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use std::hash::*; use std::ops::*; use std::cmp::*; use std::fmt; use std::pin::Pin; use std::rc::Rc; use std::cell::{Ref, RefCell}; use super::{notify_updater, exec_updater}; use super::dirty_marker::DirtyMarker; pub struct Lazy<T> { data: RefCell<Option<T>>, updater: Rc<dyn Fn() -> T>, dirty: Pin<Rc<DirtyMarker>>, } impl<T> Lazy<T> { #[inline] pub fn new<F: 'static + Fn() -> T>(updater: F) -> Self { let updater = Rc::new(updater); let dirty = Rc::pin(DirtyMarker::new(true)); Self { data: RefCell::new(None), updater, dirty } } #[inline] pub fn check_update(&self) { if self.dirty.clear_dirty() { match self.data.try_borrow_mut() { Ok(mut x) => *x = Some(exec_updater(&self.dirty, &self.updater)), Err(_) => { }, } } } #[inline] pub fn get_ref(&self) -> Ref<T> { self.check_update(); notify_updater(&self.dirty); Ref::map(self.data.borrow(), |x| x.as_ref().unwrap()) } } impl<T: Clone> Lazy<T> { #[inline] pub fn get(&self) -> T { self.check_update(); notify_updater(&self.dirty); self.data.borrow().as_ref().unwrap().clone() } } impl<T> Drop for Lazy<T> { fn drop(&mut self) { self.dirty.destroy(); } } impl<T: PartialEq> PartialEq for Lazy<T> { fn eq(&self, other: &Self) -> bool { *self.get_ref() == *other.get_ref() } } impl<T: Eq> Eq for Lazy<T> {} impl<T: PartialOrd> PartialOrd for Lazy<T> { #[inline] fn partial_cmp(&self, other: &Lazy<T>) -> Option<Ordering> { PartialOrd::partial_cmp(&*self.get_ref(), &*other.get_ref()) } #[inline] fn lt(&self, other: &Lazy<T>) -> bool { PartialOrd::lt(&*self.get_ref(), &*other.get_ref()) } #[inline] fn le(&self, other: &Lazy<T>) -> bool { PartialOrd::le(&*self.get_ref(), &*other.get_ref()) } #[inline] fn ge(&self, other: &Lazy<T>) -> bool { PartialOrd::ge(&*self.get_ref(), &*other.get_ref()) } #[inline] fn gt(&self, other: &Lazy<T>) -> bool { PartialOrd::gt(&*self.get_ref(), &*other.get_ref()) } } impl<T: Ord> Ord for Lazy<T> { #[inline] fn cmp(&self, other: &Lazy<T>) -> Ordering { Ord::cmp(&*self.get_ref(), &*other.get_ref()) } } impl<T: Hash> Hash for Lazy<T> { fn hash<H: Hasher>(&self, state: &mut H) { (*self.get_ref()).hash(state); } } impl<T: Clone> Clone for Lazy<T> { #[inline] fn clone(&self) -> Lazy<T> { let updater = self.updater.clone(); let dirty = Rc::pin(DirtyMarker::new(false)); Self { data: RefCell::new(None), updater, dirty } } } impl<T: fmt::Display> fmt::Display for Lazy<T> { fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { fmt::Display::fmt(&*self.get_ref(), f) } } impl<T: fmt::Debug> fmt::Debug for Lazy<T> { fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { fmt::Debug::fmt(&*self.get_ref(), f) } }