Add sequence protocol to the c-api

youknowone · Jun 2, 2026 · Jun 2, 2026 · Jun 2, 2026 · Jun 2, 2026 · df23d3a16f59a1f9da7e7c74fe1d8ceabee58700
commit df23d3a16f59a1f9da7e7c74fe1d8ceabee58700
diff --git a/crates/capi/src/abstract_.rs b/crates/capi/src/abstract_.rs
@@ -5,8 +5,10 @@ pub use mapping::*;
 use rustpython_vm::builtins::{PyDict, PyStr, PyTuple};
 use rustpython_vm::function::{FuncArgs, KwArgs, PosArgs};
 use rustpython_vm::{AsObject, Py, PyObjectRef, PyResult, VirtualMachine};
+pub use sequence::*;
 
 mod mapping;
+mod sequence;
 
 const PY_VECTORCALL_ARGUMENTS_OFFSET: usize = 1usize << (usize::BITS as usize - 1);
 

diff --git a/crates/capi/src/abstract_/sequence.rs b/crates/capi/src/abstract_/sequence.rs
@@ -0,0 +1,276 @@
+use crate::{PyObject, pystate::with_vm};
+use core::ffi::c_int;
+
+#[unsafe(no_mangle)]
+pub unsafe extern "C" fn PySequence_Check(obj: *mut PyObject) -> c_int {
+    with_vm(|_vm| {
+        let obj = unsafe { &*obj };
+        Ok(obj.sequence_unchecked().check())
+    })
+}
+
+#[unsafe(no_mangle)]
+pub unsafe extern "C" fn PySequence_Concat(
+    obj1: *mut PyObject,
+    obj2: *mut PyObject,
+) -> *mut PyObject {
+    with_vm(|vm| {
+        let obj1 = unsafe { &*obj1 };
+        let obj2 = unsafe { &*obj2 };
+        obj1.try_sequence(vm)?.concat(obj2, vm)
+    })
+}
+
+#[unsafe(no_mangle)]
+pub unsafe extern "C" fn PySequence_Count(obj: *mut PyObject, value: *mut PyObject) -> isize {
+    with_vm(|vm| {
+        let obj = unsafe { &*obj };
+        let value = unsafe { &*value };
+        obj.try_sequence(vm)?.count(value, vm)
+    })
+}
+
+#[unsafe(no_mangle)]
+pub unsafe extern "C" fn PySequence_DelItem(obj: *mut PyObject, index: isize) -> c_int {
+    with_vm(|vm| {
+        let obj = unsafe { &*obj };
+        obj.try_sequence(vm)?.del_item(index, vm)
+    })
+}
+
+#[unsafe(no_mangle)]
+pub unsafe extern "C" fn PySequence_DelSlice(obj: *mut PyObject, low: isize, high: isize) -> c_int {
+    with_vm(|vm| {
+        let obj = unsafe { &*obj };
+        obj.try_sequence(vm)?.del_slice(low, high, vm)
+    })
+}
+
+#[unsafe(no_mangle)]
+pub unsafe extern "C" fn PySequence_GetItem(obj: *mut PyObject, index: isize) -> *mut PyObject {
+    with_vm(|vm| {
+        let obj = unsafe { &*obj };
+        obj.try_sequence(vm)?.get_item(index, vm)
+    })
+}
+
+#[unsafe(no_mangle)]
+pub unsafe extern "C" fn PySequence_GetSlice(
+    obj: *mut PyObject,
+    low: isize,
+    high: isize,
+) -> *mut PyObject {
+    with_vm(|vm| {
+        let obj = unsafe { &*obj };
+        obj.try_sequence(vm)?.get_slice(low, high, vm)
+    })
+}
+
+#[unsafe(no_mangle)]
+pub unsafe extern "C" fn PySequence_InPlaceConcat(
+    obj1: *mut PyObject,
+    obj2: *mut PyObject,
+) -> *mut PyObject {
+    with_vm(|vm| {
+        let obj1 = unsafe { &*obj1 };
+        let obj2 = unsafe { &*obj2 };
+        obj1.try_sequence(vm)?.inplace_concat(obj2, vm)
+    })
+}
+
+#[unsafe(no_mangle)]
+pub unsafe extern "C" fn PySequence_InPlaceRepeat(
+    obj: *mut PyObject,
+    count: isize,
+) -> *mut PyObject {
+    with_vm(|vm| {
