862 lines
30 KiB
Rust
862 lines
30 KiB
Rust
//! # VirtualDom Implementation for Rust
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//!
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//! This module provides the primary mechanics to create a hook-based, concurrent VDOM for Rust.
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use crate::innerlude::*;
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use futures_channel::mpsc::{UnboundedReceiver, UnboundedSender};
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use futures_util::{Future, StreamExt};
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use fxhash::FxHashSet;
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use indexmap::IndexSet;
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use smallvec::SmallVec;
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use std::{any::Any, collections::VecDeque, iter::FromIterator, pin::Pin, sync::Arc, task::Poll};
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/// A virtual node s ystem that progresses user events and diffs UI trees.
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///
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///
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/// ## Guide
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///
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/// Components are defined as simple functions that take [`Context`] and a [`Properties`] type and return an [`Element`].
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///
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/// ```rust, ignore
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/// #[derive(Props, PartialEq)]
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/// struct AppProps {
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/// title: String
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/// }
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///
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/// fn App(cx: Scope<AppProps>) -> Element {
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/// cx.render(rsx!(
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/// div {"hello, {cx.props.title}"}
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/// ))
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/// }
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/// ```
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///
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/// Components may be composed to make complex apps.
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///
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/// ```rust, ignore
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/// fn App(cx: Scope<AppProps>) -> Element {
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/// cx.render(rsx!(
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/// NavBar { routes: ROUTES }
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/// Title { "{cx.props.title}" }
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/// Footer {}
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/// ))
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/// }
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/// ```
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///
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/// To start an app, create a [`VirtualDom`] and call [`VirtualDom::rebuild`] to get the list of edits required to
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/// draw the UI.
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///
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/// ```rust, ignore
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/// let mut vdom = VirtualDom::new(App);
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/// let edits = vdom.rebuild();
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/// ```
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///
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/// To inject UserEvents into the VirtualDom, call [`VirtualDom::get_scheduler_channel`] to get access to the scheduler.
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///
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/// ```rust, ignore
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/// let channel = vdom.get_scheduler_channel();
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/// channel.send_unbounded(SchedulerMsg::UserEvent(UserEvent {
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/// // ...
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/// }))
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/// ```
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///
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/// While waiting for UserEvents to occur, call [`VirtualDom::wait_for_work`] to poll any futures inside the VirtualDom.
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///
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/// ```rust, ignore
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/// vdom.wait_for_work().await;
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/// ```
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///
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/// Once work is ready, call [`VirtualDom::work_with_deadline`] to compute the differences between the previous and
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/// current UI trees. This will return a [`Mutations`] object that contains Edits, Effects, and NodeRefs that need to be
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/// handled by the renderer.
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///
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/// ```rust, ignore
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/// let mutations = vdom.work_with_deadline(|| false);
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/// for edit in mutations {
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/// apply(edit);
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/// }
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/// ```
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///
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/// ## Building an event loop around Dioxus:
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///
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/// Putting everything together, you can build an event loop around Dioxus by using the methods outlined above.
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///
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/// ```rust, ignore
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/// fn App(cx: Scope<()>) -> Element {
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/// cx.render(rsx!{
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/// div { "Hello World" }
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/// })
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/// }
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///
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/// async fn main() {
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/// let mut dom = VirtualDom::new(App);
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///
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/// let mut inital_edits = dom.rebuild();
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/// apply_edits(inital_edits);
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///
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/// loop {
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/// dom.wait_for_work().await;
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/// let frame_timeout = TimeoutFuture::new(Duration::from_millis(16));
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/// let deadline = || (&mut frame_timeout).now_or_never();
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/// let edits = dom.run_with_deadline(deadline).await;
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/// apply_edits(edits);
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/// }
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/// }
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/// ```
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pub struct VirtualDom {
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scopes: ScopeArena,
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pending_messages: VecDeque<SchedulerMsg>,
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dirty_scopes: IndexSet<ScopeId>,
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channel: (
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UnboundedSender<SchedulerMsg>,
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UnboundedReceiver<SchedulerMsg>,
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),
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}
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// Methods to create the VirtualDom
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impl VirtualDom {
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/// Create a new VirtualDom with a component that does not have special props.
