substantial part of infrastructure required for track/bus duplication

This includes removing the removal of ID values in XML, and its replacement with
thread-local forcing of ID resets, implemented in a previous commit

libs/ardour/ardour/route.h

@@ -101,7 +101,7 @@ class LIBARDOUR_API Route : public SessionObject, public Automatable, public Rou
 	void set_comment (std::string str, void *src);
 
 	bool set_name (const std::string& str);
-	static void set_name_in_state (XMLNode &, const std::string &);
+	static void set_name_in_state (XMLNode &, const std::string &, bool rename_playlist = true);
 
         uint32_t order_key () const;
         bool has_order_key () const;

libs/ardour/ardour/session.h

@@ -218,7 +218,8 @@ class LIBARDOUR_API Session : public PBD::StatefulDestructible, public PBD::Scop
 	std::string new_audio_source_path_for_embedded (const std::string& existing_path);
 	std::string new_audio_source_path (const std::string&, uint32_t nchans, uint32_t chan, bool destructive, bool take_required);
 	std::string new_midi_source_path (const std::string&);
-	RouteList new_route_from_template (uint32_t how_many, const std::string& template_path, const std::string& name);
+	RouteList new_route_from_template (uint32_t how_many, const std::string& template_path, const std::string& name, PlaylistDisposition pd = NewPlaylist);
+	RouteList new_route_from_template (uint32_t how_many, XMLNode&, const std::string& name, PlaylistDisposition pd = NewPlaylist);
 	std::vector<std::string> get_paths_for_new_sources (bool allow_replacing, const std::string& import_file_path, uint32_t channels);
 
 	int bring_all_sources_into_session (boost::function<void(uint32_t,uint32_t,std::string)> callback);

libs/ardour/ardour/types.h

@@ -647,6 +647,12 @@ namespace ARDOUR {
 		RegionSelectionStart = 0x8,
 	};
 
+	enum PlaylistDisposition {
+		CopyPlaylist,
+		NewPlaylist,
+		SharePlaylist
+	};
+
 } // namespace ARDOUR
 
 

libs/ardour/diskstream.cc

@@ -864,4 +864,3 @@ Diskstream::get_buffering_presets (BufferingPreset bp,
 
 	return true;
 }
-

libs/ardour/route.cc

@@ -4172,7 +4172,7 @@ Route::set_name (const string& str)
  *  @param name New name.
  */
 void
-Route::set_name_in_state (XMLNode& node, string const & name)
+Route::set_name_in_state (XMLNode& node, string const & name, bool rename_playlist)
 {
 	node.add_property (X_("name"), name);
 
@@ -4192,7 +4192,9 @@ Route::set_name_in_state (XMLNode& node, string const & name)
 
 		} else if ((*i)->name() == X_("Diskstream")) {
 
+			if (rename_playlist) {
 				(*i)->add_property (X_("playlist"), string_compose ("%1.1", name).c_str());
+			}
 			(*i)->add_property (X_("name"), name);
 
 		}

libs/ardour/session.cc

@@ -3032,30 +3032,39 @@ Session::new_audio_route (int input_channels, int output_channels, RouteGroup* r
 }
 
 RouteList
-Session::new_route_from_template (uint32_t how_many, const std::string& template_path, const std::string& name_base)
+Session::new_route_from_template (uint32_t how_many, const std::string& template_path, const std::string& name_base, PlaylistDisposition pd)
+{
+	XMLTree tree;
+
+	if (!tree.read (template_path.c_str())) {
+		return RouteList();
+	}
+
+	return new_route_from_template (how_many, *tree.root(), name_base, pd);
+}
+
+RouteList
+Session::new_route_from_template (uint32_t how_many, XMLNode& node, const std::string& name_base, PlaylistDisposition pd)
 {
 	RouteList ret;
 	uint32_t control_id;
-	XMLTree tree;
 	uint32_t number = 0;
 	const uint32_t being_added = how_many;
-
-	if (!tree.read (template_path.c_str())) {
-		return ret;
-	}
-
-	XMLNode* node = tree.root();
-
+	/* This will prevent the use of any existing XML-provided PBD::ID
+	   values by Stateful.
+	*/
+	Stateful::ForceIDRegeneration force_ids;
 	IO::disable_connecting ();
 
 	control_id = next_control_id ();
 
 	while (how_many) {
 
-		XMLNode node_copy (*node);
+		/* We're going to modify the node contents a bit so take a
+		 * copy. The node may be re-used when duplicating more than once.
+		 */
 
-		/* Remove IDs of everything so that new ones are used */
-		node_copy.remove_property_recursively (X_("id"));
+		XMLNode node_copy (node);
 
 		try {
 			string name;
@@ -3084,7 +3093,18 @@ Session::new_route_from_template (uint32_t how_many, const std::string& template
 			}
 
 			/* set this name in the XML description that we are about to use */
-			Route::set_name_in_state (node_copy, name);
+
+			bool rename_playlist;
+			switch (pd) {
+			case NewPlaylist:
+			case CopyPlaylist:
+				rename_playlist = true;
+				break;
+			case SharePlaylist:
+				rename_playlist = false;
+			}
+
+			Route::set_name_in_state (node_copy, name, rename_playlist);
 
 			/* trim bitslots from listen sends so that new ones are used */
 			XMLNodeList children = node_copy.children ();