Add C# resolver.

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

@@ -0,0 +1,30 @@
+// Copyright (c) 2010 AlphaSierraPapa for the SharpDevelop Team (for details please see \doc\copyright.txt)
+// This code is distributed under MIT X11 license (for details please see \doc\license.txt)
+
+using System;
+using NUnit.Framework;
+
+namespace ICSharpCode.NRefactory.CSharp.Resolver
+{
+	[TestFixture]
+	public class UnaryOperatorTests
+	{
+		[Test]
+		public void TestMethod()
+		{
+			//var a = ~new X();
+			char a = 'a';
+			++a;
+			a++;
+			float b= 1;
+			++b;
+			b++;
+		}
+	}
+	
+	class X
+	{
+		//public static implicit operator int(X a) { return 0; }
+		public static implicit operator LoaderOptimization(X a) { return 0; }
+	}
+}

ICSharpCode.NRefactory.Tests/ICSharpCode.NRefactory.Tests.csproj

@@ -44,6 +44,7 @@
   </ItemGroup>
   <ItemGroup>
     <Compile Include="CSharp\Resolver\ConversionsTest.cs" />
+    <Compile Include="CSharp\Resolver\UnaryOperatorTests.cs" />
     <Compile Include="FormattingTests\TestBraceStlye.cs" />
     <Compile Include="FormattingTests\TestFormattingBugs.cs" />
     <Compile Include="FormattingTests\TestSpacingVisitor.cs" />