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///
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/// # Description
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///
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/// Later, the props can be updated by calling "update" with a new set of props, causing a set of re-renders.
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///
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/// This is useful when a component tree can be driven by external state (IE SSR) but it would be too expensive
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/// to toss out the entire tree.
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///
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///
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/// # Example
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/// ```rust, ignore
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/// fn Example(cx: Scope<()>) -> Element {
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/// cx.render(rsx!( div { "hello world" } ))
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/// }
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///
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/// let dom = VirtualDom::new(Example);
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/// ```
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///
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/// Note: the VirtualDom is not progressed, you must either "run_with_deadline" or use "rebuild" to progress it.
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pub fn new(root: Component<()>) -> Self {
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Self::new_with_props(root, ())
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}
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/// Create a new VirtualDom with the given properties for the root component.
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///
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/// # Description
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///
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/// Later, the props can be updated by calling "update" with a new set of props, causing a set of re-renders.
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///
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/// This is useful when a component tree can be driven by external state (IE SSR) but it would be too expensive
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/// to toss out the entire tree.
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///
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///
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/// # Example
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/// ```rust, ignore
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/// #[derive(PartialEq, Props)]
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/// struct SomeProps {
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/// name: &'static str
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/// }
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///
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/// fn Example(cx: Scope<SomeProps>) -> Element {
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/// cx.render(rsx!{ div{ "hello {cx.props.name}" } })
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/// }
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///
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/// let dom = VirtualDom::new(Example);
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/// ```
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///
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/// Note: the VirtualDom is not progressed on creation. You must either "run_with_deadline" or use "rebuild" to progress it.
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///
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/// ```rust, ignore
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/// let mut dom = VirtualDom::new_with_props(Example, SomeProps { name: "jane" });
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/// let mutations = dom.rebuild();
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/// ```
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pub fn new_with_props<P>(root: Component<P>, root_props: P) -> Self
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where
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P: 'static,
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{
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Self::new_with_props_and_scheduler(
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root,
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root_props,
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futures_channel::mpsc::unbounded::<SchedulerMsg>(),
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)
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}
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/// Launch the VirtualDom, but provide your own channel for receiving and sending messages into the scheduler
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///
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/// This is useful when the VirtualDom must be driven from outside a thread and it doesn't make sense to wait for the
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/// VirtualDom to be created just to retrieve its channel receiver.
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///
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/// ```rust
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/// let channel = futures_channel::mpsc::unbounded();
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/// let dom = VirtualDom::new_with_scheduler(Example, (), channel);
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/// ```
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pub fn new_with_props_and_scheduler<P: 'static>(
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root: Component<P>,
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root_props: P,
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channel: (
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UnboundedSender<SchedulerMsg>,
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UnboundedReceiver<SchedulerMsg>,
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),
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) -> Self {
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let scopes = ScopeArena::new(channel.0.clone());
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scopes.new_with_key(
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root as *const _,
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Box::new(VComponentProps {
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props: root_props,
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memo: |_a, _b| unreachable!("memo on root will neve be run"),
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render_fn: root,
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}),
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None,
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ElementId(0),
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0,
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);
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Self {
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scopes,
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channel,
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dirty_scopes: IndexSet::from_iter([ScopeId(0)]),
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pending_messages: VecDeque::new(),
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}
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}
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/// Get the [`Scope`] for the root component.
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///
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/// This is useful for traversing the tree from the root for heuristics or alternsative renderers that use Dioxus
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/// directly.
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///
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/// This method is equivalent to calling `get_scope(ScopeId(0))`
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///
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/// # Example
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///
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/// ```rust
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/// let mut dom = VirtualDom::new(example);
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/// dom.rebuild();
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///
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///
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/// ```
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pub fn base_scope(&self) -> &ScopeState {
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self.get_scope(ScopeId(0)).unwrap()
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}
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/// Get the [`ScopeState`] for a component given its [`ScopeId`]
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///
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/// # Example
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///
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///
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///
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pub fn get_scope(&self, id: ScopeId) -> Option<&ScopeState> {
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self.scopes.get_scope(id)
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}
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/// Get an [`UnboundedSender`] handle to the channel used by the scheduler.
