fix(autorouter/planar_reconfigurer): Differentiate search nodes also by length

This fixes 4x4_1206_led_matrix_breakout test.

crates/topola-egui/src/displayer.rs

@@ -312,7 +312,7 @@ impl<'a> Displayer<'a> {
                             .get(&navnode)
                             .map_or_else(String::new, |s| format!("g={:.2}", s));
                         let estimate_score_text = thetastar
-                            .cost_to_goal_estimate_scores()
+                            .estimated_costs()
                             .get(&navnode)
                             .map_or_else(String::new, |s| format!("(f={:.2})", s));
                         let debug_text = activity.navnode_debug_text(navnode).unwrap_or("");

src/astar.rs

@@ -0,0 +1,66 @@
+// SPDX-FileCopyrightText: 2025 Topola contributors
+//
+// SPDX-License-Identifier: MIT
+
+use std::{
+    collections::{btree_map::Entry, BTreeMap, BinaryHeap},
+    ops::Add,
+};
+
+use derive_getters::Getters;
+
+use crate::scored::MinScored;
+
+#[derive(Getters)]
+pub struct Astar<N, S> {
+    #[getter(skip)]
+    frontier: BinaryHeap<MinScored<S, N>>,
+    #[getter(skip)]
+    g_scores: BTreeMap<N, S>,
+    curr_node: N,
+}
+
+impl<N: Clone + Ord, S: Add<S, Output = S> + Copy + Default + PartialOrd> Astar<N, S> {
+    pub fn new(start: N) -> Self {
+        let mut frontier = BinaryHeap::new();
+        let mut scores = BTreeMap::new();
+
+        scores.insert(start.clone(), S::default());
+        frontier.push(MinScored(S::default(), start.clone()));
+
+        Self {
+            frontier,
+            g_scores: scores,
+            curr_node: start,
+        }
+    }
+
+    pub fn expand(&mut self, new_nodes: &[(S, S, N)]) -> Option<N> {
+        let curr_g_score = self.g_scores.get(&self.curr_node).unwrap().clone();
+
+        for (edge_g_cost, h_heuristic, node) in new_nodes {
+            match self.g_scores.entry(node.clone()) {
+                Entry::Occupied(mut entry) => {
+                    let entry_score = *entry.get();
+
+                    if curr_g_score + *edge_g_cost >= entry_score {
+                        continue;
+                    }
+
+                    entry.insert(curr_g_score + *edge_g_cost);
+                }
+                Entry::Vacant(entry) => {
+                    entry.insert(curr_g_score + *edge_g_cost);
+                }
+            }
+
+            self.frontier.push(MinScored(
+                curr_g_score + *edge_g_cost + *h_heuristic,
+                node.clone(),
+            ));
+        }
+
+        MinScored(_ /*f_score*/, self.curr_node) = self.frontier.pop()?;
+        Some(self.curr_node.clone())
+    }
+}

src/autorouter/mod.rs

@@ -14,7 +14,6 @@ pub mod multilayer_autoroute;
 pub mod multilayer_preconfigurer;
 pub mod multilayer_reconfigurator;
 pub mod multilayer_reconfigurer;
-pub mod permsearch;
 pub mod place_via;
 pub mod planar_autoroute;
 pub mod planar_preconfigurer;

