tsuki 0.4.8

Lua 5.4 ported to Rust
Documentation 
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use super::Mark;
use crate::Lua;
use core::cell::Cell;
use core::ptr::{null, null_mut};

/// Header of all object managed by Garbage Collector.
///
/// All object must have this struct at the beginning of its memory block.
pub struct Object<D> {
    pub(crate) global: *const Lua<D>,
    pub(super) next: Cell<*const Self>,
    pub(crate) tt: u8,
    pub(crate) marked: Mark,
    pub(super) refs: Cell<usize>,
    pub(super) refn: Cell<*mut *const Self>,
    pub(super) refp: Cell<*const Self>,
    pub(super) gclist: Cell<*const Self>,
}

impl<D> Object<D> {
    #[inline(always)]
    pub fn global(&self) -> &Lua<D> {
        unsafe { &*self.global }
    }

    #[inline(always)]
    pub(crate) unsafe fn unref(&self) {
        // Decrease references.
        self.refs.update(|v| v - 1);

        if self.refs.get() != 0 {
            return;
        }

        // Remove from list.
        let n = self.refn.replace(null_mut());
        let p = self.refp.replace(null());

        unsafe { *n = p };

        if !p.is_null() {
            unsafe { (*p).refn.set(n) };
        }
    }
}

impl<D> Default for Object<D> {
    #[inline(always)]
    fn default() -> Self {
        Self {
            global: null(),
            next: Cell::new(null()),
            tt: 0,
            marked: Mark::default(),
            refs: Cell::new(0),
            refn: Cell::new(null_mut()),
            refp: Cell::new(null()),
            gclist: Cell::new(null()),
        }
    }
}