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///
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/// # Example
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///
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/// ```rust, ignore
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/// let dom = VirtualDom::new(App);
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/// let sender = dom.get_scheduler_channel();
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/// ```
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pub fn get_scheduler_channel(&self) -> UnboundedSender<SchedulerMsg> {
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self.channel.0.clone()
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}
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/// Add a new message to the scheduler queue directly.
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///
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///
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/// This method makes it possible to send messages to the scheduler from outside the VirtualDom without having to
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/// call `get_schedule_channel` and then `send`.
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///
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/// # Example
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/// ```rust, ignore
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/// let dom = VirtualDom::new(App);
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/// dom.handle_message(SchedulerMsg::Immediate(ScopeId(0)));
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/// ```
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pub fn handle_message(&mut self, msg: SchedulerMsg) {
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if self.channel.0.unbounded_send(msg).is_ok() {
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self.process_all_messages();
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}
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}
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/// Check if the [`VirtualDom`] has any pending updates or work to be done.
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///
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/// # Example
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///
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/// ```rust, ignore
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/// let dom = VirtualDom::new(App);
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///
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/// // the dom is "dirty" when it is started and must be rebuilt to get the first render
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/// assert!(dom.has_any_work());
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/// ```
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pub fn has_work(&self) -> bool {
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!(self.dirty_scopes.is_empty() && self.pending_messages.is_empty())
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}
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/// Wait for the scheduler to have any work.
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///
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/// This method polls the internal future queue *and* the scheduler channel.
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/// To add work to the VirtualDom, insert a message via the scheduler channel.
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///
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/// This lets us poll async tasks during idle periods without blocking the main thread.
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///
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/// # Example
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///
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/// ```rust, ignore
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/// let dom = VirtualDom::new(App);
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/// let sender = dom.get_scheduler_channel();
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/// ```
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pub async fn wait_for_work(&mut self) {
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loop {
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if !self.dirty_scopes.is_empty() && self.pending_messages.is_empty() {
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break;
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}
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if self.pending_messages.is_empty() {
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if self.scopes.pending_futures.borrow().is_empty() {
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self.pending_messages
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.push_front(self.channel.1.next().await.unwrap());
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} else {
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use futures_util::future::{select, Either};
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match select(PollTasks(&mut self.scopes), self.channel.1.next()).await {
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Either::Left((_, _)) => {}
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Either::Right((msg, _)) => self.pending_messages.push_front(msg.unwrap()),
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}
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}
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}
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// Move all the messages into the queue
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self.process_all_messages();
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}
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}
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/// Manually kick the VirtualDom to process any
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pub fn process_all_messages(&mut self) {
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// clear out the scheduler queue
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while let Ok(Some(msg)) = self.channel.1.try_next() {
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self.pending_messages.push_front(msg);
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}
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// process all the messages pulled from the queue
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while let Some(msg) = self.pending_messages.pop_back() {
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self.process_message(msg);
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}
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}
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pub fn process_message(&mut self, msg: SchedulerMsg) {
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match msg {
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// just keep looping, the task is now saved but we should actually poll it
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SchedulerMsg::NewTask(id) => {
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self.scopes.pending_futures.borrow_mut().insert(id);
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}
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SchedulerMsg::UiEvent(event) => {
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if let Some(element) = event.element {
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self.scopes.call_listener_with_bubbling(event, element);
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}
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}
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SchedulerMsg::Immediate(s) => {
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self.dirty_scopes.insert(s);
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}
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}
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}
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/// Run the virtualdom with a deadline.
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///
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/// This method will perform any outstanding diffing work and try to return as many mutations as possible before the
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/// deadline is reached. This method accepts a closure that returns `true` if the deadline has been reached. To wrap
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/// your future into a deadline, consider the `now_or_never` method from `future_utils`.
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///
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/// ```rust, ignore
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/// let mut vdom = VirtualDom::new(App);
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///
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/// let timeout = TimeoutFuture::from_ms(16);
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/// let deadline = || (&mut timeout).now_or_never();
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///
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/// let mutations = vdom.work_with_deadline(deadline);
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/// ```
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///
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/// This method is useful when needing to schedule the virtualdom around other tasks on the main thread to prevent
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/// "jank". It will try to finish whatever work it has by the deadline to free up time for other work.
