feat(geometry): add easy way to detect if primitive is part of compound

src/geometry/geometry.rs

@@ -8,7 +8,7 @@ use geo::Point;
 use petgraph::{
     stable_graph::{NodeIndex, StableDiGraph},
     visit::EdgeRef,
-    Direction::{self, Incoming},
+    Direction::{self, Incoming, Outgoing},
 };
 use serde::{Deserialize, Serialize};
 
@@ -570,6 +570,13 @@ impl<
             })
             .map(|ni| self.primitive_weight(ni).retag(ni))
     }
+
+    pub fn is_part_of_any_compound(&self, primitive: PI) -> Option<GenericIndex<CW>> {
+        self.graph
+            .edges_directed(primitive.petgraph_index(), Outgoing)
+            .find(|ei| ei.weight() == &GeometryLabel::Compound)
+            .map(|ei| GenericIndex::new(ei.source()))
+    }
 }
 
 impl<PW, DW, SW, BW, CW: Copy, PI, DI, SI, BI> ManageCompounds<CW, GenericIndex<CW>>