//
// typespec.cs: Type specification
//
// Authors: Marek Safar (marek.safar@gmail.com)
//
// Dual licensed under the terms of the MIT X11 or GNU GPL
//
// Copyright 2010 Novell, Inc
//

using System;
using System.Collections.Generic;
using System.Text;

#if STATIC
using MetaType = IKVM.Reflection.Type;
using IKVM.Reflection;
#else
using MetaType = System.Type;
using System.Reflection;
#endif

namespace Mono.CSharp
{
	public class TypeSpec : MemberSpec
	{
		protected MetaType info;
		protected MemberCache cache;
		protected IList<TypeSpec> ifaces;
		TypeSpec base_type;

		Dictionary<TypeSpec[], InflatedTypeSpec> inflated_instances;

		public static readonly TypeSpec[] EmptyTypes = new TypeSpec[0];

#if !STATIC
		// Reflection Emit hacking
		static readonly Type TypeBuilder;
		static readonly Type GenericTypeBuilder;

		static TypeSpec ()
		{
			var assembly = typeof (object).Assembly;
			TypeBuilder = assembly.GetType ("System.Reflection.Emit.TypeBuilder");
			GenericTypeBuilder = assembly.GetType ("System.Reflection.MonoGenericClass");
			if (GenericTypeBuilder == null)
				GenericTypeBuilder = assembly.GetType ("System.Reflection.Emit.TypeBuilderInstantiation");
		}
#endif

		public TypeSpec (MemberKind kind, TypeSpec declaringType, ITypeDefinition definition, MetaType info, Modifiers modifiers)
			: base (kind, declaringType, definition, modifiers)
		{
			this.declaringType = declaringType;
			this.info = info;

			if (definition != null && definition.TypeParametersCount > 0)
				state |= StateFlags.IsGeneric;
		}

		#region Properties

		public override int Arity {
			get {
				return MemberDefinition.TypeParametersCount;
			}
		}

		public virtual TypeSpec BaseType {
			get {
				return base_type;
			}
			set {
				base_type = value;
			}
		}

		public virtual BuildinTypeSpec.Type BuildinType {
			get {
				return BuildinTypeSpec.Type.None;
			}
		}

		public bool HasDynamicElement {
			get {
				return (state & StateFlags.HasDynamicElement) != 0;
			}
		}

		public virtual IList<TypeSpec> Interfaces {
			get {
				return ifaces;
			}
			set {
				ifaces = value;
			}
		}

		public bool IsArray {
			get {
				return Kind == MemberKind.ArrayType;
			}
		}

		public bool IsAttribute {
			get {
				if (!IsClass)
					return false;

				var type = this;
				do {
					if (type.IsGeneric)
						return false;

					if (type == TypeManager.attribute_type)
						return true;
					
					type = type.base_type;
				} while (type != null);

				return false;
			}
		}

		public bool IsInterface {
			get {
				return Kind == MemberKind.Interface;
			}
		}

		public bool IsClass {
			get {
				return Kind == MemberKind.Class;
			}
		}

		public bool IsConstantCompatible {
			get {
				if ((Kind & (MemberKind.Enum | MemberKind.Class | MemberKind.Interface | MemberKind.Delegate | MemberKind.ArrayType)) != 0)
					return true;

				return TypeManager.IsPrimitiveType (this) || this == TypeManager.decimal_type || this == InternalType.Dynamic;
			}
		}

		public bool IsDelegate {
			get {
				return Kind == MemberKind.Delegate;
			}
		}

		public bool IsEnum {
			get { return Kind == MemberKind.Enum; }
		}

		// TODO: Should probably do
		// IsGenericType -- recursive
		// HasTypeParameter -- non-recursive
		public bool IsGenericOrParentIsGeneric {
			get {
				var ts = this;
				do {
					if (ts.IsGeneric)
						return true;
					ts = ts.declaringType;
				} while (ts != null);

				return false;
			}
		}

		public bool IsGenericParameter {
			get { return Kind == MemberKind.TypeParameter; }
		}

		public bool IsNested {
			get { return declaringType != null && Kind != MemberKind.TypeParameter; }
		}

		public bool IsPointer {
			get {
				return Kind == MemberKind.PointerType;
			}
		}

		public bool IsSealed {
			get { return (Modifiers & Modifiers.SEALED) != 0; }
		}

		public bool IsStruct {
			get { 
				return Kind == MemberKind.Struct;
			}
		}

		public bool IsTypeBuilder {
			get {
#if STATIC
				return true;
#else
				var meta = GetMetaInfo().GetType ();
				return meta == TypeBuilder || meta == GenericTypeBuilder;
#endif
			}
		}

		public MemberCache MemberCache {
			get {
				if (cache == null || (state & StateFlags.PendingMemberCacheMembers) != 0)
					InitializeMemberCache (false);

				return cache;
			}
			set {
				if (cache != null)
					throw new InternalErrorException ("Membercache reset");

				cache = value;
			}
		}

		public MemberCache MemberCacheTypes {
			get {
				if (cache == null)
					InitializeMemberCache (true);

				return cache;
			}
		}	

		public new ITypeDefinition MemberDefinition {
			get {
				return (ITypeDefinition) definition;
			}
		}

