Add infrastructure for abstracting over access to referenced objects

crates/fj-kernel/src/get.rs

@@ -0,0 +1,15 @@
+//! Infrastructure for abstracting over accessing referenced objects
+
+use crate::storage::Handle;
+
+/// Access a single referenced object
+///
+/// Object types implement this trait for the objects they reference. It can be
+/// used by other generic infrastructure to abstract over object access.
+///
+/// This trait is specifically intended to access single objects, like *the*
+/// curve that a vertex references, not *a* half-edge that a cycle references.
+pub trait Get<T> {
+    /// Access the referenced object
+    fn get(&self) -> Handle<T>;
+}

crates/fj-kernel/src/lib.rs

@@ -90,6 +90,7 @@
 pub mod algorithms;
 pub mod builder;
 pub mod geometry;
+pub mod get;
 pub mod insert;
 pub mod iter;
 pub mod objects;

crates/fj-kernel/src/objects/curve.rs

@@ -1,5 +1,6 @@
 use crate::{
     geometry::path::SurfacePath,
+    get::Get,
     storage::{Handle, HandleWrapper},
 };
 
@@ -43,6 +44,18 @@ impl Curve {
     }
 }
 
+impl Get<Surface> for Curve {
+    fn get(&self) -> Handle<Surface> {
+        self.surface().clone()
+    }
+}
+
+impl Get<GlobalCurve> for Curve {
+    fn get(&self) -> Handle<GlobalCurve> {
+        self.global_form().clone()
+    }
+}
+
 /// A curve, defined in global (3D) coordinates
 #[derive(Clone, Copy, Debug)]
 pub struct GlobalCurve;

crates/fj-kernel/src/objects/edge.rs

@@ -1,6 +1,9 @@
 use std::fmt;
 
-use crate::storage::{Handle, HandleWrapper};
+use crate::{
+    get::Get,
+    storage::{Handle, HandleWrapper},
+};
 
 use super::{Curve, GlobalCurve, GlobalVertex, Surface, Vertex};
 
@@ -57,6 +60,18 @@ impl HalfEdge {
     }
 }
 
+impl Get<GlobalEdge> for HalfEdge {
+    fn get(&self) -> Handle<GlobalEdge> {
+        self.global_form().clone()
+    }
+}
+
+impl Get<GlobalCurve> for HalfEdge {
+    fn get(&self) -> Handle<GlobalCurve> {
+        self.global_form().curve().clone()
+    }
+}
+
 impl fmt::Display for HalfEdge {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         let [a, b] = self.vertices().clone().map(|vertex| vertex.position());
@@ -115,6 +130,12 @@ impl GlobalEdge {
     }
 }
 
+impl Get<GlobalCurve> for GlobalEdge {
+    fn get(&self) -> Handle<GlobalCurve> {
+        self.curve().clone()
+    }
+}
+
 /// The vertices of a [`GlobalEdge`]
 ///
 /// Since [`GlobalEdge`] is the single global representation of an edge in

crates/fj-kernel/src/objects/vertex.rs

@@ -1,8 +1,8 @@
 use fj_math::Point;
 
-use crate::storage::Handle;
+use crate::{get::Get, storage::Handle};
 
-use super::{Curve, Surface};
+use super::{Curve, GlobalCurve, Surface};
 
 /// A vertex
 ///
@@ -56,6 +56,36 @@ impl Vertex {
     }
 }
 
+impl Get<Curve> for Vertex {
+    fn get(&self) -> Handle<Curve> {
+        self.curve().clone()
+    }
+}
+
+impl Get<SurfaceVertex> for Vertex {
+    fn get(&self) -> Handle<SurfaceVertex> {
+        self.surface_form().clone()
+    }
+}
+
+impl Get<Surface> for Vertex {
+    fn get(&self) -> Handle<Surface> {
+        self.curve().surface().clone()
+    }
+}
+
+impl Get<GlobalCurve> for Vertex {
+    fn get(&self) -> Handle<GlobalCurve> {
+        self.curve().global_form().clone()
+    }
+}
+
+impl Get<GlobalVertex> for Vertex {
+    fn get(&self) -> Handle<GlobalVertex> {
+        self.surface_form().global_form().clone()
+    }
+}
+
 /// A vertex, defined in surface (2D) coordinates
 #[derive(Clone, Debug, Eq, PartialEq, Hash, Ord, PartialOrd)]
 pub struct SurfaceVertex {
@@ -95,6 +125,18 @@ impl SurfaceVertex {
     }
 }
 
+impl Get<Surface> for SurfaceVertex {
+    fn get(&self) -> Handle<Surface> {
+        self.surface().clone()
+    }
+}
+
+impl Get<GlobalVertex> for SurfaceVertex {
+    fn get(&self) -> Handle<GlobalVertex> {
+        self.global_form().clone()
+    }
+}
+
 /// A vertex, defined in global (3D) coordinates
 ///
 /// This struct exists to distinguish between vertices and points at the type