Method iterate_mapping_keys

crates/vm/src/frame.rs:6527–6549

Helper function to iterate over mapping keys using the keys() method. This ensures proper order preservation for OrderedDict and other custom mappings.

(
        vm: &VirtualMachine,
        mapping: &PyObject,
        func_str: &Wtf8,
        mut key_handler: F,
    )

    /// Helper function to iterate over mapping keys using the keys() method.
    /// This ensures proper order preservation for OrderedDict and other custom mappings.
    fn iterate_mapping_keys<F>(
        vm: &VirtualMachine,
        mapping: &PyObject,
        func_str: &Wtf8,
        mut key_handler: F,
    ) -> PyResult<()>
    where
        F: FnMut(PyObjectRef) -> PyResult<()>,
    {
        let Some(keys_method) = vm.get_method(mapping.to_owned(), vm.ctx.intern_str("keys")) else {
            return Err(vm.new_type_error(format!(
                "{} argument after ** must be a mapping, not {}",
                func_str,
                mapping.class().name()
            )));
        };

        let keys = keys_method?.call((), vm)?.get_iter(vm)?;
        while let PyIterReturn::Return(key) = keys.next(vm)? {
            key_handler(key)?;
        }
        Ok(())
    }

    /// Vectorcall dispatch for Instruction::Call (positional args only).
    /// Uses vectorcall slot if available, otherwise falls back to FuncArgs.