Add an option to use empty topology for reference

birdvisu/providers.py

@@ -20,6 +20,15 @@ class TopologyProvider(ABC):
 	@abstractmethod
 	def get_topology(self) -> TopologyV3: ...
 
+class DummyTopologyProvider(TopologyProvider):
+	"""Returns an empty topology.
+
+	Useful when we do not want to compare anything."""
+	def get_topology(self):
+		topo = TopologyV3()
+		topo.freeze()
+		return topo
+
 class OspfFileParseError(Exception): pass
 
 class OspfFileTopologyParser:

birdvisu/ui.py

@@ -11,7 +11,7 @@ from birdvisu.annotations import AnnotatedTopology, AnnotatorID
 from birdvisu.annotations.analysis import TopologyDifference, ShortestPathTree
 from birdvisu.annotations.layout import PlaceVerticesFromFile, PlaceUnplacedVertices, EdgeWidthByCost, HighlightTopoDiff, HighlightSPDAG, HighlightShortestPath
 from birdvisu.ospfsock import BirdSocketConnection
-from birdvisu.providers import BirdSocketTopologyProvider, OspfFileTopologyProvider, OspfFileParseError
+from birdvisu.providers import BirdSocketTopologyProvider, OspfFileTopologyProvider, OspfFileParseError, DummyTopologyProvider
 from birdvisu.topo_v3 import TopologyV3, VertexID
 from birdvisu.graphics_items import RouterGraphicsItem, NetworkGraphicsItem, EdgeGraphicsItem
 
@@ -106,9 +106,13 @@ class MainWindow(QtWidgets.QMainWindow):
 		self.menubar.addAction(autoload_act)
 
 		topo_menu = self.menubar.addMenu('&Topology')
+		ref_menu = topo_menu.addMenu("&Reference")
 		open_ref_act = QtGui.QAction("&Load reference", self)
 		open_ref_act.triggered.connect(self.openRefTopology)
-		topo_menu.addAction(open_ref_act)
+		ref_menu.addAction(open_ref_act)
+		no_ref_act = QtGui.QAction("&No reference topology", self)
+		no_ref_act.triggered.connect(self.noRefTopology)
+		ref_menu.addAction(no_ref_act)
 
 		cur_topo_menu = topo_menu.addMenu("Load &current")
 		running_bird_act = QtGui.QAction('&BIRD', self)
@@ -231,6 +235,11 @@ class MainWindow(QtWidgets.QMainWindow):
 		self.highlighter = HighlightShortestPath((self.start_vertex, self.end_vertex))
 		self.apply_styles()
 	
+	@Slot()
+	def noRefTopology(self):
+		self.ref_topo_provider = DummyTopologyProvider()
+		self.refreshTopologies()
+
 	@Slot()
 	def openRefTopology(self):
 		filename = QtWidgets.QFileDialog.getOpenFileName(self, 'Open reference topology', '.', 'OSPF files (*.ospf);;All files(*)')[0]