private void UpdateCurrentState(string replacementText, ITextSelection selection, SnapshotSpan activeSpan)
{
var snapshot = activeSpan.Snapshot;
var selectionSpan = selection.GetSnapshotSpansOnBuffer(snapshot.TextBuffer).Single();
var start = selectionSpan.Start.TranslateTo(snapshot, PointTrackingMode.Positive).Position - activeSpan.Start.Position;
var end = selectionSpan.End.TranslateTo(snapshot, PointTrackingMode.Positive).Position - activeSpan.Start.Position;
this.currentState = new ActiveSpanState()
{
ReplacementText = replacementText,
SelectionAnchorPoint = selection.IsReversed ? end : start,
SelectionActivePoint = selection.IsReversed ? start : end
};
}