ICSharpCode.NRefactory/CSharp/Resolver/CSharpResolver.cs

@@ -0,0 +1,388 @@
+// Copyright (c) 2010 AlphaSierraPapa for the SharpDevelop Team (for details please see \doc\copyright.txt)
+// This code is distributed under MIT X11 license (for details please see \doc\license.txt)
+
+using System;
+using System.Collections.Generic;
+using System.Globalization;
+using ICSharpCode.NRefactory.TypeSystem;
+using ICSharpCode.NRefactory.TypeSystem.Implementation;
+
+namespace ICSharpCode.NRefactory.CSharp.Resolver
+{
+	/// <summary>
+	/// Contains the main resolver logic.
+	/// </summary>
+	public class CSharpResolver
+	{
+		static readonly ResolveResult ErrorResult = new ErrorResolveResult(SharedTypes.UnknownType);
+		static readonly ResolveResult DynamicResult = new ResolveResult(SharedTypes.Dynamic);
+		
+		readonly ITypeResolveContext context;
+		
+		/// <summary>
+		/// Gets/Sets whether the current context is <c>checked</c>.
+		/// </summary>
+		public bool IsCheckedContext { get; set; }
+		
+		public CSharpResolver(ITypeResolveContext context)
+		{
+			if (context == null)
+				throw new ArgumentNullException("context");
+			this.context = context;
+		}
+		
+		#region class OperatorMethod
+		class OperatorMethod : Immutable, IMethod
+		{
+			IList<IParameter> parameters = new List<IParameter>();
+			
+			public IList<IParameter> Parameters {
+				get { return parameters; }
+			}
+			
+			public ITypeReference ReturnType {
+				get; set;
+			}
+			
+			IList<IAttribute> IMethod.ReturnTypeAttributes {
+				get { return EmptyList<IAttribute>.Instance; }
+			}
+			
+			IList<ITypeParameter> IMethod.TypeParameters {
+				get { return EmptyList<ITypeParameter>.Instance; }
+			}
+			
+			bool IMethod.IsExtensionMethod {
+				get { return false; }
+			}
+			
+			bool IMethod.IsConstructor {
+				get { return false; }
+			}
+			
+			bool IMethod.IsDestructor {
+				get { return false; }
+			}
+			
+			bool IMethod.IsOperator {
+				get { return true; }
+			}
+			
+			ITypeDefinition IEntity.DeclaringTypeDefinition {
+				get { return null; }
+			}
+			
+			ITypeDefinition IMember.DeclaringTypeDefinition {
+				get { return null; }
+			}
+			
+			IType IMember.DeclaringType {
+				get { return null; }
+			}
+			
+			IMember IMember.MemberDefinition {
+				get { return null; }
+			}
+			
+			IList<IExplicitInterfaceImplementation> IMember.InterfaceImplementations {
+				get { return EmptyList<IExplicitInterfaceImplementation>.Instance; }
+			}
+			
+			bool IMember.IsVirtual {
+				get { return false; }
+			}
+			
+			bool IMember.IsOverride {
+				get { return false; }
+			}
+			
+			bool IMember.IsOverridable {
+				get { return false; }
+			}
+			
+			EntityType IEntity.EntityType {
+				get { return EntityType.Operator; }
+			}
+			
+			DomRegion IEntity.Region {
+				get { return DomRegion.Empty; }
+			}
+			
+			DomRegion IEntity.BodyRegion {
+				get { return DomRegion.Empty; }
+			}
+			
+			IList<IAttribute> IEntity.Attributes {
+				get { return EmptyList<IAttribute>.Instance; }
+			}
+			
+			string IEntity.Documentation {
+				get { return null; }
+			}
+			
+			Accessibility IEntity.Accessibility {
+				get { return Accessibility.Public; }
+			}
+			
+			bool IEntity.IsStatic {
+				get { return true; }
+			}
+			
+			bool IEntity.IsAbstract {
+				get { return false; }
+			}
+			
+			bool IEntity.IsSealed {
+				get { return false; }
+			}
+			
+			bool IEntity.IsShadowing {
+				get { return false; }
+			}
+			
+			bool IEntity.IsSynthetic {
+				get { return true; }
+			}
+			
+			IProjectContent IEntity.ProjectContent {
+				get { return null; }
+			}
+			
+			string INamedElement.FullName {
+				get { return "operator"; }
+			}
+			
+			string INamedElement.Name {
+				get { return "operator"; }
+			}
+			
+			string INamedElement.Namespace {
+				get { return string.Empty; }
+			}
+			
+			string INamedElement.DotNetName {
+				get { return "operator"; }
+			}
+		}
+		#endregion
+		
+		#region ResolveUnaryOperator
+		public ResolveResult ResolveUnaryOperator(UnaryOperatorType op, ResolveResult expression)
+		{
+			if (expression.Type == SharedTypes.Dynamic)
+				return DynamicResult;
+			
+			// C# 4.0 spec: §7.3.3 Unary operator overload resolution
+			string overloadableOperatorName = GetOverloadableOperatorName(op);
+			if (overloadableOperatorName == null) {
+				switch (op) {
+					case UnaryOperatorType.Dereference:
+						PointerType p = expression.Type as PointerType;
+						if (p != null)
+							return new ResolveResult(p.ElementType);
+						else
+							return ErrorResult;
+					case UnaryOperatorType.AddressOf:
+						return new ResolveResult(new PointerType(expression.Type));
+					default:
+						throw new ArgumentException("Invalid value for UnaryOperatorType", "op");
+				}
+			}
+			// If the type is nullable, get the underlying type:
+			IType type = NullableType.GetUnderlyingType(expression.Type);
+			bool isNullable = type != null;
+			if (!isNullable)
+				type = expression.Type;
+			
+			// the operator is overloadable:
+			// TODO: implicit support for user operators
+			//var candidateSet = GetUnaryOperatorCandidates();
+			
+			UnaryOperatorMethod[] methodGroup;
+			switch (op) {
+				case UnaryOperatorType.Increment:
+				case UnaryOperatorType.Decrement:
+				case UnaryOperatorType.PostIncrement:
+				case UnaryOperatorType.PostDecrement:
+					// C# 4.0 spec: §7.6.9 Postfix increment and decrement operators
+					// C# 4.0 spec: §7.7.5 Prefix increment and decrement operators
+					TypeCode code = ReflectionHelper.GetTypeCode(type);
+					if (type.IsEnum() || (code >= TypeCode.SByte && code <= TypeCode.Decimal))
+						return new ResolveResult(expression.Type);
+					else
+						return ErrorResult;
+				case UnaryOperatorType.Plus:
+					methodGroup = unaryPlusOperators;
+					break;
+				case UnaryOperatorType.Minus:
+					methodGroup = IsCheckedContext ? checkedUnaryMinusOperators : uncheckedUnaryMinusOperators;
+					break;
+				case UnaryOperatorType.Not:
+					methodGroup = logicalNegationOperator;
+					break;
+				case UnaryOperatorType.BitNot:
+					if (type.IsEnum()) {
+						if (expression.IsCompileTimeConstant && expression.ConstantValue != null) {
+							// evaluate as (E)(~(U)x);
+							var U = expression.ConstantValue.GetType().ToTypeReference().Resolve(context);
+							var unpackedEnum = new ConstantResolveResult(U, expression.ConstantValue);
+							return ResolveCast(expression.Type, ResolveUnaryOperator(op, unpackedEnum));
+						} else {
+							return new ResolveResult(expression.Type);
+						}
+					} else {
+						methodGroup = bitwiseComplementOperators;
+						break;
+					}
+				default:
+					throw new InvalidOperationException();
+			}
+			throw new NotImplementedException();
+		}
+		
+		object GetUserUnaryOperatorCandidates()
+		{
+			// C# 4.0 spec: §7.3.5 Candidate user-defined operators
+			throw new NotImplementedException();
+		}
+		
+		static string GetOverloadableOperatorName(UnaryOperatorType op)
+		{
+			switch (op) {
+				case UnaryOperatorType.Not:
+					return "op_LogicalNot";
+				case UnaryOperatorType.BitNot:
+					return "op_OnesComplement";
+				case UnaryOperatorType.Minus:
+					return "op_UnaryNegation";
+				case UnaryOperatorType.Plus:
+					return "op_UnaryPlus";
+				case UnaryOperatorType.Increment:
+				case UnaryOperatorType.PostIncrement:
+					return "op_Increment";
+				case UnaryOperatorType.Decrement:
+				case UnaryOperatorType.PostDecrement:
+					return "op_Decrement";
+				default:
+					return null;
+			}
+		}
+		
+		abstract class UnaryOperatorMethod : OperatorMethod
+		{
+			public abstract object Invoke(object input);
+		}
+		
+		sealed class LambdaUnaryOperatorMethod<T> : UnaryOperatorMethod
+		{
+			readonly Func<T, T> func;
+			
+			public LambdaUnaryOperatorMethod(Func<T, T> func)
+			{
+				this.func = func;
+			}
+			
+			public override object Invoke(object input)
+			{
+				return func((T)input);
+			}
+		}
+		
+		sealed class LiftedUnaryOperatorMethod : UnaryOperatorMethod
+		{
+			UnaryOperatorMethod baseMethod;
+			
+			public LiftedUnaryOperatorMethod(UnaryOperatorMethod baseMethod)
+			{
+				this.baseMethod = baseMethod;
+				this.ReturnType = NullableType.Create(baseMethod.ReturnType);
+				this.Parameters.Add(new DefaultParameter(NullableType.Create(baseMethod.Parameters[0].Type), string.Empty));
+			}
+			
+			public override object Invoke(object input)
+			{
+				if (input == null)
+					return null;
+				else
+					return baseMethod.Invoke(input);
+			}
+		}
+		
+		static UnaryOperatorMethod[] Lift(params UnaryOperatorMethod[] methods)
+		{
+			UnaryOperatorMethod[] lifted = new UnaryOperatorMethod[methods.Length * 2];
+			methods.CopyTo(lifted, 0);
+			for (int i = 0; i < methods.Length; i++) {
+				lifted[methods.Length + i] = new LiftedUnaryOperatorMethod(methods[i]);
+			}
+			return lifted;
+		}
+		
+		// C# 4.0 spec: §7.7.1 Unary plus operator
+		static readonly UnaryOperatorMethod[] unaryPlusOperators = Lift(
+			new LambdaUnaryOperatorMethod<int>(i => +i),
+			new LambdaUnaryOperatorMethod<uint>(i => +i),
+			new LambdaUnaryOperatorMethod<long>(i => +i),
+			new LambdaUnaryOperatorMethod<ulong>(i => +i),
+			new LambdaUnaryOperatorMethod<float>(i => +i),
+			new LambdaUnaryOperatorMethod<double>(i => +i),
+			new LambdaUnaryOperatorMethod<decimal>(i => +i)
+		);
+		
+		// C# 4.0 spec: §7.7.2 Unary minus operator
+		static readonly UnaryOperatorMethod[] uncheckedUnaryMinusOperators = Lift(
+			new LambdaUnaryOperatorMethod<int>(i => unchecked(-i)),
+			new LambdaUnaryOperatorMethod<long>(i => unchecked(-i)),
+			new LambdaUnaryOperatorMethod<float>(i => -i),
+			new LambdaUnaryOperatorMethod<double>(i => -i),
+			new LambdaUnaryOperatorMethod<decimal>(i => -i)
+		);
+		static readonly UnaryOperatorMethod[] checkedUnaryMinusOperators = Lift(
+			new LambdaUnaryOperatorMethod<int>(i => checked(-i)),
+			new LambdaUnaryOperatorMethod<long>(i => checked(-i)),
+			new LambdaUnaryOperatorMethod<float>(i => -i),
+			new LambdaUnaryOperatorMethod<double>(i => -i),
+			new LambdaUnaryOperatorMethod<decimal>(i => -i)
+		);
+		
+		// C# 4.0 spec: §7.7.3 Logical negation operator
+		static readonly UnaryOperatorMethod[] logicalNegationOperator = Lift(new LambdaUnaryOperatorMethod<bool>(b => !b));
+		
+		// C# 4.0 spec: §7.7.4 Bitwise complement operator
+		static readonly UnaryOperatorMethod[] bitwiseComplementOperators = Lift(
+			new LambdaUnaryOperatorMethod<int>(i => ~i),
+			new LambdaUnaryOperatorMethod<uint>(i => ~i),
+			new LambdaUnaryOperatorMethod<long>(i => ~i),
+			new LambdaUnaryOperatorMethod<ulong>(i => ~i)
+		);
+		#endregion
+		
+		#region ResolveCast
+		public ResolveResult ResolveCast(IType targetType, ResolveResult expression)
+		{
+			if (expression.IsError)
+				return new ErrorResolveResult(targetType);
+			
+			// C# 4.0 spec: §7.7.6 Cast expressions
+			if (expression.IsCompileTimeConstant) {
+				TypeCode code = ReflectionHelper.GetTypeCode(targetType);
+				if (code >= TypeCode.Boolean && code <= TypeCode.Decimal) {
+					try {
+						return new ConstantResolveResult(targetType, Convert.ChangeType(expression.ConstantValue, code, CultureInfo.InvariantCulture));
+					} catch (InvalidCastException) {
+						return new ErrorResolveResult(targetType);
+					}
+				} else if (code == TypeCode.String) {
+					if (expression.ConstantValue == null || expression.ConstantValue is string)
+						return new ConstantResolveResult(targetType, expression.ConstantValue);
+					else
+						return new ErrorResolveResult(targetType);
+				} else if (targetType.IsEnum()) {
+					throw new NotImplementedException();
+				}
+			}
+			return new ResolveResult(targetType);
+		}
+		#endregion
+	}
+}

