refactor(autorouter/presorter): Move some SCC code to new file

src/autorouter/mod.rs

@@ -18,6 +18,7 @@ pub mod presorter;
 pub mod ratline;
 pub mod ratsnest;
 pub mod remove_bands;
+pub mod scc;
 pub mod selection;
 
 pub use autorouter::*;

src/autorouter/permuter.rs

@@ -6,13 +6,12 @@ use std::iter::Skip;
 
 use enum_dispatch::enum_dispatch;
 use itertools::{Itertools, Permutations};
-use petgraph::graph::NodeIndex;
 use specctra_core::mesadata::AccessMesadata;
 
 use crate::{
     autorouter::{
         autoroute::AutorouteExecutionStepper, presorter::SccIntersectionsAndLengthPresorter,
-        ratline::RatlineIndex, Autorouter, AutorouterOptions,
+        ratline::RatlineIndex, scc::Scc, Autorouter, AutorouterOptions,
     },
     drawing::graph::MakePrimitiveRef,
     geometry::{GenericNode, GetLayer},
@@ -51,7 +50,7 @@ impl RatlinesPermuter {
 }
 
 pub struct SccPermutationsRatlinePermuter {
-    sccs_permutations_iter: Skip<Permutations<std::vec::IntoIter<Vec<NodeIndex<usize>>>>>,
+    sccs_permutations_iter: Skip<Permutations<std::vec::IntoIter<Scc>>>,
     original_ratlines: Vec<RatlineIndex>,
 }
 
@@ -85,14 +84,14 @@ impl PermuteRatlines for SccPermutationsRatlinePermuter {
 
         for scc in scc_permutation {
             for ratline in self.original_ratlines.iter() {
-                if scc.contains(
+                if scc.node_indices().contains(
                     &autorouter
                         .ratsnest()
                         .graph()
                         .edge_endpoints(*ratline)
                         .unwrap()
                         .0,
-                ) && scc.contains(
+                ) && scc.node_indices().contains(
                     &autorouter
                         .ratsnest()
                         .graph()

src/autorouter/presorter.rs

@@ -6,14 +6,10 @@ use std::cmp::Ordering;
 
 use derive_getters::{Dissolve, Getters};
 use enum_dispatch::enum_dispatch;
-use petgraph::{algo::tarjan_scc, graph::NodeIndex};
+use petgraph::algo::tarjan_scc;
 use specctra_core::mesadata::AccessMesadata;
 
-use crate::{
-    autorouter::{ratline::RatlineIndex, Autorouter},
-    geometry::shape::MeasureLength,
-    graph::MakeRef,
-};
+use crate::autorouter::{ratline::RatlineIndex, scc::Scc, Autorouter};
 
 #[enum_dispatch]
 pub trait PresortRatlines {
@@ -31,7 +27,7 @@ pub enum RatlinesPresorter {
 
 #[derive(Getters, Dissolve)]
 pub struct SccIntersectionsAndLengthPresorter {
-    sccs: Vec<Vec<NodeIndex<usize>>>,
+    sccs: Vec<Scc>,
 }
 
 impl SccIntersectionsAndLengthPresorter {
@@ -43,103 +39,21 @@ impl SccIntersectionsAndLengthPresorter {
         let mut filtered_ratsnest = autorouter.ratsnest().graph().clone();
         filtered_ratsnest.retain_edges(|_g, i| ratlines.contains(&i));
 
-        let mut sccs = tarjan_scc(&filtered_ratsnest);
+        let mut sccs: Vec<_> = tarjan_scc(&filtered_ratsnest)
+            .into_iter()
+            .map(|node_indices| Scc::new(autorouter, ratlines, &filtered_ratsnest, node_indices))
+            .collect();
 
         sccs.sort_unstable_by(|a, b| {
-            // FIXME: These calculations should probably be stored somewhere
-            // instead of being done every time.
-
-            let mut a_intersector_count = 0;
-            let mut b_intersector_count = 0;
-            let mut a_length = 0.0;
-            let mut b_length = 0.0;
-
-            // FIXME: It's inefficient to iterate over the ratlines on every
-            // sort comparison. But this is the simplest solution I arrived
-            // at after realizing that `.tarjan_scc(...)` does not sort nodes
-            // inside components.
-            for ratline in ratlines.iter() {
-                if a.contains(&filtered_ratsnest.edge_endpoints(*ratline).unwrap().0)
-                    && a.contains(&filtered_ratsnest.edge_endpoints(*ratline).unwrap().1)
-                {
-                    a_length += ratline.ref_(autorouter).length();
-                    a_intersector_count +=
-                        ratline.ref_(autorouter).interiorly_cut_ratlines().count();
-                    a_intersector_count +=
-                        ratline.ref_(autorouter).cut_other_net_primitives().count();
-                }
-            }
-
-            for ratline in ratlines.iter() {
-                if b.contains(&filtered_ratsnest.edge_endpoints(*ratline).unwrap().0)
-                    && b.contains(&filtered_ratsnest.edge_endpoints(*ratline).unwrap().1)
-                {
-                    b_length += ratline.ref_(autorouter).length();
-                    b_intersector_count +=
-                        ratline.ref_(autorouter).interiorly_cut_ratlines().count();
-                    b_intersector_count +=
-                        ratline.ref_(autorouter).cut_other_net_primitives().count();
-                }
-            }
-
-            let primary_ordering = a_intersector_count.cmp(&b_intersector_count);
+            let primary_ordering = a.intersector_count().cmp(&b.intersector_count());
 
