public ChangeInfo(ImmutableArray <TextChangeRange> changeRanges, WeakReference <SourceText> weakOldText, ChangeInfo?previous)
{
this.ChangeRanges = changeRanges;
this.WeakOldText = weakOldText;
this.Previous = previous;
Clean();
}
private static IReadOnlyList <ImmutableArray <TextChangeRange> > GetChangesBetween(SourceText oldText, ChangedText newText)
{
var list = new List <ImmutableArray <TextChangeRange> >();
ChangeInfo?change = newText._info;
list.Add(change.ChangeRanges);
while (change != null)
{
SourceText?actualOldText;
change.WeakOldText.TryGetTarget(out actualOldText);
if (actualOldText == oldText)
{
return(list);
}
change = change.Previous;
if (change != null)
{
list.Insert(0, change.ChangeRanges);
}
}
// did not find old text, so not connected?
list.Clear();
return(list);
}
private bool IsChangedFrom(SourceText oldText)
{
for (ChangeInfo?info = _info; info != null; info = info.Previous)
{
SourceText?text;
if (info.WeakOldText.TryGetTarget(out text) && text == oldText)
{
return(true);
}
}
return(false);
}
private void Clean()
{
// look for last info in the chain that still has reference to old text
ChangeInfo? lastInfo = this;
for (ChangeInfo? info = this; info != null; info = info.Previous)
{
SourceText tmp;
if (info.WeakOldText.TryGetTarget(out tmp))
{
lastInfo = info;
}
}
// break chain for any info's beyond that so they get GC'd
ChangeInfo? prev;
while (lastInfo != null)
{
prev = lastInfo.Previous;
lastInfo.Previous = null;
lastInfo = prev;
}
}
