--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/Source/ComponentModel/TypeDescriptorExtender.cs	Thu Mar 27 21:46:09 2014 +0400
@@ -0,0 +1,232 @@
+using System;
+using System.Collections;
+using System.ComponentModel;
+using System.Reflection;
+
+using BLToolkit.Reflection;
+
+namespace BLToolkit.ComponentModel
+{
+	public abstract class TypeDescriptorExtender : ICustomTypeDescriptor, ITypeDescriptionProvider
+	{
+		#region Constructors
+
+		protected TypeDescriptorExtender(Type baseType)
+		{
+			if (baseType == null)
+				throw new ArgumentNullException("baseType");
+
+			_baseObject = TypeAccessor.CreateInstanceEx(baseType);
+		}
+
+		protected TypeDescriptorExtender(object baseObject)
+		{
+			if (baseObject == null)
+				throw new ArgumentNullException("baseObject");
+
+			_baseObject = baseObject;
+		}
+
+		#endregion
+
+		#region Public Members
+
+		private readonly object _baseObject;
+		public           object  BaseObject
+		{
+			get { return _baseObject; }
+		}
+
+		#endregion
+
+		#region Protected Members
+
+		private static readonly Hashtable _hashDescriptors = new Hashtable();
+
+		[NonSerialized]
+		private ICustomTypeDescriptor _typeDescriptor;
+		private ICustomTypeDescriptor  TypeDescriptor
+		{
+			get
+			{
+				if (_typeDescriptor == null)
+				{
+					Type key1 = GetType();
+					Type key2 = _baseObject.GetType();
+
+					Hashtable tbl = (Hashtable)_hashDescriptors[key1];
+
+					if (tbl == null)
+						_hashDescriptors[key1] = tbl = new Hashtable();
+
+					_typeDescriptor = (ICustomTypeDescriptor)tbl[key2];
+
+					if (_typeDescriptor == null)
+						tbl[key2] = _typeDescriptor = CreateTypeDescriptor();
+				}
+
+				return _typeDescriptor;
+			}
+		}
+
+		private ICustomTypeDescriptor CreateTypeDescriptor()
+		{
+			return new CustomTypeDescriptorImpl(this);
+		}
+
+		#endregion
+
+		#region ICustomTypeDescriptor Members
+
+		AttributeCollection ICustomTypeDescriptor.GetAttributes()
+		{
+			return TypeDescriptor.GetAttributes();
+		}
+
+		string ICustomTypeDescriptor.GetClassName()
+		{
+			return TypeDescriptor.GetClassName();
+		}
+
+		string ICustomTypeDescriptor.GetComponentName()
+		{
+			return TypeDescriptor.GetComponentName();
+		}
+
+		TypeConverter ICustomTypeDescriptor.GetConverter()
+		{
+			return TypeDescriptor.GetConverter();
+		}
+
+		EventDescriptor ICustomTypeDescriptor.GetDefaultEvent()
+		{
+			return TypeDescriptor.GetDefaultEvent();
+		}
+
+		PropertyDescriptor ICustomTypeDescriptor.GetDefaultProperty()
+		{
+			return TypeDescriptor.GetDefaultProperty();
+		}
+
+		object ICustomTypeDescriptor.GetEditor(Type editorBaseType)
+		{
+			return TypeDescriptor.GetEditor(editorBaseType);
+		}
+
+		EventDescriptorCollection ICustomTypeDescriptor.GetEvents(Attribute[] attributes)
+		{
+			return TypeDescriptor.GetEvents(attributes);
+		}
+
+		EventDescriptorCollection ICustomTypeDescriptor.GetEvents()
+		{
+			return TypeDescriptor.GetEvents();
+		}
+
+		PropertyDescriptorCollection ICustomTypeDescriptor.GetProperties(Attribute[] attributes)
+		{
+			return TypeDescriptor.GetProperties(attributes);
+		}
+
+		PropertyDescriptorCollection ICustomTypeDescriptor.GetProperties()
+		{
+			return TypeDescriptor.GetProperties();
+		}
+
+		object ICustomTypeDescriptor.GetPropertyOwner(PropertyDescriptor pd)
+		{
+			return TypeDescriptor.GetPropertyOwner(pd);
+		}
+
+		#endregion
+
+		#region ITypeDescriptionProvider Members
+
+		[NonSerialized]
+		private ICustomTypeDescriptor _baseTypeDescriptor;
+		private ICustomTypeDescriptor  BaseTypeDescriptor
+		{
+			get
+			{
+				if (_baseTypeDescriptor == null)
+				{
+					_baseTypeDescriptor = _baseObject as ICustomTypeDescriptor ??
+						new CustomTypeDescriptorImpl(_baseObject.GetType());
+				}
+
+				return _baseTypeDescriptor;
+			}
+		}
+
+		[NonSerialized]
+		private ITypeDescriptionProvider _provider;
+		private ITypeDescriptionProvider  Provider
+		{
+			get
+			{
+				if (_provider == null)
+					_provider = TypeAccessor.GetAccessor(GetType());
+
+				return _provider;
+			}
+		}
+
+		Type   ITypeDescriptionProvider.OriginalType  { get { return GetType();      } }
+		string ITypeDescriptionProvider.ClassName     { get { return GetType().Name; } }
+		string ITypeDescriptionProvider.ComponentName { get { return GetType().Name; } }
+
+		EventDescriptor ITypeDescriptionProvider.GetEvent(string name)
+		{
+			EventInfo ei = GetType().GetEvent(name);
+
+			return ei != null ? Provider.GetEvent(name) : BaseTypeDescriptor.GetEvents()[name];
+		}
+
+		PropertyDescriptor ITypeDescriptionProvider.GetProperty(string name)
+		{
+			PropertyDescriptor pd = Provider.GetProperty(name);
+
+			return pd ?? BaseTypeDescriptor.GetProperties()[name];
+		}
+
+		AttributeCollection ITypeDescriptionProvider.GetAttributes()
+		{
+			AttributeCollection col1 = Provider.GetAttributes();
+			AttributeCollection col2 = BaseTypeDescriptor.GetAttributes();
+
+			Attribute[] attrs = new Attribute[col1.Count + col2.Count];
+
+			for (int i = 0; i < col1.Count; i++)
+				attrs[i] = col1[i];
+
+			for (int i = 0; i < col2.Count; i++)
+				attrs[col1.Count + i] = col2[i];
+
+			return new AttributeCollection(attrs);
+		}
+
+		EventDescriptorCollection ITypeDescriptionProvider.GetEvents()
+		{
+			EventDescriptorCollection col1 = Provider.GetEvents();
+			EventDescriptorCollection col2 = BaseTypeDescriptor.GetEvents();
+
+			EventDescriptorCollection col  = new EventDescriptorCollection(new EventDescriptor[0]);
+
+			foreach (EventDescriptor ed in col1)
+				col.Add(ed);
+
+			foreach (EventDescriptor ed in col2)
+				if (col.Find(ed.Name, false) == null)
+					col.Add(ed);
+
+			return col;
+		}
+
+		PropertyDescriptorCollection ITypeDescriptionProvider.GetProperties()
+		{
+			throw new Exception("The method or operation is not implemented.");
+		}
+
+		#endregion
+	}
+}