             if primary_ordering != Ordering::Equal {
                 primary_ordering
             } else {
-                let secondary_ordering = a_length.total_cmp(&b_length);
+                let secondary_ordering = a.length().total_cmp(&b.length());
 
                 secondary_ordering
             }
-
-            // Below is how I tried to do this before I realized that
-            // `.tarjan_scc(...)` does not sort nodes inside components.
-
-            /*let a_intersector_count: usize = a
-                .windows(2)
-                .map(|window| {
-                    let ratline = filtered_ratsnest.find_edge(window[0], window[1]).unwrap();
-                    ratline
-                        .ref_(autorouter)
-                        .interior_obstacle_ratlines()
-                        .count()
-                })
-                .sum();
-            let b_intersector_count: usize = b
-                .windows(2)
-                .map(|window| {
-                    let ratline = filtered_ratsnest.find_edge(window[0], window[1]).unwrap();
-                    ratline
-                        .ref_(autorouter)
-                        .interior_obstacle_ratlines()
-                        .count()
-                })
-                .sum();
-
-            let primary_ordering = a_intersector_count.cmp(&b_intersector_count);
-
-            if primary_ordering != Ordering::Equal {
-                primary_ordering
-            } else {
-                let a_length: f64 = a
-                    .windows(2)
-                    .map(|window| {
-                        let ratline = filtered_ratsnest.find_edge(window[0], window[1]).unwrap();
-                        ratline.ref_(autorouter).length()
-                    })
-                    .sum();
-                let b_length: f64 = b
-                    .windows(2)
-                    .map(|window| {
-                        let ratline = filtered_ratsnest.find_edge(window[0], window[1]).unwrap();
-                        ratline.ref_(autorouter).length()
-                    })
-                    .sum();
-
-                let secondary_ordering = a_length.total_cmp(&b_length);
-
-                secondary_ordering
-            }*/
         });
 
         Self { sccs }
@@ -156,21 +70,7 @@ impl PresortRatlines for SccIntersectionsAndLengthPresorter {
 
         for scc in self.sccs.iter() {
             for ratline in ratlines.iter() {
-                if scc.contains(
-                    &autorouter
-                        .ratsnest()
-                        .graph()
-                        .edge_endpoints(*ratline)
-                        .unwrap()
-                        .0,
-                ) && scc.contains(
-                    &autorouter
-                        .ratsnest()
-                        .graph()
-                        .edge_endpoints(*ratline)
-                        .unwrap()
-                        .1,
-                ) {
+                if scc.scc_ref(autorouter).contains(*ratline) {
                     presorted_ratlines.push(*ratline);
                 }
             }

src/autorouter/scc.rs

@@ -0,0 +1,96 @@
+// SPDX-FileCopyrightText: 2025 Topola contributors
+//
+// SPDX-License-Identifier: MIT
+
+use derive_getters::Getters;
+use petgraph::{graph::NodeIndex, prelude::StableUnGraph};
+use specctra_core::mesadata::AccessMesadata;
+
+use crate::{
+    autorouter::{
+        ratline::{RatlineIndex, RatlineWeight},
+        ratsnest::RatvertexWeight,
+        Autorouter,
+    },
+    geometry::shape::MeasureLength,
+    graph::MakeRef,
+};
+
+#[derive(Clone, Debug, Getters)]
+pub struct Scc {
+    node_indices: Vec<NodeIndex<usize>>,
+
+    length: f64,
+    intersector_count: usize,
+}
+
+impl Scc {
+    pub fn new(
+        autorouter: &mut Autorouter<impl AccessMesadata>,
+        ratlines: &[RatlineIndex],
+        filtered_ratsnest: &StableUnGraph<RatvertexWeight, RatlineWeight, usize>,
+        node_indices: Vec<NodeIndex<usize>>,
+    ) -> Self {
+        let mut this = Self {
+            node_indices,
+            length: 0.0,
+            intersector_count: 0,
+        };
+
+        for ratline in ratlines.iter() {
+            if this
+                .node_indices
+                .contains(&filtered_ratsnest.edge_endpoints(*ratline).unwrap().0)
+                && this
+                    .node_indices
+                    .contains(&filtered_ratsnest.edge_endpoints(*ratline).unwrap().1)
+            {
+                this.length += ratline.ref_(autorouter).length();
+                this.intersector_count +=
+                    ratline.ref_(autorouter).interiorly_cut_ratlines().count();
+                this.intersector_count +=
+                    ratline.ref_(autorouter).cut_other_net_primitives().count();
+            }
+        }
+
+        this
+    }
+
+    pub fn scc_ref<'a, M: AccessMesadata>(
+        &'a self,
+        autorouter: &'a Autorouter<M>,
+    ) -> SccRef<'a, M> {
+        SccRef::new(self, autorouter)
+    }
+}
+
+pub struct SccRef<'a, M: AccessMesadata> {
+    scc: &'a Scc,
+    autorouter: &'a Autorouter<M>,
+}
+
+impl<'a, M: AccessMesadata> SccRef<'a, M> {
+    pub fn new(scc: &'a Scc, autorouter: &'a Autorouter<M>) -> Self {
+        Self { scc, autorouter }
+    }
+
+    pub fn contains(&self, ratline: RatlineIndex) -> bool {
+        self.scc.node_indices().contains(
+            &self
+                .autorouter
+                .ratsnest()
+                .graph()
+                .edge_endpoints(ratline)
+                .unwrap()
+                .0,
+        ) && self.scc.node_indices().contains(
+            &self
+                .autorouter
+                .ratsnest()
+                .graph()
+                .edge_endpoints(ratline)
+                .unwrap()
+                .1,
+        )
+    }
+}