IObserver <ListChange <T> > LeftObserver()
{
return(Observer.Create <ListChange <T> >(
onNext: changes =>
{
lock (_gate)
{
var newChanges = new List <ListChange <T> >();
changes(
insert: (index, item) =>
{
newChanges.Add(ListChange.Insert(index, item));
++_leftCount;
},
replace: (index, item) => { newChanges.Add(ListChange.Replace(index, item)); },
remove: index =>
{
newChanges.Add(ListChange.Remove <T>(index));
--_leftCount;
},
clear: () =>
{
if (_rightCount == 0)
{
newChanges.Add(ListChange.Clear <T>());
}
else
{
for (var i = _leftCount - 1; i >= 0; --i)
{
newChanges.Add(ListChange.Remove <T>(i));
}
}
_leftCount = 0;
});
if (newChanges.Count > 0)
{
_observer.OnNext(ListChange.Combine(newChanges));
}
}
},
onCompleted: () =>
{
lock (_gate)
{
if (_rightCompleted)
{
_observer.OnCompleted();
}
_leftCompleted = true;
}
},
onError: e =>
{
lock (_gate)
_observer.OnError(e);
}));
}
public Optional <ListChange <T> > Clear <T>()
{
var oldTrueCount = _items.Sum();
_items = _items.Clear();
return(oldTrueCount == 0
? Optional.None <ListChange <T> >()
: ListChange.Clear <T>());
}
public static IObservableList <T> SeparateBy <T>(this IObservableList <T> self, Func <T> separator)
{
return(self
.SelectWithState(
0,
(changes, res) =>
{
var newChanges = new List <ListChange <T> >();
var count = res;
changes(
insert: (i, item) =>
{
if (i == count) // inserting at the end
{
if (count == 0) // inserting first element: skip the separator
{
newChanges.Add(ListChange.Insert(0, item));
}
else // add separator before item
{
newChanges.Add(ListChange.Insert(i * 2 - 1, separator()));
newChanges.Add(ListChange.Insert(i * 2, item));
}
}
else // add separator after item
{
newChanges.Add(ListChange.Insert(i * 2, item));
newChanges.Add(ListChange.Insert(i * 2 + 1, separator()));
}
++count;
},
replace: (i, item) =>
{
newChanges.Add(ListChange.Replace(i * 2, item));
},
remove: i =>
{
if (i == count - 1) // removing at the end
{
if (i == 0) // removing first element: no separator to remove
{
newChanges.Add(ListChange.Remove <T>(0));
}
else // remove separator before item
{
newChanges.Add(ListChange.Remove <T>(i * 2));
newChanges.Add(ListChange.Remove <T>(i * 2 - 1));
}
}
else // remove separator after item
{
newChanges.Add(ListChange.Remove <T>(i * 2 + 1));
newChanges.Add(ListChange.Remove <T>(i * 2));
}
--count;
},
clear: () =>
{
newChanges.Add(ListChange.Clear <T>());
count = 0;
});
return SelectResult.Create(ListChange.Combine(newChanges), count);
})
.UnsafeAsObservableList());
}
public void OnClear()
{
OnNext(ListChange.Clear <T>());
}
public static IObservableList <T> Switch <T>(this IObservable <IObservableList <T> > self)
{
return(self.Select(ol => ol.StartWith(ListChange.Clear <T>())).Switch().UnsafeAsObservableList());
}
