feat(router/navcord): Make it possible to visit leap navnodes

Closes https://codeberg.org/topola/topola/issues/121

src/router/navcord.rs

@@ -18,7 +18,7 @@ use crate::{
 use super::{
     draw::Draw,
     navcorder::{Navcorder, NavcorderException},
-    navmesh::{NavigableNodeIndex, Navmesh, NavnodeIndex},
+    navmesh::{NavigableNodeIndex, Navmesh, NavnodeIndex, NavnodeWeight},
 };
 
 /// The `Navcord` is a data structure that holds the movable non-borrowing data
@@ -106,17 +106,20 @@ impl Navcord {
         navmesh: &Navmesh,
         to: NavnodeIndex,
     ) -> Result<(), NavcorderException> {
-        if to == navmesh.destination_navnode() {
         let to_node_weight = navmesh.node_weight(to).unwrap();
+
+        if to == navmesh.destination_navnode() {
             let NavigableNodeIndex::FixedDot(to_dot) = to_node_weight.node() else {
                 unreachable!();
             };
 
-            self.final_termseg = Some(layout.finish(navmesh, self, to_dot).unwrap());
+            self.final_termseg = Some(layout.finish(navmesh, self, to_dot)?);
 
             // NOTE: We don't update the head here because there is currently
             // no head variant that consists only of a seg, and I'm not sure if
             // there should be one.
+        } else if matches!(to_node_weight, NavnodeWeight::Leap(..)) {
+            // Nothing to do beyond pushing the navnode onto the path.
         } else {
             self.head = self.wrap(layout, navmesh, self.head, to)?.into();
         }
@@ -134,10 +137,15 @@ impl Navcord {
     pub fn step_back<R: AccessRules>(
         &mut self,
         layout: &mut Layout<R>,
+        navmesh: &Navmesh,
     ) -> Result<(), NavcorderException> {
+        let last_node_weight = navmesh.node_weight(*self.path.last().unwrap());
+
         if let Some(final_termseg) = self.final_termseg {
             layout.remove_termseg(&mut self.recorder, final_termseg);
             self.final_termseg = None;
+        } else if matches!(last_node_weight, Some(NavnodeWeight::Leap(..))) {
+            // Nothing to do beyond popping the navnode from the path.
         } else {
             if let Head::Cane(head) = self.head {
                 self.head = layout.undo_cane(&mut self.recorder, head).unwrap();

src/router/navcorder.rs

@@ -54,7 +54,7 @@ pub trait Navcorder {
         path: &[NavnodeIndex],
     ) -> Result<(), NavcorderException>;
 
-    fn undo_path(&mut self, navcord: &mut Navcord, step_count: usize);
+    fn undo_path(&mut self, navmesh: &Navmesh, navcord: &mut Navcord, step_count: usize);
 }
 
 impl<R: AccessRules> Navcorder for Layout<R> {
@@ -93,7 +93,7 @@ impl<R: AccessRules> Navcorder for Layout<R> {
             .count();
 
         let length = navcord.path.len();
-        self.undo_path(navcord, length - prefix_length);
+        self.undo_path(navmesh, navcord, length - prefix_length);
         self.path(navmesh, navcord, &path[prefix_length..])
     }
 
@@ -106,7 +106,7 @@ impl<R: AccessRules> Navcorder for Layout<R> {
     ) -> Result<(), NavcorderException> {
         for (i, vertex) in path.iter().enumerate() {
             if let Err(err) = navcord.step_to(self, navmesh, *vertex) {
-                self.undo_path(navcord, i);
+                self.undo_path(navmesh, navcord, i);
                 return Err(err);
             }
         }
@@ -115,9 +115,9 @@ impl<R: AccessRules> Navcorder for Layout<R> {
     }
 
     #[debug_ensures(navcord.path.len() == old(navcord.path.len() - step_count))]
-    fn undo_path(&mut self, navcord: &mut Navcord, step_count: usize) {
+    fn undo_path(&mut self, navmesh: &Navmesh, navcord: &mut Navcord, step_count: usize) {
         for _ in 0..step_count {
-            let _ = navcord.step_back(self);
+            let _ = navcord.step_back(self, navmesh);
         }
     }
 }

src/router/route.rs

@@ -90,7 +90,7 @@ impl<R: AccessRules> Step<Router<'_, R>, BandTermsegIndex> for RouteStepper {
                 // NOTE(fogti): The 1 instead 0 is because the first element in the path
                 // is the source navnode. See also: `NavcordStepper::new`.
                 for _ in 1..self.navcord.path.len() {
-                    self.navcord.step_back(layout);
+                    self.navcord.step_back(layout, &self.astar.graph);
                 }
                 Err(e)
             }

src/router/router.rs

@@ -136,8 +136,8 @@ impl<R: AccessRules> AstarStrategy<Navmesh, f64, BandTermsegIndex> for RouterAst
         }
     }
 
-    fn remove_probe(&mut self, _navmesh: &Navmesh) {
-        self.navcord.step_back(self.layout);
+    fn remove_probe(&mut self, navmesh: &Navmesh) {
+        self.navcord.step_back(self.layout, navmesh);
     }
 
     fn estimate_cost(&mut self, navmesh: &Navmesh, vertex: NavnodeIndex) -> f64 {