router: split out `Trace` to its own file and give it its own methods

We'll be following this pattern:
* `Autorouter` - `Autoroute`,
* `Router` - `Route` (not yet done),
* `Tracer` - `Trace`.

Agent nouns (ending with -er) denote the object that holds large and
"unportable" parts of the state (such as `Board`, `Layout`, `Drawing`,
`Geometry`), while verbs (ending with -e) denote holders of other, more
"portable" parts of the state.

src/autorouter/autoroute.rs

@@ -14,8 +14,8 @@ pub struct Autoroute {
 
 impl Autoroute {
     pub fn new(
-        ratlines: impl IntoIterator<Item = EdgeIndex<usize>> + 'static,
         autorouter: &mut Autorouter<impl MesadataTrait>,
+        ratlines: impl IntoIterator<Item = EdgeIndex<usize>> + 'static,
     ) -> Result<Self, AutorouterError> {
         let mut ratlines_iter = Box::new(ratlines.into_iter());
 

src/autorouter/autorouter.rs

@@ -60,7 +60,7 @@ impl<M: MesadataTrait> Autorouter<M> {
     }
 
     pub fn autoroute_walk(&mut self, selection: &Selection) -> Result<Autoroute, AutorouterError> {
-        Autoroute::new(self.selected_ratlines(selection), self)
+        Autoroute::new(self, self.selected_ratlines(selection))
     }
 
     pub fn undo_autoroute(&mut self, selection: &Selection) {

src/drawing/guide.rs

@@ -38,12 +38,12 @@ pub enum Head {
 
 #[derive(Debug, Clone, Copy)]
 pub struct BareHead {
-    pub dot: FixedDotIndex,
+    pub face: FixedDotIndex,
 }
 
 impl HeadTrait for BareHead {
     fn face(&self) -> DotIndex {
-        self.dot.into()
+        self.face.into()
     }
 }
 
@@ -233,7 +233,7 @@ impl<'a, CW: Copy, R: RulesTrait> Guide<'a, CW, R> {
 
     pub fn head(&self, face: DotIndex) -> Head {
         match face {
-            DotIndex::Fixed(dot) => BareHead { dot }.into(),
+            DotIndex::Fixed(dot) => BareHead { face: dot }.into(),
             DotIndex::Loose(dot) => self.cane_head(dot).into(),
         }
     }

src/router/mod.rs

@@ -2,6 +2,7 @@ pub mod astar;
 pub mod draw;
 pub mod navmesh;
 mod router;
+pub mod trace;
 pub mod tracer;
 
 pub use router::*;

src/router/router.rs

@@ -25,7 +25,8 @@ use crate::{
             BinavvertexNodeIndex, Navmesh, NavmeshEdgeReference, NavmeshError, NavvertexIndex,
             NavvertexWeight,
         },
-        tracer::{Trace, Tracer},
+        trace::Trace,
+        tracer::Tracer,
     },
 };
 
@@ -118,13 +119,13 @@ impl<'a, R: RulesTrait> AstarStrategy<Navmesh, f64, BandFirstSegIndex>
 
         let width = self.trace.width;
         let result = self
-            .tracer
+            .trace
-            .step(navmesh, &mut self.trace, edge.target(), width);
+            .step(&mut self.tracer, navmesh, edge.target(), width);
 
         let probe_length = self.bihead_length() - prev_bihead_length;
 
         if result.is_ok() {
-            self.tracer.undo_step(navmesh, &mut self.trace);
+            self.trace.undo_step(&mut self.tracer);
             Some(probe_length)
         } else {
             None
@@ -169,7 +170,7 @@ impl Router {
         let target = navmesh.target();
 
         let mut tracer = Tracer::new(layout);
-        let mut trace = tracer.start(&navmesh, source, source_navvertex, width);
+        let mut trace = tracer.start(source, source_navvertex, width);
 
         let mut strategy = RouterAstarStrategy::new(tracer, &mut trace, target);
         let astar = Astar::new(navmesh, source_navvertex, &mut strategy);

