PyListIter

src/ffi/list.rs

@@ -0,0 +1,44 @@
+// SPDX-License-Identifier: (Apache-2.0 OR MIT)
+
+use std::ptr::NonNull;
+
+pub struct PyListIter {
+    obj: *mut pyo3_ffi::PyListObject,
+    len: usize,
+    pos: usize,
+}
+
+impl PyListIter {
+    #[inline]
+    pub fn from_pyobject(obj: *mut pyo3_ffi::PyObject) -> Self {
+        unsafe {
+            PyListIter {
+                obj: obj as *mut pyo3_ffi::PyListObject,
+                len: ffi!(Py_SIZE(obj)) as usize,
+                pos: 0,
+            }
+        }
+    }
+}
+
+impl Iterator for PyListIter {
+    type Item = NonNull<pyo3_ffi::PyObject>;
+
+    #[inline(always)]
+    fn next(&mut self) -> Option<Self::Item> {
+        if self.pos == self.len {
+            None
+        } else {
+            let elem = unsafe { *((*self.obj).ob_item).add(self.pos) };
+            self.pos += 1;
+            Some(nonnull!(elem))
+        }
+    }
+
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        (self.len, Some(self.len))
+    }
+}
+
+#[cfg(feature = "trusted_len")]
+unsafe impl std::iter::TrustedLen for PyListIter {}

src/ffi/mod.rs

@@ -3,9 +3,11 @@
 mod buffer;
 mod bytes;
 mod dict;
+mod list;
 mod pytype;
 
 pub use buffer::*;
 pub use bytes::*;
 pub use dict::*;
+pub use list::PyListIter;
 pub use pytype::*;

src/serialize/list.rs

@@ -1,5 +1,6 @@
 // SPDX-License-Identifier: (Apache-2.0 OR MIT)
 
+use crate::ffi::PyListIter;
 use crate::opt::*;
 use crate::serialize::serializer::*;
 
@@ -41,11 +42,9 @@ impl Serialize for ListSerializer {
             serializer.serialize_seq(Some(0)).unwrap().end()
         } else {
             let mut seq = serializer.serialize_seq(None).unwrap();
-            for i in 0..=ffi!(Py_SIZE(self.ptr)) as usize - 1 {
-                let elem =
-                    unsafe { *((*(self.ptr as *mut pyo3_ffi::PyListObject)).ob_item).add(i) };
+            for elem in PyListIter::from_pyobject(self.ptr) {
                 let value = PyObjectSerializer::new(
-                    elem,
+                    elem.as_ptr(),
                     self.opts,
                     self.default_calls,
                     self.recursion,