src/autorouter/permsearch.rs

@@ -1,106 +0,0 @@
-// SPDX-FileCopyrightText: 2025 Topola contributors
-//
-// SPDX-License-Identifier: MIT
-
-use std::{cmp::Ordering, collections::BinaryHeap, iter::Skip, iter::Take};
-
-use itertools::{Itertools, Permutations};
-
-#[derive(Clone, Debug)]
-struct PermsearchNode<T> {
-    curr_permutation: Vec<T>,
-    permutations: Skip<Permutations<Take<std::vec::IntoIter<T>>>>,
-    length: usize,
-}
-
-impl<T: Eq> PartialEq for PermsearchNode<T> {
-    fn eq(&self, other: &Self) -> bool {
-        self.curr_permutation == other.curr_permutation
-    }
-}
-
-impl<T: Eq> Eq for PermsearchNode<T> {}
-
-impl<T: Eq> Ord for PermsearchNode<T> {
-    fn cmp(&self, other: &Self) -> Ordering {
-        self.length.cmp(&other.length)
-    }
-}
-
-impl<T: Eq> PartialOrd for PermsearchNode<T> {
-    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
-        self.length.partial_cmp(&other.length)
-    }
-}
-
-impl<T: Clone> PermsearchNode<T> {
-    fn permute(mut self) -> Option<Self> {
-        for (i, element) in self.permutations.next()?.iter().enumerate() {
-            self.curr_permutation[i] = element.clone();
-        }
-
-        Some(self)
-    }
-
-    fn resize(self, length: usize) -> Option<Self> {
-        if length == self.length {
-            return None;
-        }
-
-        // TODO: Get rid of `self.curr_permutation` clone somehow?
-
-        Some(Self {
-            curr_permutation: self.curr_permutation.clone(),
-            permutations: self
-                .curr_permutation
-                .into_iter()
-                .take(length)
-                .permutations(length)
-                .skip(1),
-            length,
-        })
-    }
-}
-
-pub struct Permsearch<T> {
-    curr_node: PermsearchNode<T>,
-    frontier: BinaryHeap<PermsearchNode<T>>,
-}
-
-impl<T: Eq + Clone> Permsearch<T> {
-    pub fn new(original: Vec<T>) -> Self {
-        let len = original.len();
-
-        // TODO: Get rid of `original` clone somehow?
-
-        Self {
-            curr_node: PermsearchNode {
-                curr_permutation: original.clone(),
-                permutations: original.into_iter().take(len).permutations(0).skip(0),
-                length: 0,
-            },
-            frontier: BinaryHeap::new(),
-        }
-    }
-
-    pub fn step(&mut self, len: usize) -> Option<&[T]> {
-        // TODO: Get rid of `self.curr_node` clones somehow?
-
-        if let Some(resized_curr_node) = self.curr_node.clone().resize(len) {
-            if let Some(permuted_resized_curr_node) = resized_curr_node.permute() {
-                self.frontier.push(permuted_resized_curr_node);
-            }
-        }
-
-        if let Some(permuted_curr_node) = self.curr_node.clone().permute() {
-            self.frontier.push(permuted_curr_node);
-        }
-
-        self.curr_node = self.frontier.pop()?;
-        Some(&self.curr_node.curr_permutation)
-    }
-
-    pub fn curr_permutation(&self) -> &[T] {
-        &self.curr_node.curr_permutation
-    }
-}

src/autorouter/planar_reconfigurer.rs

@@ -2,15 +2,24 @@
 //
 // SPDX-License-Identifier: MIT
 
+use std::{
+    cmp::Ordering,
+    iter::{Skip, Take},
+};
+
+use derive_getters::Getters;
 use enum_dispatch::enum_dispatch;
+use itertools::{Itertools, Permutations};
 use specctra_core::mesadata::AccessMesadata;
 
-use crate::autorouter::{
-    permsearch::Permsearch,
-    planar_autoroute::{PlanarAutorouteConfiguration, PlanarAutorouteExecutionStepper},
-    planar_preconfigurer::SccIntersectionsAndLengthRatlinePlanarAutoroutePreconfigurer,
-    scc::Scc,
-    Autorouter, PlanarAutorouteOptions,
+use crate::{
+    astar::Astar,
+    autorouter::{
+        planar_autoroute::{PlanarAutorouteConfiguration, PlanarAutorouteExecutionStepper},
+        planar_preconfigurer::SccIntersectionsAndLengthRatlinePlanarAutoroutePreconfigurer,
+        scc::Scc,
+        Autorouter, PlanarAutorouteOptions,
+    },
 };
 
 #[enum_dispatch]
@@ -49,8 +58,100 @@ impl PlanarAutorouteReconfigurer {
     }
 }
 
