/// <summary>
    /// Enumerates the elements of a <see cref="T:System.Collections.Generic.List`1"/>.
    /// </summary>
    [__DynamicallyInvokable]
    [Serializable]
    public struct Enumerator : IEnumerator<T>, IDisposable, IEnumerator
    {
      private List<T> list;
      private int index;
      private int version;
      private T current;

      /// <summary>
      /// Gets the element at the current position of the enumerator.
      /// </summary>
      /// 
      /// <returns>
      /// The element in the <see cref="T:System.Collections.Generic.List`1"/> at the current position of the enumerator.
      /// </returns>
      [__DynamicallyInvokable]
      public T Current
      {
        [__DynamicallyInvokable, TargetedPatchingOptOut("Performance critical to inline this type of method across NGen image boundaries")] get
        {
          return this.current;
        }
      }

      [__DynamicallyInvokable]
      object IEnumerator.Current
      {
        [__DynamicallyInvokable] get
        {
          if (this.index == 0 || this.index == this.list._size + 1)
            ThrowHelper.ThrowInvalidOperationException(ExceptionResource.InvalidOperation_EnumOpCantHappen);
          return (object) this.Current;
        }
      }

      internal Enumerator(List<T> list)
      {
        this.list = list;
        this.index = 0;
        this.version = list._version;
        this.current = default (T);
      }

      /// <summary>
      /// Releases all resources used by the <see cref="T:System.Collections.Generic.List`1.Enumerator"/>.
      /// </summary>
      [TargetedPatchingOptOut("Performance critical to inline across NGen image boundaries")]
      [__DynamicallyInvokable]
      public void Dispose()
      {
      }

      /// <summary>
      /// Advances the enumerator to the next element of the <see cref="T:System.Collections.Generic.List`1"/>.
      /// </summary>
      /// 
      /// <returns>
      /// true if the enumerator was successfully advanced to the next element; false if the enumerator has passed the end of the collection.
      /// </returns>
      /// <exception cref="T:System.InvalidOperationException">The collection was modified after the enumerator was created. </exception>
      [__DynamicallyInvokable]
      public bool MoveNext()
      {
        List<T> list = this.list;
        if (this.version != list._version || (uint) this.index >= (uint) list._size)
          return this.MoveNextRare();
        this.current = list._items[this.index];
        ++this.index;
        return true;
      }

      private bool MoveNextRare()
      {
        if (this.version != this.list._version)
          ThrowHelper.ThrowInvalidOperationException(ExceptionResource.InvalidOperation_EnumFailedVersion);
        this.index = this.list._size + 1;
        this.current = default (T);
        return false;
      }

      [__DynamicallyInvokable]
      void IEnumerator.Reset()
      {
        if (this.version != this.list._version)
          ThrowHelper.ThrowInvalidOperationException(ExceptionResource.InvalidOperation_EnumFailedVersion);
        this.index = 0;
        this.current = default (T);
      }
    }