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use std::num::NonZeroU8;
use std::{fmt, ops};
/// Interest used in registering.
///
/// Interest are used in [registering] [`event::Source`]s with [`Poll`], they
/// indicate what readiness should be monitored for. For example if a socket is
/// registered with [readable] interests and the socket becomes writable, no
/// event will be returned from a call to [`poll`].
///
/// [registering]: struct.Registry.html#method.register
/// [`event::Source`]: ./event/trait.Source.html
/// [`Poll`]: struct.Poll.html
/// [readable]: struct.Interest.html#associatedconstant.READABLE
/// [`poll`]: struct.Poll.html#method.poll
#[derive(Copy, PartialEq, Eq, Clone, PartialOrd, Ord)]
pub struct Interest(NonZeroU8);
// These must be unique.
const READABLE: u8 = 0b0001;
const WRITABLE: u8 = 0b0010;
// The following are not available on all platforms.
const AIO: u8 = 0b0100;
const LIO: u8 = 0b1000;
const PRIORITY: u8 = 0b10000;
impl Interest {
/// Returns a `Interest` set representing readable interests.
pub const READABLE: Interest = Interest(unsafe { NonZeroU8::new_unchecked(READABLE) });
/// Returns a `Interest` set representing writable interests.
pub const WRITABLE: Interest = Interest(unsafe { NonZeroU8::new_unchecked(WRITABLE) });
/// Returns a `Interest` set representing AIO completion interests.
#[cfg(any(
target_os = "dragonfly",
target_os = "freebsd",
target_os = "ios",
target_os = "macos",
target_os = "tvos",
target_os = "visionos",
target_os = "watchos",
))]
pub const AIO: Interest = Interest(unsafe { NonZeroU8::new_unchecked(AIO) });
/// Returns a `Interest` set representing LIO completion interests.
#[cfg(target_os = "freebsd")]
pub const LIO: Interest = Interest(unsafe { NonZeroU8::new_unchecked(LIO) });
/// Returns a `Interest` set representing priority completion interests.
#[cfg(any(target_os = "linux", target_os = "android"))]
pub const PRIORITY: Interest = Interest(unsafe { NonZeroU8::new_unchecked(PRIORITY) });
/// Add together two `Interest`.
///
/// This does the same thing as the `BitOr` implementation, but is a
/// constant function.
///
/// ```
/// use mio::Interest;
///
/// const INTERESTS: Interest = Interest::READABLE.add(Interest::WRITABLE);
/// # fn silent_dead_code_warning(_: Interest) { }
/// # silent_dead_code_warning(INTERESTS)
/// ```
#[allow(clippy::should_implement_trait)]
#[must_use = "this returns the result of the operation, without modifying the original"]
pub const fn add(self, other: Interest) -> Interest {
Interest(unsafe { NonZeroU8::new_unchecked(self.0.get() | other.0.get()) })
}
/// Removes `other` `Interest` from `self`.
///
/// Returns `None` if the set would be empty after removing `other`.
///
/// ```
/// use mio::Interest;
///
/// const RW_INTERESTS: Interest = Interest::READABLE.add(Interest::WRITABLE);
///
/// // As long a one interest remain this will return `Some`.
/// let w_interest = RW_INTERESTS.remove(Interest::READABLE).unwrap();
/// assert!(!w_interest.is_readable());
/// assert!(w_interest.is_writable());
///
/// // Removing all interests from the set will return `None`.
/// assert_eq!(w_interest.remove(Interest::WRITABLE), None);
///
/// // Its also possible to remove multiple interests at once.
/// assert_eq!(RW_INTERESTS.remove(RW_INTERESTS), None);
/// ```
#[must_use = "this returns the result of the operation, without modifying the original"]
pub fn remove(self, other: Interest) -> Option<Interest> {
NonZeroU8::new(self.0.get() & !other.0.get()).map(Interest)
}
/// Returns true if the value includes readable readiness.
#[must_use]
pub const fn is_readable(self) -> bool {
(self.0.get() & READABLE) != 0
}
/// Returns true if the value includes writable readiness.
#[must_use]
pub const fn is_writable(self) -> bool {
(self.0.get() & WRITABLE) != 0
}
/// Returns true if `Interest` contains AIO readiness.
#[must_use]
pub const fn is_aio(self) -> bool {
(self.0.get() & AIO) != 0
}
/// Returns true if `Interest` contains LIO readiness.
#[must_use]
pub const fn is_lio(self) -> bool {
(self.0.get() & LIO) != 0
}
/// Returns true if `Interest` contains priority readiness.
#[must_use]
pub const fn is_priority(self) -> bool {
(self.0.get() & PRIORITY) != 0
}
}
impl ops::BitOr for Interest {
type Output = Self;
#[inline]
fn bitor(self, other: Self) -> Self {
self.add(other)
}
}
impl ops::BitOrAssign for Interest {
#[inline]
fn bitor_assign(&mut self, other: Self) {
self.0 = (*self | other).0;
}
}
impl fmt::Debug for Interest {
fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
let mut one = false;
if self.is_readable() {
if one {
write!(fmt, " | ")?
}
write!(fmt, "READABLE")?;
one = true
}
if self.is_writable() {
if one {
write!(fmt, " | ")?
}
write!(fmt, "WRITABLE")?;
one = true
}
#[cfg(any(
target_os = "dragonfly",
target_os = "freebsd",
target_os = "ios",
target_os = "macos",
target_os = "tvos",
target_os = "visionos",
target_os = "watchos",
))]
{
if self.is_aio() {
if one {
write!(fmt, " | ")?
}
write!(fmt, "AIO")?;
one = true
}
}
#[cfg(target_os = "freebsd")]
{
if self.is_lio() {
if one {
write!(fmt, " | ")?
}
write!(fmt, "LIO")?;
one = true
}
}
#[cfg(any(target_os = "linux", target_os = "android"))]
{
if self.is_priority() {
if one {
write!(fmt, " | ")?
}
write!(fmt, "PRIORITY")?;
one = true
}
}
debug_assert!(one, "printing empty interests");
Ok(())
}
}