+#[derive(Clone, Debug, Getters)]
+struct SccSearchNode {
+    curr_permutation: Vec<Scc>,
+    #[getter(skip)]
+    permutations: Skip<Permutations<Take<std::vec::IntoIter<Scc>>>>,
+    #[getter(skip)]
+    length: usize,
+}
+
+impl Ord for SccSearchNode {
+    fn cmp(&self, other: &Self) -> Ordering {
+        self.curr_permutation
+            .cmp(&other.curr_permutation)
+            .then(self.length.cmp(&other.length))
+    }
+}
+
+impl PartialOrd for SccSearchNode {
+    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
+        Some(self.cmp(other))
+    }
+}
+
+impl Eq for SccSearchNode {}
+
+impl PartialEq for SccSearchNode {
+    fn eq(&self, other: &Self) -> bool {
+        self.curr_permutation == other.curr_permutation && self.length == other.length
+    }
+}
+
+impl SccSearchNode {
+    pub fn new(sccs: Vec<Scc>) -> Self {
+        let len = sccs.len();
+
+        Self {
+            curr_permutation: sccs.clone(),
+            permutations: sccs.into_iter().take(len).permutations(0).skip(0),
+            length: 0,
+        }
+    }
+
+    pub fn expand(&self, length: usize) -> Vec<(f64, f64, Self)> {
+        let mut expanded_nodes = vec![];
+
+        if let Some(resized) = self.clone().resize(length) {
+            if let Some(permuted_resized) = resized.permute() {
+                expanded_nodes.push((
+                    0.1,
+                    (self.curr_permutation.len() - length) as f64,
+                    permuted_resized,
+                ));
+            }
+        }
+
+        if let Some(permuted) = self.clone().permute() {
+            expanded_nodes.push((
+                0.1,
+                (self.curr_permutation.len() - self.length) as f64,
+                permuted,
+            ));
+        }
+
+        expanded_nodes
+    }
+
+    fn resize(self, length: usize) -> Option<Self> {
+        if length == self.length {
+            return None;
+        }
+
+        Some(Self {
+            curr_permutation: self.curr_permutation.clone(),
+            permutations: self
+                .curr_permutation
+                .into_iter()
+                .take(length)
+                .permutations(length)
+                .skip(1),
+            length,
+        })
+    }
+
+    fn permute(mut self) -> Option<Self> {
+        for (i, element) in self.permutations.next()?.iter().enumerate() {
+            self.curr_permutation[i] = element.clone();
+        }
+
+        Some(self)
+    }
+}
+
 pub struct SccPermutationsPlanarAutorouteReconfigurer {
-    sccs_permsearch: Permsearch<Scc>,
+    sccs_search: Astar<SccSearchNode, f64>,
     preconfiguration: PlanarAutorouteConfiguration,
 }
 
@@ -66,7 +167,7 @@ impl SccPermutationsPlanarAutorouteReconfigurer {
         let sccs = presorter.dissolve();
 
         Self {
-            sccs_permsearch: Permsearch::new(sccs),
+            sccs_search: Astar::new(SccSearchNode::new(sccs)),
             preconfiguration,
         }
     }
@@ -79,7 +180,8 @@ impl MakeNextPlanarAutorouteConfiguration for SccPermutationsPlanarAutorouteReco
         stepper: &PlanarAutorouteExecutionStepper,
     ) -> Option<PlanarAutorouteConfiguration> {
         let scc_index = self
-            .sccs_permsearch
+            .sccs_search
+            .curr_node()
             .curr_permutation()
             .iter()
             .position(|scc| {
@@ -88,10 +190,13 @@ impl MakeNextPlanarAutorouteConfiguration for SccPermutationsPlanarAutorouteReco
             })
             .unwrap();
 
-        let scc_permutation = self.sccs_permsearch.step(scc_index + 1)?;
+        let next_search_node = self
+            .sccs_search
+            .expand(&self.sccs_search.curr_node().expand(scc_index + 1))?;
+        let next_permutation = next_search_node.curr_permutation();
         let mut ratlines = vec![];
 
