Method dec

aiscript-arena/src/dynamic_roots.rs:299–314

(&mut self, idx: Index)

    }

    fn dec(&mut self, idx: Index) {
        let slot = &mut self.slots[idx];
        match slot {
            Slot::Occupied { ref_count, .. } => {
                if *ref_count == 0 {
                    *slot = Slot::Vacant {
                        next_free: self.next_free,
                    };
                    self.next_free = idx;
                } else {
                    *ref_count -= 1;
                }
            }
            Slot::Vacant { .. } => panic!("taken slot has been improperly freed"),
        }
    }
}