From fc5aab4d9f4880480ba0ef9da14674be0d432600 Mon Sep 17 00:00:00 2001
From: Kinto <kinto.behr@gmail.com>
Date: Wed, 1 May 2024 21:26:35 +1000
Subject: [PATCH] Implement `FlattenOk::rfold`

---
 src/flatten_ok.rs | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/src/flatten_ok.rs b/src/flatten_ok.rs
index 257ef70ae..48f1e90a6 100644
--- a/src/flatten_ok.rs
+++ b/src/flatten_ok.rs
@@ -153,6 +153,29 @@ where
             }
         }
     }
+
+    fn rfold<B, F>(self, init: B, mut f: F) -> B
+    where
+        Self: Sized,
+        F: FnMut(B, Self::Item) -> B,
+    {
+        // Back
+        let mut acc = match self.inner_back {
+            Some(x) => x.rfold(init, |a, o| f(a, Ok(o))),
+            None => init,
+        };
+
+        acc = self.iter.rfold(acc, |acc, x| match x {
+            Ok(it) => it.into_iter().rfold(acc, |a, o| f(a, Ok(o))),
+            Err(e) => f(acc, Err(e)),
+        });
+
+        // Front
+        match self.inner_front {
+            Some(x) => x.rfold(acc, |a, o| f(a, Ok(o))),
+            None => acc,
+        }
+    }
 }
 
 impl<I, T, E> Clone for FlattenOk<I, T, E>