ICSharpCode.NRefactory/CSharp/Resolver/ConstantResolveResult.cs

@@ -1,22 +1,29 @@
-
+// Copyright (c) 2010 AlphaSierraPapa for the SharpDevelop Team (for details please see \doc\copyright.txt)
+// This code is distributed under MIT X11 license (for details please see \doc\license.txt)
+
 using System;
 using ICSharpCode.NRefactory.TypeSystem;
 
 namespace ICSharpCode.NRefactory.CSharp.Resolver
 {
-	public class ConstantResolveResult
+	/// <summary>
+	/// ResolveResult representing a compile-time constant.
+	/// </summary>
+	public class ConstantResolveResult : ResolveResult
 	{
-		public IType Type { get; set; }
-		public object Value { get; set; }
+		object constantValue;
 		
-		public ConstantResolveResult(IType type, object value)
+		public ConstantResolveResult(IType type, object constantValue) : base(type)
 		{
-			if (type == null)
-				throw new ArgumentNullException("type");
-			if (value == null)
-				throw new ArgumentNullException("value");
-			this.Type = type;
-			this.Value = value;
+			this.constantValue = constantValue;
+		}
+		
+		public override bool IsCompileTimeConstant {
+			get { return true; }
+		}
+		
+		public override object ConstantValue {
+			get { return constantValue; }
 		}
 	}
 }

ICSharpCode.NRefactory/CSharp/Resolver/Conversions.cs

@@ -26,12 +26,11 @@ namespace ICSharpCode.NRefactory.CSharp.Resolver
 		}
 		
 		#region ImplicitConversion
-		public bool ImplicitConversion(ConstantResolveResult resolveResult, IType toType)
+		public bool ImplicitConversion(ResolveResult resolveResult, IType toType)
 		{
 			if (resolveResult == null)
 				throw new ArgumentNullException("resolveResult");
-			ConstantResolveResult crr = resolveResult as ConstantResolveResult;
-			if (crr != null && (ImplicitEnumerationConversion(crr, toType) || ImplicitConstantExpressionConversion(crr, toType)))
+			if (resolveResult.IsCompileTimeConstant && (ImplicitEnumerationConversion(resolveResult, toType) || ImplicitConstantExpressionConversion(resolveResult, toType)))
 				return true;
 			return ImplicitConversion(resolveResult.Type, toType);
 		}
@@ -126,14 +125,13 @@ namespace ICSharpCode.NRefactory.CSharp.Resolver
 		#endregion
 		
