Index: TypeSystemServices.cs
===================================================================
--- TypeSystemServices.cs	(revision 1439)
+++ TypeSystemServices.cs	(working copy)
@@ -1,1167 +1,1173 @@
-#region license
-// Copyright (c) 2004, Rodrigo B. de Oliveira (rbo@acm.org)
-// All rights reserved.
-// 
-// Redistribution and use in source and binary forms, with or without modification,
-// are permitted provided that the following conditions are met:
-// 
-//     * Redistributions of source code must retain the above copyright notice,
-//     this list of conditions and the following disclaimer.
-//     * Redistributions in binary form must reproduce the above copyright notice,
-//     this list of conditions and the following disclaimer in the documentation
-//     and/or other materials provided with the distribution.
-//     * Neither the name of Rodrigo B. de Oliveira nor the names of its
-//     contributors may be used to endorse or promote products derived from this
-//     software without specific prior written permission.
-// 
-// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
-// ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
-// WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
-// DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE
-// FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
-// DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
-// SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
-// CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
-// OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
-// THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
-#endregion
-
-namespace Boo.Lang.Compiler.TypeSystem
-{
-	using System;
-	using System.Diagnostics;
-	using System.Reflection;
-	using System.Text;
-	using Boo.Lang.Compiler;	
-	using Boo.Lang.Compiler.Ast;
-
-	public class TypeSystemServices
-	{			
-		public DuckTypeImpl DuckType;
-		
-		public ExternalType ExceptionType;
-		
-		public ExternalType ApplicationExceptionType;
-		
-		public ExternalType MulticastDelegateType;
-		
-		public ExternalType DelegateType;
-		
-		public ExternalType IntPtrType;
-		
-		public ExternalType ObjectType;
-		
-		public ExternalType ValueTypeType;
-		
-		public ExternalType EnumType;
-		
-		public ExternalType RegexType;
-		
-		public ExternalType ArrayType;
-		
-		public ExternalType TypeType;
-		
-		public IType ObjectArrayType;
-	
-		public ExternalType VoidType;
-		
-		public ExternalType StringType;
-		
-		public ExternalType BoolType;
-		
-		public ExternalType CharType;
-		
-		public ExternalType SByteType;
-		
-		public ExternalType ByteType;
-		
-		public ExternalType ShortType;
-		
-		public ExternalType UShortType;
-		
-		public ExternalType IntType;
-		
-		public ExternalType UIntType;
-		
-		public ExternalType LongType;
-		
-		public ExternalType ULongType;
-		
-		public ExternalType SingleType;
-		
-		public ExternalType DoubleType;
-		
-		public ExternalType DecimalType;
-		
-		public ExternalType TimeSpanType;
-		
-		public ExternalType DateTimeType;
-		
-		public ExternalType RuntimeServicesType;
-		
-		public ExternalType BuiltinsType;
-		
-		public ExternalType ListType;
-		
-		public ExternalType HashType;
-		
-		public ExternalType ICallableType;
-		
-		public ExternalType IEnumerableType;
-		
-		public ExternalType IEnumeratorType;
-		
-		public ExternalType ICollectionType;
-		
-		public ExternalType IListType;
-		
-		public ExternalType IDictionaryType;
-		
-		System.Collections.Hashtable _primitives = new System.Collections.Hashtable();
-		
-		System.Collections.Hashtable _entityCache = new System.Collections.Hashtable();
-		
-		System.Collections.Hashtable _arrayCache = new System.Collections.Hashtable();
-		
-		System.Collections.Hashtable _anonymousCallableTypes = new System.Collections.Hashtable();
-		
-		public static readonly IType ErrorEntity = Boo.Lang.Compiler.TypeSystem.Error.Default;
-		
-		public readonly BooCodeBuilder CodeBuilder;
-		
-		StringBuilder _buffer = new StringBuilder();
-		
-		Boo.Lang.Compiler.Ast.Module _anonymousTypesModule;
-		
-		CompilerContext _context;
-		
-		public TypeSystemServices() : this(new CompilerContext())
-		{
-		}
-		
-		public TypeSystemServices(CompilerContext context)		
-		{			
-			if (null == context)
-			{
-				throw new ArgumentNullException("context");
-			}
-			
-			_context = context;
-
-			CodeBuilder = new BooCodeBuilder(this);			
-			
-			Cache(typeof(Boo.Lang.Builtins.duck), DuckType = new DuckTypeImpl(this));
-			Cache(VoidType = new VoidTypeImpl(this));
-			Cache(ObjectType = new ExternalType(this, Types.Object));
-			Cache(RegexType = new ExternalType(this, Types.Regex));
-			Cache(ValueTypeType = new ExternalType(this, typeof(System.ValueType)));
-			Cache(EnumType = new ExternalType(this, typeof(System.Enum)));
-			Cache(ArrayType = new ExternalType(this, Types.Array));
-			Cache(TypeType = new ExternalType(this, Types.Type));
-			Cache(StringType = new ExternalType(this, Types.String));
-			Cache(BoolType = new ExternalType(this, Types.Bool));
-			Cache(SByteType = new ExternalType(this, Types.SByte));
-			Cache(CharType = new ExternalType(this, Types.Char));
-			Cache(ShortType = new ExternalType(this, Types.Short));
-			Cache(IntType = new ExternalType(this, Types.Int));
-			Cache(LongType = new ExternalType(this, Types.Long));
-			Cache(ByteType = new ExternalType(this, Types.Byte));
-			Cache(UShortType = new ExternalType(this, Types.UShort));
-			Cache(UIntType = new ExternalType(this, Types.UInt));
-			Cache(ULongType = new ExternalType(this, Types.ULong));
-			Cache(SingleType = new ExternalType(this, Types.Single));
-			Cache(DoubleType = new ExternalType(this, Types.Double));
-			Cache(DecimalType = new ExternalType(this, Types.Decimal));
-			Cache(TimeSpanType = new ExternalType(this, Types.TimeSpan));
-			Cache(DateTimeType = new ExternalType(this, Types.DateTime));
-			Cache(RuntimeServicesType = new ExternalType(this, Types.RuntimeServices));
-			Cache(BuiltinsType = new ExternalType(this, Types.Builtins));
-			Cache(ListType = new ExternalType(this, Types.List));
-			Cache(HashType = new ExternalType(this, Types.Hash));
-			Cache(ICallableType = new ExternalType(this, Types.ICallable));
-			Cache(IEnumerableType = new ExternalType(this, Types.IEnumerable));
-			Cache(IEnumeratorType = new ExternalType(this, typeof(System.Collections.IEnumerator)));
-			Cache(ICollectionType = new ExternalType(this, Types.ICollection));
-			Cache(IListType = new ExternalType(this, Types.IList));
-			Cache(IDictionaryType = new ExternalType(this, Types.IDictionary));
-			Cache(ApplicationExceptionType = new ExternalType(this, Types.ApplicationException));
-			Cache(ExceptionType = new ExternalType(this, Types.Exception));
-			Cache(IntPtrType = new ExternalType(this, Types.IntPtr));
-			Cache(MulticastDelegateType = new ExternalType(this, Types.MulticastDelegate));
-			Cache(DelegateType = new ExternalType(this, Types.Delegate));
-			
-			ObjectArrayType = GetArrayType(ObjectType);
-			
-			PreparePrimitives();
-		}
-		
-		public CompilerContext Context
-		{
-			get
-			{
-				return _context;
-			}
-		}
-		
-		public IType GetMostGenericType(IType current, IType candidate)
-		{
-			if (current.IsAssignableFrom(candidate))
-			{
-				return current;
-			}
-			
-			if (candidate.IsAssignableFrom(current))
-			{
-				return candidate;
-			}
-			
-			if (IsNumberOrBool(current) && IsNumberOrBool(candidate))
-			{
-				return GetPromotedNumberType(current, candidate);
-			}
-			
-			if (IsCallableType(current) && IsCallableType(candidate))
-			{
-				return ICallableType;
-			}
-			
-			IType obj = ObjectType;			
-			if (current.IsClass && candidate.IsClass)
-			{
-				if (current ==  obj || candidate == obj)
-				{
-					return obj;
-				}
-				if (current.GetTypeDepth() < candidate.GetTypeDepth())
-				{
-					return GetMostGenericType(current.BaseType, candidate);
-				}			
-				return GetMostGenericType(current, candidate.BaseType);
-			}			
-			return obj;
-		}
-		
-		public IType GetPromotedNumberType(IType left, IType right)
-		{
-			if (left == DecimalType ||
-				right == DecimalType)
-			{
-				return DecimalType;
-			}
-			if (left == DoubleType ||
-				right == DoubleType)
-			{
-				return DoubleType;
-			}
-			if (left == SingleType ||
-				right == SingleType)
-			{
-				return SingleType;
-			}
-			if (left == ULongType)
-			{
-				if (right == SByteType ||
-				    right == ShortType ||
-				    right == IntType ||
-				    right == LongType)
-				{
-					// This is against the C# spec but allows expressions like:
-					//    ulong x = 4
-					//    y = x + 1
-					// y will be long.
-					// C# disallows mixing ulongs and signed numbers
-					// but in the above case it promotes the constant to ulong
-					// and the result is ulong.
