From 7990e85865237fbd266868a7499d48a0fe3e1c8e Mon Sep 17 00:00:00 2001
From: Hanno Braun <hanno@braun-odw.eu>
Date: Wed, 27 Sep 2023 11:11:16 +0200
Subject: [PATCH] Add `Handles::replace`

---
 crates/fj-core/src/objects/handles.rs | 25 +++++++++++++++++++++++--
 1 file changed, 23 insertions(+), 2 deletions(-)

diff --git a/crates/fj-core/src/objects/handles.rs b/crates/fj-core/src/objects/handles.rs
index 51c910ce4..d9ee8b6a5 100644
--- a/crates/fj-core/src/objects/handles.rs
+++ b/crates/fj-core/src/objects/handles.rs
@@ -111,6 +111,27 @@ impl<T> Handles<T> {
         handle: &Handle<T>,
         update: impl FnOnce(&Handle<T>) -> Handle<T>,
     ) -> Self
+    where
+        T: Debug + Ord,
+    {
+        self.replace(handle, |handle| [update(handle)])
+    }
+
+    /// Create a new instance in which the provided item has been replaced
+    ///
+    /// This is a more general version of [`Handles::update`] which can replace
+    /// a single item with multiple others.
+    ///
+    /// # Panics
+    ///
+    /// Panics, if the provided item is not present.
+    /// Panics, if the update results in a duplicate item.
+    #[must_use]
+    pub fn replace<const N: usize>(
+        &self,
+        handle: &Handle<T>,
+        replace: impl FnOnce(&Handle<T>) -> [Handle<T>; N],
+    ) -> Self
     where
         T: Debug + Ord,
     {
@@ -135,10 +156,10 @@ impl<T> Handles<T> {
             before.push(next.clone());
         }
 
-        let updated = update(handle);
+        let replaced = replace(handle);
         let after = iter;
 
-        before.into_iter().chain([updated]).chain(after).collect()
+        before.into_iter().chain(replaced).chain(after).collect()
     }
 }