Newtonsoft.Json\Serialization\DefaultReferenceResolver.cs

#region License

// Copyright (c) 2007 James Newton-King

//

// 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.

#endregion

using System;

using System.Collections.Generic;

using System.Linq;

using System.Runtime.CompilerServices;

using System.Text;

using Newtonsoft.Json.Utilities;

using System.Globalization;

namespace Newtonsoft.Json.Serialization

{

  internal class DefaultReferenceResolver : IReferenceResolver

  {

    private class ReferenceEqualsEqualityComparer : IEqualityComparer<object>

    {

      bool IEqualityComparer<object>.Equals(object x, object y)

      {

        return ReferenceEquals(x, y);

      }

      int IEqualityComparer<object>.GetHashCode(object obj)

      {

#if !PocketPC

        // put objects in a bucket based on their reference

        return RuntimeHelpers.GetHashCode(obj);

#else

        // put all objects in the same bucket so ReferenceEquals is called on all

        return -1;

#endif

      }

    }

    private int _referenceCount;

    private BidirectionalDictionary<string, object> _mappings;

    private BidirectionalDictionary<string, object> Mappings

    {

      get

      {

        // override equality comparer for object key dictionary

        // object will be modified as it deserializes and might have mutable hashcode

        if (_mappings == null)

          _mappings = new BidirectionalDictionary<string, object>(

            EqualityComparer<string>.Default,

            new ReferenceEqualsEqualityComparer());

        return _mappings;

      }

    }

    public object ResolveReference(string reference)

    {

      object value;

      Mappings.TryGetByFirst(reference, out value);

      return value;

    }

    public string GetReference(object value)

    {

      string reference;

      if (!Mappings.TryGetBySecond(value, out reference))

      {

        _referenceCount++;

        reference = _referenceCount.ToString(CultureInfo.InvariantCulture);

        Mappings.Add(reference, value);

      }

      return reference;

    }

    public void AddReference(string reference, object value)

    {

      Mappings.Add(reference, value);

    }

    public bool IsReferenced(object value)

    {

      string reference;

      return Mappings.TryGetBySecond(value, out reference);

    }

  }

}