private IChangeSet <T> Process(IChangeSet <T> changes)
{
//if all removes and not Clear, then more efficient to try clear range
if (changes.TotalChanges == changes.Removes && changes.All(c => c.Reason != ListChangeReason.Clear) && changes.Removes > 1)
{
var removed = changes.Unified().Select(u => u.Current);
_innerList.RemoveMany(removed);
return(_innerList.CaptureChanges());
}
return(ProcessImpl(changes));
}
private IChangeSet <TDestination> Process(ChangeAwareList <TDestination> transformed, IChangeSet <TSource> source)
{
//TODO: This is very inefficient as it flattens range operation
//need to find a means of re-forming ranges
var children = source.Unified().SelectMany(change =>
{
var many = _manyselector(change.Current);
return(many.Select(m => new TransformedItem <TDestination>(change.Reason, m)));
});
foreach (var child in children)
{
switch (child.Reason)
{
case ListChangeReason.Add:
transformed.Add(child.Current);
break;
case ListChangeReason.Replace:
transformed.Remove(child.Previous.Value);
transformed.Add(child.Current);
break;
case ListChangeReason.Remove:
transformed.Remove(child.Current);
break;
case ListChangeReason.Clear:
transformed.Clear();
break;
}
}
return(transformed.CaptureChanges());
}
private IChangeSet <TDestination> Process(IChangeSet <TSource> changes)
{
Transform(changes);
var changed = _transformed.CaptureChanges();
return(changed.Transform(container => container.Destination));
}
private IChangeSet <T> ProcessImpl(ChangeAwareList <T> target, IChangeSet <T> changes)
{
foreach (var change in changes)
{
switch (change.Reason)
{
case ListChangeReason.Add:
{
var current = change.Item.Current;
Insert(target, current);
break;
}
case ListChangeReason.AddRange:
{
var ordered = change.Range.OrderBy(t => t, _comparer).ToList();
if (target.Count == 0)
{
target.AddRange(ordered);
}
else
{
ordered.ForEach(item => Insert(target, item));
}
break;
}
case ListChangeReason.Replace:
{
var current = change.Item.Current;
//TODO: check whether an item should stay in the same position
//i.e. update and move
Remove(target, change.Item.Previous.Value);
Insert(target, current);
break;
}
case ListChangeReason.Remove:
{
var current = change.Item.Current;
Remove(target, current);
break;
}
case ListChangeReason.RemoveRange:
{
target.RemoveMany(change.Range);
break;
}
case ListChangeReason.Clear:
{
target.Clear();
break;
}
}
}
return(target.CaptureChanges());
}
private IChangeSet <T> Reset(ChangeAwareList <T> original, ChangeAwareList <T> target)
{
var sorted = original.OrderBy(t => t, _comparer).ToList();
target.Clear();
target.AddRange(sorted);
return(target.CaptureChanges());
}
private IChangeSet <T> Page(IChangeSet <T> changeset = null)
{
if (changeset != null)
{
_all.Clone(changeset);
}
var previous = _paged;
int pages = CalculatePages();
int page = _parameters.Page > pages ? pages : _parameters.Page;
int skip = _parameters.Size * (page - 1);
var current = _all.Skip(skip)
.Take(_parameters.Size)
.ToList();
var adds = current.Except(previous);
var removes = previous.Except(current);
_paged.RemoveMany(removes);
adds.ForEach(t =>
{
var index = current.IndexOf(t);
_paged.Insert(index, t);
});
var startIndex = skip;
var moves = changeset.EmptyIfNull()
.Where(change => change.Reason == ListChangeReason.Moved &&
change.MovedWithinRange(startIndex, startIndex + _parameters.Size));
foreach (var change in moves)
{
//check whether an item has moved within the same page
var currentIndex = change.Item.CurrentIndex - startIndex;
var previousIndex = change.Item.PreviousIndex - startIndex;
_paged.Move(previousIndex, currentIndex);
}
//find replaces [Is this ever the case that it can be reached]
for (int i = 0; i < current.Count; i++)
{
var currentItem = current[i];
var previousItem = previous[i];
if (ReferenceEquals(currentItem, previousItem))
{
continue;
}
var index = _paged.IndexOf(currentItem);
_paged.Move(i, index);
}
return(_paged.CaptureChanges());
}
public IObservable <IChangeSet <T> > Run()
{
return(_source.Select(changes =>
{
_filtered.Filter(changes, _predicate);
return _filtered.CaptureChanges();
})
.NotEmpty());
}
private IChangeSet <T> ChangeComparer(ChangeAwareList <T> target, IComparer <T> comparer)
{
_comparer = comparer;
var sorted = target.OrderBy(t => t, _comparer).ToList();
target.Clear();
target.AddRange(sorted);
return(target.CaptureChanges());
}
public IObservable <IChangeSet <T> > Run()
{
return(Observable.Create <IChangeSet <T> >(observer =>
{
var filtered = new ChangeAwareList <T>();
return _source.Select(changes =>
{
filtered.Filter(changes, _predicate);
return filtered.CaptureChanges();
}).NotEmpty().SubscribeSafe(observer);
}));
}
