git.delta.rocks / jrsonnet / refs/commits / 91108e4246a4

10	rc::Rc,10	rc::Rc,
11};11};
1212
13struct LazyValInternals {13enum LazyValInternals {
14	Computed(Val),
14	pub f: Option<Box<dyn Fn() -> Result<Val>>>,15	Waiting(Box<dyn Fn() -> Result<Val>>),
15	pub cached: RefCell<Option<Val>>,
16}16}
17#[derive(Clone)]17#[derive(Clone)]
18pub struct LazyVal(Rc<LazyValInternals>);18pub struct LazyVal(Rc<RefCell<LazyValInternals>>);
19impl LazyVal {19impl LazyVal {
20	pub fn new(f: Box<dyn Fn() -> Result<Val>>) -> Self {20	pub fn new(f: Box<dyn Fn() -> Result<Val>>) -> Self {
21		LazyVal(Rc::new(LazyValInternals {21		LazyVal(Rc::new(RefCell::new(LazyValInternals::Waiting(f))))
22			f: Some(f),
23			cached: RefCell::new(None),
24		}))
25	}22	}
26	pub fn new_resolved(val: Val) -> Self {23	pub fn new_resolved(val: Val) -> Self {
27		LazyVal(Rc::new(LazyValInternals {24		LazyVal(Rc::new(RefCell::new(LazyValInternals::Computed(val))))
28			f: None,
29			cached: RefCell::new(Some(val)),
30		}))
31	}25	}
32	pub fn evaluate(&self) -> Result<Val> {26	pub fn evaluate(&self) -> Result<Val> {
33		{
34			let cached = self.0.cached.borrow();
35			if cached.is_some() {27		let new_value = match &*self.0.borrow() {
36				return Ok(cached.clone().unwrap());28			LazyValInternals::Computed(v) => return Ok(v.clone()),
29			LazyValInternals::Waiting(f) => f()?,
37			}30		};
38		}
39		let result = (self.0.f.as_ref().unwrap())()?;
40		self.0.cached.borrow_mut().replace(result.clone());31		*self.0.borrow_mut() = LazyValInternals::Computed(new_value.clone());
41		Ok(result)32		Ok(new_value)
42	}33	}
43}34}
4435
56}47}
57impl Debug for LazyVal {48impl Debug for LazyVal {
58	fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {49	fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
59		if self.0.cached.borrow().is_some() {
60			write!(f, "{:?}", self.0.cached.borrow().clone().unwrap())
61		} else {
62			write!(f, "Lazy")50		write!(f, "Lazy")
63		}
64	}51	}
65}52}
66impl PartialEq for LazyVal {53impl PartialEq for LazyVal {