src/router/trace.rs

@@ -0,0 +1,118 @@
+use contracts::debug_ensures;
+use petgraph::data::DataMap;
+
+use crate::{
+    drawing::{
+        bend::LooseBendIndex,
+        dot::FixedDotIndex,
+        graph::PrimitiveIndex,
+        guide::{BareHead, CaneHead, Head},
+        rules::RulesTrait,
+    },
+    router::{
+        draw::Draw,
+        navmesh::{BinavvertexNodeIndex, Navmesh, NavvertexIndex},
+        tracer::{Tracer, TracerException},
+    },
+};
+
+#[derive(Debug)]
+pub struct Trace {
+    pub path: Vec<NavvertexIndex>,
+    pub head: Head,
+    pub width: f64,
+}
+
+impl Trace {
+    pub fn new(source: FixedDotIndex, source_navvertex: NavvertexIndex, width: f64) -> Trace {
+        Self {
+            path: vec![source_navvertex],
+            head: BareHead { face: source }.into(),
+            width,
+        }
+    }
+
+    #[debug_ensures(ret.is_ok() -> matches!(self.head, Head::Cane(..)))]
+    #[debug_ensures(ret.is_ok() -> self.path.len() == old(self.path.len() + 1))]
+    #[debug_ensures(ret.is_err() -> self.path.len() == old(self.path.len()))]
+    pub fn step(
+        &mut self,
+        tracer: &mut Tracer<impl RulesTrait>,
+        navmesh: &Navmesh,
+        to: NavvertexIndex,
+        width: f64,
+    ) -> Result<(), TracerException> {
+        self.head = self.wrap(tracer, navmesh, self.head, to, width)?.into();
+        self.path.push(to);
+
+        Ok::<(), TracerException>(())
+    }
+
+    #[debug_ensures(self.path.len() == old(self.path.len() - 1))]
+    pub fn undo_step(&mut self, tracer: &mut Tracer<impl RulesTrait>) {
+        if let Head::Cane(head) = self.head {
+            self.head = Draw::new(tracer.layout).undo_cane(head).unwrap();
+        } else {
+            panic!();
+        }
+
+        self.path.pop();
+    }
+
+    fn wrap(
+        &mut self,
+        tracer: &mut Tracer<impl RulesTrait>,
+        navmesh: &Navmesh,
+        head: Head,
+        around: NavvertexIndex,
+        width: f64,
+    ) -> Result<CaneHead, TracerException> {
+        let cw = self
+            .maybe_cw(navmesh, around)
+            .ok_or(TracerException::CannotWrap)?;
+
+        match self.binavvertex(navmesh, around) {
+            BinavvertexNodeIndex::FixedDot(dot) => {
+                self.wrap_around_fixed_dot(tracer, head, dot, cw, width)
+            }
+            BinavvertexNodeIndex::FixedBend(_fixed_bend) => todo!(),
+            BinavvertexNodeIndex::LooseBend(loose_bend) => {
+                self.wrap_around_loose_bend(tracer, head, loose_bend, cw, width)
+            }
+        }
+    }
+
+    fn wrap_around_fixed_dot(
+        &mut self,
+        tracer: &mut Tracer<impl RulesTrait>,
+        head: Head,
+        around: FixedDotIndex,
+        cw: bool,
+        width: f64,
+    ) -> Result<CaneHead, TracerException> {
+        Ok(Draw::new(tracer.layout).cane_around_dot(head, around.into(), cw, width)?)
+    }
+
+    fn wrap_around_loose_bend(
+        &mut self,
+        tracer: &mut Tracer<impl RulesTrait>,
+        head: Head,
+        around: LooseBendIndex,
+        cw: bool,
+        width: f64,
+    ) -> Result<CaneHead, TracerException> {
+        Ok(Draw::new(tracer.layout).cane_around_bend(head, around.into(), cw, width)?)
+    }
+
+    fn binavvertex(&self, navmesh: &Navmesh, navvertex: NavvertexIndex) -> BinavvertexNodeIndex {
+        navmesh.node_weight(navvertex).unwrap().node
+    }
+
+    fn primitive(&self, navmesh: &Navmesh, navvertex: NavvertexIndex) -> PrimitiveIndex {
+        self.binavvertex(navmesh, navvertex).into()
+    }
+
+    fn maybe_cw(&self, navmesh: &Navmesh, navvertex: NavvertexIndex) -> Option<bool> {
+        navmesh.node_weight(navvertex).unwrap().maybe_cw
+    }
+}

src/router/tracer.rs

@@ -18,6 +18,7 @@ use crate::{
     router::{
         draw::{Draw, DrawException},
         navmesh::{BinavvertexNodeIndex, Navmesh, NavvertexIndex, NavvertexWeight},
+        trace::Trace,
     },
 };
 
@@ -29,13 +30,6 @@ pub enum TracerException {
     CannotWrap,
 }
 
-#[derive(Debug)]
-pub struct Trace {
-    pub path: Vec<NavvertexIndex>,
-    pub head: Head,
-    pub width: f64,
-}
-
 #[derive(Debug)]
 pub struct Tracer<'a, R: RulesTrait> {
     pub layout: &'a mut Layout<R>,
@@ -48,16 +42,11 @@ impl<'a, R: RulesTrait> Tracer<'a, R> {
 
     pub fn start(
         &mut self,
-        _navmesh: &Navmesh,
         source: FixedDotIndex,
         source_navvertex: NavvertexIndex,
         width: f64,
     ) -> Trace {
-        Trace {
+        Trace::new(source, source_navvertex, width)
-            path: vec![source_navvertex],
-            head: BareHead { dot: source }.into(),
-            width,
-        }
     }
 
     pub fn finish(
@@ -87,7 +76,7 @@ impl<'a, R: RulesTrait> Tracer<'a, R> {
             .count();
 
         let length = trace.path.len();
-        self.undo_path(navmesh, trace, length - prefix_length);
+        self.undo_path(trace, length - prefix_length);
         Ok::<(), TracerException>(self.path(navmesh, trace, &path[prefix_length..], width)?)
     }
 
