/source/library/Interlace/Binding/ViewConverters/EqualityConverter.cs

#region Using Directives and Copyright Notice



// Copyright (c) 2007-2010, Computer Consultancy Pty Ltd

// All rights reserved.

// 

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//       notice, this list of conditions and the following disclaimer.

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//       documentation and/or other materials provided with the distribution.

//     * Neither the name of the Computer Consultancy Pty Ltd 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" 

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using System;

using System.Collections.Generic;

using System.Text;



using Interlace.Binding.Views;



#endregion



namespace Interlace.Binding.ViewConverters

{

    public class EqualityConverter : ViewConverterBase

    {

        bool _negate;

        object[] _values;



        public EqualityConverter(bool negate, params object[] values)

        {

            _negate = negate;

            _values = values;

        }



        public static EqualityConverter EqualsNull

        {

            get 

            {

                return new EqualityConverter(false, new object[] { null });

            }

        }



        public static EqualityConverter NotEqualsNull

        {

            get 

            {

                return new EqualityConverter(true, new object[] { null });

            }

        }



        public override object ModelToView(object obj)

        {

            foreach (object value in _values)

            {

                if (object.Equals(value, obj)) return !_negate;

            }



            return _negate;

        }



        public override object ViewToModel(object obj)

        {

            throw new InvalidOperationException("A change was made to the view that had an " +

                "attached EqualityConverter, which is read only.");

        }

    }

}