 		public Identifier NameIdentifier {
 			get {
-				return (Identifier)GetChildByRole (Roles.Identifier);
+				return (Identifier)GetChildByRole (Roles.Identifier) ?? Identifier.Null;
 			}
 		}
 		
-		public INode Initializer {
+		public DomNode Initializer {
 			get {
-				return GetChildByRole (Roles.Initializer);
+				return GetChildByRole (Roles.Initializer) ?? DomNode.Null;
 			}
 		}
 		
-		public override S AcceptVisitor<T, S> (IDomVisitor<T, S> visitor, T data)
+		public override S AcceptVisitor<T, S> (DomVisitor<T, S> visitor, T data)
 		{
 			return visitor.VisitEnumMemberDeclaration (this, data);
 		}

ICSharpCode.NRefactory/CSharp/Dom/GeneralScope/NamespaceDeclaration.cs

@@ -1,4 +1,4 @@
-// 
+// 
 // NamespaceDeclaration.cs
 //  
 // Author:
@@ -26,12 +26,17 @@
 
 using System;
 using System.Collections.Generic;
-using ICSharpCode.NRefactory.TypeSystem;
 
 namespace ICSharpCode.NRefactory.CSharp
 {
-	public class NamespaceDeclaration : AbstractNode
+	public class NamespaceDeclaration : DomNode
 	{
+		public override NodeType NodeType {
+			get {
+				return NodeType.Unknown;
+			}
+		}
+		
 		public string Name {
 			get {
 				return NameIdentifier.QualifiedName;
@@ -47,13 +52,25 @@ namespace ICSharpCode.NRefactory.CSharp
 			}
 		}
 		
+		public CSharpTokenNode LBrace {
+			get {
+				return (CSharpTokenNode)GetChildByRole (Roles.LBrace) ?? CSharpTokenNode.Null;
+			}
+		}
+		
+		public CSharpTokenNode RBrace {
+			get {
+				return (CSharpTokenNode)GetChildByRole (Roles.RBrace) ?? CSharpTokenNode.Null;
+			}
+		}
+		
 		public QualifiedIdentifier NameIdentifier {
 			get {
 				return (QualifiedIdentifier)GetChildByRole (Roles.Identifier);
 			}
 		}
 		
-		public IEnumerable<INode> Members {
+		public IEnumerable<DomNode> Members {
 			get { return GetChildrenByRole(Roles.Member); }
 		}
 		
@@ -66,7 +83,7 @@ namespace ICSharpCode.NRefactory.CSharp
 			return name1 + "." + name2;
 		}
 		
-		public override S AcceptVisitor<T, S> (IDomVisitor<T, S> visitor, T data)
+		public override S AcceptVisitor<T, S> (DomVisitor<T, S> visitor, T data)
 		{
 			return visitor.VisitNamespaceDeclaration (this, data);
 		}

ICSharpCode.NRefactory/CSharp/Dom/GeneralScope/TypeDeclaration.cs

@@ -1,4 +1,4 @@
-// 
+// 
 // TypeDeclaration.cs
 //  
 // Author:
@@ -35,28 +35,27 @@ namespace ICSharpCode.NRefactory.CSharp
 	{
 		public const int TypeKeyword      = 100;
 		
-		public Identifier NameIdentifier {
+		public override NodeType NodeType {
 			get {
-				return (Identifier)GetChildByRole (Roles.Identifier);
+				return NodeType.Type;
 			}
 		}
 		
-		public string Name {
+		public Identifier NameIdentifier {
 			get {
-				return NameIdentifier.Name;
+				return (Identifier)GetChildByRole (Roles.Identifier);
 			}
 		}
 		
-		public IEnumerable<AbstractMemberBase> Members {
+		public string Name {
 			get {
-				return GetChildrenByRole (Roles.Member).Cast<AbstractMemberBase> ();
+				return NameIdentifier.Name;
 			}
 		}
 		
-		// TODO: rename to TypeParameters, more specific return type
-		public IEnumerable<INode> TypeArguments {
+		public IEnumerable<DomNode> TypeParameters {
 			get {
-				return GetChildrenByRole (Roles.TypeArgument).Cast<INode> ();
+				return GetChildrenByRole (Roles.TypeArgument);
 			}
 		}
 		
@@ -68,13 +67,13 @@ namespace ICSharpCode.NRefactory.CSharp
 		
 		public CSharpTokenNode LBrace {
 			get {
-				return (CSharpTokenNode)GetChildByRole (Roles.LBrace);
+				return (CSharpTokenNode)GetChildByRole (Roles.LBrace) ?? CSharpTokenNode.Null;
 			}
 		}
 		
 		public CSharpTokenNode RBrace {
 			get {
-				return (CSharpTokenNode)GetChildByRole (Roles.RBrace);
+				return (CSharpTokenNode)GetChildByRole (Roles.RBrace) ?? CSharpTokenNode.Null;
 			}
 		}
 		
@@ -83,7 +82,13 @@ namespace ICSharpCode.NRefactory.CSharp
 			set;
 		}
 		
-		public override S AcceptVisitor<T, S> (IDomVisitor<T, S> visitor, T data)
+		public IEnumerable<AbstractMemberBase> Members {
+			get {
+				return GetChildrenByRole (Roles.Member).Cast<AbstractMemberBase> ();
+			}
+		}
+		
+		public override S AcceptVisitor<T, S> (DomVisitor<T, S> visitor, T data)
 		{
 			return visitor.VisitTypeDeclaration (this, data);
 		}

ICSharpCode.NRefactory/CSharp/Dom/GeneralScope/UsingAliasDeclaration.cs

@@ -1,4 +1,4 @@
-// 
+// 
 // UsingAliasDeclaration.cs
 //  
 // Author:
@@ -30,22 +30,27 @@ namespace ICSharpCode.NRefactory.CSharp
 {
 	public class UsingAliasDeclaration : UsingDeclaration
 	{
-		public const int Assignment      = 103;
-		public const int AliasRole       = 104;
+		public const int AliasRole       = 100;
+		
+		public override NodeType NodeType {
+			get {
+				return NodeType.Unknown;
+			}
+		}
 		
 		public string Alias {
 			get {
-				return AliasIdentifier.Name;
+				return AliasIdentifier.QualifiedName;
 			}
 		}
 		
-		public Identifier AliasIdentifier {
+		public QualifiedIdentifier AliasIdentifier {
 			get {
-				return (Identifier)GetChildByRole (AliasRole);
+				return (QualifiedIdentifier)GetChildByRole (AliasRole);
 			}
 		}
 		
-		public override S AcceptVisitor<T, S> (IDomVisitor<T, S> visitor, T data)
+		public override S AcceptVisitor<T, S> (DomVisitor<T, S> visitor, T data)
 		{
 			return visitor.VisitUsingAliasDeclaration (this, data);
 		}

ICSharpCode.NRefactory/CSharp/Dom/GeneralScope/UsingDeclaration.cs

@@ -25,12 +25,17 @@
 // THE SOFTWARE.
 
 using System;
-using ICSharpCode.NRefactory.TypeSystem;
 
 namespace ICSharpCode.NRefactory.CSharp
 {
-	public class UsingDeclaration : AbstractNode
+	public class UsingDeclaration : DomNode
 	{
+		public override NodeType NodeType {
+			get {
+				return NodeType.Unknown;
+			}
+		}
+		
 		public string Namespace {
 			get {
 				return NameIdentifier.QualifiedName;
@@ -43,7 +48,7 @@ namespace ICSharpCode.NRefactory.CSharp
 			}
 		}
 		
-		public override S AcceptVisitor<T, S> (IDomVisitor<T, S> visitor, T data)
+		public override S AcceptVisitor<T, S> (DomVisitor<T, S> visitor, T data)
 		{
 			return visitor.VisitUsingDeclaration (this, data);
 		}

ICSharpCode.NRefactory/CSharp/Dom/IDomVisitor.cs

@@ -1,140 +0,0 @@
-// 
-// IDomVisitor.cs
-//  
-// Author:
-//       Mike Krüger <mkrueger@novell.com>
-// 
-// Copyright (c) 2009 Novell, Inc (http://www.novell.com)
-// 
-// 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.NRefactory.CSharp
-{
-	public interface IDomVisitor<T, S>
-	{
-		S VisitCompilationUnit (CompilationUnit unit, T data);
-		
-		#region General scope
-		S VisitAttribute (Attribute attribute, T data);
-		S VisitAttributeSection (AttributeSection attributeSection, T data);
-		S VisitDelegateDeclaration (DelegateDeclaration delegateDeclaration, T data);
-		S VisitNamespaceDeclaration (NamespaceDeclaration namespaceDeclaration, T data);
-		S VisitTypeDeclaration (TypeDeclaration typeDeclaration, T data);
-		S VisitEnumMemberDeclaration (EnumMemberDeclaration enumMemberDeclaration, T data);
-		S VisitUsingDeclaration (UsingDeclaration usingDeclaration, T data);
-		S VisitUsingAliasDeclaration (UsingAliasDeclaration usingDeclaration, T data);
-		S VisitFullTypeName (FullTypeName fullTypeName, T data);
-		S VisitIdentifier (Identifier identifier, T data);
-		S VisitParameterDeclaration (ParameterDeclaration parameterDeclaration, T data);
-		S VisitConstraint (Constraint constraint, T data);
-		S VisitComposedType (ComposedType composedType, T data);
-		#endregion
-		
-		#region Type members
-		S VisitConstructorDeclaration (ConstructorDeclaration constructorDeclaration, T data);
-		S VisitConstructorInitializer (ConstructorInitializer constructorInitializer, T data);
-		S VisitDestructorDeclaration (DestructorDeclaration destructorDeclaration, T data);
-		S VisitEventDeclaration (EventDeclaration eventDeclaration, T data);
-		S VisitFieldDeclaration (FieldDeclaration fieldDeclaration, T data);
-		S VisitIndexerDeclaration (IndexerDeclaration indexerDeclaration, T data);
-		S VisitMethodDeclaration (MethodDeclaration methodDeclaration, T data);
-		S VisitOperatorDeclaration (OperatorDeclaration operatorDeclaration, T data);
-		S VisitPropertyDeclaration (PropertyDeclaration propertyDeclaration, T data);
-		S VisitAccessorDeclaration (Accessor accessorDeclaration, T data);
-		S VisitVariableInitializer (VariableInitializer variableInitializer, T data);
-		#endregion
-		
-		#region Statements
-		S VisitBlockStatement (BlockStatement blockStatement, T data);
-		S VisitExpressionStatement (ExpressionStatement expressionStatement, T data);
-		S VisitBreakStatement (BreakStatement breakStatement, T data);
-		S VisitCheckedStatement (CheckedStatement checkedStatement, T data);
-		S VisitContinueStatement (ContinueStatement continueStatement, T data);
-		S VisitEmptyStatement (EmptyStatement emptyStatement, T data);
-		S VisitFixedStatement (FixedStatement fixedStatement, T data);
-		S VisitForeachStatement (ForeachStatement foreachStatement, T data);
-		S VisitForStatement (ForStatement forStatement, T data);
-		S VisitGotoStatement (GotoStatement gotoStatement, T data);
-		S VisitIfElseStatement (IfElseStatement ifElseStatement, T data);
-		S VisitLabelStatement (LabelStatement labelStatement, T data);
-		S VisitLockStatement (LockStatement lockStatement, T data);
-		S VisitReturnStatement (ReturnStatement returnStatement, T data);
-		S VisitSwitchStatement (SwitchStatement switchStatement, T data);
-		S VisitSwitchSection (SwitchSection switchSection, T data);
-		S VisitCaseLabel (CaseLabel caseLabel, T data);
-		
-		S VisitThrowStatement (ThrowStatement throwStatement, T data);
-		S VisitTryCatchStatement (TryCatchStatement tryCatchStatement, T data);
-		S VisitCatchClause (CatchClause catchClause, T data);
-		
-		S VisitUncheckedStatement (UncheckedStatement uncheckedStatement, T data);
-		S VisitUnsafeStatement (UnsafeStatement unsafeStatement, T data);
-		S VisitUsingStatement (UsingStatement usingStatement, T data);
-		S VisitVariableDeclarationStatement (VariableDeclarationStatement variableDeclarationStatement, T data);
-		S VisitWhileStatement (WhileStatement whileStatement, T data);
-		S VisitYieldStatement (YieldStatement yieldStatement, T data);
-		#endregion
-		
-		#region Expressions
-		S VisitAnonymousMethodExpression (AnonymousMethodExpression anonymousMethodExpression, T data);
-		S VisitLambdaExpression (LambdaExpression lambdaExpression, T data);
-		S VisitAssignmentExpression (AssignmentExpression assignmentExpression, T data);
-		S VisitBaseReferenceExpression (BaseReferenceExpression baseReferenceExpression, T data);
-		S VisitBinaryOperatorExpression (BinaryOperatorExpression binaryOperatorExpression, T data);
-		S VisitCastExpression (CastExpression castExpression, T data);
-		S VisitCheckedExpression (CheckedExpression checkedExpression, T data);
-		S VisitConditionalExpression (ConditionalExpression conditionalExpression, T data);
-		S VisitIdentifierExpression (IdentifierExpression identifierExpression, T data);
-		S VisitIndexerExpression (IndexerExpression indexerExpression, T data);
-		S VisitInvocationExpression (InvocationExpression invocationExpression, T data);
-		S VisitDirectionExpression (DirectionExpression directionExpression, T data);
-		S VisitMemberReferenceExpression (MemberReferenceExpression memberReferenceExpression, T data);
-		S VisitNullReferenceExpression (NullReferenceExpression nullReferenceExpression, T data);
-		S VisitObjectCreateExpression (ObjectCreateExpression objectCreateExpression, T data);
-		S VisitArrayObjectCreateExpression (ArrayObjectCreateExpression arrayObjectCreateExpression, T data);
-		
-		S VisitParenthesizedExpression (ParenthesizedExpression parenthesizedExpression, T data);
-		S VisitPointerReferenceExpression (PointerReferenceExpression pointerReferenceExpression, T data);
-		S VisitPrimitiveExpression(PrimitiveExpression primitiveExpression, T data);
-		S VisitSizeOfExpression (SizeOfExpression sizeOfExpression, T data);
-		S VisitStackAllocExpression (StackAllocExpression stackAllocExpression, T data);
-		S VisitThisReferenceExpression(ThisReferenceExpression thisReferenceExpression, T data);
-		S VisitTypeOfExpression (TypeOfExpression typeOfExpression, T data);
-		S VisitUnaryOperatorExpression (UnaryOperatorExpression unaryOperatorExpression, T data);
-		S VisitUncheckedExpression (UncheckedExpression uncheckedExpression, T data);
-		S VisitAsExpression (AsExpression asExpression, T data);
-		S VisitIsExpression (IsExpression isExpression, T data);
-		S VisitDefaultValueExpression (DefaultValueExpression defaultValueExpression, T data);
-		S VisitArgListExpression (ArgListExpression argListExpression, T data);
-		#endregion
-		
-		#region Query Expressions
-		S VisitQueryExpressionFromClause (QueryExpressionFromClause queryExpressionFromClause, T data);
-		S VisitQueryExpressionWhereClause (QueryExpressionWhereClause queryExpressionWhereClause, T data);
-		S VisitQueryExpressionJoinClause (QueryExpressionJoinClause queryExpressionJoinClause, T data);
-		S VisitQueryExpressionGroupClause (QueryExpressionGroupClause queryExpressionGroupClause, T data);
-		S VisitQueryExpressionLetClause (QueryExpressionLetClause queryExpressionLetClause, T data);
-		S VisitQueryExpressionOrderClause (QueryExpressionOrderClause queryExpressionOrderClause, T data);
-		S VisitQueryExpressionOrdering (QueryExpressionOrdering queryExpressionOrdering, T data);
-		S VisitQueryExpressionSelectClause (QueryExpressionSelectClause queryExpressionSelectClause, T data);
-		#endregion
-	}
-}