-					// Since its too late here to promote the constant,
-					// maybe we should return LongType.  I didn't chose ULongType
-					// because in other cases <unsigned> <op> <signed> returns <signed>.
-					return LongType;
-				}
-				return ULongType;
-			}
-			if (right == ULongType)
-			{
-				if (left == SByteType ||
-				    left == ShortType ||
-				    left == IntType ||
-				    left == LongType)
-				{
-					// This is against the C# spec but allows expressions like:
-					//    ulong x = 4
-					//    y = 1 + x
-					// y will be long.
-					// C# disallows mixing ulongs and signed numbers
-					// but in the above case it promotes the constant to ulong
-					// and the result is ulong.
-					// Since its too late here to promote the constant,
-					// maybe we should return LongType.  I didn't chose ULongType
-					// because in other cases <signed> <op> <unsigned> returns <signed>.
-					return LongType;
-				}
-				return ULongType;
-			}
-			if (left == LongType ||
-				right == LongType)
-			{
-				return LongType;
-			}
-			if (left == UIntType)
-			{
-				if (right == SByteType ||
-				    right == ShortType ||
-				    right == IntType)
-				{
-					// This is allowed per C# spec and y is long:
-					//    uint x = 4
-					//    y = x + 1
-					// C# promotes <uint> <op> <signed> to <long> also
-					// but in the above case it promotes the constant to uint first
-					// and the result of "x + 1" is uint.
-					// Since its too late here to promote the constant,
-					// "y = x + 1" will be long in boo.
-					return LongType;
-				}
-				return UIntType;
-			}
-			if (right == UIntType)
-			{
-				if (left == SByteType ||
-				    left == ShortType ||
-				    left == IntType)
-				{
-					// This is allowed per C# spec and y is long:
-					//    uint x = 4
-					//    y = 1 + x
-					// C# promotes <signed> <op> <uint> to <long> also
-					// but in the above case it promotes the constant to uint first
-					// and the result of "1 + x" is uint.
-					// Since its too late here to promote the constant,
-					// "y = x + 1" will be long in boo.
-					return LongType;
-				}
-				return UIntType;
-			}
-			if (left == IntType ||
-				right == IntType ||
-				left == ShortType ||
-				right == ShortType ||
-				left == UShortType ||
-				right == UShortType ||
-				left == ByteType ||
-				right == ByteType ||
-				left == SByteType ||
-				right == SByteType)
-			{
-				return IntType;
-			}
-			return left;
-		}
-		
-		public bool IsCallable(IType type)
-		{
-			return (TypeType == type) || IsCallableType(type);
-		}
-		
-		bool IsCallableType(IType type)
-		{			
-			return (ICallableType.IsAssignableFrom(type)) ||
-				(type is Boo.Lang.Compiler.TypeSystem.ICallableType);
-		}
-		
-		public AnonymousCallableType GetCallableType(IMethod method)
-		{
-			CallableSignature signature = new CallableSignature(method);
-			return GetCallableType(signature);
-		}
-		
-		public AnonymousCallableType GetCallableType(CallableSignature signature)
-		{
-			AnonymousCallableType type = (AnonymousCallableType)_anonymousCallableTypes[signature];
-			if (null == type)
-			{
-				type = new AnonymousCallableType(this, signature);
-				_anonymousCallableTypes.Add(signature, type);
-			}
-			return type;
-		}
-		
-		public IType GetConcreteCallableType(Node sourceNode, CallableSignature signature)
-		{
-			AnonymousCallableType type = GetCallableType(signature);
-			return GetConcreteCallableType(sourceNode, type);
-		}
-		
-		public IType GetEnumeratorItemType(IType iteratorType)
-		{
-			if (iteratorType.IsArray)
-			{
-				return ((IArrayType)iteratorType).GetElementType();
-			}
-			else
-			{
-				if (iteratorType.IsClass)
-				{
-					IType enumeratorItemType = GetEnumeratorItemTypeFromAttribute(iteratorType);
-					if (null != enumeratorItemType)
-					{
-						return enumeratorItemType;
-					}
-				}
-			}
-			return ObjectType;
-		}
-		
-		public IType GetExpressionType(Expression node)
-		{			
-			IType type = node.ExpressionType;
-			if (null == type)
-			{
-				throw CompilerErrorFactory.InvalidNode(node);
-			}
-			return type;
-		}
-		
-		public IType GetConcreteExpressionType(Expression expression)
-		{
-			IType type = GetExpressionType(expression);
-			AnonymousCallableType anonymousType = type as AnonymousCallableType;
-			if (null != anonymousType)
-			{
-				IType concreteType = GetConcreteCallableType(expression, anonymousType);
-				expression.ExpressionType = concreteType;
-				return concreteType;
-			}
-			return type;
-		}
-		
-		public void MapToConcreteExpressionTypes(ExpressionCollection items)
-		{
-			foreach (Expression item in items)
-			{
-				GetConcreteExpressionType(item);
-			}
-		}
-		
-		public Boo.Lang.Compiler.Ast.Module GetAnonymousTypesModule()
-		{
-			if (null == _anonymousTypesModule)
-			{
-				_anonymousTypesModule = new Boo.Lang.Compiler.Ast.Module();
-				_anonymousTypesModule.Entity = new ModuleEntity(_context.NameResolutionService, 
-																this,
-																_anonymousTypesModule);
-				_context.CompileUnit.Modules.Add(_anonymousTypesModule);
-			}
-			return _anonymousTypesModule;
-		}
-		
-		public ClassDefinition CreateCallableDefinition(string name)
-		{
-			ClassDefinition cd = new ClassDefinition();
-			cd.BaseTypes.Add(CodeBuilder.CreateTypeReference(this.MulticastDelegateType));
-			cd.BaseTypes.Add(CodeBuilder.CreateTypeReference(this.ICallableType));
-			cd.Name = name;
-			cd.Modifiers = TypeMemberModifiers.Final;
-			cd.Members.Add(CreateCallableConstructor());
-			cd.Members.Add(CreateCallMethod());			
-			cd.Entity = new InternalCallableType(this, cd);
-			return cd;
-		}
-		
-		Method CreateCallMethod()
-		{
-			Method method = new Method("Call");
-			method.Modifiers = TypeMemberModifiers.Public|TypeMemberModifiers.Virtual;
-			method.Parameters.Add(CodeBuilder.CreateParameterDeclaration(1, "args", ObjectArrayType));
-			method.ReturnType = CodeBuilder.CreateTypeReference(ObjectType);
-			method.Entity = new InternalMethod(this, method);
-			return method;
-		}
-		
-		Constructor CreateCallableConstructor()
-		{
-			Constructor constructor = new Constructor();
-			constructor.Modifiers = TypeMemberModifiers.Public;
-			constructor.ImplementationFlags = MethodImplementationFlags.Runtime;
-			constructor.Parameters.Add(
-						CodeBuilder.CreateParameterDeclaration(1, "instance", ObjectType));
-			constructor.Parameters.Add(
-						CodeBuilder.CreateParameterDeclaration(2, "method", IntPtrType));
-			constructor.Entity = new InternalConstructor(this, constructor);						
-			return constructor;
-		}
-		
-		public bool AreTypesRelated(IType lhs, IType rhs)
-		{
-			return lhs.IsAssignableFrom(rhs) ||
-				(lhs.IsInterface && rhs.IsInterface) ||
-				CanBeReachedByDownCastOrPromotion(lhs, rhs);
-		}
-		
-		public bool IsCallableTypeAssignableFrom(ICallableType lhs, IType rhs)
-		{
-			if (lhs == rhs || Null.Default == rhs)
-			{
-				return true;
-			}
-			
-			ICallableType other = rhs as ICallableType;
-			if (null != other)
-			{			
-				CallableSignature lvalue = lhs.GetSignature();
-				CallableSignature rvalue = other.GetSignature(); 
-				if (lvalue == rvalue)
-				{
-					return true;
-				}
-				
-				IParameter[] lparams = lvalue.Parameters;
-				IParameter[] rparams = rvalue.Parameters;
-				if (lparams.Length >= rparams.Length)
-				{
-					for (int i=0; i<rparams.Length; ++i)
-					{
-						IType lparamType = lparams[i].Type;
-						IType rparamType = rparams[i].Type;
-						if (!AreTypesRelated(lparamType, rparamType))
-						{
-							return false;
-						}
-					}
-					
-					if (VoidType != lvalue.ReturnType)
-					{				
-						return AreTypesRelated(lvalue.ReturnType, rvalue.ReturnType);
-					}
-					
-					return true;
-				}
-			}
-			return false;
-		}
-		
-		public static bool CheckOverrideSignature(IMethod impl, IMethod baseMethod)
-		{
-			IParameter[] implParameters = impl.GetParameters();
-			IParameter[] baseParameters = baseMethod.GetParameters();
