Add task::from_fn

src/task/from_fn.rs

@@ -0,0 +1,39 @@
+use super::Task;
+use std::marker::PhantomData;
+
+pub fn from_fn<F, M, O>(f: F) -> FromFn<F, M>
+where
+ F: FnMut(&mut M) -> O,
+{
+ FromFn {
+ f,
+ _marker: PhantomData,
+ }
+}
+
+pub struct FromFn<F, M> {
+ f: F,
+ _marker: PhantomData<M>,
+}
+
+impl<F, M, O> Task<M> for FromFn<F, M>
+where
+ F: FnMut(&mut M) -> O,
+{
+ type Output = O;
+
+ type State = ();
+
+ fn build(&mut self, _cx: &super::Context<M, ()>, model: &mut M) -> (Self::Output, Self::State) {
+ ((self.f)(model), ())
+ }
+
+ fn rebuild(
+ &mut self,
+ _cx: &super::Context<M, ()>,
+ model: &mut M,
+ _state: &mut Self::State,
+ ) -> Self::Output {
+ (self.f)(model)
+ }
+}

src/task/mod.rs

@@ -1,12 +1,21 @@
 use std::rc::Rc;
 
+mod from_fn;
+pub use self::from_fn::{from_fn, FromFn};
+
 mod then;
 pub use self::then::Then;
 
 pub struct Context<M, A> {
  waker: Rc<dyn Fn(Rc<dyn Fn(&mut M) -> Option<A>>)>,
 }
 
+impl<M, A> Context<M, A> {
+ pub fn update(&self, f: impl Fn(&mut M) -> Option<A> + 'static) {
+ (self.waker)(Rc::new(f))
+ }
+}
+
 pub trait Task<M, A = ()> {
  type Output;