Fix a bug in the handling of producers

CHANGELOG.md

@@ -0,0 +1,7 @@
+# 0.1.1
+
+Fixed a bug in `MapfoldReduceProducerIter::next_back` discovered by @cuviper.
+
+# 0.1.0
+
+Initial release!

Cargo.toml

@@ -1,11 +1,11 @@
 [package]
 name = "rayon_croissant"
-version = "0.1.0" # don't forget to update documentation link on bump
+version = "0.1.1" # don't forget to update documentation link on bump
 authors = ["Anthony Ramine <n.oxyde@gmail.com>"]
 description = "<lqd> bikeshedding the name: something that is mapped folded and collected, a 🥐"
 license = "Apache-2.0 OR MIT"
 repository = "https://github.com/nox/rayon_croissant"
-documentation = "https://docs.rs/rayon_croissant/0.1.0/"
+documentation = "https://docs.rs/rayon_croissant/0.1.1/"
 readme = "README.md"
 categories = ["concurrency", "data-structures"]
 keywords = ["arc", "split", "atomic", "thread"]

src/producer.rs

@@ -196,6 +196,7 @@ where
         let input = self.input_iter.next_back()?;
         let mut singleton = Target::default();
         let output = (self.mapfold)(&mut singleton, input);
+        mem::swap(&mut self.back_sink, &mut singleton);
         (self.reduce)(&mut self.back_sink, singleton);
         Some(output)
     }

tests/producer.rs

@@ -0,0 +1,35 @@
+extern crate rayon;
+extern crate rayon_croissant;
+
+use rayon::prelude::{ParallelIterator, IndexedParallelIterator, IntoParallelRefIterator};
+use rayon_croissant::ParallelIteratorExt;
+
+#[test]
+fn test_zip_rev() {
+    let ingredients = &["jambon", "beurre", "fromage", "baguette"];
+    let scores = &[0, 1, 2, 3];
+
+    let mut names = vec![];
+    let rev_scores = ingredients
+        .par_iter()
+        .cloned()
+        .zip(scores.par_iter().cloned())
+        .with_min_len(2)
+        .mapfold_reduce_into(
+            &mut names,
+            |names, (name, score)| {
+                names.push(name);
+                score
+            },
+            |left_names, mut right_names| {
+                left_names.append(&mut right_names);
+            },
+        )
+        // Reversing *after* a call to mapfold_reduce_into shouldn't
+        // change the result of the folding operation.
+        .rev()
+        .collect::<Vec<_>>();
+
+    assert_eq!(names, ingredients);
+    assert_eq!(rev_scores, [3, 2, 1, 0]);
+}