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use std::{
cell::{Ref, RefCell, RefMut},
ops::Deref,
};
pub type Observer<V> = Box<dyn FnMut(&V) -> bool>;
pub struct Observable<V> {
value: RefCell<V>,
observers: RefCell<Vec<Observer<V>>>,
}
impl<V> Deref for Observable<V> {
type Target = RefCell<V>;
fn deref(&self) -> &Self::Target {
&self.value
}
}
impl<V> Observable<V> {
pub fn new(value: V) -> Self {
Self {
observers: Default::default(),
value: RefCell::new(value),
}
}
pub fn add_observer(&self, observer: Observer<V>) {
self.observers.borrow_mut().push(observer);
}
pub fn notify(&self) {
let mut observers = self.observers.borrow_mut();
let mut to_remove = vec![];
{
let mut x = 0usize;
for observer in &mut *observers {
if (observer)(&*self.value.borrow_mut()) {
to_remove.push(x);
} else {
x += 1;
}
}
}
for x in to_remove {
drop(observers.remove(x));
}
}
pub fn borrow(&self) -> Ref<V> {
self.value.borrow()
}
pub fn borrow_mut(&self) -> RefMut<V> {
self.value.borrow_mut()
}
}
impl<V> From<V> for Observable<V> {
fn from(v: V) -> Self {
Self::new(v)
}
}