private async Task UpdateNavigationStack(List <ScreenInstance <TViewModel> > newNavigationStack)
{
lock (_mutex)
{
if (_navigationInProgress != null && !_navigationInProgress.IsFinished)
{
_navigationInProgress.Cancel();
_navigationStack.Clear();
_navigationStack.AddRange(_navigationInProgress.StackBeforeNavigation);
}
_navigationInProgress = null;
}
_navigationInProgress = new NavigationInProgress <TViewModel>(_navigationStack.ToArray());
var navigationOperation = new NavigationOperation <TViewModel>();
int commonIndexLimit = 0;
for (;
commonIndexLimit < newNavigationStack.Count &&
commonIndexLimit < _navigationStack.Count &&
newNavigationStack[commonIndexLimit] == _navigationStack[commonIndexLimit];
++commonIndexLimit)
{
}
//generate pop instructions
for (int i = _navigationStack.Count - 1; i >= commonIndexLimit; i--)
{
navigationOperation.Add(new PopAction <TViewModel>(_navigationStack[i]));
}
_navigationStack.RemoveRange(commonIndexLimit, _navigationStack.Count - commonIndexLimit);
//generate push instructions
if (_navigationStack.Capacity < newNavigationStack.Count)
{
_navigationStack.Capacity = newNavigationStack.Count + 3; //Why 3 ? because we could use some margin and 3 is a nice small number !
}
for (int i = commonIndexLimit; i < newNavigationStack.Count; ++i)
{
navigationOperation.Add(new PushAction <TViewModel>(newNavigationStack[i]));
_navigationStack.Add(newNavigationStack[i]);
}
await _presenterService.UpdateNavigation(navigationOperation, _navigationInProgress);
}
