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use std::fmt::Display;
use std::time::{Instant, Duration};
use tokio_core::reactor::Handle;
use futures::Future;
use log::LogLevel;
use void::Void;
use log_error::LogError;
use until::Until;
use infallible::Infallible;
use finally::Finally;
use with_timeout::WithTimeout;
use BoxFuture;
/// Extension trait for `Future`.
pub trait FutureExt: Future + Sized {
/// Wraps a future into a boxed future, making type-checking easier at the expense of an extra
/// layer of indirection at runtime.
fn into_boxed(self) -> BoxFuture<Self::Item, Self::Error>
where
Self: 'static
{
Box::new(self)
}
/// Run this future until some condition is met. If `condition` resolves before `self` then
/// `None` is returned.
///
/// # Example
/// ```rust
/// let my_future_with_timeout = my_future.until(Timeout::new(Duration::from_secs(1)));
/// ```
fn until<C>(self, condition: C) -> Until<Self, C>
where
C: Future<Item=()>,
Self::Error: From<C::Error>
{
Until::new(self, condition)
}
/// For futures which can't fail (ie. which have error type `Void`), cast the error type to
/// some inferred type.
fn infallible<E>(self) -> Infallible<Self, E>
where
Self: Future<Error=Void>
{
Infallible::new(self)
}
/// Take a future which returns `()` and log its error if it fails. The returned future cannot
/// fail and will always resolve to `()`.
fn log_error(self, level: LogLevel, description: &'static str) -> LogError<Self>
where
Self: Future<Item=()>,
Self::Error: Display,
{
LogError::new(self, level, description)
}
/// Executes the future and runs the provided callback when the future finishes. The callback
/// will also be run if the entire future is dropped.
fn finally<D>(self, on_drop: D) -> Finally<Self, D>
where
D: FnOnce()
{
Finally::new(self, on_drop)
}
/// Runs the future for the given duration, returning its value in an option, or returning
/// `None` if the timeout expires.
fn with_timeout(self, duration: Duration, handle: &Handle) -> WithTimeout<Self> {
WithTimeout::new(self, duration, handle)
}
/// Runs the future until the given instant, returning its value in an option, or returning
/// `None` if the timeout expires.
fn with_timeout_at(self, instant: Instant, handle: &Handle) -> WithTimeout<Self> {
WithTimeout::new_at(self, instant, handle)
}
}
impl<T: Future + Sized> FutureExt for T {}