 		#region ImplicitEnumerationConversion
-		bool ImplicitEnumerationConversion(ConstantResolveResult rr, IType toType)
+		bool ImplicitEnumerationConversion(ResolveResult rr, IType toType)
 		{
 			// C# 4.0 spec: §6.1.3
 			TypeCode constantType = ReflectionHelper.GetTypeCode(rr.Type);
-			if (constantType >= TypeCode.SByte && constantType <= TypeCode.Decimal && Convert.ToDecimal(rr.Value) == 0) {
-				toType = UnpackNullable(toType) ?? toType;
-				ITypeDefinition toDef = toType.GetDefinition();
-				return toDef.ClassType == ClassType.Enum;
+			if (constantType >= TypeCode.SByte && constantType <= TypeCode.Decimal && Convert.ToDecimal(rr.ConstantValue) == 0) {
+				toType = NullableType.GetUnderlyingType(toType) ?? toType;
+				return toType.IsEnum();
 			}
 			return false;
 		}
@@ -143,30 +141,21 @@ namespace ICSharpCode.NRefactory.CSharp.Resolver
 		bool ImplicitNullableConversion(IType fromType, IType toType)
 		{
 			// C# 4.0 spec: §6.1.4
-			IType t = UnpackNullable(toType);
+			IType t = NullableType.GetUnderlyingType(toType);
 			if (t != null) {
-				IType s = UnpackNullable(fromType) ?? fromType;
+				IType s = NullableType.GetUnderlyingType(fromType) ?? fromType;
 				return IdentityConversion(s, t) || ImplicitNumericConversion(s, t);
 			} else {
 				return false;
 			}
 		}
-		
-		static IType UnpackNullable(IType type)
-		{
-			ParameterizedType pt = type as ParameterizedType;
-			if (pt != null && pt.TypeArguments.Count == 1 && pt.FullName == "System.Nullable")
-				return pt.TypeArguments[0];
-			else
-				return null;
-		}
 		#endregion
 		
 		#region NullLiteralConversion
 		bool NullLiteralConversion(IType fromType, IType toType)
 		{
 			// C# 4.0 spec: §6.1.5
-			return fromType == SharedTypes.Null && (UnpackNullable(toType) != null);
+			return fromType == SharedTypes.Null && NullableType.IsNullable(toType);
 			// This function only handles the conversion from the null literal to nullable value types,
 			// reference types are handled by ImplicitReferenceConversion instead.
 		}
@@ -271,7 +260,7 @@ namespace ICSharpCode.NRefactory.CSharp.Resolver
 		bool BoxingConversion(IType fromType, IType toType)
 		{
 			// C# 4.0 spec: §6.1.7
-			fromType = UnpackNullable(fromType) ?? fromType;
+			fromType = NullableType.GetUnderlyingType(fromType) ?? fromType;
 			return fromType.IsReferenceType == false && toType.IsReferenceType == true && IsSubtypeOf(fromType, toType);
 		}
 		#endregion
@@ -285,16 +274,16 @@ namespace ICSharpCode.NRefactory.CSharp.Resolver
 		#endregion
 		
 		#region ImplicitConstantExpressionConversion
-		bool ImplicitConstantExpressionConversion(ConstantResolveResult rr, IType toType)
+		bool ImplicitConstantExpressionConversion(ResolveResult rr, IType toType)
 		{
 			// C# 4.0 spec: §6.1.9
 			TypeCode fromTypeCode = ReflectionHelper.GetTypeCode(rr.Type);
-			TypeCode toTypeCode = ReflectionHelper.GetTypeCode(UnpackNullable(toType) ?? toType);
+			TypeCode toTypeCode = ReflectionHelper.GetTypeCode(NullableType.GetUnderlyingType(toType) ?? toType);
 			if (fromTypeCode == TypeCode.Int64) {
-				long val = (long)rr.Value;
+				long val = (long)rr.ConstantValue;
 				return val >= 0 && toTypeCode == TypeCode.UInt64;
 			} else if (fromTypeCode == TypeCode.Int32) {
-				int val = (int)rr.Value;
+				int val = (int)rr.ConstantValue;
 				switch (toTypeCode) {
 					case TypeCode.SByte:
 						return val >= SByte.MinValue && val <= SByte.MaxValue;
@@ -321,10 +310,10 @@ namespace ICSharpCode.NRefactory.CSharp.Resolver
 		/// Gets the better conversion (C# 4.0 spec, §7.5.3.3)
 		/// </summary>
 		/// <returns>0 = neither is better; 1 = t1 is better; 2 = t2 is better</returns>
-		public int BetterConversion(ConstantResolveResult rr, IType t1, IType t2)
+		public int BetterConversion(ResolveResult resolveResult, IType t1, IType t2)
 		{
 			// TODO: implement the special logic for anonymous functions
-			return BetterConversion(rr.Type, t1, t2);
+			return BetterConversion(resolveResult.Type, t1, t2);
 		}
 		
