SurrogateSelector.cs

using System.Runtime.InteropServices;
using System.Security;

namespace System.Runtime.Serialization
{
    [ComVisible(true)]
    public class SurrogateSelector : ISurrogateSelector
    {
        internal SurrogateHashtable m_surrogates;

        internal ISurrogateSelector m_nextSelector;

        public SurrogateSelector()
        {
            m_surrogates = new SurrogateHashtable(32);
        }

        public virtual void AddSurrogate(Type type, StreamingContext context, ISerializationSurrogate surrogate)
        {
            if (type == null)
            {
                throw new ArgumentNullException("type");
            }
            if (surrogate == null)
            {
                throw new ArgumentNullException("surrogate");
            }
            SurrogateKey key = new SurrogateKey(type, context);
            m_surrogates.Add(key, surrogate);
        }

        [SecurityCritical]
        private static bool HasCycle(ISurrogateSelector selector)
        {
            ISurrogateSelector surrogateSelector = selector;
            ISurrogateSelector surrogateSelector2 = selector;
            while (surrogateSelector != null)
            {
                surrogateSelector = surrogateSelector.GetNextSelector();
                if (surrogateSelector == null)
                {
                    return true;
                }
                if (surrogateSelector == surrogateSelector2)
                {
                    return false;
                }
                surrogateSelector = surrogateSelector.GetNextSelector();
                surrogateSelector2 = surrogateSelector2.GetNextSelector();
                if (surrogateSelector == surrogateSelector2)
                {
                    return false;
                }
            }
            return true;
        }

        [SecurityCritical]
        public virtual void ChainSelector(ISurrogateSelector selector)
        {
            if (selector == null)
            {
                throw new ArgumentNullException("selector");
            }
            if (selector == this)
            {
                throw new SerializationException(Environment.GetResourceString("Serialization_DuplicateSelector"));
            }
            if (!HasCycle(selector))
            {
                throw new ArgumentException(Environment.GetResourceString("Serialization_SurrogateCycleInArgument"), "selector");
            }
            ISurrogateSelector nextSelector = selector.GetNextSelector();
            ISurrogateSelector surrogateSelector = selector;
            while (nextSelector != null && nextSelector != this)
            {
                surrogateSelector = nextSelector;
                nextSelector = nextSelector.GetNextSelector();
            }
            if (nextSelector == this)
            {
                throw new ArgumentException(Environment.GetResourceString("Serialization_SurrogateCycle"), "selector");
            }
            nextSelector = selector;
            ISurrogateSelector surrogateSelector2 = selector;
            while (nextSelector != null)
            {
                nextSelector = ((nextSelector != surrogateSelector) ? nextSelector.GetNextSelector() : GetNextSelector());
                if (nextSelector == null)
                {
                    break;
                }
                if (nextSelector == surrogateSelector2)
                {
                    throw new ArgumentException(Environment.GetResourceString("Serialization_SurrogateCycle"), "selector");
                }
                nextSelector = ((nextSelector != surrogateSelector) ? nextSelector.GetNextSelector() : GetNextSelector());
                surrogateSelector2 = ((surrogateSelector2 != surrogateSelector) ? surrogateSelector2.GetNextSelector() : GetNextSelector());
                if (nextSelector == surrogateSelector2)
                {
                    throw new ArgumentException(Environment.GetResourceString("Serialization_SurrogateCycle"), "selector");
                }
            }
            ISurrogateSelector nextSelector2 = m_nextSelector;
            m_nextSelector = selector;
            if (nextSelector2 != null)
            {
                surrogateSelector.ChainSelector(nextSelector2);
            }
        }

        [SecurityCritical]
        public virtual ISurrogateSelector GetNextSelector()
        {
            return m_nextSelector;
        }

        [SecurityCritical]
        public virtual ISerializationSurrogate GetSurrogate(Type type, StreamingContext context, out ISurrogateSelector selector)
        {
            if (type == null)
            {
                throw new ArgumentNullException("type");
            }
            selector = this;
            SurrogateKey key = new SurrogateKey(type, context);
            ISerializationSurrogate serializationSurrogate = (ISerializationSurrogate)m_surrogates[key];
            if (serializationSurrogate != null)
            {
                return serializationSurrogate;
            }
            if (m_nextSelector != null)
            {
                return m_nextSelector.GetSurrogate(type, context, out selector);
            }
            return null;
        }

        public virtual void RemoveSurrogate(Type type, StreamingContext context)
        {
            if (type == null)
            {
                throw new ArgumentNullException("type");
            }
            SurrogateKey key = new SurrogateKey(type, context);
            m_surrogates.Remove(key);
        }
    }
}