src/traits.rs

@@ -5,7 +5,7 @@ use crate::maps::{EdgeMap, VertexMap};
 pub trait GraphTopology {
     type Vertex: Copy + Eq;
     type Edge: Copy + Eq;
-    type IncidenceCursor: IncidenceCursor<Self> + Copy;
+    type IncidenceCursor: IncidenceCursor<Self>;
 
     fn vertex_count(&self) -> usize;
     fn vertex_capacity(&self) -> usize;
@@ -31,6 +31,6 @@ pub trait GraphTopologyDeletion: GraphTopology {
     fn delete_edge(&mut self, e: Self::Edge);
 }
 
-pub trait IncidenceCursor<G: GraphTopology + ?Sized> {
+pub trait IncidenceCursor<G: GraphTopology + ?Sized>: Copy {
     fn next(&mut self, graph: &G) -> Option<(G::Vertex, G::Edge)>;
 }