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///
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/// If the work is not finished by the deadline, Dioxus will store it for later and return when work_with_deadline
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/// is called again. This means you can ensure some level of free time on the VirtualDom's thread during the work phase.
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///
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/// For use in the web, it is expected that this method will be called to be executed during "idle times" and the
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/// mutations to be applied during the "paint times" IE "animation frames". With this strategy, it is possible to craft
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/// entirely jank-free applications that perform a ton of work.
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///
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/// In general use, Dioxus is plenty fast enough to not need to worry about this.
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///
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/// # Example
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///
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/// ```rust, ignore
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/// fn App(cx: Scope<()>) -> Element {
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/// cx.render(rsx!( div {"hello"} ))
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/// }
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///
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/// let mut dom = VirtualDom::new(App);
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///
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/// loop {
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/// let mut timeout = TimeoutFuture::from_ms(16);
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/// let deadline = move || (&mut timeout).now_or_never();
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///
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/// let mutations = dom.run_with_deadline(deadline).await;
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///
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/// apply_mutations(mutations);
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/// }
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/// ```
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pub fn work_with_deadline(&mut self, mut deadline: impl FnMut() -> bool) -> Vec<Mutations> {
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let mut committed_mutations = vec![];
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while !self.dirty_scopes.is_empty() {
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let scopes = &self.scopes;
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let mut diff_state = DiffState::new(scopes);
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let mut ran_scopes = FxHashSet::default();
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// Sort the scopes by height. Theoretically, we'll de-duplicate scopes by height
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self.dirty_scopes
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.retain(|id| scopes.get_scope(*id).is_some());
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self.dirty_scopes.sort_by(|a, b| {
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let h1 = scopes.get_scope(*a).unwrap().height;
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let h2 = scopes.get_scope(*b).unwrap().height;
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h1.cmp(&h2).reverse()
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});
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if let Some(scopeid) = self.dirty_scopes.pop() {
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if !ran_scopes.contains(&scopeid) {
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ran_scopes.insert(scopeid);
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self.scopes.run_scope(scopeid);
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let (old, new) = (self.scopes.wip_head(scopeid), self.scopes.fin_head(scopeid));
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diff_state.stack.push(DiffInstruction::Diff { new, old });
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diff_state.stack.scope_stack.push(scopeid);
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let scope = scopes.get_scope(scopeid).unwrap();
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diff_state.stack.element_stack.push(scope.container);
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}
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}
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if diff_state.work(&mut deadline) {
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let DiffState { mutations, .. } = diff_state;
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for scope in &mutations.dirty_scopes {
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self.dirty_scopes.remove(scope);
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}
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committed_mutations.push(mutations);
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} else {
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// leave the work in an incomplete state
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//
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// todo: we should store the edits and re-apply them later
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// for now, we just dump the work completely (threadsafe)
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return committed_mutations;
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}
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}
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committed_mutations
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}
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/// Performs a *full* rebuild of the virtual dom, returning every edit required to generate the actual dom from scratch.
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///
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/// The diff machine expects the RealDom's stack to be the root of the application.
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///
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/// Tasks will not be polled with this method, nor will any events be processed from the event queue. Instead, the
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/// root component will be ran once and then diffed. All updates will flow out as mutations.
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///
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/// All state stored in components will be completely wiped away.
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///
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/// # Example
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/// ```rust, ignore
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/// static App: Component<()> = |cx, props| cx.render(rsx!{ "hello world" });
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/// let mut dom = VirtualDom::new();
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/// let edits = dom.rebuild();
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///
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/// apply_edits(edits);
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/// ```
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pub fn rebuild(&mut self) -> Mutations {
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let scope_id = ScopeId(0);
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let mut diff_state = DiffState::new(&self.scopes);
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self.scopes.run_scope(scope_id);
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diff_state
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.stack
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.create_node(self.scopes.fin_head(scope_id), MountType::Append);
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diff_state.stack.element_stack.push(ElementId(0));
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diff_state.stack.scope_stack.push(scope_id);
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diff_state.work(|| false);
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diff_state.mutations
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}
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/// Compute a manual diff of the VirtualDom between states.
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///
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/// This can be useful when state inside the DOM is remotely changed from the outside, but not propagated as an event.