		// TODO: Wouldn't be better to rely on cast to InflatedTypeSpec and
		// remove the property, YES IT WOULD !!!
		public virtual TypeSpec[] TypeArguments {
			get { return TypeSpec.EmptyTypes; }
		}

		#endregion

		public bool AddInterface (TypeSpec iface)
		{
			if ((state & StateFlags.InterfacesExpanded) != 0)
				throw new InternalErrorException ("Modifying expanded interface list");

			if (ifaces == null) {
				ifaces = new List<TypeSpec> () { iface };
				return true;
			}

			if (!ifaces.Contains (iface)) {
				ifaces.Add (iface);
				return true;
			}

			return false;
		}

		public AttributeUsageAttribute GetAttributeUsage (PredefinedAttribute pa)
		{
			if (Kind != MemberKind.Class)
				throw new InternalErrorException ();

			if (!pa.IsDefined)
				return Attribute.DefaultUsageAttribute;

			AttributeUsageAttribute aua = null;
			var type = this;
			while (type != null) {
				aua = type.MemberDefinition.GetAttributeUsage (pa);
				if (aua != null)
					break;

				type = type.BaseType;
			}

			return aua;
		}

		public virtual MetaType GetMetaInfo ()
		{
			return info;
		}

		public virtual TypeSpec GetDefinition ()
		{
			return this;
		}

		public override string GetSignatureForError ()
		{
			string s;

			if (IsNested) {
				s = DeclaringType.GetSignatureForError ();
			} else if (MemberDefinition is AnonymousTypeClass) {
				return ((AnonymousTypeClass) MemberDefinition).GetSignatureForError ();
			} else {
				s = MemberDefinition.Namespace;
			}

			if (!string.IsNullOrEmpty (s))
				s += ".";

			return s + Name + GetTypeNameSignature ();
		}

		protected virtual string GetTypeNameSignature ()
		{
			if (!IsGeneric)
				return null;

			return "<" + TypeManager.CSharpName (MemberDefinition.TypeParameters) + ">";
		}

		public bool ImplementsInterface (TypeSpec iface, bool variantly)
		{
			var t = this;
			do {
				if (t.Interfaces != null) {	// TODO: Try t.iface
					foreach (TypeSpec i in t.Interfaces) {
						if (i == iface || TypeSpecComparer.IsEqual (i, iface))
							return true;

						if (variantly && TypeSpecComparer.Variant.IsEqual (i, iface))
							return true;
					}
				}

				t = t.BaseType;
			} while (t != null);

			return false;
		}

		protected virtual void InitializeMemberCache (bool onlyTypes)
		{
			MemberDefinition.LoadMembers (this, onlyTypes, ref cache);

			if (onlyTypes)
				state |= StateFlags.PendingMemberCacheMembers;
			else
				state &= ~StateFlags.PendingMemberCacheMembers;
		}

		//
		// Is @baseClass base implementation of @type. With enabled @dynamicIsEqual the slower
		// comparison is used to hide differences between `object' and `dynamic' for generic
		// types. Should not be used for comparisons where G<object> != G<dynamic>
		//
		public static bool IsBaseClass (TypeSpec type, TypeSpec baseClass, bool dynamicIsObject)
		{
			if (dynamicIsObject && baseClass.IsGeneric) {
				//
				// Returns true for a hierarchies like this when passing baseClass of A<dynamic>
				//
				// class B : A<object> {}
				//
				while (type != null) {
					type = type.BaseType;
					if (TypeSpecComparer.IsEqual (type, baseClass))
						return true;
				}

				return false;
			}

			while (type != null) {
				type = type.BaseType;
				if (type == baseClass)
					return true;
			}

			return false;
		}

		public override MemberSpec InflateMember (TypeParameterInflator inflator)
		{
			var targs = IsGeneric ? MemberDefinition.TypeParameters : TypeSpec.EmptyTypes;

