Function get_awaitable_iter

crates/vm/src/coroutine.rs:293–333

Get an awaitable iterator from an object. Returns the object itself if it's a coroutine or iterable coroutine (generator with CO_ITERABLE_COROUTINE flag). Otherwise calls `__await__()` and validates the result.

(obj: PyObjectRef, vm: &VirtualMachine)

/// Returns the object itself if it's a coroutine or iterable coroutine (generator with
/// CO_ITERABLE_COROUTINE flag). Otherwise calls `__await__()` and validates the result.
pub fn get_awaitable_iter(obj: PyObjectRef, vm: &VirtualMachine) -> PyResult {
    use crate::builtins::{PyCoroutine, PyGenerator};
    use crate::protocol::PyIter;

    if obj.downcastable::<PyCoroutine>()
        || obj.downcast_ref::<PyGenerator>().is_some_and(|g| {
            g.as_coro()
                .frame()
                .code
                .flags
                .contains(crate::bytecode::CodeFlags::ITERABLE_COROUTINE)
        })
    {
        return Ok(obj);
    }

    if let Some(await_method) = vm.get_method(obj.clone(), identifier!(vm, __await__)) {
        let result = await_method?.call((), vm)?;
        // __await__() must NOT return a coroutine (PEP 492)
        if result.downcastable::<PyCoroutine>()
            || result.downcast_ref::<PyGenerator>().is_some_and(|g| {
                g.as_coro()
                    .frame()
                    .code
                    .flags
                    .contains(crate::bytecode::CodeFlags::ITERABLE_COROUTINE)
            })
        {
            return Err(vm.new_type_error("__await__() returned a coroutine"));
        }
        if !PyIter::check(&result) {
            return Err(vm.new_type_error(format!(
                "__await__() returned non-iterator of type '{}'",
                result.class().name()
            )));
        }
        return Ok(result);
    }

    Err(vm.new_type_error(format!("'{}' object can't be awaited", obj.class().name())))
}

/// Emit DeprecationWarning for the deprecated 3-argument throw() signature.
pub fn warn_deprecated_throw_signature(