Merge pull request RustPython#4190 from dvermd/takewhile_reduce

add takewhile.__reduce__

Author: youknowone

Lib/test/test_itertools.py

@@ -1349,8 +1349,6 @@ def __index__(self):
         self.assertEqual(list(islice(range(100), IntLike(10), IntLike(50), IntLike(5))),
                          list(range(10,50,5)))
 
-    # TODO: RUSTPYTHON
-    @unittest.expectedFailure
     def test_takewhile(self):
         data = [1, 3, 5, 20, 2, 4, 6, 8]
         self.assertEqual(list(takewhile(underten, data)), [1, 3, 5])

vm/src/stdlib/itertools.rs

@@ -467,7 +467,15 @@ mod decl {
     }
 
     #[pyclass(with(IterNext, Constructor), flags(BASETYPE))]
-    impl PyItertoolsTakewhile {}
+    impl PyItertoolsTakewhile {
+        #[pymethod(magic)]
+        fn reduce(zelf: PyRef<Self>) -> (PyTypeRef, (PyObjectRef, PyIter)) {
+            (
+                zelf.class().clone(),
+                (zelf.predicate.clone(), zelf.iterable.clone()),
+            )
+        }
+    }
     impl IterNextIterable for PyItertoolsTakewhile {}
     impl IterNext for PyItertoolsTakewhile {
         fn next(zelf: &Py<Self>, vm: &VirtualMachine) -> PyResult<PyIterReturn> {