private void CheckContentStart()
{
if (_redirectState == RedirectState.WritingRedirectElementAttrs)
{
//Check required href attribute
if (_state.Href == null)
{
throw new ArgumentNullException("", @"'href' attribute of exsl:document element must be specified.");
}
//Are we writing to this URI already?
if (_states.Cast <OutputState>().Any(nestedState => nestedState.Href == _state.Href))
{
throw new ArgumentException("Cannot write to " + _state.Href + " two documents simultaneously.");
}
_state.InitWriter(_outResolver);
_redirectState = RedirectState.Redirecting;
}
}