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///
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/// In this case, every component will be diffed, even if their props are memoized. This method is intended to be used
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/// to force an update of the DOM when the state of the app is changed outside of the app.
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///
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/// To force a reflow of the entire VirtualDom, use `ScopeId(0)` as the scope_id.
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///
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/// # Example
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/// ```rust, ignore
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/// #[derive(PartialEq, Props)]
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/// struct AppProps {
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/// value: Shared<&'static str>,
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/// }
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///
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/// static App: Component<AppProps> = |cx, props|{
|
||
/// let val = cx.value.borrow();
|
||
/// cx.render(rsx! { div { "{val}" } })
|
||
/// };
|
||
///
|
||
/// let value = Rc::new(RefCell::new("Hello"));
|
||
/// let mut dom = VirtualDom::new_with_props(App, AppProps { value: value.clone(), });
|
||
///
|
||
/// let _ = dom.rebuild();
|
||
///
|
||
/// *value.borrow_mut() = "goodbye";
|
||
///
|
||
/// let edits = dom.diff();
|
||
/// ```
|
||
pub fn hard_diff(&mut self, scope_id: ScopeId) -> Mutations {
|
||
let mut diff_machine = DiffState::new(&self.scopes);
|
||
self.scopes.run_scope(scope_id);
|
||
|
||
let (old, new) = (
|
||
diff_machine.scopes.wip_head(scope_id),
|
||
diff_machine.scopes.fin_head(scope_id),
|
||
);
|
||
|
||
diff_machine.force_diff = true;
|
||
diff_machine.stack.push(DiffInstruction::Diff { old, new });
|
||
diff_machine.stack.scope_stack.push(scope_id);
|
||
|
||
let scope = diff_machine.scopes.get_scope(scope_id).unwrap();
|
||
diff_machine.stack.element_stack.push(scope.container);
|
||
diff_machine.work(|| false);
|
||
|
||
diff_machine.mutations
|
||
}
|
||
|
||
/// Renders an `rsx` call into the Base Scope's allocator.
|
||
///
|
||
/// Useful when needing to render nodes from outside the VirtualDom, such as in a test.
|
||
///
|
||
/// ```rust
|
||
/// fn Base(cx: Scope<()>) -> Element {
|
||
/// rsx!(cx, div {})
|
||
/// }
|
||
///
|
||
/// let dom = VirtualDom::new(Base);
|
||
/// let nodes = dom.render_nodes(rsx!("div"));
|
||
/// ```
|
||
pub fn render_vnodes<'a>(&'a self, lazy_nodes: Option<LazyNodes<'a, '_>>) -> &'a VNode<'a> {
|
||
let scope = self.scopes.get_scope(ScopeId(0)).unwrap();
|
||
let frame = scope.wip_frame();
|
||
let factory = NodeFactory { bump: &frame.bump };
|
||
let node = lazy_nodes.unwrap().call(factory);
|
||
frame.bump.alloc(node)
|
||
}
|
||
|
||
/// Renders an `rsx` call into the Base Scope's allocator.
|
||
///
|
||
/// Useful when needing to render nodes from outside the VirtualDom, such as in a test.
|
||
///
|
||
/// ```rust
|
||
/// fn Base(cx: Scope<()>) -> Element {
|
||
/// rsx!(cx, div {})
|
||
/// }
|
||
///
|
||
/// let dom = VirtualDom::new(Base);
|
||
/// let nodes = dom.render_nodes(rsx!("div"));
|
||
/// ```
|
||
pub fn diff_vnodes<'a>(&'a self, old: &'a VNode<'a>, new: &'a VNode<'a>) -> Mutations<'a> {
|
||
let mut machine = DiffState::new(&self.scopes);
|
||
machine.stack.push(DiffInstruction::Diff { new, old });
|
||
machine.stack.element_stack.push(ElementId(0));
|
||
machine.stack.scope_stack.push(ScopeId(0));
|
||
machine.work(|| false);
|
||
machine.mutations
|
||
}
|
||
|
||
/// Renders an `rsx` call into the Base Scope's allocator.
|
||
///
|
||
/// Useful when needing to render nodes from outside the VirtualDom, such as in a test.
