ITextUndoHistory ITextUndoHistoryRegistry.RegisterHistory(object context) {
ITextUndoHistory history;
if (!_map.TryGetValue(context, out history)) {
history = new BasicUndoHistory(context);
foreach (var c in GetDependentContexts(context)) {
// If this context already has an attached history, don't replace it.
// This happens for ephemeral projection buffers for previews created
// by the diff for a quick fix.
_map.GetValue(c, _ => history);
}
}
return history;
}
internal BasicUndoTransaction(BasicUndoHistory textUndoHistory, string description) {
_textUndoHistory = textUndoHistory;
Description = description;
}