			//
			// When inflating nested type from inside the type instance will be same
			// because type parameters are same for all nested types
			//
			if (DeclaringType == inflator.TypeInstance) {
				return MakeGenericType (targs);
			}

			return new InflatedTypeSpec (this, inflator.TypeInstance, targs);
		}

		public InflatedTypeSpec MakeGenericType (TypeSpec[] targs)
		{
			if (targs.Length == 0 && !IsNested)
				throw new ArgumentException ("Empty type arguments for type " + GetSignatureForError ());

			InflatedTypeSpec instance;

			if (inflated_instances == null) {
				inflated_instances = new Dictionary<TypeSpec[], InflatedTypeSpec> (TypeSpecComparer.Default);

				if (IsNested) {
					instance = this as InflatedTypeSpec;
					if (instance != null) {
						//
						// Nested types could be inflated on already inflated instances
						// Caching this type ensured we are using same instance for
						// inside/outside inflation using local type parameters
						//
						inflated_instances.Add (TypeArguments, instance);
					}
				}
			}

			if (!inflated_instances.TryGetValue (targs, out instance)) {
				if (GetDefinition () != this && !IsNested)
					throw new InternalErrorException ("`{0}' must be type definition or nested non-inflated type to MakeGenericType",
						GetSignatureForError ());

				instance = new InflatedTypeSpec (this, declaringType, targs);
				inflated_instances.Add (targs, instance);
			}

			return instance;
		}

		public virtual TypeSpec Mutate (TypeParameterMutator mutator)
		{
			return this;
		}

		public void SetMetaInfo (MetaType info)
		{
			if (this.info != null)
				throw new InternalErrorException ("MetaInfo reset");

			this.info = info;
		}

		public void SetExtensionMethodContainer ()
		{
			modifiers |= Modifiers.METHOD_EXTENSION;
		}
	}

	public sealed class BuildinTypeSpec : TypeSpec
	{
		public enum Type
		{
			None = 0,

			// TODO: Reorder it more carefully so we can do fast compares
			Object,
			ValueType,
			Attribute,
			Int,
			UInt,
			Long,
			ULong,
			Float,
			Double,
			Char,
			Short,
			Decimal,
			Bool,
			SByte,
			Byte,
			UShort,
			String,
			Enum,
			Delegate,
			MulticastDelegate,
			Void,
			Array,
			Type,
			IEnumerator,
			IEnumerable,
			IDisposable,
			IntPtr,
			UIntPtr,
			RuntimeFieldHandle,
			RuntimeTypeHandle,
			Exception,

			Null,
			Dynamic
		}

		readonly Type type;
		readonly string ns;
		readonly string name;

		public BuildinTypeSpec (MemberKind kind, string ns, string name, Type buildinKind)
			: base (kind, null, null, null, Modifiers.PUBLIC)
		{
			this.type = buildinKind;
			this.ns = ns;
			this.name = name;
		}

		public BuildinTypeSpec (string name, Type buildinKind)
			: this (MemberKind.InternalCompilerType, "", name, buildinKind)
		{
			// Make all internal types CLS-compliant, non-obsolete, compact
			state = (state & ~(StateFlags.CLSCompliant_Undetected | StateFlags.Obsolete_Undetected | StateFlags.MissingDependency_Undetected)) | StateFlags.CLSCompliant;
		}

		#region Properties

		public override int Arity {
			get {
				return 0;
			}
		}

		public override BuildinTypeSpec.Type BuildinType {
			get {
				return type;
			}
		}

		public string FullName {
			get {
				return ns + '.' + name;
			}
		}

		public override string Name {
			get {
				return name;
			}
		}

		public string Namespace {
			get {
				return ns;
			}
		}

		#endregion

		public override string GetSignatureForError ()
		{
			switch (Name) {
			case "Int32": return "int";
			case "Int64": return "long";
			case "String": return "string";
			case "Boolean": return "bool";
			case "Void": return "void";
			case "Object": return "object";
			case "UInt32": return "uint";
			case "Int16": return "short";
			case "UInt16": return "ushort";
			case "UInt64": return "ulong";
			case "Single": return "float";
			case "Double": return "double";
			case "Decimal": return "decimal";
			case "Char": return "char";
			case "Byte": return "byte";
			case "SByte": return "sbyte";
			}

			if (ns.Length == 0)
				return name;

			return FullName;
		}

		public void SetDefinition (ITypeDefinition td, MetaType type, Modifiers mod)
		{
			this.definition = td;
			this.info = type;
			this.modifiers |= (mod & ~Modifiers.AccessibilityMask);
		}

