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/*! Locking mechanism. Don't mind this.

*/

use std::{
    error::Error,
    fmt::Display,
    rc::Rc,
    sync::atomic::{AtomicBool, Ordering},
};

#[derive(Clone)]
pub(crate) struct UnmountedLock(Rc<AtomicBool>);

impl PartialEq for UnmountedLock {
    fn eq(&self, other: &UnmountedLock) -> bool {
        Rc::ptr_eq(&self.0, &other.0)
    }
}

impl UnmountedLock {
    pub(crate) fn new_mounted() -> Self {
        Self(Rc::new(AtomicBool::new(true)))
    }
    pub(crate) fn is_mounted(&self) -> bool {
        self.0.load(Ordering::Acquire)
    }
    pub(crate) fn unmount(&self) {
        self.0.store(false, Ordering::Release)
    }
    pub(crate) fn as_ptr(&self) -> *const AtomicBool {
        Rc::as_ptr(&self.0)
    }
}

/** A failure where the subtree you are trying to do something with had been unmounted.

For example, [crate::hooks::Reference] have many methods that may error out with this.

*/
#[derive(Debug)]
pub struct SubtreeUnmountedError;

impl Display for SubtreeUnmountedError {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        f.write_str("Attempted to use an unmounted subtree.")
    }
}

impl Error for SubtreeUnmountedError {}