-			
-			if (implParameters.Length == baseParameters.Length)
-			{
-				for (int i=0; i<implParameters.Length; ++i)
-				{
-					if (implParameters[i].Type != baseParameters[i].Type)
-					{
-						return false;
-					}
-				}
-				return true;
-			}
-			return false;
-		}
-		
-		public bool CanBeReachedByDownCastOrPromotion(IType expectedType, IType actualType)
-		{			
-			if (actualType.IsAssignableFrom(expectedType))
-			{
-				return true;
-			}
-			if (expectedType.IsValueType)
-			{
-				return IsNumber(expectedType) && IsNumber(actualType);
-			}
-			return false;
-		}
-		
-		public bool CanBeExplicitlyCastToInteger(IType type)
-		{
-			return type.IsEnum || type == this.CharType; 
-		}
-		
-		public bool IsIntegerNumber(IType type)
-		{
-			return
-				type == this.ShortType ||
-				type == this.IntType ||
-				type == this.LongType ||
-				type == this.SByteType ||
-				type == this.UShortType ||
-				type == this.UIntType ||				
-				type == this.ULongType ||
-				type == this.ByteType;
-		}
-		
-		public bool IsIntegerOrBool(IType type)	
-		{
-			return BoolType == type || IsIntegerNumber(type);
-		}
-		
-		public bool IsNumberOrBool(IType type)
-		{
-			return BoolType == type || IsNumber(type);
-		}
-		
-		public bool IsNumber(IType type)
-		{
-			return
-				IsPrimitiveNumber(type) ||
-				type == this.DecimalType;
-		}
-		
-		public bool IsPrimitiveNumber(IType type)
-		{
-			return
-				IsIntegerNumber(type) ||
-				type == this.DoubleType ||
-				type == this.SingleType;
-		}
-		
-		public static bool IsUnknown(Expression node)
-		{
-			IType type = node.ExpressionType;
-			if (null != type)
-			{
-				return IsUnknown(type);
-			}
-			return false;
-		}
-		
-		public static bool IsUnknown(IType tag)
-		{
-			return EntityType.Unknown == tag.EntityType;
-		}
-		
-		public static bool IsError(Expression node)
-		{				 
-			IType type = node.ExpressionType;
-			if (null != type)
-			{
-				return IsError(type);
-			}
-			return false;
-		}
-		
-		public static bool IsErrorAny(ExpressionCollection collection)
-		{
-			foreach (Expression n in collection)
-			{
-				if (IsError(n))
-				{
-					return true;
-				}
-			}
-			return false;
-		}
-		
-		public bool IsBuiltin(IEntity tag)
-		{
-			if (EntityType.Method == tag.EntityType)
-			{
-				return BuiltinsType == ((IMethod)tag).DeclaringType;
-			}
-			return false;
-		}		
-		
-		public static bool IsError(IEntity tag)
-		{
-			return EntityType.Error == tag.EntityType;
-		}
-		
-		public static TypeMemberModifiers GetAccess(IAccessibleMember member)
-		{
-			if (member.IsPublic)
-			{
-				return TypeMemberModifiers.Public;
-			}
-			else if (member.IsProtected)
-			{
-				return TypeMemberModifiers.Protected;
-			}
-			return TypeMemberModifiers.Private;
-		}
-		
-		public static IEntity GetEntity(Node node)
-		{
-			if (null == node)
-			{
-				throw new ArgumentNullException("node");
-			}
-			
-			IEntity tag = node.Entity;
-			if (null == tag)
-			{
-				InvalidNode(node);
-			}
-			return tag;
-		}	
-		
-		public static IType GetReferencedType(Expression typeref)
-		{
-			switch (typeref.NodeType)
-			{
-				case NodeType.TypeofExpression:
-				{
-					return GetType(((TypeofExpression)typeref).Type);
-				}
-				case NodeType.ReferenceExpression:
-				case NodeType.MemberReferenceExpression:
-				{
-					return typeref.Entity as IType;					
-				}
-			}
-			return null;
-		}
-		
-		public static IType GetType(Node node)
-		{
-			return ((ITypedEntity)GetEntity(node)).Type;
-		}
-		
-		public IType Map(System.Type type)
-		{				
-			ExternalType tag = (ExternalType)_entityCache[type];
-			if (null == tag)
-			{
-				if (type.IsArray)
-				{
-					return GetArrayType(Map(type.GetElementType()));
-				}				
-				else
-				{
-					if (type.IsSubclassOf(Types.MulticastDelegate))
-					{
-						tag = new ExternalCallableType(this, type);
-					}
-					else
-					{
-						tag = new ExternalType(this, type);
-					}
-				}
-				Cache(tag);
-			}
-			return tag;
-		}
-		
-		public IArrayType GetArrayType(IType elementType)
-		{
-			IArrayType tag = (IArrayType)_arrayCache[elementType];
-			if (null == tag)
-			{
-				tag = new ArrayType(this, elementType);
-				_arrayCache.Add(elementType, tag);
-			}
-			return tag;
-		}
-		
-		public IParameter[] Map(Boo.Lang.Compiler.Ast.ParameterDeclarationCollection parameters)
-		{
-			IParameter[] mapped = new IParameter[parameters.Count];
-			for (int i=0; i<mapped.Length; ++i)
-			{
-				mapped[i] = (IParameter)GetEntity(parameters[i]);
-			}
-			return mapped;
-		}
-		
-		public IParameter[] Map(System.Reflection.ParameterInfo[] parameters)
-		{			
-			IParameter[] mapped = new IParameter[parameters.Length];
-			for (int i=0; i<parameters.Length; ++i)
-			{
-				mapped[i] = new ExternalParameter(this, parameters[i]);
-			}
-			return mapped;
-		}
-		
-		public IConstructor Map(ConstructorInfo constructor)
-		{
-			object key = GetCacheKey(constructor);
-			IConstructor entity = (IConstructor)_entityCache[key];
-			if (null == entity)
-			{
-				entity = new ExternalConstructor(this, constructor);
-				_entityCache[key] = entity;
-			}
-			return entity;
-		}
-		
-		public IMethod Map(MethodInfo method)
-		{
-			object key = GetCacheKey(method);
-			IMethod entity = (IMethod)_entityCache[key];
-			if (null == entity)
-			{
-				entity = new ExternalMethod(this, method);
-				_entityCache[key] = entity;
-			}
-			return entity;
-		}
-		
-		public IEntity Map(System.Reflection.MemberInfo[] info)
-		{
-			if (info.Length > 1)
-			{
-				IEntity[] tags = new IEntity[info.Length];
-				for (int i=0; i<tags.Length; ++i)
-				{
-					tags[i] = Map(info[i]);
-				}
-				return new Ambiguous(tags);
-			}
-			if (info.Length > 0)
-			{
-				return Map(info[0]);
-			}
-			return null;
-		}
-		
-		public IEntity Map(System.Reflection.MemberInfo mi)
-		{
-			IEntity tag = (IEntity)_entityCache[GetCacheKey(mi)];
-			if (null == tag)
-			{			
-				switch (mi.MemberType)
-				{
-					case MemberTypes.Method:
-					{
-						return Map((System.Reflection.MethodInfo)mi);
-					}
-					
-					case MemberTypes.Constructor:
-					{
-						return Map((System.Reflection.ConstructorInfo)mi);
-					}
-					
-					case MemberTypes.Field:
-					{
-						tag = new ExternalField(this, (System.Reflection.FieldInfo)mi);
-						break;
-					}
-					
-					case MemberTypes.Property:
-					{
-						tag = new ExternalProperty(this, (System.Reflection.PropertyInfo)mi);
-						break;
-					}
-					
-					case MemberTypes.Event:
-					{
-						tag = new ExternalEvent(this, (System.Reflection.EventInfo)mi);
-						break;
-					}
-					
-					case MemberTypes.NestedType:
-					{
-						return Map((System.Type)mi);
-					}
-					
-					default:
-					{
-						throw new NotImplementedException(mi.ToString());
-					}
-				}
-				_entityCache.Add(GetCacheKey(mi), tag);
-			}
-			return tag;
-		}
-		
-		public string GetSignature(IMethod method)
-		{
-			return GetSignature(method, true);
-		}
-		
-		public string GetSignature(IMethod method, bool includeFullName)
-		{
-			_buffer.Length = 0;
-			if (includeFullName)
-			{
-				_buffer.Append(method.FullName);
-			}
-			else
-			{
-				_buffer.Append(method.Name);
-			}
-			_buffer.Append("(");
-			
-			IParameter[] parameters = method.GetParameters();
-			for (int i=0; i<parameters.Length; ++i)
-			{
-				if (i > 0) { _buffer.Append(", "); }
-				_buffer.Append(parameters[i].Type.FullName);
-			}
-			_buffer.Append(")");
-			return _buffer.ToString();
-		}
-		
-		public object GetCacheKey(System.Reflection.MemberInfo mi)
-		{
-			return mi;
-		}
-		
-		public IEntity ResolvePrimitive(string name)
-		{
-			return (IEntity)_primitives[name];
-		}
-		
-		public bool IsPrimitive(string name)
-		{
-			return _primitives.ContainsKey(name);
-		}
-		
-		/// <summary>
-		/// checks if the passed type will be equivalente to
-		/// System.Object in runtime (accounting for the presence
-		/// of duck typing).
