ExpandoClass.cs

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using System.Collections.Generic;
 
namespace System.Dynamic;
 
internal sealed class ExpandoClass
{
    private readonly string[] _keys;
 
    private readonly int _hashCode;
 
    private Dictionary<int, List<WeakReference>> _transitions;
 
    internal static readonly ExpandoClass Empty = new ExpandoClass();
 
    internal string[] Keys => _keys;
 
    internal ExpandoClass()
    {
        _hashCode = 6551;
        _keys = Array.Empty<string>();
    }
 
    internal ExpandoClass(string[] keys, int hashCode)
    {
        _hashCode = hashCode;
        _keys = keys;
    }
 
    internal ExpandoClass FindNewClass(string newKey)
    {
        int hashCode = _hashCode ^ newKey.GetHashCode();
        lock (this)
        {
            List<WeakReference> transitionList = GetTransitionList(hashCode);
            for (int i = 0; i < transitionList.Count; i++)
            {
                if (!(transitionList[i].Target is ExpandoClass expandoClass))
                {
                    transitionList.RemoveAt(i);
                    i--;
                }
                else if (string.Equals(expandoClass._keys[expandoClass._keys.Length - 1], newKey, StringComparison.Ordinal))
                {
                    return expandoClass;
                }
            }
            string[] array = new string[_keys.Length + 1];
            Array.Copy(_keys, array, _keys.Length);
            array[_keys.Length] = newKey;
            ExpandoClass expandoClass2 = new ExpandoClass(array, hashCode);
            transitionList.Add(new WeakReference(expandoClass2));
            return expandoClass2;
        }
    }
 
    private List<WeakReference> GetTransitionList(int hashCode)
    {
        if (_transitions == null)
        {
            _transitions = new Dictionary<int, List<WeakReference>>();
        }
        if (!_transitions.TryGetValue(hashCode, out var value))
        {
            value = (_transitions[hashCode] = new List<WeakReference>());
        }
        return value;
    }
 
    internal int GetValueIndex(string name, bool caseInsensitive, ExpandoObject obj)
    {
        if (caseInsensitive)
        {
            return GetValueIndexCaseInsensitive(name, obj);
        }
        return GetValueIndexCaseSensitive(name);
    }
 
    internal int GetValueIndexCaseSensitive(string name)
    {
        for (int i = 0; i < _keys.Length; i++)
        {
            if (string.Equals(_keys[i], name, StringComparison.Ordinal))
            {
                return i;
            }
        }
        return -1;
    }
 
    private int GetValueIndexCaseInsensitive(string name, ExpandoObject obj)
    {
        int num = -1;
        lock (obj.LockObject)
        {
            for (int num2 = _keys.Length - 1; num2 >= 0; num2--)
            {
                if (string.Equals(_keys[num2], name, StringComparison.OrdinalIgnoreCase) && !obj.IsDeletedMember(num2))
                {
                    if (num != -1)
                    {
                        return -2;
                    }
                    num = num2;
                }
            }
            return num;
        }
    }
}