Repository: rust-itertools/itertools (rust)
Issue: Implement Clone for CircularTupleWindows
The current implementation of `CircularTupleWindows` uses `std::iter::Cycle<I>`, which already requires the underlying iterator implement `Clone`, so this is a simple addition.
Pull request description: Impl Clone for CircularTupleWindows
Fixes #685

Patch:
diff --git a/src/tuple_impl.rs b/src/tuple_impl.rs
index f4488db..fdf0865 100644
--- a/src/tuple_impl.rs
+++ b/src/tuple_impl.rs
@@ -201,7 +201,7 @@ impl<I, T> FusedIterator for TupleWindows<I, T>
 /// See [`.circular_tuple_windows()`](crate::Itertools::circular_tuple_windows) for more
 /// information.
 #[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
-#[derive(Debug)]
+#[derive(Debug, Clone)]
 pub struct CircularTupleWindows<I, T: Clone>
     where I: Iterator<Item = T::Item> + Clone,
           T: TupleCollect + Clone


Test patch:
diff --git a/tests/quick.rs b/tests/quick.rs
index 0adcf1a..94111f5 100644
--- a/tests/quick.rs
+++ b/tests/quick.rs
@@ -1010,7 +1010,71 @@ quickcheck! {
     }
 }
 
+// tuple iterators
 quickcheck! {
+    fn equal_circular_tuple_windows_1(a: Vec<u8>) -> bool {
+        let x = a.iter().map(|e| (e,) );
+        let y = a.iter().circular_tuple_windows::<(_,)>();
+        itertools::assert_equal(x,y);
+        true
+    }
+
+    fn equal_circular_tuple_windows_2(a: Vec<u8>) -> bool {
+        let x = (0..a.len()).map(|start_idx| (
+            &a[start_idx],
+            &a[(start_idx + 1) % a.len()],
+        ));
+        let y = a.iter().circular_tuple_windows::<(_, _)>();
+        itertools::assert_equal(x,y);
+        true
+    }
+
+    fn equal_circular_tuple_windows_3(a: Vec<u8>) -> bool {
+        let x = (0..a.len()).map(|start_idx| (
+            &a[start_idx],
+            &a[(start_idx + 1) % a.len()],
+            &a[(start_idx + 2) % a.len()],
+        ));
+        let y = a.iter().circular_tuple_windows::<(_, _, _)>();
+        itertools::assert_equal(x,y);
+        true
+    }
+
+    fn equal_circular_tuple_windows_4(a: Vec<u8>) -> bool {
+        let x = (0..a.len()).map(|start_idx| (
+            &a[start_idx],
+            &a[(start_idx + 1) % a.len()],
+            &a[(start_idx + 2) % a.len()],
+            &a[(start_idx + 3) % a.len()],
+        ));
+        let y = a.iter().circular_tuple_windows::<(_, _, _, _)>();
+        itertools::assert_equal(x,y);
+        true
+    }
+
+    fn equal_cloned_circular_tuple_windows(a: Vec<u8>) -> bool {
+        let x = a.iter().circular_tuple_windows::<(_, _, _, _)>();
+        let y = x.clone();
+        itertools::assert_equal(x,y);
+        true
+    }
+
+    fn equal_cloned_circular_tuple_windows_noninitial(a: Vec<u8>) -> bool {
+        let mut x = a.iter().circular_tuple_windows::<(_, _, _, _)>();
+        let _ = x.next();
+        let y = x.clone();
+        itertools::assert_equal(x,y);
+        true
+    }
+
+    fn equal_cloned_circular_tuple_windows_complete(a: Vec<u8>) -> bool {
+        let mut x = a.iter().circular_tuple_windows::<(_, _, _, _)>();
+        for _ in x.by_ref() {}
+        let y = x.clone();
+        itertools::assert_equal(x,y);
+        true
+    }
+
     fn equal_tuple_windows_1(a: Vec<u8>) -> bool {
         let x = a.windows(1).map(|s| (&s[0], ));
         let y = a.iter().tuple_windows::<(_,)>();