System.Windows.Forms/System.Windows.Forms/ListBindingHelper.cs

// Permission is hereby granted, free of charge, to any person obtaining
// a copy of this software and associated documentation files (the
// "Software"), to deal in the Software without restriction, including
// without limitation the rights to use, copy, modify, merge, publish,
// distribute, sublicense, and/or sell copies of the Software, and to
// permit persons to whom the Software is furnished to do so, subject to
// the following conditions:
//
// The above copyright notice and this permission notice shall be
// included in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
// LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
// OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
// WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
//
// Copyright (c) 2007 Novell, Inc.
//
// Author:
// 	Carlos Alberto Cortez <calberto.cortez@gmail.com>
//      Ivan Zlatev <contact@i-nz.net>
//

using System;
using System.Collections;
using System.ComponentModel;
using System.Reflection;
using System.Collections.Generic;

namespace System.Windows.Forms
{

	public static class ListBindingHelper
	{
		public static object GetList (object list)
		{
			if (list is IListSource)
				return ((IListSource) list).GetList ();
			return list;
		}

		public static object GetList (object dataSource, string dataMember)
		{
			dataSource = GetList (dataSource);
			if (dataSource == null || dataMember == null || dataMember.Length == 0)
				return dataSource;

			PropertyDescriptor property = GetListItemProperties (dataSource).Find (dataMember, true);
			if (property == null)
				throw new ArgumentException ("dataMember");

			object item = null;

			ICurrencyManagerProvider currencyManagerProvider = dataSource as ICurrencyManagerProvider;
			if (currencyManagerProvider != null && currencyManagerProvider.CurrencyManager != null) {
				CurrencyManager currencyManager = currencyManagerProvider.CurrencyManager;
				if (currencyManager != null && currencyManager.Count > 0 && currencyManager.Current != null)
					item = currencyManager.Current;
			}

			if (item == null) {
				if (dataSource is IEnumerable) {
					if (dataSource is IList) {
						IList list = (IList) dataSource;
						item = list.Count > 0 ? list[0] : null;
					} else {
						IEnumerator e = ((IEnumerable) dataSource).GetEnumerator ();
						if (e != null && e.MoveNext ())
							item = e.Current;
					}
				} else {
					item = dataSource;
				}
			}

			if (item != null)
				return property.GetValue (item);
			return null;
		}

		public static Type GetListItemType (object list)
		{
			return GetListItemType (list, String.Empty);
		}

		public static Type GetListItemType (object dataSource, string dataMember)
		{
			if (dataSource == null)
				return null;

			if (dataMember != null && dataMember.Length > 0) {
				PropertyDescriptor property = GetProperty (dataSource, dataMember);
				if (property == null)
					return typeof (object);

				return property.PropertyType;
			}

			if (dataSource is Array)
				return dataSource.GetType ().GetElementType ();

			// IEnumerable seems to have higher precedence over IList
			if (dataSource is IEnumerable) {
				IEnumerator enumerator = ((IEnumerable) dataSource).GetEnumerator ();
				if (enumerator.MoveNext () && enumerator.Current != null)
					return enumerator.Current.GetType ();

				if (dataSource is IList || dataSource.GetType () == typeof (IList<>)) {
					PropertyInfo property = GetPropertyByReflection (dataSource.GetType (), "Item");
					if (property != null) // `Item' could be interface-explicit, and thus private
						return property.PropertyType;
				}

				// fallback to object
				return typeof (object);
			}

			return dataSource.GetType ();
		}

		public static PropertyDescriptorCollection GetListItemProperties (object list)
		{
			return GetListItemProperties (list, null);
		}

		public static PropertyDescriptorCollection GetListItemProperties (object list, PropertyDescriptor [] listAccessors)
		{
			list = GetList (list);

			if (list == null)
				return new PropertyDescriptorCollection (null);

			if (list is ITypedList)
				return ((ITypedList)list).GetItemProperties (listAccessors);

			if (listAccessors == null || listAccessors.Length == 0) {
				Type item_type = GetListItemType (list);
				return TypeDescriptor.GetProperties (item_type,
					new Attribute [] { new BrowsableAttribute (true) });
			}

			// Take into account only the first property
			Type property_type = listAccessors [0].PropertyType;
			if (typeof (IList).IsAssignableFrom (property_type) || typeof (IList<>).IsAssignableFrom (property_type)) {

				PropertyInfo property = GetPropertyByReflection (property_type, "Item");
				return TypeDescriptor.GetProperties (property.PropertyType);
			}

			return new PropertyDescriptorCollection (new PropertyDescriptor [0]);
		}

		public static PropertyDescriptorCollection GetListItemProperties (object dataSource, string dataMember,
			PropertyDescriptor [] listAccessors)
		{
			throw new NotImplementedException ();
		}

		public static string GetListName (object list, PropertyDescriptor [] listAccessors)
		{
			if (list == null)
				return String.Empty;

			Type item_type = GetListItemType (list);
			return item_type.Name;
		}

		static PropertyDescriptor GetProperty (object obj, string property_name)
		{
			return TypeDescriptor.GetProperties (obj,
							     new Attribute [] { new BrowsableAttribute (true) })[property_name];
		}

		//
		// Need to use reflection as we need to bypass the TypeDescriptor.GetProperties () limitations
		//
		static PropertyInfo GetPropertyByReflection (Type type, string property_name)
		{
			foreach (PropertyInfo prop in type.GetProperties (BindingFlags.Public | BindingFlags.Instance))
				if (prop.Name == property_name)
					return prop;

			return null;
		}
	}
}