ICSharpCode.NRefactory/CSharp/Dom/Identifier.cs

@@ -25,12 +25,32 @@
 // THE SOFTWARE.
 
 using System;
-using ICSharpCode.NRefactory.TypeSystem;
 
 namespace ICSharpCode.NRefactory.CSharp
 {
-	public class Identifier : AbstractNode
+	public class Identifier : DomNode
 	{
+		public static readonly new Identifier Null = new NullIdentifier ();
+		class NullIdentifier : Identifier
+		{
+			public override bool IsNull {
+				get {
+					return true;
+				}
+			}
+			
+			public override S AcceptVisitor<T, S> (DomVisitor<T, S> visitor, T data)
+			{
+				return default (S);
+			}
+		}
+		
+		public override NodeType NodeType {
+			get {
+				return NodeType.Unknown;
+			}
+		}
+		
 		public string Name {
 			get;
 			set;
@@ -65,7 +85,7 @@ namespace ICSharpCode.NRefactory.CSharp
 			this.startLocation = location;
 		}
 		
-		public override S AcceptVisitor<T, S> (IDomVisitor<T, S> visitor, T data)
+		public override S AcceptVisitor<T, S> (DomVisitor<T, S> visitor, T data)
 		{
 			return visitor.VisitIdentifier (this, data);
 		}

ICSharpCode.NRefactory/CSharp/Dom/NodeType.cs

@@ -1,5 +1,5 @@
-// 
-// INode.cs
+// 
+// NodeType.cs
 //  
 // Author:
 //       Mike Krüger <mkrueger@novell.com>
@@ -25,58 +25,18 @@
 // THE SOFTWARE.
 
 using System;
-using System.Collections.Generic;
 
 namespace ICSharpCode.NRefactory.CSharp
 {
-	public interface INode
+	public enum NodeType
 	{
-		INode Parent { 
-			get;
-			set;
-		}
-		
-		IEnumerable<INode> Children {
-			get;
-		}
-		
-		INode GetChildByRole (int role);
-		
-		int Role {
-			get;
-			set;
-		}
-		
-		
-		INode NextSibling {
-			get;
-			set;
-		}
-		
-		INode PrevSibling {
-			get;
-			set;
-		}
+		Unknown,
 		
-		INode FirstChild {
-			get;
-			set;
-		}
-		
-		INode LastChild {
-			get;
-			set;
-		}
-		
-		DomLocation StartLocation {
-			get;
-		}
-		
-		DomLocation EndLocation {
-			get;
-		}
-		
-		
-		S AcceptVisitor<T, S> (IDomVisitor<T, S> visitor, T data);
+		Type,
+		Member,
+		Statement,
+		Expression,
+		Token
 	}
+
 }

ICSharpCode.NRefactory/CSharp/Dom/QualifiedIdentifier.cs

@@ -1,4 +1,4 @@
-// 
+// 
 // QualifiedIdentifier.cs
 //  
 // Author:
@@ -25,27 +25,27 @@
 // THE SOFTWARE.
 
 using System;
+using System.Text;
 using System.Collections.Generic;
 using System.Linq;
-using System.Text;
 
 namespace ICSharpCode.NRefactory.CSharp
 {
-	public class QualifiedIdentifier : AbstractNode
+	public class QualifiedIdentifier : DomNode
 	{
+		public override NodeType NodeType {
+			get {
+				return NodeType.Unknown;
+			}
+		}
+		
 		public string QualifiedName {
 			get {
 				StringBuilder builder = new StringBuilder ();
-				int i = 0;
 				foreach (Identifier identifier in GetChildrenByRole (Roles.Identifier)) {
-					if (i > 0) {
-						if (i == 1 && HasDoubleColon)
-							builder.Append ("::");
-						else
-							builder.Append ('.');
-					}
+					if (builder.Length > 0)
+						builder.Append ('.');
 					builder.Append (identifier.Name);
-					i++;
 				}
 				return builder.ToString ();
 			}
@@ -64,5 +64,10 @@ namespace ICSharpCode.NRefactory.CSharp
 		public QualifiedIdentifier ()
 		{
 		}
+		
+		public override S AcceptVisitor<T, S> (DomVisitor<T, S> visitor, T data)
+		{
+			return default (S);
+		}
 	}
 }

ICSharpCode.NRefactory/CSharp/Dom/Statements/BlockStatement.cs

@@ -25,32 +25,53 @@
 // THE SOFTWARE.
 
 using System;
-using ICSharpCode.NRefactory.TypeSystem;
 using System.Collections.Generic;
 
 namespace ICSharpCode.NRefactory.CSharp
 {
-	public class BlockStatement : AbstractNode
+	public class BlockStatement : DomNode
 	{
+		public static readonly new BlockStatement Null = new NullBlockStatement ();
+		class NullBlockStatement : BlockStatement
+		{
+			public override bool IsNull {
+				get {
+					return true;
+				}
+			}
+			
+			public override S AcceptVisitor<T, S> (DomVisitor<T, S> visitor, T data)
+			{
+				return default (S);
+			}
+		}
+		
+		
+		public override NodeType NodeType {
+			get {
+				return NodeType.Statement;
+			}
+		}
+
 		public CSharpTokenNode LBrace {
 			get {
-				return (CSharpTokenNode)GetChildByRole (Roles.LBrace);
+				return (CSharpTokenNode)GetChildByRole (Roles.LBrace) ?? CSharpTokenNode.Null;
 			}
 		}
 		
 		public CSharpTokenNode RBrace {
 			get {
-				return (CSharpTokenNode)GetChildByRole (Roles.RBrace);
+				return (CSharpTokenNode)GetChildByRole (Roles.RBrace) ?? CSharpTokenNode.Null;
 			}
 		}
 		
-		public IEnumerable<INode> Statements {
+		public IEnumerable<DomNode> Statements {
 			get {
 				return GetChildrenByRole (Roles.Statement);
 			}
 		}
 		
-		public override S AcceptVisitor<T, S> (IDomVisitor<T, S> visitor, T data)
+		public override S AcceptVisitor<T, S> (DomVisitor<T, S> visitor, T data)
 		{
 			return visitor.VisitBlockStatement (this, data);
 		}

ICSharpCode.NRefactory/CSharp/Dom/Statements/BreakStatement.cs

@@ -25,19 +25,24 @@
 // THE SOFTWARE.
 
 using System;
-using ICSharpCode.NRefactory.TypeSystem;
 
 namespace ICSharpCode.NRefactory.CSharp
 {
-	public class BreakStatement : AbstractNode
+	public class BreakStatement : DomNode
 	{
-		public INode BreakKeyword {
+		public override NodeType NodeType {
 			get {
-				return GetChildByRole (Roles.Keyword);
+				return NodeType.Statement;
+			}
+		}
+
+		public CSharpTokenNode BreakKeyword {
+			get {
+				return (CSharpTokenNode)GetChildByRole (Roles.Keyword) ?? CSharpTokenNode.Null;
 			}
 		}
 		
-		public override S AcceptVisitor<T, S> (IDomVisitor<T, S> visitor, T data)
+		public override S AcceptVisitor<T, S> (DomVisitor<T, S> visitor, T data)
 		{
 			return visitor.VisitBreakStatement (this, data);
 		}

ICSharpCode.NRefactory/CSharp/Dom/Statements/CheckedStatement.cs

@@ -1,4 +1,4 @@
-// 
+// 
 // CheckedStatement.cs
 //  
 // Author:
@@ -25,17 +25,22 @@
 // THE SOFTWARE.
 
 using System;
-using ICSharpCode.NRefactory.TypeSystem;
 
 namespace ICSharpCode.NRefactory.CSharp
 {
-	public class CheckedStatement : AbstractNode
+	public class CheckedStatement : DomNode
 	{
+		public override NodeType NodeType {
+			get {
+				return NodeType.Statement;
+			}
+		}
+		
 		public BlockStatement Block {
-			get { return (BlockStatement)GetChildByRole (Roles.Body); }
+			get { return (BlockStatement)GetChildByRole (Roles.Body) ?? BlockStatement.Null; }
 		}
 		
-		public override S AcceptVisitor<T, S> (IDomVisitor<T, S> visitor, T data)
+		public override S AcceptVisitor<T, S> (DomVisitor<T, S> visitor, T data)
 		{
 			return visitor.VisitCheckedStatement (this, data);
 		}

ICSharpCode.NRefactory/CSharp/Dom/Statements/ContinueStatement.cs

@@ -25,17 +25,22 @@
 // THE SOFTWARE.
 
 using System;
-using ICSharpCode.NRefactory.TypeSystem;
 
 namespace ICSharpCode.NRefactory.CSharp
 {
-	public class ContinueStatement : AbstractNode
+	public class ContinueStatement : DomNode
 	{
-		public INode ContinueKeyword {
-			get { return GetChildByRole (Roles.Keyword); }
+		public override NodeType NodeType {
+			get {
+				return NodeType.Statement;
+			}
+		}
+
+		public CSharpTokenNode ContinueKeyword {
+			get { return (CSharpTokenNode)GetChildByRole (Roles.Keyword) ?? CSharpTokenNode.Null; }
 		}
 		
-		public override S AcceptVisitor<T, S> (IDomVisitor<T, S> visitor, T data)
+		public override S AcceptVisitor<T, S> (DomVisitor<T, S> visitor, T data)
 		{
 			return visitor.VisitContinueStatement (this, data);
 		}

ICSharpCode.NRefactory/CSharp/Dom/Statements/EmptyStatement.cs

@@ -25,12 +25,17 @@
 // THE SOFTWARE.
 
 using System;
-using ICSharpCode.NRefactory.TypeSystem;
 
 namespace ICSharpCode.NRefactory.CSharp
 {
-	public class EmptyStatement : AbstractNode
+	public class EmptyStatement : DomNode
 	{
+		public override NodeType NodeType {
+			get {
+				return NodeType.Statement;
+			}
+		}
+
 		public DomLocation Location {
 			get;
 			set;
@@ -41,13 +46,14 @@ namespace ICSharpCode.NRefactory.CSharp
 				return Location;
 			}
 		}
+		
 		public override DomLocation EndLocation {
 			get {
-				return new DomLocation (Location.Line, Location.Column + 1);
+				return new DomLocation (Location.Line, Location.Column);
 			}
 		}
 		
-		public override S AcceptVisitor<T, S> (IDomVisitor<T, S> visitor, T data)
+		public override S AcceptVisitor<T, S> (DomVisitor<T, S> visitor, T data)
 		{
 			return visitor.VisitEmptyStatement (this, data);
 		}

ICSharpCode.NRefactory/CSharp/Dom/Statements/ExpressionStatement.cs

@@ -1,4 +1,4 @@
-// 
+// 
 // ExpressionStatement.cs
 //  
 // Author:
@@ -25,19 +25,24 @@
 // THE SOFTWARE.
 
 using System;
-using ICSharpCode.NRefactory.TypeSystem;
 
 namespace ICSharpCode.NRefactory.CSharp
 {
-	public class ExpressionStatement : AbstractNode
+	public class ExpressionStatement : DomNode
 	{
-		public INode Expression {
+		public override NodeType NodeType {
 			get {
-				return GetChildByRole(Roles.Expression);
+				return NodeType.Statement;
 			}
 		}
 		
-		public override S AcceptVisitor<T, S> (IDomVisitor<T, S> visitor, T data)
+		public DomNode Expression {
+			get {
+				return GetChildByRole (Roles.Expression);
+			}
+		}
+
+		public override S AcceptVisitor<T, S> (DomVisitor<T, S> visitor, T data)
 		{
 			return visitor.VisitExpressionStatement (this, data);
 		}

ICSharpCode.NRefactory/CSharp/Dom/Statements/FixedStatement.cs

@@ -25,25 +25,30 @@
 // THE SOFTWARE.
 
 using System;
-using ICSharpCode.NRefactory.TypeSystem;
 
 namespace ICSharpCode.NRefactory.CSharp
 {
-	public class FixedStatement : AbstractNode
+	public class FixedStatement : DomNode
 	{
 		public const int PointerDeclarationRole = 100;
 		public const int FixedKeywordRole = 101;
 		public const int DeclaratorRole = 102;
 		
-		public INode EmbeddedStatement {
-			get { return (INode)GetChildByRole (Roles.EmbeddedStatement); }
+		public override NodeType NodeType {
+			get {
+				return NodeType.Statement;
+			}
+		}
+
+		public DomNode EmbeddedStatement {
+			get { return GetChildByRole (Roles.EmbeddedStatement) ?? DomNode.Null; }
 		}
 		
-		public INode PointerDeclaration {
-			get { return GetChildByRole (PointerDeclarationRole); }
+		public DomNode PointerDeclaration {
+			get { return GetChildByRole (PointerDeclarationRole) ?? DomNode.Null; }
 		}
 		
-		public override S AcceptVisitor<T, S> (IDomVisitor<T, S> visitor, T data)
+		public override S AcceptVisitor<T, S> (DomVisitor<T, S> visitor, T data)
 		{
 			return visitor.VisitFixedStatement (this, data);
 		}

ICSharpCode.NRefactory/CSharp/Dom/Statements/ForStatement.cs

@@ -25,38 +25,43 @@
 // THE SOFTWARE.
 
 using System;
-using ICSharpCode.NRefactory.TypeSystem;
 using System.Collections.Generic;
 
 namespace ICSharpCode.NRefactory.CSharp
 {
-	public class ForStatement : AbstractNode
+	public class ForStatement : DomNode
 	{
-		public INode EmbeddedStatement {
-			get { return (INode)GetChildByRole (Roles.EmbeddedStatement); }
+		public override NodeType NodeType {
+			get {
+				return NodeType.Statement;
+			}
+		}
+
+		public DomNode EmbeddedStatement {
+			get { return GetChildByRole (Roles.EmbeddedStatement) ?? DomNode.Null; }
 		}
 		
-		public INode Condition {
-			get { return GetChildByRole (Roles.Condition); }
+		public DomNode Condition {
+			get { return GetChildByRole (Roles.Condition) ?? DomNode.Null; }
 		}
 		
-		public IEnumerable<INode> Initializers {
+		public IEnumerable<DomNode> Initializers {
 			get { return GetChildrenByRole (Roles.Initializer); }
 		}
 		
-		public IEnumerable<INode> Iterators {
+		public IEnumerable<DomNode> Iterators {
 			get { return GetChildrenByRole (Roles.Iterator); }
 		}
 		
 		public CSharpTokenNode LPar {
-			get { return (CSharpTokenNode)GetChildByRole (Roles.LPar); }
+			get { return (CSharpTokenNode)GetChildByRole (Roles.LPar) ?? CSharpTokenNode.Null; }
 		}
 		
 		public CSharpTokenNode RPar {
-			get { return (CSharpTokenNode)GetChildByRole (Roles.RPar); }
+			get { return (CSharpTokenNode)GetChildByRole (Roles.RPar) ?? CSharpTokenNode.Null; }
 		}
 		
-		public override S AcceptVisitor<T, S> (IDomVisitor<T, S> visitor, T data)
+		public override S AcceptVisitor<T, S> (DomVisitor<T, S> visitor, T data)
 		{
 			return visitor.VisitForStatement (this, data);
 		}

ICSharpCode.NRefactory/CSharp/Dom/Statements/ForeachStatement.cs

@@ -25,33 +25,38 @@
 // THE SOFTWARE.
 