@@ -100,8 +89,8 @@ impl<'a, R: RulesTrait> Tracer<'a, R> {
         width: f64,
     ) -> Result<(), TracerException> {
         for (i, vertex) in path.iter().enumerate() {
-            if let Err(err) = self.step(navmesh, trace, *vertex, width) {
+            if let Err(err) = trace.step(self, navmesh, *vertex, width) {
-                self.undo_path(navmesh, trace, i);
+                self.undo_path(trace, i);
                 return Err(err.into());
             }
         }
@@ -110,92 +99,9 @@ impl<'a, R: RulesTrait> Tracer<'a, R> {
     }
 
     #[debug_ensures(trace.path.len() == old(trace.path.len() - step_count))]
-    pub fn undo_path(&mut self, navmesh: &Navmesh, trace: &mut Trace, step_count: usize) {
+    pub fn undo_path(&mut self, trace: &mut Trace, step_count: usize) {
         for _ in 0..step_count {
-            self.undo_step(navmesh, trace);
+            trace.undo_step(self);
-        }
-    }
-
-    #[debug_ensures(ret.is_ok() -> matches!(trace.head, Head::Cane(..)))]
-    #[debug_ensures(ret.is_ok() -> trace.path.len() == old(trace.path.len() + 1))]
-    #[debug_ensures(ret.is_err() -> trace.path.len() == old(trace.path.len()))]
-    pub fn step(
-        &mut self,
-        navmesh: &Navmesh,
-        trace: &mut Trace,
-        to: NavvertexIndex,
-        width: f64,
-    ) -> Result<(), TracerException> {
-        trace.head = self.wrap(navmesh, trace.head, to, width)?.into();
-        trace.path.push(to);
-
-        Ok::<(), TracerException>(())
-    }
-
-    fn wrap(
-        &mut self,
-        navmesh: &Navmesh,
-        head: Head,
-        around: NavvertexIndex,
-        width: f64,
-    ) -> Result<CaneHead, TracerException> {
-        let cw = self
-            .maybe_cw(navmesh, around)
-            .ok_or(TracerException::CannotWrap)?;
-
-        match self.binavvertex(navmesh, around) {
-            BinavvertexNodeIndex::FixedDot(dot) => {
-                self.wrap_around_fixed_dot(navmesh, head, dot, cw, width)
-            }
-            BinavvertexNodeIndex::FixedBend(_fixed_bend) => todo!(),
-            BinavvertexNodeIndex::LooseBend(loose_bend) => {
-                self.wrap_around_loose_bend(navmesh, head, loose_bend, cw, width)
         }
     }
 }
-
-    fn wrap_around_fixed_dot(
-        &mut self,
-        _navmesh: &Navmesh,
-        head: Head,
-        around: FixedDotIndex,
-        cw: bool,
-        width: f64,
-    ) -> Result<CaneHead, TracerException> {
-        Ok(Draw::new(self.layout).cane_around_dot(head, around.into(), cw, width)?)
-    }
-
-    fn wrap_around_loose_bend(
-        &mut self,
-        _navmesh: &Navmesh,
-        head: Head,
-        around: LooseBendIndex,
-        cw: bool,
-        width: f64,
-    ) -> Result<CaneHead, TracerException> {
-        Ok(Draw::new(self.layout).cane_around_bend(head, around.into(), cw, width)?)
-    }
-
-    #[debug_ensures(trace.path.len() == old(trace.path.len() - 1))]
-    pub fn undo_step(&mut self, _navmesh: &Navmesh, trace: &mut Trace) {
-        if let Head::Cane(head) = trace.head {
-            trace.head = Draw::new(self.layout).undo_cane(head).unwrap();
-        } else {
-            panic!();
-        }
-
-        trace.path.pop();
-    }
-
-    fn maybe_cw(&self, navmesh: &Navmesh, navvertex: NavvertexIndex) -> Option<bool> {
-        navmesh.node_weight(navvertex).unwrap().maybe_cw
-    }
-
-    fn binavvertex(&self, navmesh: &Navmesh, navvertex: NavvertexIndex) -> BinavvertexNodeIndex {
-        navmesh.node_weight(navvertex).unwrap().node
-    }
-
-    fn primitive(&self, navmesh: &Navmesh, navvertex: NavvertexIndex) -> PrimitiveIndex {
-        self.binavvertex(navmesh, navvertex).into()
-    }
-}