-		/// </summary>
-		public bool IsSystemObject(IType type)
-		{
-			return type == ObjectType || type == DuckType;
-		}
-		
-		void PreparePrimitives()
-		{
-			AddPrimitiveType("duck", DuckType);
-			AddPrimitiveType("void", VoidType);
-			AddPrimitiveType("bool", BoolType);
-			AddPrimitiveType("char", CharType);
-			AddPrimitiveType("date", DateTimeType);
-			AddPrimitiveType("timespan", TimeSpanType);
-			AddPrimitiveType("string", StringType);
-			AddPrimitiveType("object", ObjectType);
-			AddPrimitiveType("regex", RegexType);
-			AddPrimitiveType("sbyte", SByteType);
-			AddPrimitiveType("byte", ByteType);
-			AddPrimitiveType("short", ShortType);
-			AddPrimitiveType("ushort", UShortType);
-			AddPrimitiveType("int", IntType);
-			AddPrimitiveType("uint", UIntType);
-			AddPrimitiveType("long", LongType);
-			AddPrimitiveType("ulong", ULongType);
-			AddPrimitiveType("single", SingleType);
-			AddPrimitiveType("double", DoubleType);
-			AddPrimitiveType("decimal", DecimalType);
-			AddPrimitiveType("callable", ICallableType);
-			AddBuiltin(BuiltinFunction.Len);
-			AddBuiltin(BuiltinFunction.AddressOf);
-			AddBuiltin(BuiltinFunction.Eval);
-			AddBuiltin(BuiltinFunction.Switch);
-		}
-		
-		void AddPrimitiveType(string name, ExternalType type)
-		{
-			_primitives[name] = type;
-		}
-		
-		void AddBuiltin(BuiltinFunction function)
-		{
-			_primitives[function.Name] = function;
-		}
-		
-		void AddPrimitive(string name, IEntity tag)
-		{
-			_primitives[name] = tag;
-		}
-		
-		void Cache(ExternalType tag)
-		{
-			_entityCache[tag.ActualType] = tag;
-		}
-		
-		void Cache(object key, IType tag)
-		{
-			_entityCache[key] = tag;
-		}
-		
-		Method CreateBeginInvokeMethod(ICallableType anonymousType)
-		{
-			Method method = CodeBuilder.CreateRuntimeMethod("BeginInvoke", Map(typeof(IAsyncResult)),
-												anonymousType.GetSignature().Parameters);
-												
-			int delta=method.Parameters.Count;
-			method.Parameters.Add(
-					CodeBuilder.CreateParameterDeclaration(delta+1, "callback", Map(typeof(AsyncCallback))));
-			method.Parameters.Add(
-					CodeBuilder.CreateParameterDeclaration(delta+1, "asyncState", ObjectType));
-			return method;
-		}
-		
-		Method CreateBeginInvokeOverload(ICallableType anonymousType, Method beginInvoke, out MethodInvocationExpression mie)
-		{
-			InternalMethod beginInvokeEntity = (InternalMethod)beginInvoke.Entity;
-			
-			Method overload = CodeBuilder.CreateMethod("BeginInvoke", Map(typeof(IAsyncResult)),
-										TypeMemberModifiers.Public);
-			CodeBuilder.DeclareParameters(overload, 1, anonymousType.GetSignature().Parameters);
-			
-			mie = CodeBuilder.CreateMethodInvocation(
-						CodeBuilder.CreateSelfReference(beginInvokeEntity.DeclaringType),
-						beginInvokeEntity);
-						
-			foreach (ParameterDeclaration parameter in overload.Parameters)
-			{
-				mie.Arguments.Add(CodeBuilder.CreateReference(parameter));
-			}
-			
-			overload.Body.Add(new ReturnStatement(mie));
-			return overload;
-		}
-		
-		Method CreateBeginInvokeSimplerOverload(ICallableType anonymousType, Method beginInvoke)
-		{
-			MethodInvocationExpression mie;
-			Method overload = CreateBeginInvokeOverload(anonymousType, beginInvoke, out mie);
-			
-			mie.Arguments.Add(CodeBuilder.CreateNullLiteral());
-			mie.Arguments.Add(CodeBuilder.CreateNullLiteral());
-			
-			return overload;
-		}
-		
-		Method CreateBeginInvokeCallbackOnlyOverload(ICallableType anonymousType, Method beginInvoke)
-		{
-			MethodInvocationExpression mie;
-			
-			Method overload = CreateBeginInvokeOverload(anonymousType, beginInvoke, out mie);
-			ParameterDeclaration callback = CodeBuilder.CreateParameterDeclaration(overload.Parameters.Count+1,
-										"callback", Map(typeof(AsyncCallback)));
-			overload.Parameters.Add(callback);
-
-			mie.Arguments.Add(CodeBuilder.CreateReference(callback));			
-			mie.Arguments.Add(CodeBuilder.CreateNullLiteral());
-			
-			return overload;
-		}
-		
-		public Method CreateEndInvokeMethod(ICallableType anonymousType)
-		{
-			CallableSignature signature = anonymousType.GetSignature();
-			Method method = CodeBuilder.CreateRuntimeMethod("EndInvoke", signature.ReturnType);
-			int delta=method.Parameters.Count;
-			method.Parameters.Add(
-				CodeBuilder.CreateParameterDeclaration(delta+1, "result", Map(typeof(IAsyncResult))));
-			return method;
-		}
-		
-		Method CreateInvokeMethod(AnonymousCallableType anonymousType)
-		{
-			CallableSignature signature = anonymousType.GetSignature();
-			return CodeBuilder.CreateRuntimeMethod("Invoke", signature.ReturnType, signature.Parameters);
-		}
-		
-		public IConstructor GetDefaultConstructor(IType type)
-		{
-			IConstructor[] constructors = type.GetConstructors();
-			for (int i=0; i<constructors.Length; ++i)
-			{
-				IConstructor constructor = constructors[i];
-				if (0 == constructor.GetParameters().Length)
-				{
-					return constructor;
-				}
-			}
-			return null;
-		}
-		
-		IType GetExternalEnumeratorItemType(IType iteratorType)
-		{
-			Type type = ((ExternalType)iteratorType).ActualType;
-			EnumeratorItemTypeAttribute attribute = (EnumeratorItemTypeAttribute)System.Attribute.GetCustomAttribute(type, typeof(EnumeratorItemTypeAttribute));
-			if (null != attribute)
-			{
-				return Map(attribute.ItemType);
-			}
-			return null;
-		}
-		
-		IType GetEnumeratorItemTypeFromAttribute(IType iteratorType)
-		{
-			AbstractInternalType internalType = iteratorType as AbstractInternalType;
-			if (null == internalType)
-			{
-				return GetExternalEnumeratorItemType(iteratorType);
-			}
-			
-			IType enumeratorItemTypeAttribute = Map(typeof(EnumeratorItemTypeAttribute));
-			foreach (Boo.Lang.Compiler.Ast.Attribute attribute in internalType.TypeDefinition.Attributes)
-			{				
-				IConstructor constructor = GetEntity(attribute) as IConstructor;
-				if (null != constructor)
-				{
-					if (constructor.DeclaringType == enumeratorItemTypeAttribute)
-					{
-						return GetType(attribute.Arguments[0]);
-					}
-				}
-			}
-			return null;
-		}
-		
-		public virtual IType GetConcreteCallableType(Node sourceNode, AnonymousCallableType anonymousType)
-		{
-			if (null == anonymousType.ConcreteType)
-			{
-				anonymousType.ConcreteType = CreateConcreteCallableType(sourceNode, anonymousType);
-			}
-			return anonymousType.ConcreteType;
-		}
-		
-		protected virtual IType CreateConcreteCallableType(Node sourceNode, AnonymousCallableType anonymousType)
-		{
-			Boo.Lang.Compiler.Ast.Module module = GetAnonymousTypesModule();
-			
-			string name = string.Format("___callable{0}", module.Members.Count);
-			ClassDefinition cd = CreateCallableDefinition(name);
-			cd.Modifiers |= TypeMemberModifiers.Public;
-			cd.LexicalInfo = sourceNode.LexicalInfo;
-			
-			cd.Members.Add(CreateInvokeMethod(anonymousType));
-			
-			Method beginInvoke = CreateBeginInvokeMethod(anonymousType);
-			cd.Members.Add(beginInvoke);
-			cd.Members.Add(CreateBeginInvokeCallbackOnlyOverload(anonymousType, beginInvoke));
-			cd.Members.Add(CreateBeginInvokeSimplerOverload(anonymousType, beginInvoke));
-			
-			cd.Members.Add(CreateEndInvokeMethod(anonymousType));
-			_anonymousTypesModule.Members.Add(cd);
-			
-			return (IType)cd.Entity;
-		}
-		
-		private static void InvalidNode(Node node)
-		{
-			throw CompilerErrorFactory.InvalidNode(node);
-		}
-
-		public class DuckTypeImpl : ExternalType
-		{	
-			public DuckTypeImpl(TypeSystemServices typeSystemServices) : 
-				base(typeSystemServices, Types.Object)
-			{
-			}
-		}	
-		
-		#region VoidTypeImpl
-		class VoidTypeImpl : ExternalType
-		{			
-			internal VoidTypeImpl(TypeSystemServices manager) : base(manager, Types.Void)
-			{				
-			}		
-			
-			override public bool Resolve(Boo.Lang.List targetList, string name, EntityType flags)
-			{	
-				return false;
-			}	
-			
-			override public bool IsSubclassOf(IType other)
-			{
-				return false;
-			}
-			
-			override public bool IsAssignableFrom(IType other)
-			{
-				return false;
-			}
-		}
-
-		#endregion
-	}
-}
+#region license
+// Copyright (c) 2004, Rodrigo B. de Oliveira (rbo@acm.org)
+// All rights reserved.