 using System;
-using ICSharpCode.NRefactory.TypeSystem;
 
 namespace ICSharpCode.NRefactory.CSharp
 {
-	public class ForeachStatement : AbstractNode
+	public class ForeachStatement : DomNode
 	{
 		public const int ForEachKeywordRole = 100;
 		public const int InKeywordRole = 101;
-			
-		public INode EmbeddedStatement {
-			get { return (INode)GetChildByRole (Roles.EmbeddedStatement); }
+		
+		public override NodeType NodeType {
+			get {
+				return NodeType.Statement;
+			}
+		}
+
+		public DomNode EmbeddedStatement {
+			get { return GetChildByRole (Roles.EmbeddedStatement) ?? DomNode.Null; }
 		}
 		
-		public INode Expression {
-			get { return GetChildByRole (Roles.Initializer); }
+		public DomNode Expression {
+			get { return GetChildByRole (Roles.Initializer) ?? DomNode.Null; }
 		}
 		
-		public INode VariableType {
-			get { return (INode)GetChildByRole (Roles.ReturnType); }
+		public DomNode VariableType {
+			get { return GetChildByRole (Roles.ReturnType) ?? DomNode.Null; }
 		}
 		
 		public CSharpTokenNode LPar {
-			get { return (CSharpTokenNode)GetChildByRole (Roles.LPar); }
+			get { return (CSharpTokenNode)GetChildByRole (Roles.LPar) ?? CSharpTokenNode.Null; }
 		}
 		
 		public CSharpTokenNode RPar {
-			get { return (CSharpTokenNode)GetChildByRole (Roles.RPar); }
+			get { return (CSharpTokenNode)GetChildByRole (Roles.RPar) ?? CSharpTokenNode.Null; }
 		}
 		
 		public string VariableName {
@@ -62,11 +67,11 @@ namespace ICSharpCode.NRefactory.CSharp
 		
 		public Identifier VariableNameIdentifier {
 			get {
-				return (Identifier)GetChildByRole (Roles.Identifier);
+				return (Identifier)GetChildByRole (Roles.Identifier) ?? Identifier.Null;
 			}
 		}
 		
-		public override S AcceptVisitor<T, S> (IDomVisitor<T, S> visitor, T data)
+		public override S AcceptVisitor<T, S> (DomVisitor<T, S> visitor, T data)
 		{
 			return visitor.VisitForeachStatement (this, data);
 		}

ICSharpCode.NRefactory/CSharp/Dom/Statements/GotoStatement.cs

@@ -1,4 +1,4 @@
-// 
+// 
 // GotoStatement.cs
 //  
 // Author:
@@ -25,32 +25,34 @@
 // THE SOFTWARE.
 
 using System;
-using ICSharpCode.NRefactory.TypeSystem;
 
 namespace ICSharpCode.NRefactory.CSharp
 {
-	public class GotoStatement : AbstractNode
+	public class GotoStatement : DomNode
 	{
 		public const int DefaultKeywordRole = 100;
 		public const int CaseKeywordRole = 101;
 		
+		public override NodeType NodeType {
+			get {
+				return NodeType.Statement;
+			}
+		}
+
 		public GotoType GotoType {
 			get;
 			set;
 		}
 		
 		public string Label {
-			get { 
-				Identifier i = this.LabelExpression as Identifier;
-				return i != null ? i.Name : null;
-			}
+			get { return ((Identifier)LabelExpression).Name; }
 		}
 
-		public INode LabelExpression {
-			get { return GetChildByRole (Roles.Expression); }
+		public DomNode LabelExpression {
+			get { return GetChildByRole (Roles.Expression) ?? DomNode.Null; }
 		}
 		
-		public override S AcceptVisitor<T, S> (IDomVisitor<T, S> visitor, T data)
+		public override S AcceptVisitor<T, S> (DomVisitor<T, S> visitor, T data)
 		{
 			return visitor.VisitGotoStatement (this, data);
 		}

ICSharpCode.NRefactory/CSharp/Dom/Statements/IfElseStatement.cs

@@ -25,46 +25,51 @@
 // THE SOFTWARE.
 
 using System;
-using ICSharpCode.NRefactory.TypeSystem;
 
 namespace ICSharpCode.NRefactory.CSharp
 {
-	public class IfElseStatement : AbstractNode
+	public class IfElseStatement : DomNode
 	{
 		public const int TrueEmbeddedStatementRole = 100;
 		public const int FalseEmbeddedStatementRole = 101;
 		public const int IfKeywordRole = 102;
 		public const int ElseKeywordRole = 103;
 		
-		public INode TrueEmbeddedStatement {
-			get { return (INode)GetChildByRole (TrueEmbeddedStatementRole); }
+		public override NodeType NodeType {
+			get {
+				return NodeType.Statement;
+			}
+		}
+
+		public DomNode TrueEmbeddedStatement {
+			get { return GetChildByRole (TrueEmbeddedStatementRole) ?? DomNode.Null; }
 		}
 		
-		public INode FalseEmbeddedStatement {
-			get { return (INode)GetChildByRole (FalseEmbeddedStatementRole); }
+		public DomNode FalseEmbeddedStatement {
+			get { return GetChildByRole (FalseEmbeddedStatementRole) ?? DomNode.Null; }
 		}
 
-		public INode Condition {
-			get { return (INode)GetChildByRole (Roles.Condition); }
+		public DomNode Condition {
+			get { return GetChildByRole (Roles.Condition) ?? DomNode.Null; }
 		}
 		
 		public CSharpTokenNode LPar {
-			get { return (CSharpTokenNode)GetChildByRole (Roles.LPar); }
+			get { return (CSharpTokenNode)GetChildByRole (Roles.LPar) ?? CSharpTokenNode.Null; }
 		}
 		
 		public CSharpTokenNode RPar {
-			get { return (CSharpTokenNode)GetChildByRole (Roles.RPar); }
+			get { return (CSharpTokenNode)GetChildByRole (Roles.RPar) ?? CSharpTokenNode.Null; }
 		}
 		
 		public CSharpTokenNode IfKeyword {
-			get { return (CSharpTokenNode)GetChildByRole (IfKeywordRole); }
+			get { return (CSharpTokenNode)GetChildByRole (IfKeywordRole) ?? CSharpTokenNode.Null; }
 		}
 		
 		public CSharpTokenNode ElseKeyword {
-			get { return (CSharpTokenNode)GetChildByRole (ElseKeywordRole); }
+			get { return (CSharpTokenNode)GetChildByRole (ElseKeywordRole) ?? CSharpTokenNode.Null; }
 		}
 		
-		public override S AcceptVisitor<T, S> (IDomVisitor<T, S> visitor, T data)
+		public override S AcceptVisitor<T, S> (DomVisitor<T, S> visitor, T data)
 		{
 			return visitor.VisitIfElseStatement (this, data);
 		}

ICSharpCode.NRefactory/CSharp/Dom/Statements/LabelStatement.cs

@@ -25,21 +25,26 @@
 // THE SOFTWARE.
 
 using System;
-using ICSharpCode.NRefactory.TypeSystem;
 
 namespace ICSharpCode.NRefactory.CSharp
 {
-	public class LabelStatement : AbstractNode
+	public class LabelStatement : DomNode
 	{
+		public override NodeType NodeType {
+			get {
+				return NodeType.Statement;
+			}
+		}
+
 		public string Label {
 			get { return LabelIdentifier.Name; }
 		}
 
 		public Identifier LabelIdentifier {
-			get { return (Identifier)GetChildByRole (Roles.Identifier); }
+			get { return (Identifier)GetChildByRole (Roles.Identifier) ?? Identifier.Null; }
 		}
 		
-		public override S AcceptVisitor<T, S> (IDomVisitor<T, S> visitor, T data)
+		public override S AcceptVisitor<T, S> (DomVisitor<T, S> visitor, T data)
 		{
 			return visitor.VisitLabelStatement (this, data);
 		}

ICSharpCode.NRefactory/CSharp/Dom/Statements/LockStatement.cs

@@ -25,29 +25,34 @@
 // THE SOFTWARE.
 
 using System;
-using ICSharpCode.NRefactory.TypeSystem;
 
 namespace ICSharpCode.NRefactory.CSharp
 {
-	public class LockStatement : AbstractNode
+	public class LockStatement : DomNode
 	{
-		public INode Expression {
-			get { return GetChildByRole (Roles.Expression); }
+		public override NodeType NodeType {
+			get {
+				return NodeType.Statement;
+			}
+		}
+
+		public DomNode Expression {
+			get { return GetChildByRole (Roles.Expression) ?? DomNode.Null; }
 		}
 		
-		public INode EmbeddedStatement {
-			get { return (INode)GetChildByRole (Roles.EmbeddedStatement); }
+		public DomNode EmbeddedStatement {
+			get { return GetChildByRole (Roles.EmbeddedStatement) ?? DomNode.Null; }
 		}
 		
 		public CSharpTokenNode LPar {
-			get { return (CSharpTokenNode)GetChildByRole (Roles.LPar); }
+			get { return (CSharpTokenNode)GetChildByRole (Roles.LPar) ?? CSharpTokenNode.Null; }
 		}
 		
 		public CSharpTokenNode RPar {
-			get { return (CSharpTokenNode)GetChildByRole (Roles.RPar); }
+			get { return (CSharpTokenNode)GetChildByRole (Roles.RPar) ?? CSharpTokenNode.Null; }
 		}
 		
-		public override S AcceptVisitor<T, S> (IDomVisitor<T, S> visitor, T data)
+		public override S AcceptVisitor<T, S> (DomVisitor<T, S> visitor, T data)
 		{
 			return visitor.VisitLockStatement (this, data);
 		}

ICSharpCode.NRefactory/CSharp/Dom/Statements/ReturnStatement.cs

@@ -25,17 +25,22 @@
 // THE SOFTWARE.
 
 using System;
-using ICSharpCode.NRefactory.TypeSystem;
 
 namespace ICSharpCode.NRefactory.CSharp
 {
-	public class ReturnStatement : AbstractNode
+	public class ReturnStatement : DomNode
 	{
-		public INode Expression {
-			get { return GetChildByRole (Roles.Expression); }
+		public override NodeType NodeType {
+			get {
+				return NodeType.Statement;
+			}
+		}
+
+		public DomNode Expression {
+			get { return GetChildByRole (Roles.Expression) ?? DomNode.Null; }
 		}
 		
-		public override S AcceptVisitor<T, S> (IDomVisitor<T, S> visitor, T data)
+		public override S AcceptVisitor<T, S> (DomVisitor<T, S> visitor, T data)
 		{
 			return visitor.VisitReturnStatement (this, data);
 		}

ICSharpCode.NRefactory/CSharp/Dom/Statements/SwitchStatement.cs

@@ -26,17 +26,22 @@
 
 using System;
 using System.Linq;
-using ICSharpCode.NRefactory.TypeSystem;
 using System.Collections.Generic;
 
 namespace ICSharpCode.NRefactory.CSharp
 {
-	public class SwitchStatement : AbstractNode
+	public class SwitchStatement : DomNode
 	{
 		public const int SwitchSectionRole = 100;
 		
-		public INode Expression {
-			get { return GetChildByRole (Roles.Expression); }
+		public override NodeType NodeType {
+			get {
+				return NodeType.Statement;
+			}
+		}
+
+		public DomNode Expression {
+			get { return GetChildByRole (Roles.Expression) ?? DomNode.Null; }
 		}
 		
 		public IEnumerable<SwitchSection> SwitchSections {
@@ -44,54 +49,69 @@ namespace ICSharpCode.NRefactory.CSharp
 		}
 		
 		public CSharpTokenNode LPar {
-			get { return (CSharpTokenNode)GetChildByRole (Roles.LPar); }
+			get { return (CSharpTokenNode)GetChildByRole (Roles.LPar) ?? CSharpTokenNode.Null; }
 		}
 		
 		public CSharpTokenNode RPar {
-			get { return (CSharpTokenNode)GetChildByRole (Roles.RPar); }
+			get { return (CSharpTokenNode)GetChildByRole (Roles.RPar) ?? CSharpTokenNode.Null; }
 		}
+		
 		public CSharpTokenNode LBrace {
-			get { return (CSharpTokenNode)GetChildByRole (Roles.LBrace); }
+			get { return (CSharpTokenNode)GetChildByRole (Roles.LBrace) ?? CSharpTokenNode.Null; }
 		}
 		
 		public CSharpTokenNode RBrace {
-			get { return (CSharpTokenNode)GetChildByRole (Roles.RBrace); }
+			get { return (CSharpTokenNode)GetChildByRole (Roles.RBrace) ?? CSharpTokenNode.Null; }
 		}
 		
-		public override S AcceptVisitor<T, S> (IDomVisitor<T, S> visitor, T data)
+		public override S AcceptVisitor<T, S> (DomVisitor<T, S> visitor, T data)
 		{
 			return visitor.VisitSwitchStatement (this, data);
 		}
 	}
 	
-	public class SwitchSection : AbstractNode
+	public class SwitchSection : DomNode
 	{
 		public const int CaseLabelRole = 100;
 		
+		public override NodeType NodeType {
+			get {
+				return NodeType.Unknown;
+			}
+		}
+		
 		public IEnumerable<CaseLabel> CaseLabels {
 			get { return GetChildrenByRole (CaseLabelRole).Cast<CaseLabel> (); }
 		}
 		
-		public IEnumerable<INode> Statements {
+		public IEnumerable<DomNode> Statements {
 			get {
-				BlockStatement block = (BlockStatement)GetChildByRole (Roles.Body);
-				return block.Statements;
+				var body = GetChildByRole (Roles.Body);
+				if (body is BlockStatement)
+					return ((BlockStatement)body).Statements;
+				return new DomNode[] { body };
 			}
 		}
 		
-		public override S AcceptVisitor<T, S> (IDomVisitor<T, S> visitor, T data)
+		public override S AcceptVisitor<T, S> (DomVisitor<T, S> visitor, T data)
 		{
 			return visitor.VisitSwitchSection (this, data);
 		}
 	}
 	
-	public class CaseLabel : AbstractNode
+	public class CaseLabel : DomNode
 	{
-		public INode Expression {
-			get { return GetChildByRole (Roles.Expression); }
+		public override NodeType NodeType {
+			get {
+				return NodeType.Unknown;
+			}
+		}
+		
+		public DomNode Expression {
+			get { return GetChildByRole (Roles.Expression) ?? DomNode.Null; }
 		}
 		
-		public override S AcceptVisitor<T, S> (IDomVisitor<T, S> visitor, T data)
+		public override S AcceptVisitor<T, S> (DomVisitor<T, S> visitor, T data)
 		{
 			return visitor.VisitCaseLabel (this, data);
 		}

ICSharpCode.NRefactory/CSharp/Dom/Statements/ThrowStatement.cs

@@ -25,17 +25,22 @@
 // THE SOFTWARE.
 
 using System;
-using ICSharpCode.NRefactory.TypeSystem;
 
 namespace ICSharpCode.NRefactory.CSharp
 {
-	public class ThrowStatement : AbstractNode
+	public class ThrowStatement : DomNode
 	{
-		public INode Expression {
-			get { return GetChildByRole (Roles.Expression); }
+		public override NodeType NodeType {
+			get {
+				return NodeType.Statement;
+			}
+		}
+
+		public DomNode Expression {
+			get { return GetChildByRole (Roles.Expression) ?? DomNode.Null; }
 		}
 		
-		public override S AcceptVisitor<T, S> (IDomVisitor<T, S> visitor, T data)
+		public override S AcceptVisitor<T, S> (DomVisitor<T, S> visitor, T data)
 		{
 			return visitor.VisitThrowStatement (this, data);
 		}

