public void NavigateTo(NavigationEntry entry)
{
if (_currentEntry == entry)
{
return;
}
if (_backwardEntries.Contains(entry))
{
while (BackwardAvailable)
{
NavigateBackward();
if (_currentEntry == entry)
{
break;
}
}
}
if (_forwardEntries.Contains(entry))
{
while (ForwardAvailable)
{
NavigateForward();
if (_currentEntry == entry)
{
break;
}
}
}
}
private void DoNavigateAction(NavigationEntry entry)
{
_navigationNesting++;
try {
entry.Action();
} finally {
_navigationNesting--;
}
}
public void Clear()
{
if (_currentEntry == null)
{
return;
}
_backwardEntries.Clear();
_forwardEntries.Clear();
_currentEntry = null;
_version++;
}
public void AddNavigationAction(NavigationEntry entry)
{
if (_navigationNesting >= 1)
{
return;
}
_forwardEntries.Clear();
if (_currentEntry != null)
{
_backwardEntries.Push(_currentEntry);
}
_currentEntry = entry;
_version++;
}
public void NavigateBackward()
{
if (_navigationNesting >= 1)
{
return;
}
if (!BackwardAvailable)
{
return;
}
if (_currentEntry != null)
{
_forwardEntries.Push(_currentEntry);
}
_currentEntry = _backwardEntries.Pop();
DoNavigateAction(_currentEntry);
_version++;
}