+// 
+// Redistribution and use in source and binary forms, with or without modification,
+// are permitted provided that the following conditions are met:
+// 
+//     * Redistributions of source code must retain the above copyright notice,
+//     this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above copyright notice,
+//     this list of conditions and the following disclaimer in the documentation
+//     and/or other materials provided with the distribution.
+//     * Neither the name of Rodrigo B. de Oliveira nor the names of its
+//     contributors may be used to endorse or promote products derived from this
+//     software without specific prior written permission.
+// 
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+// ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+// WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+// DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE
+// FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+// DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+// SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+// CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+// OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+// THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+#endregion
+
+namespace Boo.Lang.Compiler.TypeSystem
+{
+	using System;
+	using System.Diagnostics;
+	using System.Reflection;
+	using System.Text;
+	using Boo.Lang.Compiler;	
+	using Boo.Lang.Compiler.Ast;
+
+	public class TypeSystemServices
+	{			
+		public DuckTypeImpl DuckType;
+		
+		public ExternalType ExceptionType;
+		
+		public ExternalType ApplicationExceptionType;
+		
+		public ExternalType MulticastDelegateType;
+		
+		public ExternalType DelegateType;
+		
+		public ExternalType IntPtrType;
+		
+		public ExternalType ObjectType;
+		
+		public ExternalType ValueTypeType;
+		
+		public ExternalType EnumType;
+		
+		public ExternalType RegexType;
+		
+		public ExternalType ArrayType;
+		
+		public ExternalType TypeType;
+		
+		public IType ObjectArrayType;
+	
+		public ExternalType VoidType;
+		
+		public ExternalType StringType;
+		
+		public ExternalType BoolType;
+		
+		public ExternalType CharType;
+		
+		public ExternalType SByteType;
+		
+		public ExternalType ByteType;
+		
+		public ExternalType ShortType;
+		
+		public ExternalType UShortType;
+		
+		public ExternalType IntType;
+		
+		public ExternalType UIntType;
+		
+		public ExternalType LongType;
+		
+		public ExternalType ULongType;
+		
+		public ExternalType SingleType;
+		
+		public ExternalType DoubleType;
+		
+		public ExternalType DecimalType;
+		
+		public ExternalType TimeSpanType;
+		
+		public ExternalType DateTimeType;
+		
+		public ExternalType RuntimeServicesType;
+		
+		public ExternalType BuiltinsType;
+		
+		public ExternalType ListType;
+		
+		public ExternalType HashType;
+		
+		public ExternalType ICallableType;
+		
+		public ExternalType IEnumerableType;
+		
+		public ExternalType IEnumeratorType;
+		
+		public ExternalType ICollectionType;
+		
+		public ExternalType IListType;
+		
+		public ExternalType IDictionaryType;
+		
+		System.Collections.Hashtable _primitives = new System.Collections.Hashtable();
+		
+		System.Collections.Hashtable _entityCache = new System.Collections.Hashtable();
+		
+		System.Collections.Hashtable _arrayCache = new System.Collections.Hashtable();
+		
+		System.Collections.Hashtable _anonymousCallableTypes = new System.Collections.Hashtable();
+		
+		public static readonly IType ErrorEntity = Boo.Lang.Compiler.TypeSystem.Error.Default;
+		
+		public readonly BooCodeBuilder CodeBuilder;
+		
+		StringBuilder _buffer = new StringBuilder();
+		
+		Boo.Lang.Compiler.Ast.Module _anonymousTypesModule;
+		
+		CompilerContext _context;
+		
+		public TypeSystemServices() : this(new CompilerContext())
+		{
+		}
+		
+		public TypeSystemServices(CompilerContext context)		
+		{			
+			if (null == context)
+			{
+				throw new ArgumentNullException("context");
+			}
+			
+			_context = context;
+
+			CodeBuilder = new BooCodeBuilder(this);			
+			
+			Cache(typeof(Boo.Lang.Builtins.duck), DuckType = new DuckTypeImpl(this));
+			Cache(VoidType = new VoidTypeImpl(this));
+			Cache(ObjectType = new ExternalType(this, Types.Object));
+			Cache(RegexType = new ExternalType(this, Types.Regex));
+			Cache(ValueTypeType = new ExternalType(this, typeof(System.ValueType)));
+			Cache(EnumType = new ExternalType(this, typeof(System.Enum)));
+			Cache(ArrayType = new ExternalType(this, Types.Array));
+			Cache(TypeType = new ExternalType(this, Types.Type));
+			Cache(StringType = new ExternalType(this, Types.String));
+			Cache(BoolType = new ExternalType(this, Types.Bool));
+			Cache(SByteType = new ExternalType(this, Types.SByte));
+			Cache(CharType = new ExternalType(this, Types.Char));
+			Cache(ShortType = new ExternalType(this, Types.Short));
+			Cache(IntType = new ExternalType(this, Types.Int));
+			Cache(LongType = new ExternalType(this, Types.Long));
+			Cache(ByteType = new ExternalType(this, Types.Byte));
+			Cache(UShortType = new ExternalType(this, Types.UShort));
+			Cache(UIntType = new ExternalType(this, Types.UInt));
+			Cache(ULongType = new ExternalType(this, Types.ULong));
+			Cache(SingleType = new ExternalType(this, Types.Single));
+			Cache(DoubleType = new ExternalType(this, Types.Double));
+			Cache(DecimalType = new ExternalType(this, Types.Decimal));
+			Cache(TimeSpanType = new ExternalType(this, Types.TimeSpan));
+			Cache(DateTimeType = new ExternalType(this, Types.DateTime));
+			Cache(RuntimeServicesType = new ExternalType(this, Types.RuntimeServices));
+			Cache(BuiltinsType = new ExternalType(this, Types.Builtins));
+			Cache(ListType = new ExternalType(this, Types.List));
+			Cache(HashType = new ExternalType(this, Types.Hash));
+			Cache(ICallableType = new ExternalType(this, Types.ICallable));
+			Cache(IEnumerableType = new ExternalType(this, Types.IEnumerable));
+			Cache(IEnumeratorType = new ExternalType(this, typeof(System.Collections.IEnumerator)));
+			Cache(ICollectionType = new ExternalType(this, Types.ICollection));
+			Cache(IListType = new ExternalType(this, Types.IList));
+			Cache(IDictionaryType = new ExternalType(this, Types.IDictionary));
+			Cache(ApplicationExceptionType = new ExternalType(this, Types.ApplicationException));
+			Cache(ExceptionType = new ExternalType(this, Types.Exception));
+			Cache(IntPtrType = new ExternalType(this, Types.IntPtr));
+			Cache(MulticastDelegateType = new ExternalType(this, Types.MulticastDelegate));
+			Cache(DelegateType = new ExternalType(this, Types.Delegate));
+			
+			ObjectArrayType = GetArrayType(ObjectType);
+			
+			PreparePrimitives();
+		}
+		
+		public CompilerContext Context
+		{
+			get
+			{
+				return _context;
+			}
+		}
+		
+		public IType GetMostGenericType(IType current, IType candidate)
+		{
+			if (current.IsAssignableFrom(candidate))
+			{
+				return current;
+			}
+			
+			if (candidate.IsAssignableFrom(current))
+			{
+				return candidate;
+			}
+			
+			if (IsNumberOrBool(current) && IsNumberOrBool(candidate))
+			{
+				return GetPromotedNumberType(current, candidate);
+			}
+			
+			if (IsCallableType(current) && IsCallableType(candidate))
+			{
+				return ICallableType;
+			}
+			IType obj;
+			if (Context.Parameters.DuckByDefault)
+				obj = DuckType;
+			else
+				obj = ObjectType;
+			
+			if (current.IsClass && candidate.IsClass)
+			{
+				if (current ==  obj || candidate == obj)
+				{
+					return obj;
+				}
+				if (current.GetTypeDepth() < candidate.GetTypeDepth())
+				{
+					return GetMostGenericType(current.BaseType, candidate);
+				}			
+				return GetMostGenericType(current, candidate.BaseType);
+			}			
+			return obj;
+		}
+		
+		public IType GetPromotedNumberType(IType left, IType right)
+		{
+			if (left == DecimalType ||
+				right == DecimalType)
+			{
+				return DecimalType;
+			}
+			if (left == DoubleType ||
+				right == DoubleType)
+			{
+				return DoubleType;
+			}
+			if (left == SingleType ||
+				right == SingleType)
+			{
+				return SingleType;
+			}
+			if (left == ULongType)
+			{
+				if (right == SByteType ||
+				    right == ShortType ||
+				    right == IntType ||
+				    right == LongType)
+				{
+					// This is against the C# spec but allows expressions like:
+					//    ulong x = 4
+					//    y = x + 1
+					// y will be long.
+					// C# disallows mixing ulongs and signed numbers
+					// but in the above case it promotes the constant to ulong
+					// and the result is ulong.
+					// Since its too late here to promote the constant,
+					// maybe we should return LongType.  I didn't chose ULongType
+					// because in other cases <unsigned> <op> <signed> returns <signed>.
