Check attributes before making mutable copy

digraphs · Sep 2, 2024 · 4e2bc04 · 4e2bc04
1 parent 2ca273f
commit 4e2bc04
Showing 1 changed file with 6 additions and 4 deletions.
diff --git a/gap/planar.gi b/gap/planar.gi
@@ -33,27 +33,29 @@
 InstallMethod(PlanarEmbedding, "for a digraph", [IsDigraph],
 function(D)
   local C;
+  if HasIsPlanarDigraph(D) and not IsPlanarDigraph(D) then
+    return fail;
+  fi;
   C := DigraphMutableCopy(D);
   DigraphRemoveAllMultipleEdges(C);
   DigraphRemoveLoops(C);
   if IsEmptyDigraph(C) or DigraphNrVertices(C) < 3 then
     return OutNeighbors(C);
-  elif HasIsPlanarDigraph(C) and not IsPlanarDigraph(C) then
-    return fail;
   fi;
   return PLANAR_EMBEDDING(C);
 end);
 
 InstallMethod(OuterPlanarEmbedding, "for a digraph", [IsDigraph],
 function(D)
   local C;
+  if HasIsPlanarDigraph(D) and not IsPlanarDigraph(D) then
+    return fail;
+  fi;
   C := DigraphMutableCopy(D);
   DigraphRemoveAllMultipleEdges(C);
   DigraphRemoveLoops(C);
   if IsEmptyDigraph(C) or DigraphNrVertices(C) < 3 then
     return OutNeighbors(C);
-  elif HasIsOuterPlanarDigraph(C) and not IsOuterPlanarDigraph(C) then
-    return fail;
   fi;
   return OUTER_PLANAR_EMBEDDING(C);
 end);