Replace Edge::line_segment with Edges method

I'm aware that I did the opposite not that long ago, but that was then.
Now, I'm facing the need of having to track curves in the `Shape` API,
and then the constructors will no longer work on `Edge`, at least
without passing a `&mut Shape` into them.

src/kernel/algorithms/approximation.rs

@@ -150,10 +150,7 @@ mod tests {
         kernel::{
             geometry::Surface,
             shape::Shape,
-            topology::{
-                edges::{Cycle, Edge},
-                faces::Face,
-            },
+            topology::{edges::Cycle, faces::Face},
         },
         math::{Point, Scalar, Segment},
     };
@@ -214,11 +211,9 @@ mod tests {
         let v2 = shape.vertices().add(b);
         let v3 = shape.vertices().add(c);
 
-        let ab = shape
-            .edges()
-            .add(Edge::line_segment([v1.clone(), v2.clone()]));
-        let bc = shape.edges().add(Edge::line_segment([v2, v3.clone()]));
-        let ca = shape.edges().add(Edge::line_segment([v3, v1]));
+        let ab = shape.edges().add_line_segment([v1.clone(), v2.clone()]);
+        let bc = shape.edges().add_line_segment([v2, v3.clone()]);
+        let ca = shape.edges().add_line_segment([v3, v1]);
 
         let cycle = Cycle {
             edges: vec![ab, bc, ca],
@@ -255,12 +250,10 @@ mod tests {
         let v3 = shape.vertices().add(c);
         let v4 = shape.vertices().add(d);
 
-        let ab = shape
-            .edges()
-            .add(Edge::line_segment([v1.clone(), v2.clone()]));
-        let bc = shape.edges().add(Edge::line_segment([v2, v3.clone()]));
-        let cd = shape.edges().add(Edge::line_segment([v3, v4.clone()]));
-        let da = shape.edges().add(Edge::line_segment([v4, v1]));
+        let ab = shape.edges().add_line_segment([v1.clone(), v2.clone()]);
+        let bc = shape.edges().add_line_segment([v2, v3.clone()]);
+        let cd = shape.edges().add_line_segment([v3, v4.clone()]);
+        let da = shape.edges().add_line_segment([v4, v1]);
 
         let abcd = shape.cycles().add(Cycle {
             edges: vec![ab, bc, cd, da],

src/kernel/algorithms/sweep.rs

@@ -71,10 +71,7 @@ mod tests {
         kernel::{
             geometry::{surfaces::Swept, Surface},
             shape::{handle::Handle, Shape},
-            topology::{
-                edges::{Cycle, Edge},
-                faces::Face,
-            },
+            topology::{edges::Cycle, faces::Face},
         },
         math::{Point, Scalar, Vector},
     };
@@ -115,15 +112,9 @@ mod tests {
             let b = shape.vertices().add(b.into());
             let c = shape.vertices().add(c.into());
 
-            let ab = shape
-                .edges()
-                .add(Edge::line_segment([a.clone(), b.clone()]));
-            let bc = shape
-                .edges()
-                .add(Edge::line_segment([b.clone(), c.clone()]));
-            let ca = shape
-                .edges()
-                .add(Edge::line_segment([c.clone(), a.clone()]));
+            let ab = shape.edges().add_line_segment([a.clone(), b.clone()]);
+            let bc = shape.edges().add_line_segment([b.clone(), c.clone()]);
+            let ca = shape.edges().add_line_segment([c.clone(), a.clone()]);
 
             let cycles = shape.cycles().add(Cycle {
                 edges: vec![ab, bc, ca],

src/kernel/shape/edges.rs

@@ -1,4 +1,7 @@
-use crate::kernel::topology::edges::Edge;
+use crate::kernel::{
+    geometry::{Curve, Line},
+    topology::{edges::Edge, vertices::Vertex},
+};
 
 use super::handle::{Handle, Storage};
 
@@ -23,4 +26,20 @@ impl Edges {
     pub fn add(&mut self, edge: Edge) -> Handle<Edge> {
         Storage::new(edge).handle()
     }
+
+    /// Add a line segment to the shape
+    ///
+    /// Calls [`Edges::add`] internally, and is subject to the same
+    /// restrictions.
+    pub fn add_line_segment(
+        &mut self,
+        vertices: [Handle<Vertex>; 2],
+    ) -> Handle<Edge> {
+        self.add(Edge {
+            curve: Curve::Line(Line::from_points(
+                vertices.clone().map(|vertex| vertex.point()),
+            )),
+            vertices: Some(vertices),
+        })
+    }
 }

src/kernel/shapes/sketch.rs

@@ -3,10 +3,7 @@ use crate::{
     kernel::{
         geometry::Surface,
         shape::Shape,
-        topology::{
-            edges::{Cycle, Edge},
-            faces::Face,
-        },
+        topology::{edges::Cycle, faces::Face},
     },
     math::{Aabb, Point, Scalar},
 };
@@ -40,7 +37,7 @@ impl ToShape for fj::Sketch {
                 let a = window[0].clone();
                 let b = window[1].clone();
 
-                let edge = shape.edges().add(Edge::line_segment([a, b]));
+                let edge = shape.edges().add_line_segment([a, b]);
                 edges.push(edge);
             }
 

src/kernel/topology/edges.rs

@@ -1,6 +1,6 @@
 use crate::{
     kernel::{
-        geometry::{Circle, Curve, Line},
+        geometry::{Circle, Curve},
         shape::handle::Handle,
     },
     math::{Point, Scalar, Vector},
@@ -46,16 +46,6 @@ pub struct Edge {
 }
 
 impl Edge {
-    /// Create a line segment
-    pub fn line_segment(vertices: [Handle<Vertex>; 2]) -> Self {
-        Edge {
-            curve: Curve::Line(Line::from_points(
-                vertices.clone().map(|vertex| vertex.point()),
-            )),
-            vertices: Some(vertices),
-        }
-    }
-
     /// Create a circle
     pub fn circle(radius: Scalar) -> Self {
         Edge {