+					return LongType;
+				}
+				return ULongType;
+			}
+			if (right == ULongType)
+			{
+				if (left == SByteType ||
+				    left == ShortType ||
+				    left == IntType ||
+				    left == LongType)
+				{
+					// This is against the C# spec but allows expressions like:
+					//    ulong x = 4
+					//    y = 1 + x
+					// y will be long.
+					// C# disallows mixing ulongs and signed numbers
+					// but in the above case it promotes the constant to ulong
+					// and the result is ulong.
+					// Since its too late here to promote the constant,
+					// maybe we should return LongType.  I didn't chose ULongType
+					// because in other cases <signed> <op> <unsigned> returns <signed>.
+					return LongType;
+				}
+				return ULongType;
+			}
+			if (left == LongType ||
+				right == LongType)
+			{
+				return LongType;
+			}
+			if (left == UIntType)
+			{
+				if (right == SByteType ||
+				    right == ShortType ||
+				    right == IntType)
+				{
+					// This is allowed per C# spec and y is long:
+					//    uint x = 4
+					//    y = x + 1
+					// C# promotes <uint> <op> <signed> to <long> also
+					// but in the above case it promotes the constant to uint first
+					// and the result of "x + 1" is uint.
+					// Since its too late here to promote the constant,
+					// "y = x + 1" will be long in boo.
+					return LongType;
+				}
+				return UIntType;
+			}
+			if (right == UIntType)
+			{
+				if (left == SByteType ||
+				    left == ShortType ||
+				    left == IntType)
+				{
+					// This is allowed per C# spec and y is long:
+					//    uint x = 4
+					//    y = 1 + x
+					// C# promotes <signed> <op> <uint> to <long> also
+					// but in the above case it promotes the constant to uint first
+					// and the result of "1 + x" is uint.
+					// Since its too late here to promote the constant,
+					// "y = x + 1" will be long in boo.
+					return LongType;
+				}
+				return UIntType;
+			}
+			if (left == IntType ||
+				right == IntType ||
+				left == ShortType ||
+				right == ShortType ||
+				left == UShortType ||
+				right == UShortType ||
+				left == ByteType ||
+				right == ByteType ||
+				left == SByteType ||
+				right == SByteType)
+			{
+				return IntType;
+			}
+			return left;
+		}
+		
+		public bool IsCallable(IType type)
+		{
+			return (TypeType == type) || IsCallableType(type);
+		}
+		
+		bool IsCallableType(IType type)
+		{			
+			return (ICallableType.IsAssignableFrom(type)) ||
+				(type is Boo.Lang.Compiler.TypeSystem.ICallableType);
+		}
+		
+		public AnonymousCallableType GetCallableType(IMethod method)
+		{
+			CallableSignature signature = new CallableSignature(method);
+			return GetCallableType(signature);
+		}
+		
+		public AnonymousCallableType GetCallableType(CallableSignature signature)
+		{
+			AnonymousCallableType type = (AnonymousCallableType)_anonymousCallableTypes[signature];
+			if (null == type)
+			{
+				type = new AnonymousCallableType(this, signature);
+				_anonymousCallableTypes.Add(signature, type);
+			}
+			return type;
+		}
+		
+		public IType GetConcreteCallableType(Node sourceNode, CallableSignature signature)
+		{
+			AnonymousCallableType type = GetCallableType(signature);
+			return GetConcreteCallableType(sourceNode, type);
+		}
+		
+		public IType GetEnumeratorItemType(IType iteratorType)
+		{
+			if (iteratorType.IsArray)
+			{
+				return ((IArrayType)iteratorType).GetElementType();
+			}
+			else
+			{
+				if (iteratorType.IsClass)
+				{
+					IType enumeratorItemType = GetEnumeratorItemTypeFromAttribute(iteratorType);
+					if (null != enumeratorItemType)
+					{
+						return enumeratorItemType;
+					}
+				}
+			}
+			if(Context.Parameters.DuckByDefault)
+				return DuckType;
+			return ObjectType;
+		}
+		
+		public IType GetExpressionType(Expression node)
+		{			
+			IType type = node.ExpressionType;
+			if (null == type)
+			{
+				throw CompilerErrorFactory.InvalidNode(node);
+			}
+			return type;
+		}
+		
+		public IType GetConcreteExpressionType(Expression expression)
+		{
+			IType type = GetExpressionType(expression);
+			AnonymousCallableType anonymousType = type as AnonymousCallableType;
+			if (null != anonymousType)
+			{
+				IType concreteType = GetConcreteCallableType(expression, anonymousType);
+				expression.ExpressionType = concreteType;
+				return concreteType;
+			}
+			return type;
+		}
+		
+		public void MapToConcreteExpressionTypes(ExpressionCollection items)
+		{
+			foreach (Expression item in items)
+			{
+				GetConcreteExpressionType(item);
+			}
+		}
+		
+		public Boo.Lang.Compiler.Ast.Module GetAnonymousTypesModule()
+		{
+			if (null == _anonymousTypesModule)
+			{
+				_anonymousTypesModule = new Boo.Lang.Compiler.Ast.Module();
+				_anonymousTypesModule.Entity = new ModuleEntity(_context.NameResolutionService, 
+																this,
+																_anonymousTypesModule);
+				_context.CompileUnit.Modules.Add(_anonymousTypesModule);
+			}
+			return _anonymousTypesModule;
+		}
+		
+		public ClassDefinition CreateCallableDefinition(string name)
+		{
+			ClassDefinition cd = new ClassDefinition();
+			cd.BaseTypes.Add(CodeBuilder.CreateTypeReference(this.MulticastDelegateType));
+			cd.BaseTypes.Add(CodeBuilder.CreateTypeReference(this.ICallableType));
+			cd.Name = name;
+			cd.Modifiers = TypeMemberModifiers.Final;
+			cd.Members.Add(CreateCallableConstructor());
+			cd.Members.Add(CreateCallMethod());			
+			cd.Entity = new InternalCallableType(this, cd);
+			return cd;
+		}
+		
+		Method CreateCallMethod()
+		{
+			Method method = new Method("Call");
+			method.Modifiers = TypeMemberModifiers.Public|TypeMemberModifiers.Virtual;
+			method.Parameters.Add(CodeBuilder.CreateParameterDeclaration(1, "args", ObjectArrayType));
+			method.ReturnType = CodeBuilder.CreateTypeReference(ObjectType);
+			method.Entity = new InternalMethod(this, method);
+			return method;
+		}
+		
+		Constructor CreateCallableConstructor()
+		{
+			Constructor constructor = new Constructor();
+			constructor.Modifiers = TypeMemberModifiers.Public;
+			constructor.ImplementationFlags = MethodImplementationFlags.Runtime;
+			constructor.Parameters.Add(
+						CodeBuilder.CreateParameterDeclaration(1, "instance", ObjectType));
+			constructor.Parameters.Add(
+						CodeBuilder.CreateParameterDeclaration(2, "method", IntPtrType));
+			constructor.Entity = new InternalConstructor(this, constructor);						
+			return constructor;
+		}
+		
+		public bool AreTypesRelated(IType lhs, IType rhs)
+		{
+			return lhs.IsAssignableFrom(rhs) ||
+				(lhs.IsInterface && rhs.IsInterface) ||
+				CanBeReachedByDownCastOrPromotion(lhs, rhs);
+		}
+		
+		public bool IsCallableTypeAssignableFrom(ICallableType lhs, IType rhs)
+		{
+			if (lhs == rhs || Null.Default == rhs)
+			{
+				return true;
+			}
+			
+			ICallableType other = rhs as ICallableType;
+			if (null != other)
+			{			
+				CallableSignature lvalue = lhs.GetSignature();
+				CallableSignature rvalue = other.GetSignature(); 
+				if (lvalue == rvalue)
+				{
+					return true;
+				}
+				
+				IParameter[] lparams = lvalue.Parameters;
+				IParameter[] rparams = rvalue.Parameters;
+				if (lparams.Length >= rparams.Length)
+				{
+					for (int i=0; i<rparams.Length; ++i)
+					{
+						IType lparamType = lparams[i].Type;
+						IType rparamType = rparams[i].Type;
+						if (!AreTypesRelated(lparamType, rparamType))
+						{
+							return false;
+						}
+					}
+					
+					if (VoidType != lvalue.ReturnType)
+					{				
+						return AreTypesRelated(lvalue.ReturnType, rvalue.ReturnType);
+					}
+					
+					return true;
+				}
+			}
+			return false;
+		}
+		
+		public static bool CheckOverrideSignature(IMethod impl, IMethod baseMethod)
+		{
+			IParameter[] implParameters = impl.GetParameters();
+			IParameter[] baseParameters = baseMethod.GetParameters();
+			
+			if (implParameters.Length == baseParameters.Length)
