# pyasync.rs - source
Source of the Rust file `/home/runner/.cargo/registry/src/github.com-1ecc6299db9ec823/pyo3-0.13.2/src/class/pyasync.rs`.
Keywords: rust, rustlang, rust-lang

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    // Copyright (c) 2017-present PyO3 Project and Contributors

    //! Python Async/Await Interface.
    //!
    //! Check [the Python C API information](
    //! https://docs.python.org/3/c-api/typeobj.html#async-object-structures)
    //!
    //! [PEP-0492](https://www.python.org/dev/peps/pep-0492/)
    //!

    use crate::callback::IntoPyCallbackOutput;
    use crate::derive_utils::TryFromPyCell;
    use crate::err::PyResult;
    use crate::{ffi, IntoPy, IntoPyPointer, PyClass, PyObject, Python};

    /// Python Async/Await support interface.
    ///
    /// Each method in this trait corresponds to Python async/await implementation.
    #[allow(unused_variables)]
    pub trait PyAsyncProtocol<'p>: PyClass {
        fn __await__(slf: Self::Receiver) -> Self::Result
        where
            Self: PyAsyncAwaitProtocol<'p>,
        {
            unimplemented!()
        }

        fn __aiter__(slf: Self::Receiver) -> Self::Result
        where
            Self: PyAsyncAiterProtocol<'p>,
        {
            unimplemented!()
        }

        fn __anext__(slf: Self::Receiver) -> Self::Result
        where
            Self: PyAsyncAnextProtocol<'p>,
        {
            unimplemented!()
        }

        fn __aenter__(&'p mut self) -> Self::Result
        where
            Self: PyAsyncAenterProtocol<'p>,
        {
            unimplemented!()
        }

        fn __aexit__(
            &'p mut self,
            exc_type: Option<Self::ExcType>,
            exc_value: Option<Self::ExcValue>,
            traceback: Option<Self::Traceback>,
        ) -> Self::Result
        where
            Self: PyAsyncAexitProtocol<'p>,
        {
            unimplemented!()
        }
    }

    pub trait PyAsyncAwaitProtocol<'p>: PyAsyncProtocol<'p> {
        type Receiver: TryFromPyCell<'p, Self>;
        type Result: IntoPyCallbackOutput<PyObject>;
    }

    pub trait PyAsyncAiterProtocol<'p>: PyAsyncProtocol<'p> {
        type Receiver: TryFromPyCell<'p, Self>;
        type Result: IntoPyCallbackOutput<PyObject>;
    }

    pub trait PyAsyncAnextProtocol<'p>: PyAsyncProtocol<'p> {
        type Receiver: TryFromPyCell<'p, Self>;
        type Result: IntoPyCallbackOutput<PyIterANextOutput>;
    }

    pub trait PyAsyncAenterProtocol<'p>: PyAsyncProtocol<'p> {
        type Result: IntoPyCallbackOutput<PyObject>;
    }

    pub trait PyAsyncAexitProtocol<'p>: PyAsyncProtocol<'p> {
        type ExcType: crate::FromPyObject<'p>;
        type ExcValue: crate::FromPyObject<'p>;
        type Traceback: crate::FromPyObject<'p>;
        type Result: IntoPyCallbackOutput<PyObject>;
    }

    py_unarys_func!(await_, PyAsyncAwaitProtocol, Self::__await__);
    py_unarys_func!(aiter, PyAsyncAiterProtocol, Self::__aiter__);
    py_unarys_func!(anext, PyAsyncAnextProtocol, Self::__anext__);

    /// Output of `__anext__`.
    pub enum IterANextOutput<T, U> {
        Yield(T),
        Return(U),
    }

    pub type PyIterANextOutput = IterANextOutput<PyObject, PyObject>;

    impl IntoPyCallbackOutput<*mut ffi::PyObject> for PyIterANextOutput {
        fn convert(self, _py: Python) -> PyResult<*mut ffi::PyObject> {
            match self {
                IterANextOutput::Yield(o) => Ok(o.into_ptr()),
                IterANextOutput::Return(opt) => {
                    Err(crate::exceptions::PyStopAsyncIteration::new_err((opt,)))
                }
            }
        }
    }

    impl<T, U> IntoPyCallbackOutput<PyIterANextOutput> for IterANextOutput<T, U>
    where
        T: IntoPy<PyObject>,
        U: IntoPy<PyObject>,
    {
        fn convert(self, py: Python) -> PyResult<PyIterANextOutput> {
            match self {
                IterANextOutput::Yield(o) => Ok(IterANextOutput::Yield(o.into_py(py))),
                IterANextOutput::Return(o) => Ok(IterANextOutput::Return(o.into_py(py))),
            }
        }
    }

    impl<T> IntoPyCallbackOutput<PyIterANextOutput> for Option<T>
    where
        T: IntoPy<PyObject>,
    {
        fn convert(self, py: Python) -> PyResult<PyIterANextOutput> {
            match self {
                Some(o) => Ok(PyIterANextOutput::Yield(o.into_py(py))),
                None => Ok(PyIterANextOutput::Return(py.None())),
            }
        }
    }