-        for scc in scc_permutation {
+        for scc in next_permutation {
             for ratline in self.preconfiguration.ratlines.iter() {
                 if scc.node_indices().contains(
                     &autorouter

src/autorouter/scc.rs

@@ -2,7 +2,7 @@
 //
 // SPDX-License-Identifier: MIT
 
-use std::collections::BTreeSet;
+use std::{cmp::Ordering, collections::BTreeSet};
 
 use derive_getters::Getters;
 use petgraph::{graph::NodeIndex, prelude::StableUnGraph};
@@ -26,6 +26,18 @@ pub struct Scc {
     length: f64,
 }
 
+impl Ord for Scc {
+    fn cmp(&self, other: &Self) -> Ordering {
+        self.node_indices.cmp(&other.node_indices)
+    }
+}
+
+impl PartialOrd for Scc {
+    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
+        Some(self.cmp(other))
+    }
+}
+
 impl PartialEq for Scc {
     fn eq(&self, other: &Self) -> bool {
         self.node_indices == other.node_indices

src/lib.rs

@@ -21,6 +21,7 @@
 pub mod graph;
 #[macro_use]
 pub mod drawing;
+pub mod astar;
 pub mod autorouter;
 pub mod bimapset;
 pub mod board;
@@ -29,6 +30,7 @@ pub mod interactor;
 pub mod layout;
 pub mod math;
 pub mod router;
+pub mod scored;
 pub mod specctra;
 pub mod stepper;
 pub mod triangulation;

src/router/thetastar.rs

@@ -18,52 +18,9 @@ use petgraph::algo::Measure;
 use petgraph::visit::{EdgeRef, GraphBase, IntoEdgeReferences, IntoEdges};
 use thiserror::Error;
 
-use std::cmp::Ordering;
-
+use crate::scored::MinScored;
 use crate::stepper::{EstimateProgress, LinearScale, Step};
 
-#[derive(Copy, Clone, Debug)]
-pub struct MinScored<K, T>(pub K, pub T);
-
-impl<K: PartialOrd, T> PartialEq for MinScored<K, T> {
-    #[inline]
-    fn eq(&self, other: &MinScored<K, T>) -> bool {
-        self.cmp(other) == Ordering::Equal
-    }
-}
-
-impl<K: PartialOrd, T> Eq for MinScored<K, T> {}
-
-impl<K: PartialOrd, T> PartialOrd for MinScored<K, T> {
-    #[inline]
-    fn partial_cmp(&self, other: &MinScored<K, T>) -> Option<Ordering> {
-        Some(self.cmp(other))
-    }
-}
-
-impl<K: PartialOrd, T> Ord for MinScored<K, T> {
-    #[inline]
-    fn cmp(&self, other: &MinScored<K, T>) -> Ordering {
-        let a = &self.0;
-        let b = &other.0;
-        if a == b {
-            Ordering::Equal
-        } else if a < b {
-            Ordering::Greater
-        } else if a > b {
-            Ordering::Less
-        } else if a.ne(a) && b.ne(b) {
-            // these are the NaN cases
-            Ordering::Equal
-        } else if a.ne(a) {
-            // Order NaN less, so that it is last in the MinScore order
-            Ordering::Less
-        } else {
-            Ordering::Greater
-        }
-    }
-}
-
 #[derive(Debug)]
 pub struct PathTracker<G>
 where
@@ -179,7 +136,7 @@ where
     /// Also known as the g-scores, or just g.
     scores: BTreeMap<G::NodeId, K>,
     /// Also known as the f-scores, or just f.
-    cost_to_goal_estimate_scores: BTreeMap<G::NodeId, K>,
+    estimated_costs: BTreeMap<G::NodeId, K>,
     #[getter(skip)]
     path_tracker: PathTracker<G>,
     // FIXME: To work around edge references borrowing from the graph we collect then reiterate over them.
@@ -218,7 +175,7 @@ where
             graph,
             frontier: BinaryHeap::new(),
             scores: BTreeMap::new(),
-            cost_to_goal_estimate_scores: BTreeMap::new(),
+            estimated_costs: BTreeMap::new(),
             path_tracker: PathTracker::<G>::new(),
             edge_ids: Vec::new(),
             progress_estimate_value: K::default(),
@@ -288,7 +245,7 @@ where
                         return Ok(ControlFlow::Break((cost, path, result)));
                     }
 