private IChangeSet <T> Virtualise(List <T> all, ChangeAwareList <T> virtualised, IChangeSet <T> changeset = null)
{
if (changeset != null)
{
all.Clone(changeset);
}
var previous = virtualised;
var current = all.Skip(_parameters.StartIndex)
.Take(_parameters.Size)
.ToList();
var adds = current.Except(previous);
var removes = previous.Except(current);
virtualised.RemoveMany(removes);
adds.ForEach(t =>
{
var index = current.IndexOf(t);
virtualised.Insert(index, t);
});
var moves = changeset.EmptyIfNull()
.Where(change => change.Reason == ListChangeReason.Moved &&
change.MovedWithinRange(_parameters.StartIndex, _parameters.StartIndex + _parameters.Size));
foreach (var change in moves)
{
//check whether an item has moved within the same page
var currentIndex = change.Item.CurrentIndex - _parameters.StartIndex;
var previousIndex = change.Item.PreviousIndex - _parameters.StartIndex;
virtualised.Move(previousIndex, currentIndex);
}
//find replaces [Is this ever the case that it can be reached]
for (var i = 0; i < current.Count; i++)
{
var currentItem = current[i];
var previousItem = previous[i];
if (ReferenceEquals(currentItem, previousItem))
{
continue;
}
var index = virtualised.IndexOf(currentItem);
virtualised.Move(i, index);
}
return(virtualised.CaptureChanges());
}
public IObservable <IChangeSet <T> > Run()
{
return(Observable.Create <IChangeSet <T> >(observer =>
{
var allWithMatch = new List <ItemWithMatch>();
var all = new List <T>();
var filtered = new ChangeAwareList <T>();
var locker = new object();
//requery wehn controller either fires changed or requery event
var refresher = _predicates.Synchronize(locker)
.Select(predicate =>
{
Requery(predicate, allWithMatch, all, filtered);
var changed = filtered.CaptureChanges();
return changed;
});
var shared = _source.Synchronize(locker).Publish();
//take current filter state of all items
var updateall = shared.Synchronize(locker)
.Transform(t => new ItemWithMatch(t, _predicate(t)))
.Subscribe(allWithMatch.Clone);
//filter result list
var filter = shared.Synchronize(locker)
.Select(changes =>
{
filtered.Filter(changes, _predicate);
var changed = filtered.CaptureChanges();
return changed;
});
var subscriber = refresher.Merge(filter).NotEmpty().SubscribeSafe(observer);
return new CompositeDisposable(updateall, subscriber, shared.Connect());
}));
}
public Continuation <IChangeSet <T> > Write(IChangeSet <T> changes)
{
if (changes == null)
{
throw new ArgumentNullException(nameof(changes));
}
IChangeSet <T> result;
lock (_locker)
{
try
{
_data.Clone(changes);
result = _data.CaptureChanges();
}
catch (Exception ex)
{
return(new Continuation <IChangeSet <T> >(ex));
}
}
return(new Continuation <IChangeSet <T> >(result));
}
private IChangeSet <IGroup <TObject, TGroupKey> > Regroup(ChangeAwareList <IGroup <TObject, TGroupKey> > result,
IDictionary <TGroupKey, Group <TObject, TGroupKey> > groupCollection,
IReadOnlyCollection <ItemWithValue <TObject, TGroupKey> > currentItems)
{
//TODO: We need to update ItemWithValue>
foreach (var itemWithValue in currentItems)
{
var currentGroupKey = itemWithValue.Value;
var newGroupKey = _groupSelector(itemWithValue.Item);
if (newGroupKey.Equals(currentGroupKey))
{
continue;
}
//remove from the old group
var currentGroupLookup = GetCache(groupCollection, currentGroupKey);
var currentGroupCache = currentGroupLookup.Group;
currentGroupCache.Edit(innerList => innerList.Remove(itemWithValue.Item));
if (currentGroupCache.List.Count == 0)
{
groupCollection.Remove(currentGroupKey);
result.Remove(currentGroupCache);
}
//Mark the old item with the new cache group
itemWithValue.Value = newGroupKey;
//add to the new group
var newGroupLookup = GetCache(groupCollection, newGroupKey);
var newGroupCache = newGroupLookup.Group;
newGroupCache.Edit(innerList => innerList.Add(itemWithValue.Item));
if (newGroupLookup.WasCreated)
{
result.Add(newGroupCache);
}
}
return(result.CaptureChanges());
}
private IChangeSet <T> Reorder(ChangeAwareList <T> target)
{
int index = -1;
var sorted = target.OrderBy(t => t, _comparer).ToList();
foreach (var item in sorted)
{
index++;
var existing = target[index];
//if item is in the same place,
if (ReferenceEquals(item, existing))
{
continue;
}
//Cannot use binary search as Resort is implicit of a mutable change
var old = target.IndexOf(item);
target.Move(old, index);
}
return(target.CaptureChanges());
}
private IChangeSet <IGroup <TObject, TGroupKey> > Process(ChangeAwareList <IGroup <TObject, TGroupKey> > result, IDictionary <TGroupKey, Group <TObject, TGroupKey> > groupCollection, IChangeSet <ItemWithValue <TObject, TGroupKey> > changes)
{
//TODO.This flattened enumerator is inefficient as range operations are lost.
