1use std::cell::RefCell;23use gcmodule::{Cc, Trace};45#[derive(Clone, Trace)]6pub struct FutureWrapper<V: Trace + 'static>(pub Cc<RefCell<Option<V>>>);7impl<T: Trace + 'static> FutureWrapper<T> {8 pub fn new() -> Self {9 Self(Cc::new(RefCell::new(None)))10 }11 pub fn fill(self, value: T) {12 assert!(self.0.borrow().is_none(), "wrapper is filled already");13 self.0.borrow_mut().replace(value);14 }15}16impl<T: Clone + Trace + 'static> FutureWrapper<T> {17 pub fn unwrap(&self) -> T {18 self.0.borrow().as_ref().cloned().unwrap()19 }20}2122impl<T: Trace + 'static> Default for FutureWrapper<T> {23 fn default() -> Self {24 Self::new()25 }26}