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// Smelling Salts
//
// Copyright (c) 2020 Jeron Aldaron Lau
//
// Licensed under the Apache License, Version 2.0, <LICENSE-APACHE or
// https://apache.org/licenses/LICENSE-2.0>, or the Zlib License, <LICENSE-ZLIB
// or http://opensource.org/licenses/Zlib>, at your option. This file may not be
// copied, modified, or distributed except according to those terms.

pub(crate) const EPOLLIN: u32 = 0x_001;
const EPOLLOUT: u32 = 0x_004;
const EPOLLET: u32 = 1 << 31;

/// Which events to watch for to trigger a wake-up.
#[derive(Debug, Copy, Clone)]
pub struct Watcher(pub(crate) u32);

impl Watcher {
    /// Create empty Watcher (requesting nothing)
    pub fn new() -> Watcher {
        Watcher(EPOLLET)
    }

    /// Create Watcher from raw bitmask
    ///
    /// # Safety
    /// This function requires the correct usage of the bitflags from the epoll
    /// C API.
    #[allow(unsafe_code)]
    pub unsafe fn from_raw(raw: u32) -> Watcher {
        Watcher(EPOLLET | raw)
    }

    /// Watch for input from device.
    pub fn input(mut self) -> Self {
        self.0 |= EPOLLIN;
        self
    }

    /// Watch for device to be ready for output.
    pub fn output(mut self) -> Self {
        self.0 |= EPOLLOUT;
        self
    }
}

impl Default for Watcher {
    fn default() -> Self {
        Self::new()
    }
}