+        let obj = unsafe { &*obj };
+        obj.try_sequence(vm)?.inplace_repeat(count, vm)
+    })
+}
+
+#[unsafe(no_mangle)]
+pub unsafe extern "C" fn PySequence_Index(obj: *mut PyObject, value: *mut PyObject) -> isize {
+    with_vm(|vm| {
+        let obj = unsafe { &*obj };
+        let value = unsafe { &*value };
+        obj.try_sequence(vm)?.index(value, vm)
+    })
+}
+
+#[unsafe(no_mangle)]
+pub unsafe extern "C" fn PySequence_List(obj: *mut PyObject) -> *mut PyObject {
+    with_vm(|vm| {
+        let obj = unsafe { &*obj };
+        Ok(obj.try_sequence(vm)?.list(vm))
+    })
+}
+
+#[unsafe(no_mangle)]
+pub unsafe extern "C" fn PySequence_Repeat(obj: *mut PyObject, count: isize) -> *mut PyObject {
+    with_vm(|vm| {
+        let obj = unsafe { &*obj };
+        obj.try_sequence(vm)?.repeat(count, vm)
+    })
+}
+
+#[unsafe(no_mangle)]
+pub unsafe extern "C" fn PySequence_SetItem(
+    obj: *mut PyObject,
+    index: isize,
+    value: *mut PyObject,
+) -> c_int {
+    with_vm(|vm| {
+        let obj = unsafe { &*obj };
+        let value = unsafe { &*value };
+        obj.try_sequence(vm)?.set_item(index, value.to_owned(), vm)
+    })
+}
+
+#[unsafe(no_mangle)]
+pub unsafe extern "C" fn PySequence_SetSlice(
+    obj: *mut PyObject,
+    low: isize,
+    high: isize,
+    value: *mut PyObject,
+) -> c_int {
+    with_vm(|vm| {
+        let obj = unsafe { &*obj };
+        let value = unsafe { &*value };
+        obj.try_sequence(vm)?
+            .set_slice(low, high, value.to_owned(), vm)
+    })
+}
+
+#[unsafe(no_mangle)]
+pub unsafe extern "C" fn PySequence_Size(obj: *mut PyObject) -> isize {
+    with_vm(|vm| {
+        let obj = unsafe { &*obj };
+        obj.try_sequence(vm)?.length(vm)
+    })
+}
+
+#[unsafe(no_mangle)]
+pub unsafe extern "C" fn PySequence_Tuple(obj: *mut PyObject) -> *mut PyObject {
+    with_vm(|vm| {
+        let obj = unsafe { &*obj };
+        Ok(obj.try_sequence(vm)?.tuple(vm))
+    })
+}
+
+#[unsafe(no_mangle)]
+pub extern "C" fn PySequence_Contains(obj: *mut PyObject, value: *mut PyObject) -> c_int {
+    with_vm(|vm| {
+        let obj = unsafe { &*obj };
+        let value = unsafe { &*value };
+        obj.sequence_unchecked().contains(value, vm)
+    })
+}
+
+#[cfg(false)]
+mod tests {
+    use pyo3::prelude::*;
+    use pyo3::types::{PyAnyMethods, PyDict, PyList, PySequence, PySequenceMethods, PyTuple};
+
+    #[test]
+    fn item_and_size_ops() {
+        Python::attach(|py| {
+            let list = PyList::new(py, [1, 2, 3]).unwrap();
+            let seq = list.cast_into::<PySequence>().unwrap();
+
+            assert_eq!(seq.len().unwrap(), 3);
+            assert_eq!(seq.get_item(1).unwrap().extract::<i32>().unwrap(), 2);
+
+            seq.set_item(1, 4).unwrap();
+            assert_eq!(seq.get_item(1).unwrap().extract::<i32>().unwrap(), 4);
+
+            seq.del_item(1).unwrap();
+            assert_eq!(seq.get_item(1).unwrap().extract::<i32>().unwrap(), 3);
+        });
+    }
+
+    #[test]
+    fn slice_ops() {
+        Python::attach(|py| {