		public void SetDefinition (TypeSpec ts)
		{
			this.definition = ts.MemberDefinition;
			this.info = ts.GetMetaInfo ();
			this.BaseType = ts.BaseType;
			this.Interfaces = ts.Interfaces;
			this.modifiers = ts.Modifiers;
		}
	}

	static class TypeSpecComparer
	{
		//
		// Does strict reference comparion only
		//
		public static readonly DefaultImpl Default = new DefaultImpl ();

		public class DefaultImpl : IEqualityComparer<TypeSpec[]>
		{
			#region IEqualityComparer<TypeSpec[]> Members

			bool IEqualityComparer<TypeSpec[]>.Equals (TypeSpec[] x, TypeSpec[] y)
			{
				if (x == y)
					return true;

				if (x.Length != y.Length)
					return false;

				for (int i = 0; i < x.Length; ++i)
					if (x[i] != y[i])
						return false;

				return true;
			}

			int IEqualityComparer<TypeSpec[]>.GetHashCode (TypeSpec[] obj)
			{
				int hash = 0;
				for (int i = 0; i < obj.Length; ++i)
					hash = (hash << 5) - hash + obj[i].GetHashCode ();

				return hash;
			}

			#endregion
		}

		//
		// When comparing type signature of overrides or overloads
		// this version tolerates different MVARs at same position
		//
		public static class Override
		{
			public static bool IsEqual (TypeSpec a, TypeSpec b)
			{
				if (a == b)
					return true;

				//
				// Consider the following example:
				//
				//     public abstract class A
				//     {
				//        public abstract T Foo<T>();
				//     }
				//
				//     public class B : A
				//     {
				//        public override U Foo<T>() { return default (U); }
				//     }
				//
				// Here, `T' and `U' are method type parameters from different methods
				// (A.Foo and B.Foo), so both `==' and Equals() will fail.
				//
				// However, since we're determining whether B.Foo() overrides A.Foo(),
				// we need to do a signature based comparision and consider them equal.
				//

				var tp_a = a as TypeParameterSpec;
				if (tp_a != null) {
					var tp_b = b as TypeParameterSpec;
					return tp_b != null && tp_a.IsMethodOwned == tp_b.IsMethodOwned && tp_a.DeclaredPosition == tp_b.DeclaredPosition;
				}

				var ac_a = a as ArrayContainer;
				if (ac_a != null) {
					var ac_b = b as ArrayContainer;
					return ac_b != null && ac_a.Rank == ac_b.Rank && IsEqual (ac_a.Element, ac_b.Element);
				}

				if (a == InternalType.Dynamic || b == InternalType.Dynamic)
					return b == TypeManager.object_type || a == TypeManager.object_type;

				if (a.MemberDefinition != b.MemberDefinition)
					return false;

				do {
					for (int i = 0; i < a.TypeArguments.Length; ++i) {
						if (!IsEqual (a.TypeArguments[i], b.TypeArguments[i]))
							return false;
					}

					a = a.DeclaringType;
					b = b.DeclaringType;
				} while (a != null);

				return true;
			}

			//
			// Compares unordered arrays
			//
			public static bool IsSame (TypeSpec[] a, TypeSpec[] b)
			{
				if (a == b)
					return true;

				if (a == null || b == null || a.Length != b.Length)
					return false;

				for (int ai = 0; ai < a.Length; ++ai) {
					bool found = false;
					for (int bi = 0; bi < b.Length; ++bi) {
						if (IsEqual (a[ai], b[bi])) {
							found = true;
							break;
						}
					}

					if (!found)
						return false;
				}

				return true;
			}

			public static bool IsEqual (AParametersCollection a, AParametersCollection b)
			{
				if (a == b)
					return true;

				if (a.Count != b.Count)
					return false;

				for (int i = 0; i < a.Count; ++i) {
					if (!IsEqual (a.Types[i], b.Types[i]))
						return false;

					const Parameter.Modifier ref_out = Parameter.Modifier.REF | Parameter.Modifier.OUT;
					if ((a.FixedParameters[i].ModFlags & ref_out) != (b.FixedParameters[i].ModFlags & ref_out))
						return false;
				}

				return true;
			}
		}

		//
		// Type variance equality comparison
		//
		public static class Variant
		{
			public static bool IsEqual (TypeSpec type1, TypeSpec type2)
			{
				if (!type1.IsGeneric || !type2.IsGeneric)
					return false;

				var target_type_def = type2.MemberDefinition;
				if (type1.MemberDefinition != target_type_def)
					return false;

				var t1_targs = type1.TypeArguments;
				var t2_targs = type2.TypeArguments;
				var targs_definition = target_type_def.TypeParameters;