ICSharpCode.NRefactory/CSharp/Dom/Statements/TryCatchStatement.cs

@@ -26,12 +26,11 @@
 
 using System;
 using System.Linq;
-using ICSharpCode.NRefactory.TypeSystem;
 using System.Collections.Generic;
 
 namespace ICSharpCode.NRefactory.CSharp
 {
-	public class TryCatchStatement : AbstractNode
+	public class TryCatchStatement : DomNode
 	{
 		public const int TryKeywordRole     = 100;
 		public const int FinallyKeywordRole = 101;
@@ -39,36 +38,48 @@ namespace ICSharpCode.NRefactory.CSharp
 		public const int FinallyBlockRole   = 103;
 		public const int CatchClauseRole    = 104;
 		
+		public override NodeType NodeType {
+			get {
+				return NodeType.Statement;
+			}
+		}
+
 		public CSharpTokenNode TryKeyword {
-			get { return (CSharpTokenNode)GetChildByRole (TryKeywordRole); }
+			get { return (CSharpTokenNode)GetChildByRole (TryKeywordRole) ?? CSharpTokenNode.Null; }
 		}
 		
 		public CSharpTokenNode FinallyKeyword {
-			get { return (CSharpTokenNode)GetChildByRole (FinallyKeywordRole); }
+			get { return (CSharpTokenNode)GetChildByRole (FinallyKeywordRole) ?? CSharpTokenNode.Null; }
 		}
 		
 		public BlockStatement TryBlock {
-			get { return (BlockStatement)GetChildByRole (TryBlockRole); }
+			get { return (BlockStatement)GetChildByRole (TryBlockRole) ?? BlockStatement.Null; }
 		}
 		
 		public BlockStatement FinallyBlock {
-			get { return (BlockStatement)GetChildByRole (FinallyBlockRole); }
+			get { return (BlockStatement)GetChildByRole (FinallyBlockRole) ?? BlockStatement.Null; }
 		}
 		
 		public IEnumerable<CatchClause> CatchClauses {
 			get { return GetChildrenByRole (CatchClauseRole).Cast<CatchClause> (); }
 		}
 		
-		public override S AcceptVisitor<T, S> (IDomVisitor<T, S> visitor, T data)
+		public override S AcceptVisitor<T, S> (DomVisitor<T, S> visitor, T data)
 		{
 			return visitor.VisitTryCatchStatement (this, data);
 		}
 	}
 	
-	public class CatchClause : AbstractNode
+	public class CatchClause : DomNode
 	{
-		public INode ReturnType {
-			get { return (INode)GetChildByRole (Roles.ReturnType); }
+		public override NodeType NodeType {
+			get {
+				return NodeType.Unknown;
+			}
+		}
+		
+		public DomNode ReturnType {
+			get { return GetChildByRole (Roles.ReturnType); }
 		}
 		
 		public string VariableName {
@@ -95,7 +106,7 @@ namespace ICSharpCode.NRefactory.CSharp
 			get { return (CSharpTokenNode)GetChildByRole (Roles.Keyword); }
 		}
 		
-		public override S AcceptVisitor<T, S> (IDomVisitor<T, S> visitor, T data)
+		public override S AcceptVisitor<T, S> (DomVisitor<T, S> visitor, T data)
 		{
 			return visitor.VisitCatchClause (this, data);
 		}

ICSharpCode.NRefactory/CSharp/Dom/Statements/UncheckedStatement.cs

@@ -1,4 +1,4 @@
-// 
+// 
 // UncheckedStatement.cs
 //  
 // Author:
@@ -25,17 +25,23 @@
 // THE SOFTWARE.
 
 using System;
-using ICSharpCode.NRefactory.TypeSystem;
 
 namespace ICSharpCode.NRefactory.CSharp
 {
-	public class UncheckedStatement : AbstractNode
+	public class UncheckedStatement : DomNode
 	{
+		public override NodeType NodeType {
+			get {
+				return NodeType.Statement;
+			}
+		}
+
 		public BlockStatement Block {
-			get { return (BlockStatement)GetChildByRole (Roles.Body); }
+			get { return (BlockStatement)GetChildByRole (Roles.Body) ?? BlockStatement.Null; }
 		}
 		
-		public override S AcceptVisitor<T, S> (IDomVisitor<T, S> visitor, T data)
+		
+		public override S AcceptVisitor<T, S> (DomVisitor<T, S> visitor, T data)
 		{
 			return visitor.VisitUncheckedStatement (this, data);
 		}

ICSharpCode.NRefactory/CSharp/Dom/Statements/UnsafeStatement.cs

@@ -25,17 +25,22 @@
 // THE SOFTWARE.
 
 using System;
-using ICSharpCode.NRefactory.TypeSystem;
 
 namespace ICSharpCode.NRefactory.CSharp
 {
-	public class UnsafeStatement : AbstractNode
+	public class UnsafeStatement : DomNode
 	{
+		public override NodeType NodeType {
+			get {
+				return NodeType.Statement;
+			}
+		}
+
 		public BlockStatement Block {
-			get { return (BlockStatement)GetChildByRole (Roles.Body); }
+			get { return (BlockStatement)GetChildByRole (Roles.Body) ?? BlockStatement.Null; }
 		}
 		
-		public override S AcceptVisitor<T, S> (IDomVisitor<T, S> visitor, T data)
+		public override S AcceptVisitor<T, S> (DomVisitor<T, S> visitor, T data)
 		{
 			return visitor.VisitUnsafeStatement (this, data);
 		}

ICSharpCode.NRefactory/CSharp/Dom/Statements/UsingStatement.cs

@@ -25,30 +25,35 @@
 // THE SOFTWARE.
 
 using System;
-using ICSharpCode.NRefactory.TypeSystem;
 
 namespace ICSharpCode.NRefactory.CSharp
 {
-	public class UsingStatement : AbstractNode
+	public class UsingStatement : DomNode
 	{
-		public INode Statement {
-			get { return GetChildByRole (Roles.Statement); }
+		public override NodeType NodeType {
+			get {
+				return NodeType.Statement;
+			}
+		}
+
+		public DomNode Statement {
+			get { return GetChildByRole (Roles.Statement) ?? DomNode.Null; }
 		}
 		
-		public INode EmbeddedStatement {
-			get { return (INode)GetChildByRole (Roles.EmbeddedStatement); }
+		public DomNode EmbeddedStatement {
+			get { return GetChildByRole (Roles.EmbeddedStatement) ?? DomNode.Null; }
 		}
 		
 		public CSharpTokenNode LPar {
-			get { return (CSharpTokenNode)GetChildByRole (Roles.LPar); }
+			get { return (CSharpTokenNode)GetChildByRole (Roles.LPar) ?? CSharpTokenNode.Null; }
 		}
 		
 		public CSharpTokenNode RPar {
-			get { return (CSharpTokenNode)GetChildByRole (Roles.RPar); }
+			get { return (CSharpTokenNode)GetChildByRole (Roles.RPar) ?? CSharpTokenNode.Null; }
 		}
 		
 		
-		public override S AcceptVisitor<T, S> (IDomVisitor<T, S> visitor, T data)
+		public override S AcceptVisitor<T, S> (DomVisitor<T, S> visitor, T data)
 		{
 			return visitor.VisitUsingStatement (this, data);
 		}

ICSharpCode.NRefactory/CSharp/Dom/Statements/VariableDeclarationStatement.cs

@@ -1,6 +1,6 @@
-// 
+// 
 // VariableDeclarationStatement.cs
-//
+//  
 // Author:
 //       Mike Krüger <mkrueger@novell.com>
 // 
@@ -26,15 +26,22 @@
 
 using System;
 using System.Linq;
-using ICSharpCode.NRefactory.TypeSystem;
 using System.Collections.Generic;
 
 namespace ICSharpCode.NRefactory.CSharp
 {
-	public class VariableDeclarationStatement : AbstractNode
+	public class VariableDeclarationStatement : DomNode
 	{
-		public IEnumerable<INode> ModifierTokens {
-			get { return base.GetChildrenByRole (Roles.Modifier); }
+		public override NodeType NodeType {
+			get {
+				return NodeType.Statement;
+			}
+		}
+
+		public IEnumerable<CSharpModifierToken> ModifierTokens {
+			get {
+				return base.GetChildrenByRole (Roles.Modifier).Cast <CSharpModifierToken>();
+			}
 		}
 		
 		public Modifiers Modifiers {
@@ -47,15 +54,19 @@ namespace ICSharpCode.NRefactory.CSharp
 			}
 		}
 		
-		public INode ReturnType {
-			get { return (INode)GetChildByRole (Roles.ReturnType); }
+		public DomNode ReturnType {
+			get { return GetChildByRole (Roles.ReturnType) ?? DomNode.Null; }
 		}
 		
 		public IEnumerable<VariableInitializer> Variables {
 			get { return base.GetChildrenByRole (Roles.Initializer).Cast<VariableInitializer> (); }
 		}
 		
-		public override S AcceptVisitor<T, S> (IDomVisitor<T, S> visitor, T data)
+		public CSharpTokenNode Semicolon {
+			get { return (CSharpTokenNode)GetChildByRole (Roles.Semicolon) ?? CSharpTokenNode.Null; }
+		}
+		
+		public override S AcceptVisitor<T, S> (DomVisitor<T, S> visitor, T data)
 		{
 			return visitor.VisitVariableDeclarationStatement (this, data);
 		}

ICSharpCode.NRefactory/CSharp/Dom/Statements/WhileStatement.cs

@@ -25,45 +25,50 @@
 // THE SOFTWARE.
 
 using System;
-using ICSharpCode.NRefactory.TypeSystem;
 
 namespace ICSharpCode.NRefactory.CSharp
 {
-	public class WhileStatement : AbstractNode
+	public class WhileStatement : DomNode
 	{
 		public const int DoKeywordRole = 101;
 		public const int WhileKeywordRole = 102;
 		
+		public override NodeType NodeType {
+			get {
+				return NodeType.Statement;
+			}
+		}
+
 		public WhilePosition WhilePosition {
 			get;
 			set;
 		}
 		
-		public INode EmbeddedStatement {
-			get { return (INode)GetChildByRole (Roles.EmbeddedStatement); }
+		public DomNode EmbeddedStatement {
+			get { return GetChildByRole (Roles.EmbeddedStatement) ?? DomNode.Null; }
 		}
 		
-		public INode Condition {
-			get { return GetChildByRole (Roles.Condition); }
+		public DomNode Condition {
+			get { return GetChildByRole (Roles.Condition) ?? DomNode.Null; }
 		}
 		
 		public CSharpTokenNode DoKeyword {
-			get { return (CSharpTokenNode)GetChildByRole (DoKeywordRole); }
+			get { return (CSharpTokenNode)GetChildByRole (DoKeywordRole) ?? CSharpTokenNode.Null; }
 		}
 		
 		public CSharpTokenNode WhileKeyword {
-			get { return (CSharpTokenNode)GetChildByRole (WhileKeywordRole); }
+			get { return (CSharpTokenNode)GetChildByRole (WhileKeywordRole) ?? CSharpTokenNode.Null; }
 		}
 		
 		public CSharpTokenNode LPar {
-			get { return (CSharpTokenNode)GetChildByRole (Roles.LPar); }
+			get { return (CSharpTokenNode)GetChildByRole (Roles.LPar) ?? CSharpTokenNode.Null; }
 		}
 		
 		public CSharpTokenNode RPar {
-			get { return (CSharpTokenNode)GetChildByRole (Roles.RPar); }
+			get { return (CSharpTokenNode)GetChildByRole (Roles.RPar) ?? CSharpTokenNode.Null; }
 		}
 		
-		public override S AcceptVisitor<T, S> (IDomVisitor<T, S> visitor, T data)
+		public override S AcceptVisitor<T, S> (DomVisitor<T, S> visitor, T data)
 		{
 			return visitor.VisitWhileStatement (this, data);
 		}

ICSharpCode.NRefactory/CSharp/Dom/Statements/YieldStatement.cs

@@ -1,4 +1,4 @@
-// 
+// 
 // YieldStatement.cs
 //  
 // Author:
@@ -25,21 +25,26 @@
 // THE SOFTWARE.
 
 using System;
-using ICSharpCode.NRefactory.TypeSystem;
 
 namespace ICSharpCode.NRefactory.CSharp
 {
-	public class YieldStatement : AbstractNode
+	public class YieldStatement : DomNode
 	{
 		public const int YieldKeywordRole = 100;
 		public const int ReturnKeywordRole = 101;
 		public const int BreakKeywordRole = 102;
 		
-		public INode Expression {
-			get { return GetChildByRole (Roles.Expression); }
+		public override NodeType NodeType {
+			get {
+				return NodeType.Statement;
+			}
+		}
+
+		public DomNode Expression {
+			get { return GetChildByRole (Roles.Expression) ?? DomNode.Null; }
 		}
 		
-		public override S AcceptVisitor<T, S> (IDomVisitor<T, S> visitor, T data)
+		public override S AcceptVisitor<T, S> (DomVisitor<T, S> visitor, T data)
 		{
 			return visitor.VisitYieldStatement (this, data);
 		}

ICSharpCode.NRefactory/CSharp/Dom/TypeMembers/AbstractMember.cs

@@ -1,4 +1,4 @@
-// 
+// 
 // AbstractMember.cs
 //  
 // Author:
@@ -25,7 +25,6 @@
 // THE SOFTWARE.
 
 using System;
-using ICSharpCode.NRefactory.TypeSystem;
 
 namespace ICSharpCode.NRefactory.CSharp
 {
@@ -33,31 +32,30 @@ namespace ICSharpCode.NRefactory.CSharp
 	{
 		const int PrivateImplementationTypeRole = 100;
 		
-		public INode ReturnType {
+		public DomNode ReturnType {
 			get {
-				return (INode)GetChildByRole (Roles.ReturnType);
+				return GetChildByRole (Roles.ReturnType) ?? DomNode.Null;
 			}
 		}
 		
 		/// <summary>
 		/// Only supported on members that can be declared in an interface.
 		/// </summary>
-		public INode PrivateImplementationType {
+		public DomNode PrivateImplementationType {
 			get {
-				return (INode)GetChildByRole (PrivateImplementationTypeRole);
+				return GetChildByRole (PrivateImplementationTypeRole) ?? DomNode.Null;
 			}
 		}
 		
 		public Identifier NameIdentifier {
 			get {
-				return (Identifier)GetChildByRole (Roles.Identifier);
+				return (Identifier)GetChildByRole (Roles.Identifier) ?? Identifier.Null;
 			}
 		}
 		
 		public string Name {
 			get {
-				Identifier nameIdentifier = this.NameIdentifier;
-				return nameIdentifier != null ? nameIdentifier.Name : null;
+				return NameIdentifier.Name;
 			}
 		}
 	}

ICSharpCode.NRefactory/CSharp/Dom/TypeMembers/AbstractMemberBase.cs

@@ -1,4 +1,4 @@
-// 
+// 
 // AbstractMemberBase.cs
 //  
 // Author:
@@ -26,14 +26,19 @@
 
 using System;
 using System.Linq;
-using ICSharpCode.NRefactory.TypeSystem;
 using System.Collections.Generic;
 
 namespace ICSharpCode.NRefactory.CSharp
 {
-	public abstract class AbstractMemberBase : AbstractNode
+	public abstract class AbstractMemberBase : DomNode
 	{
-		public IEnumerable<CSharpModifierToken> ModifierTokens { 
+		public override NodeType NodeType {
+			get {
+				return NodeType.Member;
+			}
+		}
+		
+		public IEnumerable<CSharpModifierToken> ModifierTokens {
 			get {
 				return base.GetChildrenByRole (Roles.Modifier).Cast <CSharpModifierToken>();
 			}