 		/// <summary>

ICSharpCode.NRefactory/CSharp/Resolver/ErrorResolveResult.cs

@@ -0,0 +1,22 @@
+// Copyright (c) 2010 AlphaSierraPapa for the SharpDevelop Team (for details please see \doc\copyright.txt)
+// This code is distributed under MIT X11 license (for details please see \doc\license.txt)
+
+using System;
+using ICSharpCode.NRefactory.TypeSystem;
+
+namespace ICSharpCode.NRefactory.CSharp.Resolver
+{
+	/// <summary>
+	/// Represents a resolve error.
+	/// </summary>
+	public class ErrorResolveResult : ResolveResult
+	{
+		public ErrorResolveResult(IType type) : base(type)
+		{
+		}
+		
+		public override bool IsError {
+			get { return true; }
+		}
+	}
+}

ICSharpCode.NRefactory/CSharp/Resolver/ResolveResult.cs

@@ -0,0 +1,40 @@
+// Copyright (c) 2010 AlphaSierraPapa for the SharpDevelop Team (for details please see \doc\copyright.txt)
+// This code is distributed under MIT X11 license (for details please see \doc\license.txt)
+
+using System;
+using ICSharpCode.NRefactory.TypeSystem;
+using ICSharpCode.NRefactory.TypeSystem.Implementation;
+
+namespace ICSharpCode.NRefactory.CSharp.Resolver
+{
+	/// <summary>
+	/// Represents the result of resolving an expression.
+	/// </summary>
+	public class ResolveResult
+	{
+		IType type;
+		
+		public ResolveResult(IType type)
+		{
+			if (type == null)
+				throw new ArgumentNullException("type");
+			this.type = type;
+		}
+		
+		public IType Type {
+			get { return type; }
+		}
+		
+		public virtual bool IsCompileTimeConstant {
+			get { return false; }
+		}
+		
+		public virtual object ConstantValue {
+			get { return null; }
+		}
+		
+		public virtual bool IsError {
+			get { return false; }
+		}
+	}
+}

ICSharpCode.NRefactory/ICSharpCode.NRefactory.csproj

@@ -141,6 +141,9 @@
     <Compile Include="CSharp\Parser\mcs\roottypes.cs" />
     <Compile Include="CSharp\Resolver\ConstantResolveResult.cs" />
     <Compile Include="CSharp\Resolver\Conversions.cs" />
+    <Compile Include="CSharp\Resolver\CSharpResolver.cs" />
+    <Compile Include="CSharp\Resolver\ErrorResolveResult.cs" />
+    <Compile Include="CSharp\Resolver\ResolveResult.cs" />
     <Compile Include="Properties\AssemblyInfo.cs" />
     <Compile Include="TypeSystem\Accessibility.cs" />
     <Compile Include="TypeSystem\AmbiguousType.cs" />
@@ -198,6 +201,7 @@
     <Compile Include="TypeSystem\ITypeParameter.cs" />
     <Compile Include="TypeSystem\ITypeReference.cs" />
     <Compile Include="TypeSystem\ITypeResolveContext.cs" />
+    <Compile Include="TypeSystem\NullableType.cs" />
     <Compile Include="TypeSystem\ParameterizedType.cs" />
     <Compile Include="TypeSystem\TypeVisitor.cs" />
     <Compile Include="TypeSystem\IVariable.cs" />