+            let list = PyList::new(py, [1, 2, 3, 4]).unwrap();
+            let seq = list.cast_into::<PySequence>().unwrap();
+
+            let sub = seq.get_slice(1, 3).unwrap();
+            assert_eq!(sub.get_item(0).unwrap().extract::<i32>().unwrap(), 2);
+            assert_eq!(sub.get_item(1).unwrap().extract::<i32>().unwrap(), 3);
+
+            let repl = PyList::new(py, [8, 9]).unwrap();
+            seq.set_slice(1, 3, &repl).unwrap();
+            assert_eq!(seq.get_item(1).unwrap().extract::<i32>().unwrap(), 8);
+            assert_eq!(seq.get_item(2).unwrap().extract::<i32>().unwrap(), 9);
+
+            seq.del_slice(1, 3).unwrap();
+            assert_eq!(seq.get_item(0).unwrap().extract::<i32>().unwrap(), 1);
+            assert_eq!(seq.get_item(1).unwrap().extract::<i32>().unwrap(), 4);
+        });
+    }
+
+    #[test]
+    fn concat_repeat_and_inplace_ops() {
+        Python::attach(|py| {
+            let list = PyList::new(py, [1, 2]).unwrap();
+            let seq = list.cast_into::<PySequence>().unwrap();
+            let rhs = PyList::new(py, [3])
+                .unwrap()
+                .cast_into::<PySequence>()
+                .unwrap();
+
+            let concat = seq.concat(&rhs).unwrap();
+            assert_eq!(concat.get_item(2).unwrap().extract::<i32>().unwrap(), 3);
+
+            let repeat = seq.repeat(2).unwrap();
+            assert_eq!(repeat.get_item(2).unwrap().extract::<i32>().unwrap(), 1);
+
+            let iadd_rhs = PyList::new(py, [4])
+                .unwrap()
+                .cast_into::<PySequence>()
+                .unwrap();
+            seq.in_place_concat(&iadd_rhs).unwrap();
+            assert_eq!(seq.get_item(2).unwrap().extract::<i32>().unwrap(), 4);
+
+            seq.in_place_repeat(2).unwrap();
+            assert_eq!(seq.get_item(5).unwrap().extract::<i32>().unwrap(), 4);
+        });
+    }
+
+    #[test]
+    fn count_index_contains_and_convert_ops() {
+        Python::attach(|py| {
+            let tuple = PyTuple::new(py, [1, 2, 1])
+                .unwrap()
+                .cast_into::<PySequence>()
+                .unwrap();
+
+            assert_eq!(tuple.count(1).unwrap(), 2);
+            assert_eq!(tuple.index(2).unwrap(), 1);
+            assert!(tuple.contains(1).unwrap());
+
+            let as_list = tuple.to_list().unwrap().cast_into::<PySequence>().unwrap();
+            assert_eq!(as_list.get_item(0).unwrap().extract::<i32>().unwrap(), 1);
+
+            let as_tuple = as_list
+                .to_tuple()
+                .unwrap()
+                .cast_into::<PySequence>()
+                .unwrap();
+            assert_eq!(as_tuple.get_item(2).unwrap().extract::<i32>().unwrap(), 1);
+        });
+    }
+
+    #[test]
+    fn contains_works_for_dict() {
+        Python::attach(|py| {
+            let dict = PyDict::new(py);
+            dict.set_item("k", 1).unwrap();
+
+            let any = dict.into_any();
+            assert!(any.contains("k").unwrap());
+            assert!(!any.contains("missing").unwrap());
+        });
+    }
+}