feat: Add boundary edge traversal in SimpleReplacement

hugr-core/src/hugr/patch/port_types.rs

@@ -8,9 +8,9 @@ use derive_more::From;
 
 /// A port in either the host or replacement graph.
 ///
-/// This is used to represent boundary edges that will be added between the host and
-/// replacement graphs when applying a rewrite.
-#[derive(Debug, Clone, Copy)]
+/// This is used to represent boundary edges that will be added between the host
+/// and replacement graphs when applying a rewrite.
+#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
 pub enum BoundaryPort<HostNode, P> {
     /// A port in the host graph.
     Host(HostNode, P),
@@ -19,22 +19,39 @@ pub enum BoundaryPort<HostNode, P> {
 }
 
 /// A port in the host graph.
-#[derive(Debug, Clone, Copy, From)]
+#[derive(Debug, Clone, Copy, From, PartialEq, Eq, PartialOrd, Ord, Hash)]
 pub struct HostPort<N, P>(pub N, pub P);
 
 /// A port in the replacement graph.
-#[derive(Debug, Clone, Copy, From, PartialEq, Eq, PartialOrd, Ord)]
+#[derive(Debug, Clone, Copy, From, PartialEq, Eq, PartialOrd, Ord, Hash)]
 pub struct ReplacementPort<P>(pub Node, pub P);
 
 impl<HostNode: Copy, P> BoundaryPort<HostNode, P> {
     /// Maps a boundary port according to the insertion mapping.
-    /// Host ports are unchanged, while Replacement ports are mapped according to the `index_map`.
+    /// Host ports are unchanged, while Replacement ports are mapped according
+    /// to the `index_map`.
     pub fn map_replacement(self, index_map: &HashMap<Node, HostNode>) -> (HostNode, P) {
         match self {
             BoundaryPort::Host(node, port) => (node, port),
             BoundaryPort::Replacement(node, port) => (*index_map.get(&node).unwrap(), port),
         }
     }
+
+    /// Returns the replacement port if this is a replacement port.
+    pub fn as_replacement(self) -> Option<(Node, P)> {
+        match self {
+            BoundaryPort::Replacement(node, port) => Some((node, port)),
+            BoundaryPort::Host(_, _) => None,
+        }
+    }
+
+    /// Returns the host port if this is a host port.
+    pub fn as_host(self) -> Option<(HostNode, P)> {
+        match self {
+            BoundaryPort::Host(node, port) => Some((node, port)),
+            BoundaryPort::Replacement(_, _) => None,
+        }
+    }
 }
 
 impl<N, P> From<HostPort<N, P>> for BoundaryPort<N, P> {