ICSharpCode.NRefactory/CSharp/Dom/TypeMembers/Accessor.cs

@@ -0,0 +1,64 @@
+// 
+// PropertyDeclaration.cs
+//  
+// Author:
+//       Mike Krüger <mkrueger@novell.com>
+// 
+// Copyright (c) 2010 Novell, Inc (http://www.novell.com)
+// 
+// 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.NRefactory.CSharp
+{
+	public class Accessor : AbstractMember
+	{
+		public static readonly new Accessor Null = new NullAccessor ();
+		class NullAccessor : Accessor
+		{
+			public override bool IsNull {
+				get {
+					return true;
+				}
+			}
+			
+			public override S AcceptVisitor<T, S> (DomVisitor<T, S> visitor, T data)
+			{
+				return default (S);
+			}
+		}
+		
+		public DomLocation Location {
+			get;
+			set;
+		}
+		
+		public BlockStatement Body {
+			get {
+				return (BlockStatement)GetChildByRole (Roles.Body) ?? BlockStatement.Null;
+			}
+		}
+		
+		public override S AcceptVisitor<T, S> (DomVisitor<T, S> visitor, T data)
+		{
+			return visitor.VisitAccessorDeclaration (this, data);
+		}
+	}
+}

ICSharpCode.NRefactory/CSharp/Dom/TypeMembers/ConstructorDeclaration.cs

@@ -1,4 +1,4 @@
-// 
+// 
 // ConstructorDeclaration.cs
 //  
 // Author:
@@ -26,7 +26,6 @@
 
 using System;
 using System.Linq;
-using ICSharpCode.NRefactory.TypeSystem;
 using System.Collections.Generic;
 
 namespace ICSharpCode.NRefactory.CSharp
@@ -35,26 +34,34 @@ namespace ICSharpCode.NRefactory.CSharp
 	{
 		public BlockStatement Body {
 			get {
-				return (BlockStatement)GetChildByRole (Roles.Body);
+				return (BlockStatement)GetChildByRole (Roles.Body) ?? BlockStatement.Null;
 			}
 		}
 		
-		public ConstructorInitializer Initializer {
+		public IEnumerable<ParameterDeclaration> Parameters { 
 			get {
-				return (ConstructorInitializer)base.GetChildByRole (Roles.Initializer);
+				return base.GetChildrenByRole (Roles.Argument).Cast <ParameterDeclaration> ();
 			}
 		}
 		
-		public override S AcceptVisitor<T, S> (IDomVisitor<T, S> visitor, T data)
-		{
-			return visitor.VisitConstructorDeclaration (this, data);
+		public CSharpTokenNode LPar {
+			get { return (CSharpTokenNode)GetChildByRole (Roles.LPar) ?? CSharpTokenNode.Null; }
+		}
+		
+		public CSharpTokenNode RPar {
+			get { return (CSharpTokenNode)GetChildByRole (Roles.RPar) ?? CSharpTokenNode.Null; }
 		}
 		
-		public IEnumerable<ParameterDeclaration> Parameters {
+		public ConstructorInitializer Initializer {
 			get {
-				return GetChildrenByRole (Roles.Argument).Cast<ParameterDeclaration>();
+				return (ConstructorInitializer)base.GetChildByRole (Roles.Initializer) ?? ConstructorInitializer.Null;
 			}
 		}
+		
+		public override S AcceptVisitor<T, S> (DomVisitor<T, S> visitor, T data)
+		{
+			return visitor.VisitConstructorDeclaration (this, data);
+		}
 	}
 	
 	public enum ConstructorInitializerType {
@@ -62,20 +69,47 @@ namespace ICSharpCode.NRefactory.CSharp
 		This
 	}
 	
-	public class ConstructorInitializer : AbstractNode
+	public class ConstructorInitializer : DomNode
 	{
+		public static readonly new ConstructorInitializer Null = new NullConstructorInitializer ();
+		class NullConstructorInitializer : ConstructorInitializer
+		{
+			public override NodeType NodeType {
+				get {
+					return NodeType.Unknown;
+				}
+			}
+			
+			public override bool IsNull {
+				get {
+					return true;
+				}
+			}
+			
+			public override S AcceptVisitor<T, S> (DomVisitor<T, S> visitor, T data)
+			{
+				return default (S);
+			}
+		}
+		
+		public override NodeType NodeType {
+			get {
+				return NodeType.Unknown;
+			}
+		}
+		
 		public ConstructorInitializerType ConstructorInitializerType {
 			get;
 			set;
 		}
 		
-		public IEnumerable<INode> Arguments { 
+		public IEnumerable<DomNode> Arguments { 
 			get {
 				return base.GetChildrenByRole (Roles.Argument);
 			}
 		}
 		
-		public override S AcceptVisitor<T, S> (IDomVisitor<T, S> visitor, T data)
+		public override S AcceptVisitor<T, S> (DomVisitor<T, S> visitor, T data)
 		{
 			return visitor.VisitConstructorInitializer (this, data);
 		}

ICSharpCode.NRefactory/CSharp/Dom/TypeMembers/DestructorDeclaration.cs

@@ -26,7 +26,6 @@
 
 using System;
 using System.Linq;
-using ICSharpCode.NRefactory.TypeSystem;
 using System.Collections.Generic;
 
 namespace ICSharpCode.NRefactory.CSharp
@@ -37,11 +36,11 @@ namespace ICSharpCode.NRefactory.CSharp
 		
 		public BlockStatement Body {
 			get {
-				return (BlockStatement)GetChildByRole (Roles.Body);
+				return (BlockStatement)GetChildByRole (Roles.Body) ?? BlockStatement.Null;
 			}
 		}
 		
-		public override S AcceptVisitor<T, S> (IDomVisitor<T, S> visitor, T data)
+		public override S AcceptVisitor<T, S> (DomVisitor<T, S> visitor, T data)
 		{
 			return visitor.VisitDestructorDeclaration (this, data);
 		}

ICSharpCode.NRefactory/CSharp/Dom/TypeMembers/EventDeclaration.cs

@@ -25,7 +25,6 @@
 // THE SOFTWARE.
 
 using System;
-using ICSharpCode.NRefactory.TypeSystem;
 
 namespace ICSharpCode.NRefactory.CSharp
 {
@@ -36,29 +35,29 @@ namespace ICSharpCode.NRefactory.CSharp
 		
 		public CSharpTokenNode LBrace {
 			get {
-				return (CSharpTokenNode)GetChildByRole (Roles.LBrace);
+				return (CSharpTokenNode)GetChildByRole (Roles.LBrace) ?? CSharpTokenNode.Null;
 			}
 		}
 		
 		public CSharpTokenNode RBrace {
 			get {
-				return (CSharpTokenNode)GetChildByRole (Roles.RBrace);
+				return (CSharpTokenNode)GetChildByRole (Roles.RBrace) ?? CSharpTokenNode.Null;
 			}
 		}
 		
 		public Accessor AddAccessor {
 			get {
-				return (Accessor)GetChildByRole (EventAddRole);
+				return (Accessor)GetChildByRole (EventAddRole) ?? Accessor.Null;
 			}
 		}
 		
 		public Accessor RemoveAccessor {
 			get {
-				return (Accessor)GetChildByRole (EventRemoveRole);
+				return (Accessor)GetChildByRole (EventRemoveRole) ?? Accessor.Null;
 			}
 		}
 		
-		public override S AcceptVisitor<T, S> (IDomVisitor<T, S> visitor, T data)
+		public override S AcceptVisitor<T, S> (DomVisitor<T, S> visitor, T data)
 		{
 			return visitor.VisitEventDeclaration (this, data);
 		}

ICSharpCode.NRefactory/CSharp/Dom/TypeMembers/FieldDeclaration.cs

@@ -26,7 +26,6 @@
 
 using System;
 using System.Linq;
-using ICSharpCode.NRefactory.TypeSystem;
 using System.Collections.Generic;
 
 namespace ICSharpCode.NRefactory.CSharp
@@ -34,7 +33,7 @@ namespace ICSharpCode.NRefactory.CSharp
 	public class FieldDeclaration : AbstractMember
 	{
 		public CSharpTokenNode Semicolon {
-			get { return (CSharpTokenNode)GetChildByRole (Roles.Semicolon); }
+			get { return (CSharpTokenNode)GetChildByRole (Roles.Semicolon) ?? CSharpTokenNode.Null; }
 		}
 		
 		public IEnumerable<VariableInitializer> Variables { 
@@ -43,7 +42,7 @@ namespace ICSharpCode.NRefactory.CSharp
 			}
 		}
 		
-		public override S AcceptVisitor<T, S> (IDomVisitor<T, S> visitor, T data)
+		public override S AcceptVisitor<T, S> (DomVisitor<T, S> visitor, T data)
 		{
 			return visitor.VisitFieldDeclaration (this, data);
 		}

ICSharpCode.NRefactory/CSharp/Dom/TypeMembers/IndexerDeclaration.cs

@@ -1,4 +1,4 @@
-// 
+// 
 // IndexerDeclaration.cs
 //  
 // Author:
@@ -26,19 +26,13 @@
 
 using System;
 using System.Linq;
-using ICSharpCode.NRefactory.TypeSystem;
 using System.Collections.Generic;
 
 namespace ICSharpCode.NRefactory.CSharp
 {
 	public class IndexerDeclaration : PropertyDeclaration
 	{
-		// TODO: Parameters or Arguments?
 		public IEnumerable<ParameterDeclaration> Parameters { 
-			get { return this.Arguments; }
-		}
-		
-		public IEnumerable<ParameterDeclaration> Arguments { 
 			get {
 				return base.GetChildrenByRole (Roles.Argument).Cast <ParameterDeclaration>();
 			}
@@ -46,18 +40,18 @@ namespace ICSharpCode.NRefactory.CSharp
 		
 		public CSharpTokenNode LBracket {
 			get {
-				return (CSharpTokenNode)GetChildByRole (Roles.LBracket);
+				return (CSharpTokenNode)GetChildByRole (Roles.LBracket) ?? CSharpTokenNode.Null;
 			}
 		}
 		
 		public CSharpTokenNode RBracket {
 			get {
-				return (CSharpTokenNode)GetChildByRole (Roles.RBracket);
+				return (CSharpTokenNode)GetChildByRole (Roles.RBracket) ?? CSharpTokenNode.Null;
 			}
 		}
 		
 		
-		public override S AcceptVisitor<T, S> (IDomVisitor<T, S> visitor, T data)
+		public override S AcceptVisitor<T, S> (DomVisitor<T, S> visitor, T data)
 		{
 			return visitor.VisitIndexerDeclaration (this, data);
 		}

ICSharpCode.NRefactory/CSharp/Dom/TypeMembers/MethodDeclaration.cs

@@ -1,4 +1,4 @@
-// 
+// 
 // MethodDeclaration.cs
 //  
 // Author:
@@ -32,13 +32,8 @@ namespace ICSharpCode.NRefactory.CSharp
 {
 	public class MethodDeclaration : AbstractMember
 	{
-		// TODO: Parameters or Arguments?
-		public IEnumerable<INode> TypeParameters {
-			get { return this.TypeArguments; }
-		}
-		
-		public IEnumerable<INode> TypeArguments {
-			get { return GetChildrenByRole (Roles.TypeArgument).Cast<INode> (); }
+		public IEnumerable<DomNode> TypeParameters {
+			get { return GetChildrenByRole (Roles.TypeArgument); }
 		}
 		
 		public IEnumerable<Constraint> Constraints { 
@@ -48,41 +43,34 @@ namespace ICSharpCode.NRefactory.CSharp
 		}
 		
 		public IEnumerable<ParameterDeclaration> Parameters { 
-			get {
-				return this.Arguments;
-			}
-		}
-		
-		public IEnumerable<ParameterDeclaration> Arguments { 
 			get {
 				return base.GetChildrenByRole (Roles.Argument).Cast <ParameterDeclaration> ();
 			}
 		}
 		
-		public bool IsExtensionMethod {
-			get {
-				ParameterDeclaration pd = (ParameterDeclaration)GetChildByRole (Roles.Argument);
-				return pd != null && pd.ParameterModifier == ParameterModifier.This;
-			}
-		}
-		
 		public CSharpTokenNode LPar {
-			get { return (CSharpTokenNode)GetChildByRole (Roles.LPar); }
+			get { return (CSharpTokenNode)GetChildByRole (Roles.LPar) ?? CSharpTokenNode.Null; }
 		}
 		
 		public CSharpTokenNode RPar {
-			get { return (CSharpTokenNode)GetChildByRole (Roles.RPar); }
+			get { return (CSharpTokenNode)GetChildByRole (Roles.RPar) ?? CSharpTokenNode.Null; }
 		}
 		
 		public BlockStatement Body {
 			get {
-				return (BlockStatement)GetChildByRole (Roles.Body);
+				return (BlockStatement)GetChildByRole (Roles.Body) ?? BlockStatement.Null;
 			}
 		}
 		
+		public bool IsExtensionMethod {
+			get {
+				ParameterDeclaration pd = (ParameterDeclaration)GetChildByRole (Roles.Argument);
+				return pd != null && pd.ParameterModifier == ParameterModifier.This;
+			}
+		}
 		
 		
-		public override S AcceptVisitor<T, S> (IDomVisitor<T, S> visitor, T data)
+		public override S AcceptVisitor<T, S> (DomVisitor<T, S> visitor, T data)
 		{
 			return visitor.VisitMethodDeclaration (this, data);
 		}

ICSharpCode.NRefactory/CSharp/Dom/TypeMembers/OperatorDeclaration.cs

@@ -1,4 +1,4 @@
-// 
+// 
 // OperatorDeclaration.cs
 //  
 // Author:
@@ -29,8 +29,6 @@ using System;
 namespace ICSharpCode.NRefactory.CSharp
 {
 	public enum OperatorType {
-		// Numeric values must match those in Mono.CSharp.Operator.OpType !!
-		
 		// Unary operators
 		LogicalNot,
 		OnesComplement,
@@ -77,6 +75,11 @@ namespace ICSharpCode.NRefactory.CSharp
 			set;
 		}
 		
+		public string OverloadOperator {
+			get;
+			set;
+		}
+		
 		public CSharpTokenNode OperatorKeyword {
 			get { return (CSharpTokenNode)GetChildByRole (OperatorKeywordRole); }
 		}
@@ -85,14 +88,14 @@ namespace ICSharpCode.NRefactory.CSharp
 			get { return (CSharpTokenNode)GetChildByRole (OperatorTypeRole); }
 		}
 		
-		public override S AcceptVisitor<T, S> (IDomVisitor<T, S> visitor, T data)
+		public static string GetName(OperatorType type)
 		{
-			return visitor.VisitOperatorDeclaration (this, data);
+			return Mono.CSharp.Operator.GetMetadataName((Mono.CSharp.Operator.OpType)type);
 		}
 		
-		public static string GetName(OperatorType type) 
+		public override S AcceptVisitor<T, S> (DomVisitor<T, S> visitor, T data)
 		{
-			return Mono.CSharp.Operator.GetMetadataName((Mono.CSharp.Operator.OpType)type);
+			return visitor.VisitOperatorDeclaration (this, data);
 		}
 	}
 }

ICSharpCode.NRefactory/CSharp/Dom/TypeMembers/ParameterDeclaration.cs

@@ -38,8 +38,14 @@ namespace ICSharpCode.NRefactory.CSharp
 		This
 	}
 	
-	public class ParameterDeclaration : AbstractNode
+	public class ParameterDeclaration : DomNode
 	{
+		public override NodeType NodeType {
+			get {
+				return NodeType.Unknown;
+			}
+		}
+		
 		public ParameterModifier ParameterModifier {
 			get;
 			set;
@@ -47,7 +53,7 @@ namespace ICSharpCode.NRefactory.CSharp
 		
 		public Identifier Identifier {
 			get {
-				return (Identifier)GetChildByRole (Roles.Identifier);
+				return (Identifier)GetChildByRole (Roles.Identifier) ?? Identifier.Null;
 			}
 		}
 		
