Add basic dict function to c-api (RustPython#7929)

bschoenmaeckers · web-flow · commit a136f9047b82 · 2026-05-21T09:59:09.000+09:00
* Add basic dict function to c-api

* Fix iter

* Do not use mapping protocol
diff --git a/crates/capi/src/dictobject.rs b/crates/capi/src/dictobject.rs
@@ -0,0 +1,132 @@
+use crate::PyObject;
+use crate::object::define_py_check;
+use crate::pystate::with_vm;
+use core::ffi::c_int;
+use core::ptr::NonNull;
+use rustpython_vm::AsObject;
+use rustpython_vm::builtins::PyDict;
+
+define_py_check!(fn PyDict_Check, types.dict_type);
+define_py_check!(exact fn PyDict_CheckExact, types.dict_type);
+define_py_check!(fn PyDictKeys_Check, types.dict_keys_type);
+define_py_check!(fn PyDictValues_Check, types.dict_values_type);
+define_py_check!(fn PyDictItems_Check, types.dict_items_type);
+
+#[unsafe(no_mangle)]
+pub extern "C" fn PyDict_New() -> *mut PyObject {
+    with_vm(|vm| vm.ctx.new_dict())
+}
+
+#[unsafe(no_mangle)]
+pub unsafe extern "C" fn PyDict_SetItem(
+    dict: *mut PyObject,
+    key: *mut PyObject,
+    val: *mut PyObject,
+) -> c_int {
+    with_vm(|vm| {
+        let dict = unsafe { &*dict }.try_downcast_ref::<PyDict>(vm)?;
+        let key = unsafe { &*key };
+        let value = unsafe { &*val }.to_owned();
+        dict.inner_setitem(key, value, vm)
+    })
+}
+
+#[unsafe(no_mangle)]
+pub unsafe extern "C" fn PyDict_GetItemRef(
+    dict: *mut PyObject,
+    key: *mut PyObject,
+    result: *mut *mut PyObject,
+) -> c_int {
+    with_vm(|vm| {
+        unsafe { *result = core::ptr::null_mut() };
+        let dict = unsafe { &*dict }.try_downcast_ref::<PyDict>(vm)?;
+        let key = unsafe { &*key };
+
+        if let Some(value) = dict.inner_getitem_opt(key, vm)? {
+            unsafe {
+                *result = value.into_raw().as_ptr();
+            }
+            Ok(true)
+        } else {
+            unsafe {
+                *result = core::ptr::null_mut();
+            }
+            Ok(false)
+        }
+    })
+}
+
+#[unsafe(no_mangle)]
+pub unsafe extern "C" fn PyDict_Size(dict: *mut PyObject) -> isize {
+    with_vm(|vm| {
+        let dict = unsafe { &*dict }.try_downcast_ref::<PyDict>(vm)?;
+        Ok(dict.__len__())
+    })
+}
+
+#[unsafe(no_mangle)]
+pub unsafe extern "C" fn PyDict_Next(
+    dict: *mut PyObject,
+    pos: *mut isize,
+    key: *mut *mut PyObject,
+    value: *mut *mut PyObject,
+) -> c_int {
+    with_vm(|vm| {
+        let dict = unsafe { &*dict }.try_downcast_ref::<PyDict>(vm)?;
+        let index = unsafe { *pos } as usize;
+
+        if let Some((next_pos, k, v)) = dict.next_entry(index) {
+            unsafe {
+                *pos = next_pos as isize;
+                if let Some(key) = NonNull::new(key) {
+                    key.write(k.as_object().as_raw().cast_mut());
+                }
+                if let Some(value) = NonNull::new(value) {
+                    value.write(v.as_object().as_raw().cast_mut());
+                }
+            }
+            Ok(true)
+        } else {
+            Ok(false)
+        }
+    })
+}
+
+#[cfg(false)]
+mod tests {
+    use pyo3::prelude::*;
+    use pyo3::types::{IntoPyDict, PyDict, PyInt};
+
+    #[test]
+    fn test_create_empty_dict() {
+        Python::attach(|py| {
+            let dict = PyDict::new(py);
+            assert!(dict.is_instance_of::<PyDict>());
+        })
+    }
+
+    #[test]
+    fn test_create_dict_with_items() {
+        Python::attach(|py| {
+            let dict = [(1, 2), (3, 4)].into_py_dict(py)?;
+            let value = dict.get_item(1)?.unwrap().cast_into::<PyInt>()?;
+            assert_eq!(value, 2);
+            assert_eq!(dict.len(), 2);
+
+            Ok::<_, PyErr>(())
+        })
+        .unwrap()
+    }
+
+    #[test]
+    fn test_dict_iter() {
+        Python::attach(|py| {
+            let dict = [(1, 2), (3, 4)].into_py_dict(py).unwrap();
+            let values = dict
+                .into_iter()
+                .flat_map(|(k, v)| [k.extract().unwrap(), v.extract().unwrap()])
+                .collect::<Vec<u32>>();
+            assert_eq!(values, vec![1, 2, 3, 4]);
+        })
+    }
+}
diff --git a/crates/capi/src/lib.rs b/crates/capi/src/lib.rs
@@ -11,6 +11,7 @@ extern crate alloc;
 pub mod abstract_;
 pub mod bytesobject;
 pub mod ceval;
+pub mod dictobject;
 pub mod import;
 pub mod longobject;
 pub mod object;
diff --git a/crates/vm/src/builtins/dict.rs b/crates/vm/src/builtins/dict.rs
@@ -205,7 +205,7 @@ impl PyDict {
 
     /// Set item variant which can be called with multiple
     /// key types, such as str to name a notable one.
-    pub(crate) fn inner_setitem<K: DictKey + ?Sized>(
+    pub fn inner_setitem<K: DictKey + ?Sized>(
         &self,
         key: &K,
         value: PyObjectRef,
@@ -248,6 +248,18 @@ impl PyDict {
     pub fn size(&self) -> dict_inner::DictSize {
         self.entries.size()
     }
+
+    pub fn next_entry(&self, position: usize) -> Option<(usize, PyObjectRef, PyObjectRef)> {
+        self.entries.next_entry(position)
+    }
+
+    pub fn inner_getitem_opt<K: DictKey + ?Sized>(
+        &self,
+        key: &K,
+        vm: &VirtualMachine,
+    ) -> PyResult<Option<PyObjectRef>> {
+        self.entries.get(vm, key)
+    }
 }
 
 // Python dict methods:
