From 67d351cea077fd4845f2a8e57d1cab28f85fcc3b Mon Sep 17 00:00:00 2001
From: Hanno Braun <hanno@braun-odw.eu>
Date: Wed, 12 Oct 2022 15:47:18 +0200
Subject: [PATCH] Make method return type more flexible

This prepares for an upcoming change.
---
 crates/fj-kernel/src/partial/maybe_partial.rs | 12 +++++++++---
 crates/fj-kernel/src/partial/objects/cycle.rs | 10 ++++++----
 2 files changed, 15 insertions(+), 7 deletions(-)

diff --git a/crates/fj-kernel/src/partial/maybe_partial.rs b/crates/fj-kernel/src/partial/maybe_partial.rs
index b931e11dd..9b968b747 100644
--- a/crates/fj-kernel/src/partial/maybe_partial.rs
+++ b/crates/fj-kernel/src/partial/maybe_partial.rs
@@ -106,10 +106,16 @@ impl MaybePartial<GlobalEdge> {
 
 impl MaybePartial<HalfEdge> {
     /// Access the vertices
-    pub fn vertices(&self) -> Option<[MaybePartial<Vertex>; 2]> {
+    pub fn vertices(&self) -> [Option<MaybePartial<Vertex>>; 2] {
         match self {
-            Self::Full(full) => Some(full.vertices().clone().map(Into::into)),
-            Self::Partial(partial) => partial.vertices.clone(),
+            Self::Full(full) => {
+                full.vertices().clone().map(|vertex| Some(vertex.into()))
+            }
+            Self::Partial(partial) => partial
+                .vertices
+                .clone()
+                .map(|vertices| vertices.map(Some))
+                .unwrap_or([None, None]),
         }
     }
 }
diff --git a/crates/fj-kernel/src/partial/objects/cycle.rs b/crates/fj-kernel/src/partial/objects/cycle.rs
index be37c6a04..39b7dfbd8 100644
--- a/crates/fj-kernel/src/partial/objects/cycle.rs
+++ b/crates/fj-kernel/src/partial/objects/cycle.rs
@@ -48,9 +48,9 @@ impl PartialCycle {
             .half_edges
             .last()
             .map(|half_edge| {
-                let [_, last] = half_edge
-                    .vertices()
-                    .expect("Need half-edge vertices to extend cycle");
+                let [_, last] = half_edge.vertices().map(|vertex| {
+                    vertex.expect("Need half-edge vertices to extend cycle")
+                });
                 let last = last
                     .surface_form()
                     .expect("Need surface vertex to extend cycle");
@@ -129,7 +129,9 @@ impl PartialCycle {
 
         let vertices = [first, last].map(|option| {
             option.map(|half_edge| {
-                half_edge.vertices().expect("Need vertices to close cycle")
+                half_edge
+                    .vertices()
+                    .map(|vertex| vertex.expect("Need vertices to close cycle"))
             })
         });