@@ -58,14 +64,14 @@ namespace ICSharpCode.NRefactory.CSharp
 			}
 		}
 		
-		public INode DefaultExpression {
+		public DomNode DefaultExpression {
 			get {
-				return (INode)GetChildByRole (Roles.Expression);
+				return GetChildByRole (Roles.Expression) ?? DomNode.Null;
 			}
 		}
 		
-		public INode Type {
-			get { return GetChildByRole (Roles.ReturnType); }
+		public DomNode Type {
+			get { return GetChildByRole (Roles.ReturnType) ?? DomNode.Null; }
 		}
 		
 		public IEnumerable<AttributeSection> Attributes {
@@ -74,7 +80,7 @@ namespace ICSharpCode.NRefactory.CSharp
 			}
 		}
 		
-		public override S AcceptVisitor<T, S> (IDomVisitor<T, S> visitor, T data)
+		public override S AcceptVisitor<T, S> (DomVisitor<T, S> visitor, T data)
 		{
 			return visitor.VisitParameterDeclaration (this, data);
 		}

ICSharpCode.NRefactory/CSharp/Dom/TypeMembers/PropertyDeclaration.cs

@@ -1,4 +1,4 @@
-// 
+// 
 // PropertyDeclaration.cs
 //  
 // Author:
@@ -25,30 +25,9 @@
 // THE SOFTWARE.
 
 using System;
-using ICSharpCode.NRefactory.TypeSystem;
 
 namespace ICSharpCode.NRefactory.CSharp
 {
-	
-	public class Accessor : AbstractMemberBase
-	{
-		public DomLocation Location {
-			get;
-			set;
-		}
-		
-		public BlockStatement Body {
-			get {
-				return (BlockStatement)GetChildByRole (Roles.Body);
-			}
-		}
-		
-		public override S AcceptVisitor<T, S> (IDomVisitor<T, S> visitor, T data)
-		{
-			return visitor.VisitAccessorDeclaration (this, data);
-		}
-	}
-	
 	public class PropertyDeclaration : AbstractMember
 	{
 		public const int PropertyGetRole = 100;
@@ -56,29 +35,29 @@ namespace ICSharpCode.NRefactory.CSharp
 		
 		public CSharpTokenNode LBrace {
 			get {
-				return (CSharpTokenNode)GetChildByRole (Roles.LBrace);
+				return (CSharpTokenNode)GetChildByRole (Roles.LBrace) ?? CSharpTokenNode.Null;
 			}
 		}
 		
 		public CSharpTokenNode RBrace {
 			get {
-				return (CSharpTokenNode)GetChildByRole (Roles.RBrace);
+				return (CSharpTokenNode)GetChildByRole (Roles.RBrace) ?? CSharpTokenNode.Null;
 			}
 		}
 		
 		public Accessor GetAccessor {
 			get {
-				return (Accessor)GetChildByRole (PropertyGetRole);
+				return (Accessor)GetChildByRole (PropertyGetRole) ?? Accessor.Null;
 			}
 		}
 		
 		public Accessor SetAccessor {
 			get {
-				return (Accessor)GetChildByRole (PropertySetRole);
+				return (Accessor)GetChildByRole (PropertySetRole) ?? Accessor.Null;
 			}
 		}
 		
-		public override S AcceptVisitor<T, S> (IDomVisitor<T, S> visitor, T data)
+		public override S AcceptVisitor<T, S> (DomVisitor<T, S> visitor, T data)
 		{
 			return visitor.VisitPropertyDeclaration (this, data);
 		}

ICSharpCode.NRefactory/CSharp/Dom/TypeMembers/VariableInitializer.cs

@@ -25,12 +25,17 @@
 // THE SOFTWARE.
 
 using System;
-using ICSharpCode.NRefactory.TypeSystem;
 
 namespace ICSharpCode.NRefactory.CSharp
 {
-	public class VariableInitializer : AbstractNode
+	public class VariableInitializer : DomNode
 	{
+		public override NodeType NodeType {
+			get {
+				return NodeType.Unknown;
+			}
+		}
+
 		public string Name {
 			get {
 				return NameIdentifier.Name;
@@ -39,17 +44,22 @@ namespace ICSharpCode.NRefactory.CSharp
 		
 		public Identifier NameIdentifier {
 			get {
-				return (Identifier)GetChildByRole (Roles.Identifier);
+				return (Identifier)GetChildByRole (Roles.Identifier) ?? Identifier.Null;
 			}
 		}
 		
-		public INode Initializer {
+		public CSharpTokenNode Assign {
+			get { return (CSharpTokenNode)GetChildByRole (Roles.Assign) ?? CSharpTokenNode.Null; }
+		}
+		
+		
+		public DomNode Initializer {
 			get {
-				return GetChildByRole (Roles.Initializer);
+				return GetChildByRole (Roles.Initializer) ?? DomNode.Null;
 			}
 		}
 		
-		public override S AcceptVisitor<T, S> (IDomVisitor<T, S> visitor, T data)
+		public override S AcceptVisitor<T, S> (DomVisitor<T, S> visitor, T data)
 		{
 			return visitor.VisitVariableInitializer (this, data);
 		}

ICSharpCode.NRefactory/CSharp/Formatter/DomIndentationVisitor.cs

@@ -25,7 +25,7 @@
 // THE SOFTWARE.
 /*
 using System;
-using MonoDevelop.CSharp.Dom;
+using ICSharpCode.NRefactory.CSharp;
 using System.Text;
 using MonoDevelop.Projects.Dom;
 using Mono.TextEditor;
@@ -70,7 +70,7 @@ namespace ICSharpCode.NRefactory.CSharp
 			AutoAcceptChanges = true;
 		}
 		
-		public override object VisitCompilationUnit (MonoDevelop.CSharp.Dom.CompilationUnit unit, object data)
+		public override object VisitCompilatioICSharpCode.NRefactory.CSharparp.Dom.CompilationUnit unit, object data)
 		{
 			base.VisitCompilationUnit (unit, data);
 			if (AutoAcceptChanges)

ICSharpCode.NRefactory/CSharp/Formatter/DomSpacingVisitor.cs

@@ -25,7 +25,7 @@
 // THE SOFTWARE.
 /*
 using System;
-using MonoDevelop.CSharp.Dom;
+using ICSharpCode.NRefactory.CSharp;
 using System.Text;
 using MonoDevelop.Projects.Dom;
 using Mono.TextEditor;
@@ -72,7 +72,7 @@ namespace ICSharpCode.NRefactory.CSharp
 			}
 		}
 		
-		public override object VisitCompilationUnit (MonoDevelop.CSharp.Dom.CompilationUnit unit, object data)
+		public override object VisitCompilatioICSharpCode.NRefactory.CSharparp.Dom.CompilationUnit unit, object data)
 		{
 			base.VisitCompilationUnit (unit, data);
 			if (AutoAcceptChanges)
@@ -436,7 +436,7 @@ namespace ICSharpCode.NRefactory.CSharp
 			return base.VisitUsingStatement (usingStatement, data);
 		}
 		
-		public override object VisitSwitchStatement (MonoDevelop.CSharp.Dom.SwitchStatement switchStatement, object data)
+		public override object VisitSwiICSharpCode.NRefactory.CSharplop.CSharp.Dom.SwitchStatement switchStatement, object data)
 		{
 			ForceSpacesBefore (switchStatement.LPar, policy.SwitchParentheses);
 			

ICSharpCode.NRefactory/CSharp/Parser/TypeSystemConvertVisitor.cs

@@ -15,7 +15,7 @@ namespace ICSharpCode.NRefactory.CSharp
 	/// <summary>
 	/// Produces type and member definitions from the DOM.
 	/// </summary>
-	public class TypeSystemConvertVisitor : AbstractDomVisitor<object, IEntity>
+	public class TypeSystemConvertVisitor : DomVisitor<object, IEntity>
 	{
 		readonly ParsedFile parsedFile;
 		UsingScope usingScope;
@@ -61,7 +61,7 @@ namespace ICSharpCode.NRefactory.CSharp
 			return new DomRegion(parsedFile.FileName, start.Line, start.Column, end.Line, end.Column);
 		}
 		
-		DomRegion MakeRegion(INode node)
+		DomRegion MakeRegion(DomNode node)
 		{
 			if (node == null)
 				return DomRegion.Empty;
@@ -314,7 +314,7 @@ namespace ICSharpCode.NRefactory.CSharp
 			return m;
 		}
 		
-		DefaultExplicitInterfaceImplementation ConvertInterfaceImplementation(INode interfaceType, string memberName)
+		DefaultExplicitInterfaceImplementation ConvertInterfaceImplementation(DomNode interfaceType, string memberName)
 		{
 			return new DefaultExplicitInterfaceImplementation(ConvertType(interfaceType), memberName);
 		}
@@ -505,7 +505,7 @@ namespace ICSharpCode.NRefactory.CSharp
 		#region Types
 		static readonly GetClassTypeReference voidReference = new GetClassTypeReference("System.Void", 0);
 		
-		internal static ITypeReference ConvertType(INode node)
+		internal static ITypeReference ConvertType(DomNode node)
 		{
 			FullTypeName f = node as FullTypeName;
 			if (f != null) {
@@ -523,7 +523,7 @@ namespace ICSharpCode.NRefactory.CSharp
 		#endregion
 		
 		#region Constant Values
-		IConstantValue ConvertConstantValue(ITypeReference targetType, INode expression)
+		IConstantValue ConvertConstantValue(ITypeReference targetType, DomNode expression)
 		{
 			return new SimpleConstantValue(targetType, null);
 		}

ICSharpCode.NRefactory/CSharp/Parser/mcs/MonoSymbolFile.cs

@@ -443,18 +443,22 @@ namespace Mono.CompilerServices.SymbolWriter
 		}
 
 #if CECIL
-		protected MonoSymbolFile (string filename, Mono.Cecil.AssemblyDefinition assembly) : this (filename)
+		protected MonoSymbolFile (string filename, Mono.Cecil.ModuleDefinition module)
+			: this (filename)
 		{
-			Guid mvid = assembly.MainModule.Mvid;
+			CheckGuidMatch (module.Mvid, filename, module.FullyQualifiedName);
+		}
 
-			CheckGuidMatch (mvid, filename, assembly.MainModule.Image.FileInformation.FullName);
+		public static MonoSymbolFile ReadSymbolFile (Mono.Cecil.ModuleDefinition module)
+		{
+			return ReadSymbolFile (module, module.FullyQualifiedName);
 		}
 
-		public static MonoSymbolFile ReadSymbolFile (Mono.Cecil.AssemblyDefinition assembly, string filename)
+		public static MonoSymbolFile ReadSymbolFile (Mono.Cecil.ModuleDefinition module, string filename)
 		{
 			string name = filename + ".mdb";
 
-			return new MonoSymbolFile (name, assembly);
+			return new MonoSymbolFile (name, module);
 		}
 #else
 		protected MonoSymbolFile (string filename, Assembly assembly) : this (filename)

ICSharpCode.NRefactory/CSharp/Parser/mcs/anonymous.cs

@@ -80,8 +80,21 @@ namespace Mono.CSharp {
 		{
 			if (tparams != null) {
 				type_params = new TypeParameter[tparams.Length];
+				var src = new TypeParameterSpec[tparams.Length];
+				var dst = new TypeParameterSpec[tparams.Length];
+
 				for (int i = 0; i < type_params.Length; ++i) {
 					type_params[i] = tparams[i].CreateHoistedCopy (this, spec);
+
+					src[i] = tparams[i].Type;
+					dst[i] = type_params[i].Type;
+				}
+
+				// A copy is not enough, inflate any type parameter constraints
+				// using a new type parameters
+				var inflator = new TypeParameterInflator (null, src, dst);
+				for (int i = 0; i < type_params.Length; ++i) {
+					src[i].InflateConstraints (inflator, dst[i]);
 				}
 			}
 		}
@@ -351,6 +364,12 @@ namespace Mono.CSharp {
 				}
 			}
 
+			//
+			// Update parent cache as we most likely passed the point
+			// where the cache was constructed
+			//
+			Parent.CurrentType.MemberCache.AddMember (this.spec);
+
 			return true;
 		}
 
@@ -1588,6 +1607,9 @@ namespace Mono.CSharp {
 
 				ec.Emit (OpCodes.Ldftn, TypeBuilder.GetMethod (t.GetMetaInfo (), (MethodInfo) delegate_method.GetMetaInfo ()));
 			} else {
+				if (delegate_method.IsGeneric)
+					delegate_method = delegate_method.MakeGenericMethod (method.TypeParameters);
+
 				ec.Emit (OpCodes.Ldftn, delegate_method);
 			}
 

ICSharpCode.NRefactory/CSharp/Parser/mcs/argument.cs

@@ -10,7 +10,6 @@
 //
 
 using System;
-using System.Reflection;
 using System.Reflection.Emit;
 using System.Collections.Generic;
 
@@ -48,8 +47,14 @@ namespace Mono.CSharp
 			this.Expr = expr;
 		}
 
-		public TypeSpec Type {
-			get { return Expr.Type; }
+		#region Properties
+
+		public bool IsByRef {
+			get { return ArgType == AType.Ref || ArgType == AType.Out; }
+		}
+
+		public bool IsDefaultArgument {
+			get { return ArgType == AType.Default; }
 		}
 
 		public Parameter.Modifier Modifier {
@@ -67,6 +72,24 @@ namespace Mono.CSharp
 			}
 		}
 
+		public TypeSpec Type {
+			get { return Expr.Type; }
+		}
+
+		#endregion
+
+		public Argument Clone (Expression expr)
+		{
+			Argument a = (Argument) MemberwiseClone ();
+			a.Expr = expr;
+			return a;
+		}
+
+		public Argument Clone (CloneContext clonectx)
+		{
+			return Clone (Expr.Clone (clonectx));
+		}
+
 		public virtual Expression CreateExpressionTree (ResolveContext ec)
 		{
 			if (ArgType == AType.Default)
@@ -83,14 +106,6 @@ namespace Mono.CSharp
 			return TypeManager.CSharpName (Expr.Type);
 		}
 
-		public bool IsByRef {
-			get { return ArgType == AType.Ref || ArgType == AType.Out; }
-		}
-
-		public bool IsDefaultArgument {
-			get { return ArgType == AType.Default; }
-		}
-
 		public bool ResolveMethodGroup (ResolveContext ec)
 		{
 			SimpleName sn = Expr as SimpleName;
@@ -139,13 +154,6 @@ namespace Mono.CSharp
 			IMemoryLocation ml = (IMemoryLocation) Expr;
 			ml.AddressOf (ec, mode);
 		}
-
-		public Argument Clone (CloneContext clonectx)
-		{
-			Argument a = (Argument) MemberwiseClone ();
-			a.Expr = Expr.Clone (clonectx);
-			return a;
-		}
 	}
 
 	public class NamedArgument : Argument
@@ -395,7 +403,7 @@ namespace Mono.CSharp
 				if (!dup_args)
 					continue;
 
-				if (a.Expr is Constant) {
+				if (a.Expr is Constant || a.Expr is This) {
 					//
 					// No need to create a temporary variable for constants
 					//

ICSharpCode.NRefactory/CSharp/Parser/mcs/assign.cs

@@ -12,7 +12,6 @@
 // Copyright 2004-2008 Novell, Inc
 //
 using System;
-using System.Reflection;
 using System.Reflection.Emit;
 
 namespace Mono.CSharp {
@@ -361,7 +360,13 @@ namespace Mono.CSharp {
 			if (target_object.NodeType == System.Linq.Expressions.ExpressionType.Block)
 				return target_object;
 
