Fix support of sequence protocol for returned lists (backport #730) (#…

…735)

* Bump pyo3 from 0.17.2 to 0.17.3 (#723)

Bumps [pyo3](https://github.com/pyo3/pyo3) from 0.17.2 to 0.17.3.
- [Release notes](https://github.com/pyo3/pyo3/releases)
- [Changelog](https://github.com/PyO3/pyo3/blob/main/CHANGELOG.md)
- [Commits](PyO3/pyo3@v0.17.2...v0.17.3)

---
updated-dependencies:
- dependency-name: pyo3
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <support@github.com>

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
(cherry picked from commit d91f488)

# Conflicts:
#	Cargo.lock
#	Cargo.toml

* Fix support of sequence protocol for returned lists (#730)

* Fix support of sequence protocol for returned lists

Add the `sequence` option to PyO3's `pyclass`, so that the `sq_length`
slot is implemented [1]. Implementing this method is required for
sequence types, or Python C API functions like `PySequence_Size` will
fail with an error.

The `reversed` built-in method relies on `PySequence_*` methods. A test
reversing `NodeIndices` is added to guard against future violations of
the sequence protocol.

Fixes #696.

[1]: PyO3/pyo3#2567

* Add release note

Co-authored-by: Matthew Treinish <mtreinish@kortar.org>
(cherry picked from commit 4592bc0)

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: Tino Wagner <ich@tinowagner.com>
Co-authored-by: Ivan Carvalho <ivancarv@student.ubc.ca>

Cargo.toml

@@ -35,7 +35,7 @@ serde_json = "1.0"
 rustworkx-core = { path = "rustworkx-core", version = "=0.12.0" }
 
 [dependencies.pyo3]
-version = "0.17.2"
+version = "0.17.3"
 features = ["extension-module", "hashbrown", "num-bigint", "num-complex", "indexmap"]
 
 [dependencies.hashbrown]

releasenotes/notes/fix-sequence-protocol-e95246e864cc850a.yaml

@@ -0,0 +1,10 @@
+---
+fixes:
+  - |
+    Fixed an issue with the custom sequence return types,
+    :class:`~.BFSSuccessors`, :class:`~.NodeIndices`, :class:`~.EdgeList`,
+    :class:`~.WeightedEdgeList`, :class:`~.EdgeIndices`, and :class:`~.Chains`
+    where they previosuly were missing certain attributes that prevented them
+    being used as a sequence for certain built-in functions such as
+    ``reversed()``.
+    Fixed `#696 <https://github.com/Qiskit/rustworkx/issues/696>`__.

src/iterators.rs

@@ -475,7 +475,7 @@ impl PyConvertToPyArray for Vec<(usize, usize, PyObject)> {
 macro_rules! custom_vec_iter_impl {
     ($name:ident, $data:ident, $T:ty, $doc:literal) => {
         #[doc = $doc]
-        #[pyclass(module = "rustworkx")]
+        #[pyclass(module = "rustworkx", sequence)]
         #[derive(Clone)]
         pub struct $name {
             pub $data: Vec<$T>,

tests/rustworkx_tests/test_custom_return_types.py

@@ -174,6 +174,12 @@ def test_slices_negatives(self):
         self.assertEqual([2, 3], slice_return)
         self.assertEqual([], indices[-1:-2])
 
+    def test_reversed(self):
+        indices = self.dag.node_indices()
+        reversed_slice = indices[::-1]
+        reversed_elems = list(reversed(indices))
+        self.assertEqual(reversed_slice, reversed_elems)
+
     def test_numpy_conversion(self):
         res = self.dag.node_indexes()
         np.testing.assert_array_equal(np.asarray(res, dtype=np.uintp), np.array([0, 1]))