feat: impl GraphRef for PetgraphWrapper

Since PetgraphWrapper is a reference to a HugrView, we implement
GraphRef directly. This simplifies the implementation of several traits.

src/hugr/views/petgraph.rs

@@ -12,11 +12,28 @@ use petgraph::visit as pv;
 /// Wrapper for a HugrView that implements petgraph's traits.
 ///
 /// It can be used to apply petgraph's algorithms to a Hugr.
-#[derive(Debug, Clone, Copy)]
+#[derive(Debug)]
 pub struct PetgraphWrapper<'a, T> {
  pub(crate) hugr: &'a T,
 }
 
+impl<'a, T> Clone for PetgraphWrapper<'a, T> {
+ fn clone(&self) -> Self {
+ *self
+ }
+}
+
+impl<'a, T> Copy for PetgraphWrapper<'a, T> {}
+
+impl<'a, T> From<&'a T> for PetgraphWrapper<'a, T>
+where
+ T: HugrView,
+{
+ fn from(hugr: &'a T) -> Self {
+ Self { hugr }
+ }
+}
+
 impl<'a, T> pv::GraphBase for PetgraphWrapper<'a, T>
 where
  T: HugrView,
@@ -32,6 +49,8 @@ where
  type EdgeType = petgraph::Directed;
 }
 
+impl<'a, T> pv::GraphRef for PetgraphWrapper<'a, T> where T: HugrView {}
+
 impl<'a, T> pv::NodeCount for PetgraphWrapper<'a, T>
 where
  T: HugrView,
@@ -75,12 +94,12 @@ where
  type EdgeWeight = EdgeKind;
 }
 
-impl<'g, 'a, T> pv::IntoNodeReferences for &'g PetgraphWrapper<'a, T>
+impl<'a, T> pv::IntoNodeReferences for PetgraphWrapper<'a, T>
 where
  T: HugrView,
 {
- type NodeRef = HugrNodeRef<'g>;
- type NodeReferences = MapWithCtx<<T as HugrView>::Nodes<'g>, Self, HugrNodeRef<'g>>;
+ type NodeRef = HugrNodeRef<'a>;
+ type NodeReferences = MapWithCtx<<T as HugrView>::Nodes<'a>, Self, HugrNodeRef<'a>>;
 
  fn node_references(self) -> Self::NodeReferences {
  self.hugr
@@ -90,33 +109,33 @@ where
  }
 }
 
-impl<'g, 'a, T> pv::IntoNodeIdentifiers for &'g PetgraphWrapper<'a, T>
+impl<'a, T> pv::IntoNodeIdentifiers for PetgraphWrapper<'a, T>
 where
  T: HugrView,
 {
- type NodeIdentifiers = <T as HugrView>::Nodes<'g>;
+ type NodeIdentifiers = <T as HugrView>::Nodes<'a>;
 
  fn node_identifiers(self) -> Self::NodeIdentifiers {
  self.hugr.nodes()
  }
 }
 
-impl<'g, 'a, T> pv::IntoNeighbors for &'g PetgraphWrapper<'a, T>
+impl<'a, T> pv::IntoNeighbors for PetgraphWrapper<'a, T>
 where
  T: HugrView,
 {
- type Neighbors = <T as HugrView>::Neighbours<'g>;
+ type Neighbors = <T as HugrView>::Neighbours<'a>;
 
  fn neighbors(self, n: Self::NodeId) -> Self::Neighbors {
  self.hugr.output_neighbours(n)
  }
 }
 
-impl<'g, 'a, T> pv::IntoNeighborsDirected for &'g PetgraphWrapper<'a, T>
+impl<'a, T> pv::IntoNeighborsDirected for PetgraphWrapper<'a, T>
 where
  T: HugrView,
 {
- type NeighborsDirected = <T as HugrView>::Neighbours<'g>;
+ type NeighborsDirected = <T as HugrView>::Neighbours<'a>;
 
  fn neighbors_directed(
  self,