Sort Route xml node order by PBD::ID instead of by PresentationInfo

This prevents the node order from changing when the display order of the Routes
changes, which helps to reduce the amount of Session file change.

This is useful for testing and if keeping sessions under version control.

Resolves: #7327

1 files changed, 15 insertions, 10 deletions

diff --git a/libs/ardour/session_state.cc b/libs/ardour/session_state.cc
index c59ae00a57..35cb9c538c 100644
--- a/libs/ardour/session_state.cc
+++ b/libs/ardour/session_state.cc
@@ -1126,6 +1126,17 @@ Session::export_track_state (boost::shared_ptr<RouteList> rl, const string& path
 	return tree.write (sn.c_str());
 }
 
+namespace
+{
+struct route_id_compare {
+	bool
+	operator() (const boost::shared_ptr<Route>& r1, const boost::shared_ptr<Route>& r2)
+	{
+		return r1->id () < r2->id ();
+	}
+};
+} // anon namespace
+
 XMLNode&
 Session::state (bool full_state)
 {
@@ -1326,17 +1337,11 @@ Session::state (bool full_state)
 	{
 		boost::shared_ptr<RouteList> r = routes.reader ();
 
-		RoutePublicOrderSorter cmp;
-		RouteList public_order (*r);
-		public_order.sort (cmp);
-
-		/* the sort should have put the monitor out first */
-
-		if (_monitor_out) {
-			assert (_monitor_out == public_order.front());
-		}
+		route_id_compare cmp;
+		RouteList xml_node_order (*r);
+		xml_node_order.sort (cmp);
 
-		for (RouteList::iterator i = public_order.begin(); i != public_order.end(); ++i) {
+		for (RouteList::iterator i = xml_node_order.begin(); i != xml_node_order.end(); ++i) {
 			if (!(*i)->is_auditioner()) {
 				if (full_state) {
 					child->add_child_nocopy ((*i)->get_state());