				if (!type1.IsInterface && !type1.IsDelegate) {
					return false;
				}

				for (int i = 0; i < targs_definition.Length; ++i) {
					Variance v = targs_definition[i].Variance;
					if (v == Variance.None) {
						if (t1_targs[i] == t2_targs[i])
							continue;
						return false;
					}

					if (v == Variance.Covariant) {
						if (!Convert.ImplicitReferenceConversionExists (new EmptyExpression (t1_targs[i]), t2_targs[i]))
							return false;
					} else if (!Convert.ImplicitReferenceConversionExists (new EmptyExpression (t2_targs[i]), t1_targs[i])) {
						return false;
					}
				}

				return true;
			}
		}

		//
		// Checks whether two generic instances may become equal for some
		// particular instantiation (26.3.1).
		//
		public static class Unify
		{
			//
			// Either @a or @b must be generic type
			//
			public static bool IsEqual (TypeSpec a, TypeSpec b)
			{
				if (a.MemberDefinition != b.MemberDefinition)
					return false;

				var ta = a.TypeArguments;
				var tb = b.TypeArguments;
				for (int i = 0; i < ta.Length; i++) {
					if (!MayBecomeEqualGenericTypes (ta[i], tb[i]))
						return false;
				}

				return true;
			}

			static bool ContainsTypeParameter (TypeSpec tparam, TypeSpec type)
			{
				TypeSpec[] targs = type.TypeArguments;
				for (int i = 0; i < targs.Length; i++) {
					if (tparam == targs[i])
						return true;

					if (ContainsTypeParameter (tparam, targs[i]))
						return true;
				}

				return false;
			}

			/// <summary>
			///   Check whether `a' and `b' may become equal generic types.
			///   The algorithm to do that is a little bit complicated.
			/// </summary>
			static bool MayBecomeEqualGenericTypes (TypeSpec a, TypeSpec b)
			{
				if (a.IsGenericParameter) {
					//
					// If a is an array of a's type, they may never
					// become equal.
					//
					if (b.IsArray)
						return false;

					//
					// If b is a generic parameter or an actual type,
					// they may become equal:
					//
					//    class X<T,U> : I<T>, I<U>
					//    class X<T> : I<T>, I<float>
					// 
					if (b.IsGenericParameter)
						return a.DeclaringType == b.DeclaringType;

					//
					// We're now comparing a type parameter with a
					// generic instance.  They may become equal unless
					// the type parameter appears anywhere in the
					// generic instance:
					//
					//    class X<T,U> : I<T>, I<X<U>>
					//        -> error because you could instanciate it as
					//           X<X<int>,int>
					//
					//    class X<T> : I<T>, I<X<T>> -> ok
					//

					return !ContainsTypeParameter (a, b);
				}

				if (b.IsGenericParameter)
					return MayBecomeEqualGenericTypes (b, a);

				//
				// At this point, neither a nor b are a type parameter.
				//
				// If one of them is a generic instance, compare them (if the
				// other one is not a generic instance, they can never
				// become equal).
				//
				if (TypeManager.IsGenericType (a) || TypeManager.IsGenericType (b))
					return IsEqual (a, b);

				//
				// If both of them are arrays.
				//
				var a_ac = a as ArrayContainer;
				if (a_ac != null) {
					var b_ac = b as ArrayContainer;
					if (b_ac == null || a_ac.Rank != b_ac.Rank)
						return false;

					return MayBecomeEqualGenericTypes (a_ac.Element, b_ac.Element);
				}

				//
				// Ok, two ordinary types.
				//
				return false;
			}
		}

		public static bool Equals (TypeSpec[] x, TypeSpec[] y)
		{
			if (x == y)
				return true;

			if (x.Length != y.Length)
				return false;

			for (int i = 0; i < x.Length; ++i)
				if (!IsEqual (x[i], y[i]))
					return false;

			return true;
		}

		//
		// Identity type conversion
		//
		// Default reference comparison, it has to be used when comparing
		// two possible dynamic/internal types
		//
		public static bool IsEqual (TypeSpec a, TypeSpec b)
		{
			if (a == b) {
				// This also rejects dynamic == dynamic
				return a.Kind != MemberKind.InternalCompilerType || a == InternalType.Dynamic;
			}

