1use jrsonnet_gc::{Gc, GcCell, Trace};23#[derive(Clone, Trace)]4#[trivially_drop]5pub struct FutureWrapper<V: Trace + 'static>(pub Gc<GcCell<Option<V>>>);6impl<T: Trace + 'static> FutureWrapper<T> {7 pub fn new() -> Self {8 Self(Gc::new(GcCell::new(None)))9 }10 pub fn fill(self, value: T) {11 assert!(self.0.borrow().is_none(), "wrapper is filled already");12 self.0.borrow_mut().replace(value);13 }14}15impl<T: Clone + Trace + 'static> FutureWrapper<T> {16 pub fn unwrap(&self) -> T {17 self.0.borrow().as_ref().cloned().unwrap()18 }19}2021impl<T: Trace + 'static> Default for FutureWrapper<T> {22 fn default() -> Self {23 Self::new()24 }25}