_ctypes addressof and Structure (#5573)

* _ctypes.addressof

Signed-off-by: Ashwin Naren <arihant2math@gmail.com>

* ctypes.Structure implementation

Signed-off-by: Ashwin Naren <arihant2math@gmail.com>

* clippy fix

Signed-off-by: Ashwin Naren <arihant2math@gmail.com>

* formatting

Signed-off-by: Ashwin Naren <arihant2math@gmail.com>

---------

Signed-off-by: Ashwin Naren <arihant2math@gmail.com>

vm/src/stdlib/ctypes.rs

@@ -214,6 +214,16 @@ pub(crate) mod _ctypes {
         }
     }
 
+    #[pyfunction]
+    fn addressof(obj: PyObjectRef, vm: &VirtualMachine) -> PyResult<usize> {
+        if obj.is_instance(PyCSimple::static_type().as_ref(), vm)? {
+            let simple = obj.downcast_ref::<PyCSimple>().unwrap();
+            Ok(simple.value.as_ptr() as usize)
+        } else {
+            Err(vm.new_type_error("expected a ctypes instance".to_string()))
+        }
+    }
+
     #[pyfunction]
     fn get_errno() -> i32 {
         errno::errno().0

vm/src/stdlib/ctypes/structure.rs

@@ -1,5 +1,61 @@
+use crate::builtins::{PyList, PyStr, PyTuple, PyTypeRef};
+use crate::function::FuncArgs;
+use crate::types::GetAttr;
+use crate::{AsObject, Py, PyObjectRef, PyPayload, PyResult, VirtualMachine};
+use rustpython_common::lock::PyRwLock;
+use rustpython_vm::types::Constructor;
+use std::collections::HashMap;
+use std::fmt::Debug;
+
 #[pyclass(name = "Structure", module = "_ctypes")]
-pub struct PyCStructure {}
+#[derive(PyPayload, Debug)]
+pub struct PyCStructure {
+    #[allow(dead_code)]
+    field_data: PyRwLock<HashMap<String, PyObjectRef>>,
+    data: PyRwLock<HashMap<String, PyObjectRef>>,
+}
+
+impl Constructor for PyCStructure {
+    type Args = FuncArgs;
+
+    fn py_new(cls: PyTypeRef, _args: Self::Args, vm: &VirtualMachine) -> PyResult {
+        let fields_attr = cls
+            .get_class_attr(vm.ctx.interned_str("_fields_").unwrap())
+            .ok_or_else(|| {
+                vm.new_attribute_error("Structure must have a _fields_ attribute".to_string())
+            })?;
+        // downcast into list
+        let fields = fields_attr.downcast_ref::<PyList>().ok_or_else(|| {
+            vm.new_type_error("Structure _fields_ attribute must be a list".to_string())
+        })?;
+        let fields = fields.borrow_vec();
+        let mut field_data = HashMap::new();
+        for field in fields.iter() {
+            let field = field
+                .downcast_ref::<PyTuple>()
+                .ok_or_else(|| vm.new_type_error("Field must be a tuple".to_string()))?;
+            let name = field
+                .first()
+                .unwrap()
+                .downcast_ref::<PyStr>()
+                .ok_or_else(|| vm.new_type_error("Field name must be a string".to_string()))?;
+            let typ = field.get(1).unwrap().clone();
+            field_data.insert(name.as_str().to_string(), typ);
+        }
+        todo!("Implement PyCStructure::py_new")
+    }
+}
+
+impl GetAttr for PyCStructure {
+    fn getattro(zelf: &Py<Self>, name: &Py<PyStr>, vm: &VirtualMachine) -> PyResult {
+        let name = name.to_string();
+        let data = zelf.data.read();
+        match data.get(&name) {
+            Some(value) => Ok(value.clone()),
+            None => Err(vm.new_attribute_error(format!("No attribute named {}", name))),
+        }
+    }
+}
 
 #[pyclass(flags(BASETYPE, IMMUTABLETYPE))]
 impl PyCStructure {}