mod.rs - source
Description: Source of the Rust file `library/core/src/future/mod.rs`.

#
core/future/
mod.rs

    1#![stable(feature = "futures_api", since = "1.36.0")]
    2
    3//! Asynchronous basic functionality.
    4//!
    5//! Please see the fundamental [`async`] and [`await`] keywords and the [async book]
    6//! for more information on asynchronous programming in Rust.
    7//!
    8//! [`async`]: ../../std/keyword.async.html
    9//! [`await`]: ../../std/keyword.await.html
    10//! [async book]: https://rust-lang.github.io/async-book/
    11
    12use crate::ptr::NonNull;
    13use crate::task::Context;
    14
    15mod async_drop;
    16mod future;
    17mod into_future;
    18mod join;
    19mod pending;
    20mod poll_fn;
    21mod ready;
    22
    23#[unstable(feature = "async_drop", issue = "126482")]
    24pub use async_drop::{AsyncDrop, async_drop_in_place};
    25#[stable(feature = "into_future", since = "1.64.0")]
    26pub use into_future::IntoFuture;
    27#[stable(feature = "future_readiness_fns", since = "1.48.0")]
    28pub use pending::{Pending, pending};
    29#[stable(feature = "future_poll_fn", since = "1.64.0")]
    30pub use poll_fn::{PollFn, poll_fn};
    31#[stable(feature = "future_readiness_fns", since = "1.48.0")]
    32pub use ready::{Ready, ready};
    33
    34#[stable(feature = "futures_api", since = "1.36.0")]
    35pub use self::future::Future;
    36#[unstable(feature = "future_join", issue = "91642")]
    37pub use self::join::join;
    38
    39/// This type is needed because:
    40///
    41/// a) Coroutines cannot implement `for<'a, 'b> Coroutine<&'a mut Context<'b>>`, so we need to pass
    42///    a raw pointer (see <https://github.com/rust-lang/rust/issues/68923>).
    43/// b) Raw pointers and `NonNull` aren't `Send` or `Sync`, so that would make every single future
    44///    non-Send/Sync as well, and we don't want that.
    45///
    46/// It also simplifies the HIR lowering of `.await`.
    47#[lang = "ResumeTy"]
    48#[doc(hidden)]
    49#[unstable(feature = "gen_future", issue = "none")]
    50#[derive(Debug, Copy, Clone)]
    51pub struct ResumeTy(NonNull<Context<'static>>);
    52
    53#[unstable(feature = "gen_future", issue = "none")]
    54unsafe impl Send for ResumeTy {}
    55
    56#[unstable(feature = "gen_future", issue = "none")]
    57unsafe impl Sync for ResumeTy {}
    58
    59#[lang = "get_context"]
    60#[doc(hidden)]
    61#[unstable(feature = "gen_future", issue = "none")]
    62#[must_use]
    63#[inline]
    64pub unsafe fn get_context<'a, 'b>(cx: ResumeTy) -> &'a mut Context<'b> {
    65    // SAFETY: the caller must guarantee that `cx.0` is a valid pointer
    66    // that fulfills all the requirements for a mutable reference.
    67    unsafe { &mut *cx.0.as_ptr().cast() }
    68}