			//
			// object and dynamic are considered equivalent there is an identity conversion
			// between object and dynamic, and between constructed types that are the same
			// when replacing all occurences of dynamic with object.
			//
			if (a == InternalType.Dynamic || b == InternalType.Dynamic)
				return b == TypeManager.object_type || a == TypeManager.object_type;

			if (a == null)
				return false;

			if (a.IsArray) {
				var a_a = (ArrayContainer) a;
				var b_a = b as ArrayContainer;
				if (b_a == null)
					return false;

				return IsEqual (a_a.Element, b_a.Element) && a_a.Rank == b_a.Rank;
			}

			if (!a.IsGeneric || b == null || !b.IsGeneric)
				return false;

			if (a.MemberDefinition != b.MemberDefinition)
				return false;

			do {
				if (!Equals (a.TypeArguments, b.TypeArguments))
					return false;

				a = a.DeclaringType;
				b = b.DeclaringType;
			} while (a != null);

			return true;
		}
	}

	public interface ITypeDefinition : IMemberDefinition
	{
		IAssemblyDefinition DeclaringAssembly { get; }
		string Namespace { get; }
		int TypeParametersCount { get; }
		TypeParameterSpec[] TypeParameters { get; }

		TypeSpec GetAttributeCoClass ();
		string GetAttributeDefaultMember ();
		AttributeUsageAttribute GetAttributeUsage (PredefinedAttribute pa);
		bool IsInternalAsPublic (IAssemblyDefinition assembly);
		void LoadMembers (TypeSpec declaringType, bool onlyTypes, ref MemberCache cache);
	}

	class InternalType : TypeSpec, ITypeDefinition
	{
		public static readonly InternalType AnonymousMethod = new InternalType ("anonymous method");
		public static readonly InternalType Arglist = new InternalType ("__arglist");
		public static BuildinTypeSpec Dynamic;
		public static readonly InternalType MethodGroup = new InternalType ("method group");
		public static BuildinTypeSpec Null;
		public static readonly InternalType FakeInternalType = new InternalType ("<fake$type>");

		readonly string name;

		InternalType (string name, MemberCache cache)
			: this (name)
		{
			this.cache = cache;
		}

		InternalType (string name)
			: base (MemberKind.InternalCompilerType, null, null, null, Modifiers.PUBLIC)
		{
			this.name = name;
			this.definition = this;
			cache = MemberCache.Empty;

			// Make all internal types CLS-compliant, non-obsolete
			state = (state & ~(StateFlags.CLSCompliant_Undetected | StateFlags.Obsolete_Undetected)) | StateFlags.CLSCompliant;
		}

		#region Properties

		public override int Arity {
			get {
				return 0;
			}
		}

		IAssemblyDefinition ITypeDefinition.DeclaringAssembly {
			get {
				throw new NotImplementedException ();
			}
		}

		bool IMemberDefinition.IsImported {
			get {
				return false;
			}
		}

		public override string Name {
			get {
				return name;
			}
		}

		string ITypeDefinition.Namespace {
			get {
				return null;
			}
		}

		int ITypeDefinition.TypeParametersCount {
			get {
				return 0;
			}
		}

		TypeParameterSpec[] ITypeDefinition.TypeParameters {
			get {
				return null;
			}
		}

		#endregion

		public override string GetSignatureForError ()
		{
			return name;
		}

		#region ITypeDefinition Members

		TypeSpec ITypeDefinition.GetAttributeCoClass ()
		{
			return null;
		}

		string ITypeDefinition.GetAttributeDefaultMember ()
		{
			return null;
		}

		AttributeUsageAttribute ITypeDefinition.GetAttributeUsage (PredefinedAttribute pa)
		{
			return null;
		}

		bool ITypeDefinition.IsInternalAsPublic (IAssemblyDefinition assembly)
		{
			throw new NotImplementedException ();
		}

		void ITypeDefinition.LoadMembers (TypeSpec declaringType, bool onlyTypes, ref MemberCache cache)
		{
			throw new NotImplementedException ();
		}

		string[] IMemberDefinition.ConditionalConditions ()
		{
			return null;
		}

		ObsoleteAttribute IMemberDefinition.GetAttributeObsolete ()
		{
			return null;
		}

		bool IMemberDefinition.IsNotCLSCompliant ()
		{
			return false;
		}

		void IMemberDefinition.SetIsAssigned ()
		{
		}

		void IMemberDefinition.SetIsUsed ()
		{
		}

		#endregion
	}

	public abstract class ElementTypeSpec : TypeSpec, ITypeDefinition
	{
		protected ElementTypeSpec (MemberKind kind, TypeSpec element, MetaType info)
			: base (kind, element.DeclaringType, null, info, element.Modifiers)
		{
			this.Element = element;

