From d991949fe1b4362fca5c3bee1309159cdfae73c0 Mon Sep 17 00:00:00 2001
From: Giacomo Stevanato <giaco.stevanato@gmail.com>
Date: Tue, 20 Jul 2021 20:53:43 +0200
Subject: [PATCH] Specialize ProcessResults::fold

---
 src/process_results_impl.rs | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/src/process_results_impl.rs b/src/process_results_impl.rs
index 9da108b15..44308f378 100644
--- a/src/process_results_impl.rs
+++ b/src/process_results_impl.rs
@@ -30,6 +30,23 @@ impl<'a, I, T, E> Iterator for ProcessResults<'a, I, E>
     fn size_hint(&self) -> (usize, Option<usize>) {
         (0, self.iter.size_hint().1)
     }
+
+    fn fold<B, F>(mut self, init: B, mut f: F) -> B
+    where
+        Self: Sized,
+        F: FnMut(B, Self::Item) -> B,
+    {
+        let error = self.error;
+        self.iter
+            .try_fold(init, |acc, opt| match opt {
+                Ok(x) => Ok(f(acc, x)),
+                Err(e) => {
+                    *error = Err(e);
+                    Err(acc)
+                }
+            })
+            .unwrap_or_else(|e| e)
+    }
 }
 
 /// “Lift” a function of the values of an iterator so that it can process