//maybe can infer within each grouping whether we can regroup i.e. Another enumerator!!!
foreach (var grouping in changes.Unified().GroupBy(change => change.Current.Value))
{
//lookup group and if created, add to result set
var currentGroup = grouping.Key;
var lookup = GetCache(groupCollection, currentGroup);
var groupCache = lookup.Group;
if (lookup.WasCreated)
{
result.Add(groupCache);
}
//start a group edit session, so all changes are batched
groupCache.Edit(
list =>
{
//iterate through the group's items and process
foreach (var change in grouping)
{
switch (change.Reason)
{
case ListChangeReason.Add:
{
list.Add(change.Current.Item);
break;
}
case ListChangeReason.Replace:
{
var previousItem = change.Previous.Value.Item;
var previousGroup = change.Previous.Value.Value;
//check whether an item changing has resulted in a different group
if (previousGroup.Equals(currentGroup))
{
//find and replace
var index = list.IndexOf(previousItem);
list[index] = change.Current.Item;
}
else
{
//add to new group
list.Add(change.Current.Item);
//remove from old group
groupCollection.Lookup(previousGroup)
.IfHasValue(g =>
{
g.Edit(oldList => oldList.Remove(previousItem));
if (g.List.Count != 0)
{
return;
}
groupCollection.Remove(g.GroupKey);
result.Remove(g);
});
}
break;
}
case ListChangeReason.Remove:
{
list.Remove(change.Current.Item);
break;
}
case ListChangeReason.Clear:
{
list.Clear();
break;
}
}
}
});
if (groupCache.List.Count == 0)
{
groupCollection.Remove(groupCache.GroupKey);
result.Remove(groupCache);
}
}
return(result.CaptureChanges());
}
private IChangeSet <TValue> Process(IChangeSet <ItemWithValue <T, TValue> > updates)
{
Action <TValue> addAction = value => _valueCounters.Lookup(value)
.IfHasValue(count => _valueCounters[value] = count + 1)
.Else(() =>
{
_valueCounters[value] = 1;
_result.Add(value);
});
Action <TValue> removeAction = value =>
{
var counter = _valueCounters.Lookup(value);
if (!counter.HasValue)
{
return;
}
//decrement counter
var newCount = counter.Value - 1;
_valueCounters[value] = newCount;
if (newCount != 0)
{
return;
}
//if there are none, then remove and notify
_result.Remove(value);
};
foreach (var change in updates)
{
switch (change.Reason)
{
case ListChangeReason.Add:
{
var value = change.Item.Current.Value;
addAction(value);
break;
}
case ListChangeReason.AddRange:
{
change.Range.Select(item => item.Value).ForEach(addAction);
break;
}
// case ListChangeReason.Evaluate:
case ListChangeReason.Replace:
{
var value = change.Item.Current.Value;
var previous = change.Item.Previous.Value.Value;
if (value.Equals(previous))
{
return(_result.CaptureChanges());
}
removeAction(previous);
addAction(value);
break;
}
case ListChangeReason.Remove:
{
var previous = change.Item.Current.Value;
removeAction(previous);
break;
}
case ListChangeReason.RemoveRange:
{
change.Range.Select(item => item.Value).ForEach(removeAction);
break;
}
case ListChangeReason.Clear:
{
_result.Clear();
_valueCounters.Clear();
break;
}
}
}
return(_result.CaptureChanges());
}
private IChangeSet <TDestination> Process(IChangeSet <TSource> changes)
{
_transformed.Transform(changes, _factory);
return(_transformed.CaptureChanges());
}