			// Some flags can be copied directly from the element
			const StateFlags shared_flags = StateFlags.CLSCompliant | StateFlags.CLSCompliant_Undetected
				| StateFlags.Obsolete | StateFlags.Obsolete_Undetected | StateFlags.HasDynamicElement;
			state &= ~shared_flags;
			state |= (element.state & shared_flags);

			if (element == InternalType.Dynamic)
				state |= StateFlags.HasDynamicElement;

			// Has to use its own type definition instead of just element definition to
			// correctly identify itself for cases like x.MemberDefininition == predefined.MemberDefinition
			this.definition = this;

			cache = MemberCache.Empty;
		}

		#region Properties

		public TypeSpec Element { get; private set; }

		public override string Name {
			get {
				throw new NotSupportedException ();
			}
		}

		#endregion

		public override ObsoleteAttribute GetAttributeObsolete ()
		{
			return Element.GetAttributeObsolete ();
		}

		protected virtual string GetPostfixSignature ()
		{
			return null;
		}

		public override string GetSignatureForError ()
		{
			return Element.GetSignatureForError () + GetPostfixSignature ();
		}

		public override TypeSpec Mutate (TypeParameterMutator mutator)
		{
			var me = Element.Mutate (mutator);
			if (me == Element)
				return this;

			var mutated = (ElementTypeSpec) MemberwiseClone ();
			mutated.Element = me;
			mutated.info = null;
			return mutated;
		}

		#region ITypeDefinition Members

		IAssemblyDefinition ITypeDefinition.DeclaringAssembly {
			get {
				return Element.MemberDefinition.DeclaringAssembly;
			}
		}

		bool ITypeDefinition.IsInternalAsPublic (IAssemblyDefinition assembly)
		{
			return Element.MemberDefinition.IsInternalAsPublic (assembly);
		}

		public string Namespace {
			get { throw new NotImplementedException (); }
		}

		public int TypeParametersCount {
			get {
				return 0;
			}
		}

		public TypeParameterSpec[] TypeParameters {
			get {
				throw new NotSupportedException ();
			}
		}

		public TypeSpec GetAttributeCoClass ()
		{
			return Element.MemberDefinition.GetAttributeCoClass ();
		}

		public string GetAttributeDefaultMember ()
		{
			return Element.MemberDefinition.GetAttributeDefaultMember ();
		}

		public void LoadMembers (TypeSpec declaringType, bool onlyTypes, ref MemberCache cache)
		{
			Element.MemberDefinition.LoadMembers (declaringType, onlyTypes, ref cache);
		}

		public bool IsImported {
			get {
				return Element.MemberDefinition.IsImported;
			}
		}

		public string[] ConditionalConditions ()
		{
			return Element.MemberDefinition.ConditionalConditions ();
		}

		bool IMemberDefinition.IsNotCLSCompliant ()
		{
			return Element.MemberDefinition.IsNotCLSCompliant ();
		}

		public void SetIsAssigned ()
		{
			Element.MemberDefinition.SetIsAssigned ();
		}

		public void SetIsUsed ()
		{
			Element.MemberDefinition.SetIsUsed ();
		}

		#endregion
	}

	public class ArrayContainer : ElementTypeSpec
	{
		struct TypeRankPair : IEquatable<TypeRankPair>
		{
			TypeSpec ts;
			int rank;

			public TypeRankPair (TypeSpec ts, int rank)
			{
				this.ts = ts;
				this.rank = rank;
			}

			public override int GetHashCode ()
			{
				return ts.GetHashCode () ^ rank.GetHashCode ();
			}

			#region IEquatable<Tuple<T1,T2>> Members

			public bool Equals (TypeRankPair other)
			{
				return other.ts == ts && other.rank == rank;
			}

			#endregion
		}

		readonly int rank;
		static Dictionary<TypeRankPair, ArrayContainer> instances = new Dictionary<TypeRankPair, ArrayContainer> ();

		private ArrayContainer (TypeSpec element, int rank)
			: base (MemberKind.ArrayType, element, null)
		{
			this.rank = rank;
		}

		public int Rank {
			get {
				return rank;
			}
		}

		public MethodInfo GetConstructor ()
		{
			var mb = RootContext.ToplevelTypes.Builder;

			var arg_types = new MetaType[rank];
			for (int i = 0; i < rank; i++)
				arg_types[i] = TypeManager.int32_type.GetMetaInfo ();

			var ctor = mb.GetArrayMethod (
				GetMetaInfo (), Constructor.ConstructorName,
				CallingConventions.HasThis,
				null, arg_types);

			return ctor;
		}

		public MethodInfo GetAddressMethod ()
		{
			var mb = RootContext.ToplevelTypes.Builder;