|
||
///
|
||
///
|
||
/// ```rust
|
||
/// fn Base(cx: Scope<()>) -> Element {
|
||
/// rsx!(cx, div {})
|
||
/// }
|
||
///
|
||
/// let dom = VirtualDom::new(Base);
|
||
/// let nodes = dom.render_nodes(rsx!("div"));
|
||
/// ```
|
||
pub fn create_vnodes<'a>(&'a self, nodes: Option<LazyNodes<'a, '_>>) -> Mutations<'a> {
|
||
let mut machine = DiffState::new(&self.scopes);
|
||
machine.stack.element_stack.push(ElementId(0));
|
||
machine
|
||
.stack
|
||
.create_node(self.render_vnodes(nodes), MountType::Append);
|
||
machine.work(|| false);
|
||
machine.mutations
|
||
}
|
||
|
||
/// Renders an `rsx` call into the Base Scopes's arena.
|
||
///
|
||
/// Useful when needing to diff two rsx! calls from outside the VirtualDom, such as in a test.
|
||
///
|
||
///
|
||
/// ```rust
|
||
/// fn Base(cx: Scope<()>) -> Element {
|
||
/// rsx!(cx, div {})
|
||
/// }
|
||
///
|
||
/// let dom = VirtualDom::new(Base);
|
||
/// let nodes = dom.render_nodes(rsx!("div"));
|
||
/// ```
|
||
pub fn diff_lazynodes<'a>(
|
||
&'a self,
|
||
left: Option<LazyNodes<'a, '_>>,
|
||
right: Option<LazyNodes<'a, '_>>,
|
||
) -> (Mutations<'a>, Mutations<'a>) {
|
||
let (old, new) = (self.render_vnodes(left), self.render_vnodes(right));
|
||
|
||
let mut create = DiffState::new(&self.scopes);
|
||
create.stack.scope_stack.push(ScopeId(0));
|
||
create.stack.element_stack.push(ElementId(0));
|
||
create.stack.create_node(old, MountType::Append);
|
||
create.work(|| false);
|
||
|
||
let mut edit = DiffState::new(&self.scopes);
|
||
edit.stack.scope_stack.push(ScopeId(0));
|
||
edit.stack.element_stack.push(ElementId(0));
|
||
edit.stack.push(DiffInstruction::Diff { old, new });
|
||
edit.work(|| false);
|
||
|
||
(create.mutations, edit.mutations)
|
||
}
|
||
}
|
||
/*
|
||
Scopes and ScopeArenas are never dropped internally.
|
||
An app will always occupy as much memory as its biggest form.
|
||
|
||
This means we need to handle all specifics of drop *here*. It's easier
|
||
to reason about centralizing all the drop logic in one spot rather than scattered in each module.
|
||
|
||
Broadly speaking, we want to use the remove_nodes method to clean up *everything*
|
||
This will drop listeners, borrowed props, and hooks for all components.
|
||
We need to do this in the correct order - nodes at the very bottom must be dropped first to release
|
||
the borrow chain.
|
||
|
||
Once the contents of the tree have been cleaned up, we can finally clean up the
|
||
memory used by ScopeState itself.
|
||
|
||
questions:
|
||
should we build a vcomponent for the root?
|
||
- probably - yes?