-                    match self.cost_to_goal_estimate_scores.entry(navnode) {
+                    match self.estimated_costs.entry(navnode) {
                         Entry::Occupied(mut entry) => {
                             // If the node has already been visited with an equal or lower
                             // estimated score than now, then we do not need to re-visit it.

src/scored.rs

@@ -0,0 +1,99 @@
+// SPDX-FileCopyrightText: (None)
+//
+// SPDX-License-Identifier: MIT OR Apache-2.0
+//
+// Copied verbatim from petgraph-0.8.3.
+
+use core::cmp::Ordering;
+
+/// `MinScored<K, T>` holds a score `K` and a scored object `T` in
+/// a pair for use with a `BinaryHeap`.
+///
+/// `MinScored` compares in reverse order by the score, so that we can
+/// use `BinaryHeap` as a min-heap to extract the score-value pair with the
+/// least score.
+///
+/// **Note:** `MinScored` implements a total order (`Ord`), so that it is
+/// possible to use float types as scores.
+#[derive(Copy, Clone, Debug)]
+pub struct MinScored<K, T>(pub K, pub T);
+
+impl<K: PartialOrd, T> PartialEq for MinScored<K, T> {
+    #[inline]
+    fn eq(&self, other: &MinScored<K, T>) -> bool {
+        self.cmp(other) == Ordering::Equal
+    }
+}
+
+impl<K: PartialOrd, T> Eq for MinScored<K, T> {}
+
+impl<K: PartialOrd, T> PartialOrd for MinScored<K, T> {
+    #[inline]
+    fn partial_cmp(&self, other: &MinScored<K, T>) -> Option<Ordering> {
+        Some(self.cmp(other))
+    }
+}
+
+impl<K: PartialOrd, T> Ord for MinScored<K, T> {
+    #[inline]
+    fn cmp(&self, other: &MinScored<K, T>) -> Ordering {
+        let a = &self.0;
+        let b = &other.0;
+        if a == b {
+            Ordering::Equal
+        } else if a < b {
+            Ordering::Greater
+        } else if a > b {
+            Ordering::Less
+        } else if a.ne(a) && b.ne(b) {
+            // these are the NaN cases
+            Ordering::Equal
+        } else if a.ne(a) {
+            // Order NaN less, so that it is last in the MinScore order
+            Ordering::Less
+        } else {
+            Ordering::Greater
+        }
+    }
+}
+
+#[derive(Copy, Clone, Debug)]
+pub struct MaxScored<K, T>(pub K, pub T);
+
+impl<K: PartialOrd, T> PartialEq for MaxScored<K, T> {
+    #[inline]
+    fn eq(&self, other: &MaxScored<K, T>) -> bool {
+        self.cmp(other) == Ordering::Equal
+    }
+}
+
+impl<K: PartialOrd, T> Eq for MaxScored<K, T> {}
+
+impl<K: PartialOrd, T> PartialOrd for MaxScored<K, T> {
+    #[inline]
+    fn partial_cmp(&self, other: &MaxScored<K, T>) -> Option<Ordering> {
+        Some(self.cmp(other))
+    }
+}
+
+impl<K: PartialOrd, T> Ord for MaxScored<K, T> {
+    #[inline]
+    fn cmp(&self, other: &MaxScored<K, T>) -> Ordering {
+        let a = &self.0;
+        let b = &other.0;
+        if a == b {
+            Ordering::Equal
+        } else if a < b {
+            Ordering::Less
+        } else if a > b {
+            Ordering::Greater
+        } else if a.ne(a) && b.ne(b) {
+            // these are the NaN cases
+            Ordering::Equal
+        } else if a.ne(a) {
+            Ordering::Less
+        } else {
+            Ordering::Greater
+        }
+    }
+}