-			var source_object = System.Linq.Expressions.Expression.Convert (source.MakeExpression (ctx), target_object.Type);
+			System.Linq.Expressions.UnaryExpression source_object;
+			if (ctx.HasSet (BuilderContext.Options.CheckedScope)) {
+				source_object = System.Linq.Expressions.Expression.ConvertChecked (source.MakeExpression (ctx), target_object.Type);
+			} else {
+				source_object = System.Linq.Expressions.Expression.Convert (source.MakeExpression (ctx), target_object.Type);
+			}
+
 			return System.Linq.Expressions.Expression.Assign (target_object, source_object);
 		}
 #endif
@@ -449,11 +454,8 @@ namespace Mono.CSharp {
 
 		protected override Expression ResolveConversions (ResolveContext ec)
 		{
-			source = Convert.ExplicitConversion (ec, source, target.Type, loc);
-			if (source != null)
-				return this;
-
-			return base.ResolveConversions (ec);
+			source = EmptyCast.Create (source, target.Type);
+			return this;
 		}
 	}
 
@@ -673,8 +675,18 @@ namespace Mono.CSharp {
 				Arguments args = new Arguments (targs.Count + 1);
 				args.AddRange (targs);
 				args.Add (new Argument (source));
+
+				var binder_flags = CSharpBinderFlags.ValueFromCompoundAssignment;
+
+				//
+				// Compound assignment does target conversion using additional method
+				// call, set checked context as the binary operation can overflow
+				//
+				if (ec.HasSet (ResolveContext.Options.CheckedScope))
+					binder_flags |= CSharpBinderFlags.CheckedContext;
+
 				if (target is DynamicMemberBinder) {
-					source = new DynamicMemberBinder (ma.Name, CSharpBinderFlags.ValueFromCompoundAssignment, args, loc).Resolve (ec);
+					source = new DynamicMemberBinder (ma.Name, binder_flags, args, loc).Resolve (ec);
 
 					// Handles possible event addition/subtraction
 					if (op == Binary.Operator.Addition || op == Binary.Operator.Subtraction) {
@@ -693,7 +705,7 @@ namespace Mono.CSharp {
 							(ExpressionStatement) source, (ExpressionStatement) invoke, loc).Resolve (ec);
 					}
 				} else {
-					source = new DynamicIndexBinder (CSharpBinderFlags.ValueFromCompoundAssignment, args, loc).Resolve (ec);
+					source = new DynamicIndexBinder (binder_flags, args, loc).Resolve (ec);
 				}
 
 				return source;

ICSharpCode.NRefactory/CSharp/Parser/mcs/attribute.cs

@@ -80,8 +80,8 @@ namespace Mono.CSharp {
 		public AttributeTargets Target;
 		readonly ATypeNameExpression expression;
 
-		Arguments PosArguments;
-		Arguments NamedArguments;
+		public Arguments PosArguments;
+		public Arguments NamedArguments;
 
 		bool resolve_error;
 		bool arg_resolved;
@@ -102,7 +102,7 @@ namespace Mono.CSharp {
 		static Assembly orig_sec_assembly;
 		public static readonly object[] EmptyObject = new object [0];
 
-		IList<KeyValuePair<MemberExpr, NamedArgument>> named_values;
+		List<KeyValuePair<MemberExpr, NamedArgument>> named_values;
 
 		// Cache for parameter-less attributes
 		static Dictionary<TypeSpec, MethodSpec> att_cache;
@@ -142,7 +142,7 @@ namespace Mono.CSharp {
 		// we use @target field as a list of targets. The attribute
 		// has to be resolved only once but emitted for each target.
 		//
-		public virtual void AttachTo (Attributable target, IMemberContext context)
+		public void AttachTo (Attributable target, IMemberContext context)
 		{
 			if (this.targets == null) {
 				this.targets = new Attributable[] { target };
@@ -340,7 +340,7 @@ namespace Mono.CSharp {
 			if (Type != context.Compiler.PredefinedAttributes.DllImport)
 				return;
 
-			if (!RootContext.ToplevelTypes.HasDefaultCharSet)
+			if (!rc.CurrentMemberDefinition.Module.HasDefaultCharSet)
 				return;
 
 			const string CharSetEnumMember = "CharSet";
@@ -355,7 +355,7 @@ namespace Mono.CSharp {
 
 			var char_set = rc.Compiler.MetaImporter.ImportType (typeof (CharSet));	// TODO: typeof
 			NamedArguments.Add (new NamedArgument (CharSetEnumMember, loc,
-				Constant.CreateConstant (rc, char_set, RootContext.ToplevelTypes.DefaultCharSet, Location)));
+				Constant.CreateConstant (rc, char_set, rc.CurrentMemberDefinition.Module.DefaultCharSet, Location)));
  		}
 
 		public Report Report {
@@ -584,11 +584,11 @@ namespace Mono.CSharp {
 
 			AttributeUsageAttribute usage_attribute = new AttributeUsageAttribute ((AttributeTargets)((Constant) PosArguments [0].Expr).GetValue ());
 
-			var field = GetPropertyValue ("AllowMultiple") as BoolConstant;
+			var field = GetNamedValue ("AllowMultiple") as BoolConstant;
 			if (field != null)
 				usage_attribute.AllowMultiple = field.Value;
 
-			field = GetPropertyValue ("Inherited") as BoolConstant;
+			field = GetNamedValue ("Inherited") as BoolConstant;
 			if (field != null)
 				usage_attribute.Inherited = field.Value;
 
@@ -701,6 +701,7 @@ namespace Mono.CSharp {
 				case "field": Target = AttributeTargets.Field; return true;
 				case "method": Target = AttributeTargets.Method; return true;
 				case "property": Target = AttributeTargets.Property; return true;
+				case "module": Target = AttributeTargets.Module; return true;
 				}
 				throw new InternalErrorException ("Unknown explicit target: " + ExplicitTarget);
 			}
@@ -857,7 +858,7 @@ namespace Mono.CSharp {
 			ps.AddPermission (perm);
 		}
 
-		public Constant GetPropertyValue (string name)
+		public Constant GetNamedValue (string name)
 		{
 			if (named_values == null)
 				return null;
@@ -1110,7 +1111,7 @@ namespace Mono.CSharp {
 					na.Value.Expr.EncodeAttributeValue (context, encoder, na.Key.Type);
 				}
 			} else {
-				encoder.Stream.Write ((ushort) 0);
+				encoder.EncodeEmptyNamedArguments ();
 			}
 
 			byte[] cdata = encoder.ToArray ();
@@ -1214,21 +1215,6 @@ namespace Mono.CSharp {
 		{
 			this.ns = ns;
 		}
-		
-		public override void AttachTo (Attributable target, IMemberContext context)
-		{
-			if (ExplicitTarget == "assembly") {
-				base.AttachTo (CodeGen.Assembly, context);
-				return;
-			}
-
-			if (ExplicitTarget == "module") {
-				base.AttachTo (RootContext.ToplevelTypes, context);
-				return;
-			}
-
-			throw new NotImplementedException ("Unknown global explicit target " + ExplicitTarget);
-		}
 
 		void Enter ()
 		{
@@ -1336,8 +1322,16 @@ namespace Mono.CSharp {
 		}
 
 		public Attribute Search (PredefinedAttribute t)
+		{
+			return Search (null, t);
+		}
+
+		public Attribute Search (string explicitTarget, PredefinedAttribute t)
 		{
 			foreach (Attribute a in Attrs) {
+				if (explicitTarget != null && a.ExplicitTarget != explicitTarget)
+					continue;
+
 				if (a.ResolveType () == t)
 					return a;
 			}
@@ -1404,8 +1398,18 @@ namespace Mono.CSharp {
 			TypeParameter = 1 << 1
 		}
 
+		const ushort Version = 1;
+
+		public static readonly byte[] Empty;
+
 		public readonly BinaryWriter Stream;
 
+		static AttributeEncoder ()
+		{
+			Empty = new byte[4];
+			Array.Copy (BitConverter.GetBytes (Version), Empty, 2);
+		}
+
 		public AttributeEncoder (bool empty)
 		{
 			if (empty) {
@@ -1414,8 +1418,27 @@ namespace Mono.CSharp {
 			}
 
 			Stream = new BinaryWriter (new MemoryStream ());
-			const ushort version = 1;
-			Stream.Write (version);
+			Stream.Write (Version);
+		}
+
+		public void Encode (byte value)
+		{
+			Stream.Write (value);
+		}
+
+		public void Encode (short value)
+		{
+			Stream.Write (value);
+		}
+
+		public void Encode (int value)
+		{
+			Stream.Write (value);
+		}
+
+		public void Encode (uint value)
+		{
+			Stream.Write (value);
 		}
 
 		public void Encode (string value)
@@ -1480,6 +1503,56 @@ namespace Mono.CSharp {
 			Encode (type.MemberDefinition.IsImported ? old_type.AssemblyQualifiedName : old_type.FullName);
 		}
 
+		//
+		// Encodes single property named argument per call
+		//
+		public void EncodeNamedPropertyArgument (PropertySpec property, Constant value)
+		{
+			Stream.Write ((ushort) 1);	// length
+			Stream.Write ((byte) 0x54); // property
+			Encode (property.MemberType);
+			Encode (property.Name);
+			value.EncodeAttributeValue (null, this, property.MemberType);
+		}
+
+		//
+		// Encodes single field named argument per call
+		//
+		public void EncodeNamedFieldArgument (FieldSpec field, Constant value)
+		{
+			Stream.Write ((ushort) 1);	// length
+			Stream.Write ((byte) 0x53); // field
+			Encode (field.MemberType);
+			Encode (field.Name);
+			value.EncodeAttributeValue (null, this, field.MemberType);
+		}
+
+		public void EncodeNamedArguments<T> (T[] members, Constant[] values) where T : MemberSpec, IInterfaceMemberSpec
+		{
+			Stream.Write ((ushort) members.Length);
+
+			for (int i = 0; i < members.Length; ++i)
+			{
+				var member = members[i];
+
+				if (member.Kind == MemberKind.Field)
+					Stream.Write ((byte) 0x53);
+				else if (member.Kind == MemberKind.Property)
+					Stream.Write ((byte) 0x54);
+				else
+					throw new NotImplementedException (member.Kind.ToString ());
+
+				Encode (member.MemberType);
+				Encode (member.Name);
+				values [i].EncodeAttributeValue (null, this, member.MemberType);
+			}
+		}
+
+		public void EncodeEmptyNamedArguments ()
+		{
+			Stream.Write ((ushort) 0);
+		}
+
 		void WriteCompressedValue (int value)
 		{
 			if (value < 0x80) {
@@ -1558,23 +1631,6 @@ namespace Mono.CSharp {
 			return result;
 		}
 
-		public static void VerifyModulesClsCompliance (CompilerContext ctx)
-		{
-			Module[] modules = ctx.GlobalRootNamespace.Modules;
-			if (modules == null)
-				return;
-
-			// The first module is generated assembly
-			for (int i = 1; i < modules.Length; ++i) {
-				Module module = modules [i];
-				if (!GetClsCompliantAttributeValue (module, null)) {
-					ctx.Report.Error (3013, "Added modules must be marked with the CLSCompliant attribute " +
-						      "to match the assembly", module.Name);
-					return;
-				}
-			}
-		}
-
 		static bool GetClsCompliantAttributeValue (ICustomAttributeProvider attribute_provider, Assembly a) 
 		{
 			object[] cls_attr = attribute_provider.GetCustomAttributes (typeof (CLSCompliantAttribute), false);
@@ -1633,6 +1689,7 @@ namespace Mono.CSharp {
 		public readonly PredefinedAttribute AttributeUsage;
 		public readonly PredefinedAttribute DefaultParameterValue;
 		public readonly PredefinedAttribute OptionalParameter;
+		public readonly PredefinedAttribute UnverifiableCode;
 
 		// New in .NET 2.0
 		public readonly PredefinedAttribute DefaultCharset;
@@ -1654,7 +1711,7 @@ namespace Mono.CSharp {
 		// Optional types which are used as types and for member lookup
 		//
 		public readonly PredefinedAttribute DefaultMember;
-		public readonly PredefinedAttribute DecimalConstant;
+		public readonly PredefinedDecimalAttribute DecimalConstant;
 		public readonly PredefinedAttribute StructLayout;
 		public readonly PredefinedAttribute FieldOffset;
 
@@ -1683,6 +1740,7 @@ namespace Mono.CSharp {
 			AttributeUsage = new PredefinedAttribute ("System", "AttributeUsageAttribute");
 			DefaultParameterValue = new PredefinedAttribute ("System.Runtime.InteropServices", "DefaultParameterValueAttribute");
 			OptionalParameter = new PredefinedAttribute ("System.Runtime.InteropServices", "OptionalAttribute");
+			UnverifiableCode = new PredefinedAttribute ("System.Security", "UnverifiableCodeAttribute");
 
 			DefaultCharset = new PredefinedAttribute ("System.Runtime.InteropServices", "DefaultCharSetAttribute");
 			TypeForwarder = new PredefinedAttribute ("System.Runtime.CompilerServices", "TypeForwardedToAttribute");
@@ -1698,7 +1756,7 @@ namespace Mono.CSharp {
 			Dynamic = new PredefinedDynamicAttribute ("System.Runtime.CompilerServices", "DynamicAttribute");
 
 			DefaultMember = new PredefinedAttribute ("System.Reflection", "DefaultMemberAttribute");
-			DecimalConstant = new PredefinedAttribute ("System.Runtime.CompilerServices", "DecimalConstantAttribute");
+			DecimalConstant = new PredefinedDecimalAttribute ("System.Runtime.CompilerServices", "DecimalConstantAttribute");
 			StructLayout = new PredefinedAttribute ("System.Runtime.InteropServices", "StructLayoutAttribute");
 			FieldOffset = new PredefinedAttribute ("System.Runtime.InteropServices", "FieldOffsetAttribute");
 		}
@@ -1714,10 +1772,11 @@ namespace Mono.CSharp {
 	public class PredefinedAttribute
 	{
 		protected TypeSpec type;
-		CustomAttributeBuilder cab;
-		MethodSpec ctor;
+		protected MethodSpec ctor;
 		readonly string ns, name;
 		CompilerContext compiler;
+		List<FieldSpec> fields;
+		List<PropertySpec> properties;
 
 		static readonly TypeSpec NotFound = InternalType.Null;
 
@@ -1727,6 +1786,29 @@ namespace Mono.CSharp {
 			this.name = name;
 		}
 
+		#region Properties
+
+		public MethodSpec Constructor {
+			get {
+				return ctor;
+			}
+		}
+
+		public bool IsDefined {
+			get {
+				return type != null && type != NotFound;
+			}
+		}
+
+		public TypeSpec Type {
+			get {
+				return type;
+			}
+		}
+
+		#endregion
+
+
 		public static bool operator == (TypeSpec type, PredefinedAttribute pa)
 		{
 			return type == pa.type;
@@ -1737,10 +1819,6 @@ namespace Mono.CSharp {
 			return type != pa.type;
 		}
 
