ref_count.rs

use std::rc::*;

pub enum RefCount<T> {
    Rc(Rc<T>),
    Weak(Weak<T>),
}

impl<T> RefCount<T> {
    pub fn new_rc(value: T) -> RefCount<T> {
        RefCount::Rc(Rc::new(value))
    }

    pub fn downgrade(&self) -> Weak<T> {
        match self {
            RefCount::Rc(ref rc) => Rc::downgrade(rc),
            RefCount::Weak(ref weak) => weak.clone(),
        }
    }

    pub fn downgrade_self(&mut self) -> Weak<T> {
        let weak = match self {
            RefCount::Rc(ref rc) => Rc::downgrade(rc),
            RefCount::Weak(ref weak) => return weak.clone(),
        };
        *self = RefCount::Weak(weak.clone());
        weak
    }

    pub fn upgrade(&self) -> Option<Rc<T>> {
        match self {
            RefCount::Rc(ref rc) => Some(rc.clone()),
            RefCount::Weak(ref weak) => Weak::upgrade(weak),
        }
    }

    pub fn upgrade_self(&mut self) -> Option<Rc<T>> {
        let rc = match self {
            RefCount::Rc(ref rc) => return Some(rc.clone()),
            RefCount::Weak(ref weak) => Weak::upgrade(weak)?,
        };
        *self = RefCount::Rc(rc.clone());
        Some(rc)
    }
}

impl<T> Clone for RefCount<T> {
    fn clone(&self) -> Self {
        match self {
            RefCount::Rc(ref rc) => RefCount::Rc(rc.clone()),
            RefCount::Weak(ref weak) => RefCount::Weak(weak.clone()),
        }
    }
}