+			{
+				for (int i=0; i<implParameters.Length; ++i)
+				{
+					if (implParameters[i].Type != baseParameters[i].Type)
+					{
+						return false;
+					}
+				}
+				return true;
+			}
+			return false;
+		}
+		
+		public bool CanBeReachedByDownCastOrPromotion(IType expectedType, IType actualType)
+		{			
+			if (actualType.IsAssignableFrom(expectedType))
+			{
+				return true;
+			}
+			if (expectedType.IsValueType)
+			{
+				return IsNumber(expectedType) && IsNumber(actualType);
+			}
+			return false;
+		}
+		
+		public bool CanBeExplicitlyCastToInteger(IType type)
+		{
+			return type.IsEnum || type == this.CharType; 
+		}
+		
+		public bool IsIntegerNumber(IType type)
+		{
+			return
+				type == this.ShortType ||
+				type == this.IntType ||
+				type == this.LongType ||
+				type == this.SByteType ||
+				type == this.UShortType ||
+				type == this.UIntType ||				
+				type == this.ULongType ||
+				type == this.ByteType;
+		}
+		
+		public bool IsIntegerOrBool(IType type)	
+		{
+			return BoolType == type || IsIntegerNumber(type);
+		}
+		
+		public bool IsNumberOrBool(IType type)
+		{
+			return BoolType == type || IsNumber(type);
+		}
+		
+		public bool IsNumber(IType type)
+		{
+			return
+				IsPrimitiveNumber(type) ||
+				type == this.DecimalType;
+		}
+		
+		public bool IsPrimitiveNumber(IType type)
+		{
+			return
+				IsIntegerNumber(type) ||
+				type == this.DoubleType ||
+				type == this.SingleType;
+		}
+		
+		public static bool IsUnknown(Expression node)
+		{
+			IType type = node.ExpressionType;
+			if (null != type)
+			{
+				return IsUnknown(type);
+			}
+			return false;
+		}
+		
+		public static bool IsUnknown(IType tag)
+		{
+			return EntityType.Unknown == tag.EntityType;
+		}
+		
+		public static bool IsError(Expression node)
+		{				 
+			IType type = node.ExpressionType;
+			if (null != type)
+			{
+				return IsError(type);
+			}
+			return false;
+		}
+		
+		public static bool IsErrorAny(ExpressionCollection collection)
+		{
+			foreach (Expression n in collection)
+			{
+				if (IsError(n))
+				{
+					return true;
+				}
+			}
+			return false;
+		}
+		
+		public bool IsBuiltin(IEntity tag)
+		{
+			if (EntityType.Method == tag.EntityType)
+			{
+				return BuiltinsType == ((IMethod)tag).DeclaringType;
+			}
+			return false;
+		}		
+		
+		public static bool IsError(IEntity tag)
+		{
+			return EntityType.Error == tag.EntityType;
+		}
+		
+		public static TypeMemberModifiers GetAccess(IAccessibleMember member)
+		{
+			if (member.IsPublic)
+			{
+				return TypeMemberModifiers.Public;
+			}
+			else if (member.IsProtected)
+			{
+				return TypeMemberModifiers.Protected;
+			}
+			return TypeMemberModifiers.Private;
+		}
+		
+		public static IEntity GetEntity(Node node)
+		{
+			if (null == node)
+			{
+				throw new ArgumentNullException("node");
+			}
+			
+			IEntity tag = node.Entity;
+			if (null == tag)
+			{
+				InvalidNode(node);
+			}
+			return tag;
+		}	
+		
+		public static IType GetReferencedType(Expression typeref)
+		{
+			switch (typeref.NodeType)
+			{
+				case NodeType.TypeofExpression:
+				{
+					return GetType(((TypeofExpression)typeref).Type);
+				}
+				case NodeType.ReferenceExpression:
+				case NodeType.MemberReferenceExpression:
+				{
+					return typeref.Entity as IType;					
+				}
+			}
+			return null;
+		}
+		
+		public static IType GetType(Node node)
+		{
+			return ((ITypedEntity)GetEntity(node)).Type;
+		}
+		
+		public IType Map(System.Type type)
+		{				
+			ExternalType tag = (ExternalType)_entityCache[type];
+			if (null == tag)
+			{
+				if (type.IsArray)
+				{
+					return GetArrayType(Map(type.GetElementType()));
+				}				
+				else
+				{
+					if (type.IsSubclassOf(Types.MulticastDelegate))
+					{
+						tag = new ExternalCallableType(this, type);
+					}
+					else
+					{
+						tag = new ExternalType(this, type);
+					}
+				}
+				Cache(tag);
+			}
+			return tag;
+		}
+		
+		public IArrayType GetArrayType(IType elementType)
+		{
+			IArrayType tag = (IArrayType)_arrayCache[elementType];
+			if (null == tag)
+			{
+				tag = new ArrayType(this, elementType);
+				_arrayCache.Add(elementType, tag);
+			}
+			return tag;
+		}
+		
+		public IParameter[] Map(Boo.Lang.Compiler.Ast.ParameterDeclarationCollection parameters)
+		{
+			IParameter[] mapped = new IParameter[parameters.Count];
+			for (int i=0; i<mapped.Length; ++i)
+			{
+				mapped[i] = (IParameter)GetEntity(parameters[i]);
+			}
+			return mapped;
+		}
+		
+		public IParameter[] Map(System.Reflection.ParameterInfo[] parameters)
+		{			
+			IParameter[] mapped = new IParameter[parameters.Length];
+			for (int i=0; i<parameters.Length; ++i)
+			{
+				mapped[i] = new ExternalParameter(this, parameters[i]);
+			}
+			return mapped;
+		}
+		
+		public IConstructor Map(ConstructorInfo constructor)
+		{
+			object key = GetCacheKey(constructor);
+			IConstructor entity = (IConstructor)_entityCache[key];
+			if (null == entity)
+			{
+				entity = new ExternalConstructor(this, constructor);
+				_entityCache[key] = entity;
+			}
+			return entity;
+		}
+		
+		public IMethod Map(MethodInfo method)
+		{
+			object key = GetCacheKey(method);
+			IMethod entity = (IMethod)_entityCache[key];
+			if (null == entity)
+			{
+				entity = new ExternalMethod(this, method);
+				_entityCache[key] = entity;
+			}
+			return entity;
+		}
+		
+		public IEntity Map(System.Reflection.MemberInfo[] info)
+		{
+			if (info.Length > 1)
+			{
+				IEntity[] tags = new IEntity[info.Length];
+				for (int i=0; i<tags.Length; ++i)
+				{
+					tags[i] = Map(info[i]);
+				}
+				return new Ambiguous(tags);
+			}
+			if (info.Length > 0)
+			{
+				return Map(info[0]);
+			}
+			return null;
+		}
+		
+		public IEntity Map(System.Reflection.MemberInfo mi)
+		{
+			IEntity tag = (IEntity)_entityCache[GetCacheKey(mi)];
+			if (null == tag)
+			{			
+				switch (mi.MemberType)
+				{
+					case MemberTypes.Method:
+					{
+						return Map((System.Reflection.MethodInfo)mi);
+					}
+					
+					case MemberTypes.Constructor:
+					{
+						return Map((System.Reflection.ConstructorInfo)mi);
+					}
+					
+					case MemberTypes.Field:
+					{
+						tag = new ExternalField(this, (System.Reflection.FieldInfo)mi);
+						break;
+					}
+					
+					case MemberTypes.Property:
+					{
+						tag = new ExternalProperty(this, (System.Reflection.PropertyInfo)mi);
+						break;
+					}
+					
+					case MemberTypes.Event:
+					{
+						tag = new ExternalEvent(this, (System.Reflection.EventInfo)mi);
+						break;
+					}
+					
+					case MemberTypes.NestedType:
+					{
+						return Map((System.Type)mi);
+					}
+					
+					default:
+					{
+						throw new NotImplementedException(mi.ToString());
+					}
+				}
+				_entityCache.Add(GetCacheKey(mi), tag);
+			}
+			return tag;
+		}
+		
+		public string GetSignature(IMethod method)
+		{
+			return GetSignature(method, true);
+		}
+		
+		public string GetSignature(IMethod method, bool includeFullName)
+		{
+			_buffer.Length = 0;
+			if (includeFullName)
+			{
+				_buffer.Append(method.FullName);
+			}
+			else
+			{
+				_buffer.Append(method.Name);
+			}
+			_buffer.Append("(");
+			
+			IParameter[] parameters = method.GetParameters();
+			for (int i=0; i<parameters.Length; ++i)
+			{
+				if (i > 0) { _buffer.Append(", "); }
+				_buffer.Append(parameters[i].Type.FullName);
+			}
+			_buffer.Append(")");
+			return _buffer.ToString();
+		}
+		
+		public object GetCacheKey(System.Reflection.MemberInfo mi)
+		{
+			return mi;
+		}
+		
+		public IEntity ResolvePrimitive(string name)
+		{
+			return (IEntity)_primitives[name];
+		}
+		
+		public bool IsPrimitive(string name)
+		{
+			return _primitives.ContainsKey(name);
+		}
+		
+		/// <summary>
+		/// checks if the passed type will be equivalente to
+		/// System.Object in runtime (accounting for the presence
+		/// of duck typing).
