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#![allow(missing_docs)]
use crate::{use_callback, use_signal, UseCallback};
use dioxus_core::prelude::*;
use dioxus_core::{
prelude::{spawn, use_hook},
Task,
};
use dioxus_signals::*;
use futures_util::{future, pin_mut, FutureExt, StreamExt};
use std::ops::Deref;
use std::{cell::Cell, future::Future, rc::Rc};
/// A memo that resolves to a value asynchronously.
/// Similar to `use_future` but `use_resource` returns a value.
/// See [`Resource`] for more details.
/// ```rust
/// # use dioxus::prelude::*;
/// # #[derive(Clone)]
/// # struct WeatherLocation {
/// # city: String,
/// # country: String,
/// # coordinates: (f64, f64),
/// # }
/// # async fn get_weather(location: &WeatherLocation) -> Result<String, String> {
/// # Ok("Sunny".to_string())
/// # }
/// # #[component]
/// # fn WeatherElement (weather: String ) -> Element { rsx! { p { "The weather is {weather}" } } }
/// fn app() -> Element {
/// let country = use_signal(|| WeatherLocation {
/// city: "Berlin".to_string(),
/// country: "Germany".to_string(),
/// coordinates: (52.5244, 13.4105)
/// });
///
/// // Because the resource's future subscribes to `country` by reading it (`country.read()`),
/// // every time `country` changes the resource's future will run again and thus provide a new value.
/// let current_weather = use_resource(move || async move { get_weather(&country()).await });
///
/// rsx! {
/// // the value of the resource can be polled to
/// // conditionally render elements based off if it's future
/// // finished (Some(Ok(_)), errored Some(Err(_)),
/// // or is still running (None)
/// match current_weather.value() {
/// Some(Ok(weather)) => rsx! { WeatherElement { weather } },
/// Some(Err(e)) => rsx! { p { "Loading weather failed, {e}" } },
/// None => rsx! { p { "Loading..." } }
/// }
/// }
///}
/// ```
///
/// ## With non-reactive dependencies
/// To add non-reactive dependencies, you can use the `use_reactive` hook.
///
/// Signals will automatically be added as dependencies, so you don't need to call this method for them.
///
/// ```rust
/// # use dioxus::prelude::*;
/// # async fn sleep(delay: u32) {}
///
/// #[component]
/// fn Comp(count: u32) -> Element {
/// // Because the memo subscribes to `count` by adding it as a dependency, the memo will rerun every time `count` changes.
/// let new_count = use_resource(use_reactive((&count, |(count,)| async move {count + 1} )));
///
/// todo!()
/// }
/// ```
#[must_use = "Consider using `cx.spawn` to run a future without reading its value"]
pub fn use_resource<T, F>(mut future: impl FnMut() -> F + 'static) -> Resource<T>
where
T: 'static,
F: Future<Output = T> + 'static,
{
let mut value = use_signal(|| None);
let mut state = use_signal(|| UseResourceState::Pending);
let (rc, changed) = use_hook(|| {
let (rc, changed) = ReactiveContext::new();
(rc, Rc::new(Cell::new(Some(changed))))
});
let cb = use_callback(move || {
// Create the user's task
let fut = rc.run_in(&mut future);
// Spawn a wrapper task that polls the inner future and watch its dependencies
spawn(async move {
// move the future here and pin it so we can poll it
let fut = fut;
pin_mut!(fut);
// Run each poll in the context of the reactive scope
// This ensures the scope is properly subscribed to the future's dependencies
let res = future::poll_fn(|cx| rc.run_in(|| fut.poll_unpin(cx))).await;
// Set the value and state
state.set(UseResourceState::Ready);
value.set(Some(res));
})
});
let mut task = use_hook(|| Signal::new(cb()));
use_hook(|| {
let mut changed = changed.take().unwrap();
spawn(async move {
loop {
// Wait for the dependencies to change
let _ = changed.next().await;
// Stop the old task
task.write().cancel();
// Start a new task
task.set(cb());
}
})
});
Resource {
task,
value,
state,
callback: cb,
}
}
#[allow(unused)]
pub struct Resource<T: 'static> {
value: Signal<Option<T>>,
task: Signal<Task>,
state: Signal<UseResourceState>,
callback: UseCallback<Task>,
}
impl<T> Clone for Resource<T> {
fn clone(&self) -> Self {
*self
}
}
impl<T> Copy for Resource<T> {}
/// A signal that represents the state of the resource
// we might add more states (panicked, etc)
#[derive(Clone, Copy, PartialEq, Hash, Eq, Debug)]
pub enum UseResourceState {
/// The resource's future is still running
Pending,
/// The resource's future has been forcefully stopped
Stopped,
/// The resource's future has been paused, tempoarily
Paused,
/// The resource's future has completed
Ready,
}
impl<T> Resource<T> {
/// Restart the resource's future.
///
/// Will not cancel the previous future, but will ignore any values that it
/// generates.
pub fn restart(&mut self) {
self.task.write().cancel();
let new_task = self.callback.call();
self.task.set(new_task);
}
/// Forcefully cancel the resource's future.
pub fn cancel(&mut self) {
self.state.set(UseResourceState::Stopped);
self.task.write().cancel();
}
/// Pause the resource's future.
pub fn pause(&mut self) {
self.state.set(UseResourceState::Paused);
self.task.write().pause();
}
/// Resume the resource's future.
pub fn resume(&mut self) {
if self.finished() {
return;
}
self.state.set(UseResourceState::Pending);
self.task.write().resume();
}
/// Clear the resource's value.
pub fn clear(&mut self) {
self.value.write().take();
}
/// Get a handle to the inner task backing this resource
/// Modify the task through this handle will cause inconsistent state
pub fn task(&self) -> Task {
self.task.cloned()
}
/// Is the resource's future currently finished running?
///
/// Reading this does not subscribe to the future's state
pub fn finished(&self) -> bool {
matches!(
*self.state.peek(),
UseResourceState::Ready | UseResourceState::Stopped
)
}
/// Get the current state of the resource's future.
pub fn state(&self) -> ReadOnlySignal<UseResourceState> {
self.state.into()
}
/// Get the current value of the resource's future.
pub fn value(&self) -> ReadOnlySignal<Option<T>> {
self.value.into()
}
}
impl<T> From<Resource<T>> for ReadOnlySignal<Option<T>> {
fn from(val: Resource<T>) -> Self {
val.value.into()
}
}
impl<T> Readable for Resource<T> {
type Target = Option<T>;
type Storage = UnsyncStorage;
#[track_caller]
fn try_read_unchecked(
&self,
) -> Result<ReadableRef<'static, Self>, generational_box::BorrowError> {
self.value.try_read_unchecked()
}
#[track_caller]
fn peek_unchecked(&self) -> ReadableRef<'static, Self> {
self.value.peek_unchecked()
}
}
impl<T> IntoAttributeValue for Resource<T>
where
T: Clone + IntoAttributeValue,
{
fn into_value(self) -> dioxus_core::AttributeValue {
self.with(|f| f.clone().into_value())
}
}
impl<T> IntoDynNode for Resource<T>
where
T: Clone + IntoDynNode,
{
fn into_dyn_node(self) -> dioxus_core::DynamicNode {
self().into_dyn_node()
}
}
/// Allow calling a signal with signal() syntax
///
/// Currently only limited to copy types, though could probably specialize for string/arc/rc
impl<T: Clone> Deref for Resource<T> {
type Target = dyn Fn() -> Option<T>;
fn deref(&self) -> &Self::Target {
Readable::deref_impl(self)
}
}