linux-packaging-mono/mcs/class/System.Xaml/System.Xaml.Schema/XamlValueConverter.cs

//
// Copyright (C) 2010 Novell Inc. http://novell.com
//
// 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.
//
using System;
using System.Collections.Generic;
using System.ComponentModel;

namespace System.Xaml.Schema
{
	public class XamlValueConverter<TConverterBase> : IEquatable<XamlValueConverter<TConverterBase>>
		where TConverterBase : class
	{
		public XamlValueConverter (Type converterType, XamlType targetType)
			: this (converterType, targetType, null)
		{
		}

		public XamlValueConverter (Type converterType, XamlType targetType, string name)
		{
			if (converterType == null && targetType == null && name == null)
				throw new ArgumentException ("Either of converterType, targetType or name must be non-null");
			ConverterType = converterType;
			TargetType = targetType;
			Name = name;
		}

		TConverterBase converter_instance;
		public TConverterBase ConverterInstance {
			get {
				if (converter_instance == null)
					converter_instance = CreateInstance ();
				return converter_instance;
			}
		}
		public Type ConverterType { get; private set; }
		public string Name { get; private set; }
		public XamlType TargetType { get; private set; }

		
		public static bool operator == (XamlValueConverter<TConverterBase> converter1, XamlValueConverter<TConverterBase> converter2)
		{
			return IsNull (converter1) ? IsNull (converter2) : converter1.Equals (converter2);
		}

		static bool IsNull (XamlValueConverter<TConverterBase> a)
		{
			return Object.ReferenceEquals (a, null);
		}

		public static bool operator != (XamlValueConverter<TConverterBase> converter1, XamlValueConverter<TConverterBase> converter2)
		{
			return IsNull (converter1) ? !IsNull (converter2) : IsNull (converter2) || converter1.ConverterType != converter2.ConverterType || converter1.TargetType != converter2.TargetType || converter1.Name != converter2.Name;
		}
		
		public bool Equals (XamlValueConverter<TConverterBase> other)
		{
			return !IsNull (other) && ConverterType == other.ConverterType && TargetType == other.TargetType && Name == other.Name;
		}

		public override bool Equals (object obj)
		{
			var a = obj as XamlValueConverter<TConverterBase>;
			return Equals (a);
		}

		protected virtual TConverterBase CreateInstance ()
		{
			if (ConverterType == null)
				return null;

			if (!typeof (TConverterBase).IsAssignableFrom (ConverterType))
				throw new XamlSchemaException (String.Format ("ConverterType '{0}' is not derived from '{1}' type", ConverterType, typeof (TConverterBase)));

			if (TargetType != null && TargetType.UnderlyingType != null) {
				// special case: Enum
				if (TargetType.UnderlyingType.IsEnum)
					return (TConverterBase) (object) new EnumConverter (TargetType.UnderlyingType);
				// special case: Nullable<T>
				if (TargetType.IsNullable && TargetType.UnderlyingType.IsValueType)
					return (TConverterBase) (object) new NullableConverter (TargetType.UnderlyingType);
			}

			if (ConverterType.GetConstructor (Type.EmptyTypes) == null)
				return null;

			return (TConverterBase) Activator.CreateInstance (ConverterType, true);
		}

		public override int GetHashCode ()
		{
			var ret = ConverterType != null ? ConverterType.GetHashCode () : 0;
			ret <<= 5;
			if (TargetType != null)
				ret += TargetType.GetHashCode ();
			ret <<= 5;
			if (Name != null)
				ret += Name.GetHashCode ();
			return ret;
		}

		public override string ToString ()
		{
			if (Name != null)
				return Name;
			if (ConverterType != null && TargetType != null)
				return String.Concat (ConverterType.Name, "(", TargetType.Name, ")");
			else if (ConverterType != null)
				return ConverterType.Name;
			else
				return TargetType.Name;
		}
	}
}