+		/// </summary>
+		public bool IsSystemObject(IType type)
+		{
+			return type == ObjectType || type == DuckType;
+		}
+		
+		void PreparePrimitives()
+		{
+			AddPrimitiveType("duck", DuckType);
+			AddPrimitiveType("void", VoidType);
+			AddPrimitiveType("bool", BoolType);
+			AddPrimitiveType("char", CharType);
+			AddPrimitiveType("date", DateTimeType);
+			AddPrimitiveType("timespan", TimeSpanType);
+			AddPrimitiveType("string", StringType);
+			AddPrimitiveType("object", ObjectType);
+			AddPrimitiveType("regex", RegexType);
+			AddPrimitiveType("sbyte", SByteType);
+			AddPrimitiveType("byte", ByteType);
+			AddPrimitiveType("short", ShortType);
+			AddPrimitiveType("ushort", UShortType);
+			AddPrimitiveType("int", IntType);
+			AddPrimitiveType("uint", UIntType);
+			AddPrimitiveType("long", LongType);
+			AddPrimitiveType("ulong", ULongType);
+			AddPrimitiveType("single", SingleType);
+			AddPrimitiveType("double", DoubleType);
+			AddPrimitiveType("decimal", DecimalType);
+			AddPrimitiveType("callable", ICallableType);
+			AddBuiltin(BuiltinFunction.Len);
+			AddBuiltin(BuiltinFunction.AddressOf);
+			AddBuiltin(BuiltinFunction.Eval);
+			AddBuiltin(BuiltinFunction.Switch);
+		}
+		
+		void AddPrimitiveType(string name, ExternalType type)
+		{
+			_primitives[name] = type;
+		}
+		
+		void AddBuiltin(BuiltinFunction function)
+		{
+			_primitives[function.Name] = function;
+		}
+		
+		void AddPrimitive(string name, IEntity tag)
+		{
+			_primitives[name] = tag;
+		}
+		
+		void Cache(ExternalType tag)
+		{
+			_entityCache[tag.ActualType] = tag;
+		}
+		
+		void Cache(object key, IType tag)
+		{
+			_entityCache[key] = tag;
+		}
+		
+		Method CreateBeginInvokeMethod(ICallableType anonymousType)
+		{
+			Method method = CodeBuilder.CreateRuntimeMethod("BeginInvoke", Map(typeof(IAsyncResult)),
+												anonymousType.GetSignature().Parameters);
+												
+			int delta=method.Parameters.Count;
+			method.Parameters.Add(
+					CodeBuilder.CreateParameterDeclaration(delta+1, "callback", Map(typeof(AsyncCallback))));
+			method.Parameters.Add(
+					CodeBuilder.CreateParameterDeclaration(delta+1, "asyncState", ObjectType));
+			return method;
+		}
+		
+		Method CreateBeginInvokeOverload(ICallableType anonymousType, Method beginInvoke, out MethodInvocationExpression mie)
+		{
+			InternalMethod beginInvokeEntity = (InternalMethod)beginInvoke.Entity;
+			
+			Method overload = CodeBuilder.CreateMethod("BeginInvoke", Map(typeof(IAsyncResult)),
+										TypeMemberModifiers.Public);
+			CodeBuilder.DeclareParameters(overload, 1, anonymousType.GetSignature().Parameters);
+			
+			mie = CodeBuilder.CreateMethodInvocation(
+						CodeBuilder.CreateSelfReference(beginInvokeEntity.DeclaringType),
+						beginInvokeEntity);
+						
+			foreach (ParameterDeclaration parameter in overload.Parameters)
+			{
+				mie.Arguments.Add(CodeBuilder.CreateReference(parameter));
+			}
+			
+			overload.Body.Add(new ReturnStatement(mie));
+			return overload;
+		}
+		
+		Method CreateBeginInvokeSimplerOverload(ICallableType anonymousType, Method beginInvoke)
+		{
+			MethodInvocationExpression mie;
+			Method overload = CreateBeginInvokeOverload(anonymousType, beginInvoke, out mie);
+			
+			mie.Arguments.Add(CodeBuilder.CreateNullLiteral());
+			mie.Arguments.Add(CodeBuilder.CreateNullLiteral());
+			
+			return overload;
+		}
+		
+		Method CreateBeginInvokeCallbackOnlyOverload(ICallableType anonymousType, Method beginInvoke)
+		{
+			MethodInvocationExpression mie;
+			
+			Method overload = CreateBeginInvokeOverload(anonymousType, beginInvoke, out mie);
+			ParameterDeclaration callback = CodeBuilder.CreateParameterDeclaration(overload.Parameters.Count+1,
+										"callback", Map(typeof(AsyncCallback)));
+			overload.Parameters.Add(callback);
+
+			mie.Arguments.Add(CodeBuilder.CreateReference(callback));			
+			mie.Arguments.Add(CodeBuilder.CreateNullLiteral());
+			
+			return overload;
+		}
+		
+		public Method CreateEndInvokeMethod(ICallableType anonymousType)
+		{
+			CallableSignature signature = anonymousType.GetSignature();
+			Method method = CodeBuilder.CreateRuntimeMethod("EndInvoke", signature.ReturnType);
+			int delta=method.Parameters.Count;
+			method.Parameters.Add(
+				CodeBuilder.CreateParameterDeclaration(delta+1, "result", Map(typeof(IAsyncResult))));
+			return method;
+		}
+		
+		Method CreateInvokeMethod(AnonymousCallableType anonymousType)
+		{
+			CallableSignature signature = anonymousType.GetSignature();
+			return CodeBuilder.CreateRuntimeMethod("Invoke", signature.ReturnType, signature.Parameters);
+		}
+		
+		public IConstructor GetDefaultConstructor(IType type)
+		{
+			IConstructor[] constructors = type.GetConstructors();
+			for (int i=0; i<constructors.Length; ++i)
+			{
+				IConstructor constructor = constructors[i];
+				if (0 == constructor.GetParameters().Length)
+				{
+					return constructor;
+				}
+			}
+			return null;
+		}
+		
+		IType GetExternalEnumeratorItemType(IType iteratorType)
+		{
+			Type type = ((ExternalType)iteratorType).ActualType;
+			EnumeratorItemTypeAttribute attribute = (EnumeratorItemTypeAttribute)System.Attribute.GetCustomAttribute(type, typeof(EnumeratorItemTypeAttribute));
+			if (null != attribute)
+			{
+				return Map(attribute.ItemType);
+			}
+			return null;
+		}
+		
+		IType GetEnumeratorItemTypeFromAttribute(IType iteratorType)
+		{
+			AbstractInternalType internalType = iteratorType as AbstractInternalType;
+			if (null == internalType)
+			{
+				return GetExternalEnumeratorItemType(iteratorType);
+			}
+			
+			IType enumeratorItemTypeAttribute = Map(typeof(EnumeratorItemTypeAttribute));
+			foreach (Boo.Lang.Compiler.Ast.Attribute attribute in internalType.TypeDefinition.Attributes)
+			{				
+				IConstructor constructor = GetEntity(attribute) as IConstructor;
+				if (null != constructor)
+				{
+					if (constructor.DeclaringType == enumeratorItemTypeAttribute)
+					{
+						return GetType(attribute.Arguments[0]);
+					}
+				}
+			}
+			return null;
+		}
+		
+		public virtual IType GetConcreteCallableType(Node sourceNode, AnonymousCallableType anonymousType)
+		{
+			if (null == anonymousType.ConcreteType)
+			{
+				anonymousType.ConcreteType = CreateConcreteCallableType(sourceNode, anonymousType);
+			}
+			return anonymousType.ConcreteType;
+		}
+		
+		protected virtual IType CreateConcreteCallableType(Node sourceNode, AnonymousCallableType anonymousType)
+		{
+			Boo.Lang.Compiler.Ast.Module module = GetAnonymousTypesModule();
+			
+			string name = string.Format("___callable{0}", module.Members.Count);
+			ClassDefinition cd = CreateCallableDefinition(name);
+			cd.Modifiers |= TypeMemberModifiers.Public;
+			cd.LexicalInfo = sourceNode.LexicalInfo;
+			
+			cd.Members.Add(CreateInvokeMethod(anonymousType));
+			
+			Method beginInvoke = CreateBeginInvokeMethod(anonymousType);
+			cd.Members.Add(beginInvoke);
+			cd.Members.Add(CreateBeginInvokeCallbackOnlyOverload(anonymousType, beginInvoke));
+			cd.Members.Add(CreateBeginInvokeSimplerOverload(anonymousType, beginInvoke));
+			
+			cd.Members.Add(CreateEndInvokeMethod(anonymousType));
+			_anonymousTypesModule.Members.Add(cd);
+			
+			return (IType)cd.Entity;
+		}
+		
+		private static void InvalidNode(Node node)
+		{
+			throw CompilerErrorFactory.InvalidNode(node);
+		}
+
+		public class DuckTypeImpl : ExternalType
+		{	
+			public DuckTypeImpl(TypeSystemServices typeSystemServices) : 
+				base(typeSystemServices, Types.Object)
+			{
+			}
+		}	
+		
+		#region VoidTypeImpl
+		class VoidTypeImpl : ExternalType
+		{			
+			internal VoidTypeImpl(TypeSystemServices manager) : base(manager, Types.Void)
+			{				
+			}		
+			
+			override public bool Resolve(Boo.Lang.List targetList, string name, EntityType flags)
+			{	
+				return false;
+			}	
+			
+			override public bool IsSubclassOf(IType other)
+			{
+				return false;
+			}
+			
+			override public bool IsAssignableFrom(IType other)
+			{
+				return false;
+			}
+		}
+
+		#endregion
+	}
+}