ICSharpCode.NRefactory/TypeSystem/ExtensionMethods.cs

@@ -13,6 +13,7 @@ namespace ICSharpCode.NRefactory.TypeSystem
 	/// </summary>
 	public static class ExtensionMethods
 	{
+		#region GetAllBaseTypes
 		/// <summary>
 		/// Gets all base types.
 		/// </summary>
@@ -52,5 +53,52 @@ namespace ICSharpCode.NRefactory.TypeSystem
 			if (def != null)
 				activeTypeDefinitions.Pop();
 		}
+		#endregion
+		
+		#region IsOpen / IsUnbound
+		sealed class TypeClassificationVisitor : TypeVisitor
+		{
+			internal bool isOpen;
+			
+			public override IType VisitTypeParameter(ITypeParameter type)
+			{
+				isOpen = true;
+				return base.VisitTypeParameter(type);
+			}
+		}
+		
+		/// <summary>
+		/// Gets whether the type is an open type (contains type parameters).
+		/// </summary>
+		public static bool IsOpen(this IType type)
+		{
+			if (type == null)
+				throw new ArgumentNullException("type");
+			TypeClassificationVisitor v = new TypeClassificationVisitor();
+			type.AcceptVisitor(v);
+			return v.isOpen;
+		}
+		
+		/// <summary>
+		/// Gets whether the type is unbound.
+		/// </summary>
+		public static bool IsUnbound(this IType type)
+		{
+			if (type == null)
+				throw new ArgumentNullException("type");
+			return type is ITypeDefinition && type.TypeParameterCount > 0;
+		}
+		
+		/// <summary>
+		/// Gets whether the type is an enumeration type.
+		/// </summary>
+		public static bool IsEnum(this IType type)
+		{
+			if (type == null)
+				throw new ArgumentNullException("type");
+			ITypeDefinition def = type.GetDefinition();
+			return def != null && def.ClassType == ClassType.Enum;
+		}
+		#endregion
 	}
 }

ICSharpCode.NRefactory/TypeSystem/NullableType.cs

@@ -0,0 +1,62 @@
+// Copyright (c) 2010 AlphaSierraPapa for the SharpDevelop Team (for details please see \doc\copyright.txt)
+// This code is distributed under MIT X11 license (for details please see \doc\license.txt)
+
+using System;
+using ICSharpCode.NRefactory.TypeSystem.Implementation;
+
+namespace ICSharpCode.NRefactory.TypeSystem
+{
+	/// <summary>
+	/// Static helper methods for working with nullable types.
+	/// </summary>
+	public static class NullableType
+	{
+		/// <summary>
+		/// Gets whether the specified type is a nullable type.
+		/// </summary>
+		public static bool IsNullable(IType type)
+		{
+			return GetUnderlyingType(type) != null;
+		}
+		
+		/// <summary>
+		/// Returns the element type, if <paramref name="type"/> is a nullable type.
+		/// Otherwise, returns null.
+		/// </summary>
+		public static IType GetUnderlyingType(IType type)
+		{
+			ParameterizedType pt = type as ParameterizedType;
+			if (pt != null && pt.TypeArguments.Count == 1 && pt.FullName == "System.Nullable")
+				return pt.TypeArguments[0];
+			else
+				return null;
+		}
+		
+		/// <summary>
+		/// Creates a nullable type.
+		/// </summary>
+		public static IType Create(IType elementType, ITypeResolveContext context)
+		{
+			if (elementType == null)
+				throw new ArgumentNullException("elementType");
+			if (context == null)
+				throw new ArgumentNullException("context");
+			
+			ITypeDefinition nullable = context.GetClass("System.Nullable", 1, StringComparer.Ordinal);
+			if (nullable != null)
+				return new ParameterizedType(nullable, new [] { elementType });
+			else
+				return SharedTypes.UnknownType;
+		}
+		
+		static readonly ITypeReference NullableReference = new GetClassTypeReference("System.Nullable", 1);
+		
+		/// <summary>
+		/// Creates a nullable type reference.
+		/// </summary>
+		public static ITypeReference Create(ITypeReference elementType)
+		{
+			return new ParameterizedTypeReference(NullableReference, new [] { elementType });
+		}
+	}
+}

NRefactory.sln

@@ -1,7 +1,7 @@
 
 Microsoft Visual Studio Solution File, Format Version 11.00
 # Visual Studio 2010
-# SharpDevelop 4.0.0.6721
+# SharpDevelop 4.0.0.6745
 Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "Solution Items", "Solution Items", "{DC98210E-1646-483B-819A-2BB8272461E4}"
 	ProjectSection(SolutionItems) = postProject
 		README = README