-		public ConstructorInfo Constructor {
-			get { return ctor == null ? null : (ConstructorInfo) ctor.GetMetaInfo (); }
-		}
-
 		public override int GetHashCode ()
 		{
 			return base.GetHashCode ();
@@ -1759,47 +1837,118 @@ namespace Mono.CSharp {
 		public void EmitAttribute (ConstructorBuilder builder)
 		{
 			if (ResolveBuilder ())
-				builder.SetCustomAttribute (cab);
+				builder.SetCustomAttribute (GetCtorMetaInfo (), AttributeEncoder.Empty);
 		}
 
 		public void EmitAttribute (MethodBuilder builder)
 		{
 			if (ResolveBuilder ())
-				builder.SetCustomAttribute (cab);
+				builder.SetCustomAttribute (GetCtorMetaInfo (), AttributeEncoder.Empty);
 		}
 
 		public void EmitAttribute (PropertyBuilder builder)
 		{
 			if (ResolveBuilder ())
-				builder.SetCustomAttribute (cab);
+				builder.SetCustomAttribute (GetCtorMetaInfo (), AttributeEncoder.Empty);
 		}
 
 		public void EmitAttribute (FieldBuilder builder)
 		{
 			if (ResolveBuilder ())
-				builder.SetCustomAttribute (cab);
+				builder.SetCustomAttribute (GetCtorMetaInfo (), AttributeEncoder.Empty);
+		}
+
+		public void EmitAttribute (FieldBuilder builder, AttributeEncoder argsEncoded)
+		{
+			builder.SetCustomAttribute (GetCtorMetaInfo (), argsEncoded.ToArray ());
 		}
 
 		public void EmitAttribute (TypeBuilder builder)
 		{
 			if (ResolveBuilder ())
-				builder.SetCustomAttribute (cab);
+				builder.SetCustomAttribute (GetCtorMetaInfo (), AttributeEncoder.Empty);
+		}
+
+		public void EmitAttribute (TypeBuilder builder, AttributeEncoder argsEncoded)
+		{
+			builder.SetCustomAttribute (GetCtorMetaInfo (), argsEncoded.ToArray ());
 		}
 
 		public void EmitAttribute (AssemblyBuilder builder)
 		{
 			if (ResolveBuilder ())
-				builder.SetCustomAttribute (cab);
+				builder.SetCustomAttribute (GetCtorMetaInfo (), AttributeEncoder.Empty);
+		}
+
+		public void EmitAttribute (ModuleBuilder builder)
+		{
+			if (ResolveBuilder ())
+				builder.SetCustomAttribute (GetCtorMetaInfo (), AttributeEncoder.Empty);
 		}
 
 		public void EmitAttribute (ParameterBuilder builder)
 		{
 			if (ResolveBuilder ())
-				builder.SetCustomAttribute (cab);
+				builder.SetCustomAttribute (GetCtorMetaInfo (), AttributeEncoder.Empty);
 		}
 
-		public bool IsDefined {
-			get { return type != null && type != NotFound; }
+		public void EmitAttribute (ParameterBuilder builder, AttributeEncoder argsEncoded)
+		{
+			builder.SetCustomAttribute (GetCtorMetaInfo (), argsEncoded.ToArray ());
+		}
+
+		ConstructorInfo GetCtorMetaInfo ()
+		{
+			return (ConstructorInfo) ctor.GetMetaInfo ();
+		}
+
+		public FieldSpec GetField (string name, TypeSpec memberType, Location loc)
+		{
+			FieldSpec spec;
+			if (fields != null) {
+				spec = fields.Find (l => l.Name == name);
+			} else {
+				spec = null;
+			}
+
+			if (spec == null) {
+				spec = TypeManager.GetPredefinedField (type, name, loc, memberType);
+
+				if (spec != null) {
+					if (fields == null) {
+						fields = new List<FieldSpec> ();
+					}
+
+					fields.Add (spec);
+				}
+			}
+
+			return spec;
+		}
+
+		public PropertySpec GetProperty (string name, TypeSpec memberType, Location loc)
+		{
+			PropertySpec spec;
+
+			if (properties != null) {
+				spec = properties.Find (l => l.Name == name);
+			} else {
+				spec = null;
+			}
+
+			if (spec == null) {
+				spec = TypeManager.GetPredefinedProperty (type, name, loc, memberType);
+
+				if (spec != null) {
+					if (properties == null) {
+						properties = new List<PropertySpec> ();
+					}
+
+					properties.Add (spec);
+				}
+			}
+
+			return spec;
 		}
 
 		public void Initialize (CompilerContext ctx, bool canFail)
@@ -1826,9 +1975,9 @@ namespace Mono.CSharp {
 			return true;
 		}
 
-		bool ResolveBuilder ()
+		public bool ResolveBuilder ()
 		{
-			if (cab != null)
+			if (ctor != null)
 				return true;
 
 			//
@@ -1837,12 +1986,8 @@ namespace Mono.CSharp {
 			if (!Resolve (true))
 				return false;
 
-			var ci = TypeManager.GetPredefinedConstructor (type, Location.Null, TypeSpec.EmptyTypes);
-			if (ci == null)
-				return false;
-
-			cab = new CustomAttributeBuilder ((ConstructorInfo) ci.GetMetaInfo (), new object[0]);
-			return true;
+			ctor = TypeManager.GetPredefinedConstructor (type, Location.Null, TypeSpec.EmptyTypes);
+			return ctor != null;
 		}
 
 		public bool ResolveConstructor (Location loc, params TypeSpec[] argType)
@@ -1856,9 +2001,53 @@ namespace Mono.CSharp {
 			ctor = TypeManager.GetPredefinedConstructor (type, loc, argType);
 			return ctor != null;
 		}
+	}
 
-		public TypeSpec Type {
-			get { return type; }
+	public class PredefinedDecimalAttribute : PredefinedAttribute
+	{
+		public PredefinedDecimalAttribute (string ns, string name)
+			: base (ns, name)
+		{
+		}
+
+		public void EmitAttribute (ParameterBuilder builder, decimal value, Location loc)
+		{
+			if (!Resolve (false))
+				return;
+
+			if (ctor == null && !ResolveConstructor (loc, TypeManager.byte_type, TypeManager.byte_type, TypeManager.uint32_type, TypeManager.uint32_type, TypeManager.uint32_type))
+				return;
+
+			int[] bits = decimal.GetBits (value);
+			AttributeEncoder encoder = new AttributeEncoder (false);
+			encoder.Encode ((byte) (bits[3] >> 16));
+			encoder.Encode ((byte) (bits[3] >> 31));
+			encoder.Encode ((uint) bits[2]);
+			encoder.Encode ((uint) bits[1]);
+			encoder.Encode ((uint) bits[0]);
+			encoder.EncodeEmptyNamedArguments ();
+
+			EmitAttribute (builder, encoder);
+		}
+
+		public void EmitAttribute (FieldBuilder builder, decimal value, Location loc)
+		{
+			if (!Resolve (false))
+				return;
+
+			if (ctor == null && !ResolveConstructor (loc, TypeManager.byte_type, TypeManager.byte_type, TypeManager.uint32_type, TypeManager.uint32_type, TypeManager.uint32_type))
+				return;
+
+			int[] bits = decimal.GetBits (value);
+			AttributeEncoder encoder = new AttributeEncoder (false);
+			encoder.Encode ((byte) (bits[3] >> 16));
+			encoder.Encode ((byte) (bits[3] >> 31));
+			encoder.Encode ((uint) bits[2]);
+			encoder.Encode ((uint) bits[1]);
+			encoder.Encode ((uint) bits[0]);
+			encoder.EncodeEmptyNamedArguments ();
+
+			EmitAttribute (builder, encoder);
 		}
 	}
 

ICSharpCode.NRefactory/CSharp/Parser/mcs/cfold.cs

@@ -169,7 +169,7 @@ namespace Mono.CSharp {
 					case Binary.Operator.Subtraction:
 						result = BinaryFold (ec, oper, ((EnumConstant)left).Child, ((EnumConstant)right).Child, loc);
 						if (result != null)
-							result = result.Resolve (ec).TryReduce (ec, ((EnumConstant)left).Child.Type, loc);
+							result = result.Resolve (ec).TryReduce (ec, EnumSpec.GetUnderlyingType (lt), loc);
 						return result;
 
 					///
@@ -477,6 +477,11 @@ namespace Mono.CSharp {
 					return new EnumConstant (result, lt);
 				}
 
+				if (left is NullLiteral && right is NullLiteral) {
+					var lifted_int = new Nullable.NullableType (TypeManager.int32_type, loc).ResolveAsTypeTerminal (ec, false);
+					return (Constant) new Nullable.LiftedBinaryOperator (oper, lifted_int, right, loc).Resolve (ec);
+				}
+
 				if (!DoBinaryNumericPromotions (ec, ref left, ref right))
 					return null;
 
@@ -568,6 +573,11 @@ namespace Mono.CSharp {
 				return result;
 				
 			case Binary.Operator.Multiply:
+				if (left is NullLiteral && right is NullLiteral) {
+					var lifted_int = new Nullable.NullableType (TypeManager.int32_type, loc).ResolveAsTypeTerminal (ec, false);
+					return (Constant) new Nullable.LiftedBinaryOperator (oper, lifted_int, right, loc).Resolve (ec);
+				}
+
 				if (!DoBinaryNumericPromotions (ec, ref left, ref right))
 					return null;
 
@@ -658,6 +668,11 @@ namespace Mono.CSharp {
 				break;
 
 			case Binary.Operator.Division:
+				if (left is NullLiteral && right is NullLiteral) {
+					var lifted_int = new Nullable.NullableType (TypeManager.int32_type, loc).ResolveAsTypeTerminal (ec, false);
+					return (Constant) new Nullable.LiftedBinaryOperator (oper, lifted_int, right, loc).Resolve (ec);
+				}
+
 				if (!DoBinaryNumericPromotions (ec, ref left, ref right))
 					return null;
 
@@ -752,6 +767,11 @@ namespace Mono.CSharp {
 				break;
 				
 			case Binary.Operator.Modulus:
+				if (left is NullLiteral && right is NullLiteral) {
+					var lifted_int = new Nullable.NullableType (TypeManager.int32_type, loc).ResolveAsTypeTerminal (ec, false);
+					return (Constant) new Nullable.LiftedBinaryOperator (oper, lifted_int, right, loc).Resolve (ec);
+				}
+
 				if (!DoBinaryNumericPromotions (ec, ref left, ref right))
 					return null;
 
@@ -836,6 +856,11 @@ namespace Mono.CSharp {
 				// There is no overflow checking on left shift
 				//
 			case Binary.Operator.LeftShift:
+				if (left is NullLiteral && right is NullLiteral) {
+					var lifted_int = new Nullable.NullableType (TypeManager.int32_type, loc).ResolveAsTypeTerminal (ec, false);
+					return (Constant) new Nullable.LiftedBinaryOperator (oper, lifted_int, right, loc).Resolve (ec);
+				}
+
 				IntConstant ic = right.ConvertImplicitly (ec, TypeManager.int32_type) as IntConstant;
 				if (ic == null){
 					Binary.Error_OperatorCannotBeApplied (ec, left, right, oper, loc);
@@ -850,6 +875,10 @@ namespace Mono.CSharp {
 				if (left.Type == TypeManager.uint32_type)
 					return new UIntConstant (((UIntConstant)left).Value << lshift_val, left.Location);
 
+				// null << value => null
+				if (left is NullLiteral)
+					return (Constant) new Nullable.LiftedBinaryOperator (oper, left, right, loc).Resolve (ec);
+
 				left = left.ConvertImplicitly (ec, TypeManager.int32_type);
 				if (left.Type == TypeManager.int32_type)
 					return new IntConstant (((IntConstant)left).Value << lshift_val, left.Location);
@@ -861,6 +890,11 @@ namespace Mono.CSharp {
 				// There is no overflow checking on right shift
 				//
 			case Binary.Operator.RightShift:
+				if (left is NullLiteral && right is NullLiteral) {
+					var lifted_int = new Nullable.NullableType (TypeManager.int32_type, loc).ResolveAsTypeTerminal (ec, false);
+					return (Constant) new Nullable.LiftedBinaryOperator (oper, lifted_int, right, loc).Resolve (ec);
+				}
+
 				IntConstant sic = right.ConvertImplicitly (ec, TypeManager.int32_type) as IntConstant;
 				if (sic == null){
 					Binary.Error_OperatorCannotBeApplied (ec, left, right, oper, loc); ;
@@ -874,6 +908,10 @@ namespace Mono.CSharp {
 				if (left.Type == TypeManager.uint32_type)
 					return new UIntConstant (((UIntConstant)left).Value >> rshift_val, left.Location);
 
+				// null >> value => null
+				if (left is NullLiteral)
+					return (Constant) new Nullable.LiftedBinaryOperator (oper, left, right, loc).Resolve (ec);
+
 				left = left.ConvertImplicitly (ec, TypeManager.int32_type);
 				if (left.Type == TypeManager.int32_type)
 					return new IntConstant (((IntConstant)left).Value >> rshift_val, left.Location);
@@ -970,6 +1008,17 @@ namespace Mono.CSharp {
 				return new BoolConstant (bool_res, left.Location);
 
 			case Binary.Operator.LessThan:
+				if (right is NullLiteral) {
+					if (left is NullLiteral) {
+						var lifted_int = new Nullable.NullableType (TypeManager.int32_type, loc).ResolveAsTypeTerminal (ec, false);
+						return (Constant) new Nullable.LiftedBinaryOperator (oper, lifted_int, right, loc).Resolve (ec);
+					}
+
+					if (left is Nullable.LiftedNull) {
+						return (Constant) new Nullable.LiftedBinaryOperator (oper, left, right, loc).Resolve (ec);
+					}
+				}
+
 				if (!DoBinaryNumericPromotions (ec, ref left, ref right))
 					return null;
 
@@ -998,6 +1047,17 @@ namespace Mono.CSharp {
 				return new BoolConstant (bool_res, left.Location);
 				
 			case Binary.Operator.GreaterThan:
+				if (right is NullLiteral) {
+					if (left is NullLiteral) {
+						var lifted_int = new Nullable.NullableType (TypeManager.int32_type, loc).ResolveAsTypeTerminal (ec, false);
+						return (Constant) new Nullable.LiftedBinaryOperator (oper, lifted_int, right, loc).Resolve (ec);
+					}
+
+					if (left is Nullable.LiftedNull) {
+						return (Constant) new Nullable.LiftedBinaryOperator (oper, left, right, loc).Resolve (ec);
+					}
+				}
+
 				if (!DoBinaryNumericPromotions (ec, ref left, ref right))
 					return null;
 
@@ -1026,6 +1086,17 @@ namespace Mono.CSharp {
 				return new BoolConstant (bool_res, left.Location);
 
 			case Binary.Operator.GreaterThanOrEqual:
+				if (right is NullLiteral) {
+					if (left is NullLiteral) {
+						var lifted_int = new Nullable.NullableType (TypeManager.int32_type, loc).ResolveAsTypeTerminal (ec, false);
+						return (Constant) new Nullable.LiftedBinaryOperator (oper, lifted_int, right, loc).Resolve (ec);
+					}
+
+					if (left is Nullable.LiftedNull) {
+						return (Constant) new Nullable.LiftedBinaryOperator (oper, left, right, loc).Resolve (ec);
+					}
+				}
+
 				if (!DoBinaryNumericPromotions (ec, ref left, ref right))
 					return null;
 
@@ -1054,6 +1125,17 @@ namespace Mono.CSharp {
 				return new BoolConstant (bool_res, left.Location);
 
 			case Binary.Operator.LessThanOrEqual:
+				if (right is NullLiteral) {
+					if (left is NullLiteral) {
+						var lifted_int = new Nullable.NullableType (TypeManager.int32_type, loc).ResolveAsTypeTerminal (ec, false);
+						return (Constant) new Nullable.LiftedBinaryOperator (oper, lifted_int, right, loc).Resolve (ec);
+					}
+
+					if (left is Nullable.LiftedNull) {
+						return (Constant) new Nullable.LiftedBinaryOperator (oper, left, right, loc).Resolve (ec);
+					}
+				}
+
 				if (!DoBinaryNumericPromotions (ec, ref left, ref right))
 					return null;