			var arg_types = new MetaType[rank];
			for (int i = 0; i < rank; i++)
				arg_types[i] = TypeManager.int32_type.GetMetaInfo ();

			var address = mb.GetArrayMethod (
				GetMetaInfo (), "Address",
				CallingConventions.HasThis | CallingConventions.Standard,
				ReferenceContainer.MakeType (Element).GetMetaInfo (), arg_types);

			return address;
		}

		public MethodInfo GetGetMethod ()
		{
			var mb = RootContext.ToplevelTypes.Builder;

			var arg_types = new MetaType[rank];
			for (int i = 0; i < rank; i++)
				arg_types[i] = TypeManager.int32_type.GetMetaInfo ();

			var get = mb.GetArrayMethod (
				GetMetaInfo (), "Get",
				CallingConventions.HasThis | CallingConventions.Standard,
				Element.GetMetaInfo (), arg_types);

			return get;
		}

		public MethodInfo GetSetMethod ()
		{
			var mb = RootContext.ToplevelTypes.Builder;

			var arg_types = new MetaType[rank + 1];
			for (int i = 0; i < rank; i++)
				arg_types[i] = TypeManager.int32_type.GetMetaInfo ();

			arg_types[rank] = Element.GetMetaInfo ();

			var set = mb.GetArrayMethod (
				GetMetaInfo (), "Set",
				CallingConventions.HasThis | CallingConventions.Standard,
				TypeManager.void_type.GetMetaInfo (), arg_types);

			return set;
		}

		public override MetaType GetMetaInfo ()
		{
			if (info == null) {
				if (rank == 1)
					info = Element.GetMetaInfo ().MakeArrayType ();
				else
					info = Element.GetMetaInfo ().MakeArrayType (rank);
			}

			return info;
		}

		protected override string GetPostfixSignature()
		{
			return GetPostfixSignature (rank);
		}

		public static string GetPostfixSignature (int rank)
		{
			StringBuilder sb = new StringBuilder ();
			sb.Append ("[");
			for (int i = 1; i < rank; i++) {
				sb.Append (",");
			}
			sb.Append ("]");

			return sb.ToString ();
		}

		public static ArrayContainer MakeType (TypeSpec element)
		{
			return MakeType (element, 1);
		}

		public static ArrayContainer MakeType (TypeSpec element, int rank)
		{
			ArrayContainer ac;
			var key = new TypeRankPair (element, rank);
			if (!instances.TryGetValue (key, out ac)) {
				ac = new ArrayContainer (element, rank) {
					BaseType = TypeManager.array_type
				};

				instances.Add (key, ac);
			}

			return ac;
		}

		public static void Reset ()
		{
			instances = new Dictionary<TypeRankPair, ArrayContainer> ();
		}
	}

	class ReferenceContainer : ElementTypeSpec
	{
		static Dictionary<TypeSpec, ReferenceContainer> instances = new Dictionary<TypeSpec, ReferenceContainer> ();

		private ReferenceContainer (TypeSpec element)
			: base (MemberKind.Class, element, null)	// TODO: Kind.Class is most likely wrong
		{
		}

		public override MetaType GetMetaInfo ()
		{
			if (info == null) {
				info = Element.GetMetaInfo ().MakeByRefType ();
			}

			return info;
		}

		public static ReferenceContainer MakeType (TypeSpec element)
		{
			ReferenceContainer pc;
			if (!instances.TryGetValue (element, out pc)) {
				pc = new ReferenceContainer (element);
				instances.Add (element, pc);
			}

			return pc;
		}

		public static void Reset ()
		{
			instances = new Dictionary<TypeSpec, ReferenceContainer> ();
		}
	}

	class PointerContainer : ElementTypeSpec
	{
		static Dictionary<TypeSpec, PointerContainer> instances = new Dictionary<TypeSpec, PointerContainer> ();

		private PointerContainer (TypeSpec element)
			: base (MemberKind.PointerType, element, null)
		{
			// It's never CLS-Compliant
			state &= ~StateFlags.CLSCompliant_Undetected;
		}

		public override MetaType GetMetaInfo ()
		{
			if (info == null) {
				info = Element.GetMetaInfo ().MakePointerType ();
			}

			return info;
		}

		protected override string GetPostfixSignature()
		{
 			return "*";
		}

		public static PointerContainer MakeType (TypeSpec element)
		{
			PointerContainer pc;
			if (!instances.TryGetValue (element, out pc)) {
				pc = new PointerContainer (element);
				instances.Add (element, pc);
			}

			return pc;
		}

		public static void Reset ()
		{
			instances = new Dictionary<TypeSpec, PointerContainer> ();
		}
	}
}