geometry: make compound weights accessible from `CompoundManagerTrait`

src/drawing/drawing.rs

@@ -888,6 +888,10 @@ impl<CW: Copy, R: RulesTrait> CompoundManagerTrait<CW, GenericIndex<CW>> for Dra
             .add_to_compound(primitive, compound);
     }
 
+    fn compound_weight(&self, compound: GenericIndex<CW>) -> CW {
+        self.geometry_with_rtree.compound_weight(compound)
+    }
+
     fn compounds<W>(&self, node: GenericIndex<W>) -> impl Iterator<Item = GenericIndex<CW>> {
         self.geometry_with_rtree.compounds(node)
     }

src/drawing/graph.rs

@@ -83,6 +83,8 @@ macro_rules! impl_loose_weight {
     };
 }
 
+// TODO: This enum shouldn't exist: we shouldn't be carrying the tag around like this. Instead we
+// should be getting it from the graph when it's needed.
 #[enum_dispatch(GetNodeIndex, MakePrimitive)]
 #[derive(Debug, Hash, Clone, Copy, PartialEq, Eq)]
 pub enum PrimitiveIndex {

src/geometry/compound.rs

@@ -4,5 +4,6 @@ pub trait CompoundManagerTrait<CW: Copy, GI: GetNodeIndex + Copy> {
     fn add_compound(&mut self, weight: CW) -> GenericIndex<CW>;
     fn remove_compound(&mut self, compound: GenericIndex<CW>);
     fn add_to_compound<W>(&mut self, node: GenericIndex<W>, compound: GenericIndex<CW>);
+    fn compound_weight(&self, node: GenericIndex<CW>) -> CW;
     fn compounds<W>(&self, node: GenericIndex<W>) -> impl Iterator<Item = GenericIndex<CW>>;
 }

src/geometry/geometry.rs

@@ -507,6 +507,16 @@ impl<
         );
     }
 
+    fn compound_weight(&self, compound: GenericIndex<CW>) -> CW {
+        if let GenericNode::Compound(weight) =
+            *self.graph.node_weight(compound.node_index()).unwrap()
+        {
+            weight
+        } else {
+            unreachable!()
+        }
+    }
+
     fn compounds<W>(&self, node: GenericIndex<W>) -> impl Iterator<Item = GenericIndex<CW>> {
         self.graph
             .neighbors(node.node_index())

src/geometry/with_rtree.rs

@@ -408,6 +408,10 @@ impl<
         self.geometry.add_to_compound(primitive, compound);
     }
 
+    fn compound_weight(&self, compound: GenericIndex<CW>) -> CW {
+        self.geometry.compound_weight(compound)
+    }
+
     fn compounds<W>(&self, node: GenericIndex<W>) -> impl Iterator<Item = GenericIndex<CW>> {
         self.geometry.compounds(node)
     }

src/layout/layout.rs

@@ -236,6 +236,10 @@ impl<R: RulesTrait> CompoundManagerTrait<ZoneWeight, GenericIndex<ZoneWeight>> f
         self.drawing.add_to_compound(primitive, compound);
     }
 
+    fn compound_weight(&self, compound: GenericIndex<ZoneWeight>) -> ZoneWeight {
+        self.drawing.compound_weight(compound)
+    }
+
     fn compounds<W>(
         &self,
         node: GenericIndex<W>,