From cdcc73381586f20a03d7ca453ff2ba99d782d95f Mon Sep 17 00:00:00 2001
From: Agustin Borgna <agustin.borgna@quantinuum.com>
Date: Wed, 11 Oct 2023 11:26:04 +0100
Subject: [PATCH 1/3] feat: Compute affected nodes for `SimpleReplacement`

---
 src/hugr/rewrite/simple_replace.rs | 20 +++++++++++++++++++-
 1 file changed, 19 insertions(+), 1 deletion(-)

diff --git a/src/hugr/rewrite/simple_replace.rs b/src/hugr/rewrite/simple_replace.rs
index c40f9776c..b4b477475 100644
--- a/src/hugr/rewrite/simple_replace.rs
+++ b/src/hugr/rewrite/simple_replace.rs
@@ -53,6 +53,19 @@ impl SimpleReplacement {
     pub fn subgraph(&self) -> &SiblingSubgraph {
         &self.subgraph
     }
+
+    /// Returns the nodes affected by the replacement.
+    ///
+    /// This includes the nodes in the subgraph and the boundary neighbours that
+    /// are referenced by the replacement.
+    ///
+    /// Two `SimpleReplacement`s can be composed if their affected nodes are
+    /// disjoint.
+    pub fn affected_nodes(&self) -> impl Iterator<Item = Node> + '_ {
+        let subcirc = self.subgraph.nodes().iter().copied();
+        let out_neighs = self.nu_out.keys().map(|&(n, _)| n);
+        subcirc.chain(out_neighs)
+    }
 }
 
 impl Rewrite for SimpleReplacement {
@@ -203,7 +216,7 @@ pub(in crate::hugr::rewrite) mod test {
     use itertools::Itertools;
     use portgraph::Direction;
     use rstest::{fixture, rstest};
-    use std::collections::HashMap;
+    use std::collections::{HashMap, HashSet};
 
     use crate::builder::{
         BuildError, Container, DFGBuilder, Dataflow, DataflowHugr, DataflowSubContainer,
@@ -384,6 +397,11 @@ pub(in crate::hugr::rewrite) mod test {
             nu_inp,
             nu_out,
         };
+        assert_eq!(
+            HashSet::<_>::from_iter(r.affected_nodes()),
+            HashSet::<_>::from_iter([h_node_cx, h_node_h0, h_node_h1, h_outp_node]),
+        );
+
         h.apply_rewrite(r).unwrap();
         // Expect [DFG] to be replaced with:
         // ┌───┐┌───┐

From a34662f0c0d373f10e18db3b91a698cb011aec97 Mon Sep 17 00:00:00 2001
From: Agustin Borgna <agustin.borgna@quantinuum.com>
Date: Wed, 11 Oct 2023 11:30:03 +0100
Subject: [PATCH 2/3] drive-by: add some inlines

---
 src/hugr/rewrite/simple_replace.rs | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/src/hugr/rewrite/simple_replace.rs b/src/hugr/rewrite/simple_replace.rs
index b4b477475..c2c075c5d 100644
--- a/src/hugr/rewrite/simple_replace.rs
+++ b/src/hugr/rewrite/simple_replace.rs
@@ -30,6 +30,7 @@ pub struct SimpleReplacement {
 
 impl SimpleReplacement {
     /// Create a new [`SimpleReplacement`] specification.
+    #[inline]
     pub fn new(
         subgraph: SiblingSubgraph,
         replacement: Hugr,
@@ -45,11 +46,13 @@ impl SimpleReplacement {
     }
 
     /// The replacement hugr.
+    #[inline]
     pub fn replacement(&self) -> &Hugr {
         &self.replacement
     }
 
     /// Subgraph to be replaced.
+    #[inline]
     pub fn subgraph(&self) -> &SiblingSubgraph {
         &self.subgraph
     }
@@ -61,6 +64,7 @@ impl SimpleReplacement {
     ///
     /// Two `SimpleReplacement`s can be composed if their affected nodes are
     /// disjoint.
+    #[inline]
     pub fn affected_nodes(&self) -> impl Iterator<Item = Node> + '_ {
         let subcirc = self.subgraph.nodes().iter().copied();
         let out_neighs = self.nu_out.keys().map(|&(n, _)| n);

From ffeb85ed29771d2aed02cd83c4dc4c6494975b63 Mon Sep 17 00:00:00 2001
From: Agustin Borgna <agustin.borgna@quantinuum.com>
Date: Wed, 11 Oct 2023 14:36:36 +0100
Subject: [PATCH 3/3] Reword docs, s/affected_nodes/invalidation_set/

---
 src/hugr/rewrite/simple_replace.rs | 10 ++++------
 1 file changed, 4 insertions(+), 6 deletions(-)

diff --git a/src/hugr/rewrite/simple_replace.rs b/src/hugr/rewrite/simple_replace.rs
index c2c075c5d..2f5d9f5fd 100644
--- a/src/hugr/rewrite/simple_replace.rs
+++ b/src/hugr/rewrite/simple_replace.rs
@@ -57,15 +57,13 @@ impl SimpleReplacement {
         &self.subgraph
     }
 
-    /// Returns the nodes affected by the replacement.
-    ///
-    /// This includes the nodes in the subgraph and the boundary neighbours that
-    /// are referenced by the replacement.
+    /// Returns a set of nodes referenced by the replacement. Modifying any
+    /// these nodes will invalidate the replacement.
     ///
     /// Two `SimpleReplacement`s can be composed if their affected nodes are
     /// disjoint.
     #[inline]
-    pub fn affected_nodes(&self) -> impl Iterator<Item = Node> + '_ {
+    pub fn invalidation_set(&self) -> impl Iterator<Item = Node> + '_ {
         let subcirc = self.subgraph.nodes().iter().copied();
         let out_neighs = self.nu_out.keys().map(|&(n, _)| n);
         subcirc.chain(out_neighs)
@@ -402,7 +400,7 @@ pub(in crate::hugr::rewrite) mod test {
             nu_out,
         };
         assert_eq!(
-            HashSet::<_>::from_iter(r.affected_nodes()),
+            HashSet::<_>::from_iter(r.invalidation_set()),
             HashSet::<_>::from_iter([h_node_cx, h_node_h0, h_node_h1, h_outp_node]),
         );