/// <summary>
/// Throws exception if <see cref="IsDisposed"/> is true or <see cref="EnumerationState"/> is not equals <see cref="DataSourceEnumerationState.Enumerable"/>.
/// </summary>
protected void EnsureEnumerate()
{
if (IsDisposed)
{
throw new ObjectDisposedException("The data source has been disposed and can not be enumerated again");
}
if (!EnumerationState.HasFlag(DataSourceEnumerationState.Enumerable))
{
throw new InvalidOperationException("The data source has been already enumerated");
}
}