|
||
- store the vcomponent in the root dom
|
||
|
||
- 1: Use remove_nodes to use the ensure_drop_safety pathway to safely drop the tree
|
||
- 2: Drop the ScopeState itself
|
||
|
||
|
||
|
||
*/
|
||
impl Drop for VirtualDom {
|
||
fn drop(&mut self) {
|
||
// the best way to drop the dom is to replace the root scope with a dud
|
||
// the diff infrastructure will then finish the rest
|
||
let scope = self.scopes.get_scope(ScopeId(0)).unwrap();
|
||
|
||
// todo: move the remove nodes method onto scopearena
|
||
// this will clear *all* scopes *except* the root scope
|
||
let mut machine = DiffState::new(&self.scopes);
|
||
machine.remove_nodes([scope.root_node()], false);
|
||
|
||
// Now, clean up the root scope
|
||
// safety: there are no more references to the root scope
|
||
let scope = unsafe { &mut *self.scopes.get_scope_raw(ScopeId(0)).unwrap() };
|
||
scope.reset();
|
||
|
||
// make sure there are no "live" components
|
||
for (_, scopeptr) in self.scopes.scopes.get_mut().drain() {
|
||
let scope = unsafe { bumpalo::boxed::Box::from_raw(scopeptr) };
|
||
drop(scope);
|
||
}
|
||
|
||
for scopeptr in self.scopes.free_scopes.get_mut().drain(..) {
|
||
let mut scope = unsafe { bumpalo::boxed::Box::from_raw(scopeptr) };
|
||
scope.reset();
|
||
drop(scope);
|
||
}
|
||
|
||
// Safety: all refereneces to this caller have been dropped
|
||
// the pointer is still valid since we haven't moved it since the virtualdom was created
|
||
// ensure the root component's caller is dropped
|
||
// drop(unsafe { Box::from_raw(self.caller) });
|
||
}
|
||
}
|
||
|
||
#[derive(Debug)]
|
||
pub enum SchedulerMsg {
|
||
// events from the host
|
||
UiEvent(UserEvent),
|
||
|
||
// setstate
|
||
Immediate(ScopeId),
|
||
|
||
// an async task pushed from an event handler (or just spawned)
|
||
NewTask(ScopeId),
|
||
}
|
||
|
||
/// User Events are events that are shuttled from the renderer into the VirtualDom trhough the scheduler channel.
|
||
///
|
||
/// These events will be passed to the appropriate Element given by `mounted_dom_id` and then bubbled up through the tree
|
||
/// where each listener is checked and fired if the event name matches.
|
||
///
|
||
/// It is the expectation that the event name matches the corresponding event listener, otherwise Dioxus will panic in
|
||
/// attempting to downcast the event data.
|
||
///
|
||
/// Because Event Data is sent across threads, it must be `Send + Sync`. We are hoping to lift the `Sync` restriction but
|
||
/// `Send` will not be lifted. The entire `UserEvent` must also be `Send + Sync` due to its use in the scheduler channel.
|
||
///
|
||
/// # Example
|
||
/// ```rust
|
||
/// fn App(cx: Scope<()>) -> Element {
|
||
/// rsx!(cx, div {
|
||
/// onclick: move |_| println!("Clicked!")
|
||
/// })
|
||
/// }
|
||
///
|
||
/// let mut dom = VirtualDom::new(App);
|
||
/// let mut scheduler = dom.get_scheduler_channel();
|
||
/// scheduler.unbounded_send(SchedulerMsg::UiEvent(
|
||
/// UserEvent {
|
||
/// scope_id: None,
|
||
/// priority: EventPriority::Medium,
|
||
/// name: "click",
|
||
/// element: Some(ElementId(0)),
|
||
/// data: Arc::new(ClickEvent { .. })
|
||
/// }
|
||
/// )).unwrap();
|
||
/// ```
|
||
#[derive(Debug)]
|
||
pub struct UserEvent {
|
||
/// The originator of the event trigger
|
||
pub scope_id: Option<ScopeId>,
|
||
|
||
pub priority: EventPriority,
|
||
|
||
/// The optional real node associated with the trigger
|
||
pub element: Option<ElementId>,
|
||
|
||
/// The event type IE "onclick" or "onmouseover"
|
||
///
|
||
/// The name that the renderer will use to mount the listener.
|
||
pub name: &'static str,
|
||
|
||
/// Event Data
|
||
pub data: Arc<dyn Any + Send + Sync>,
|
||
}
|
||
|
||
/// Priority of Event Triggers.
|
||
///
|
||
/// Internally, Dioxus will abort work that's taking too long if new, more important work arrives. Unlike React, Dioxus
|
||
/// won't be afraid to pause work or flush changes to the RealDOM. This is called "cooperative scheduling". Some Renderers
|
||
/// implement this form of scheduling internally, however Dioxus will perform its own scheduling as well.
|
||
///
|
||
/// The ultimate goal of the scheduler is to manage latency of changes, prioritizing "flashier" changes over "subtler" changes.
|
||
///
|
||
/// React has a 5-tier priority system. However, they break things into "Continuous" and "Discrete" priority. For now,
|
||
/// we keep it simple, and just use a 3-tier priority system.
|
||
///
|
||
/// - NoPriority = 0
|
||
/// - LowPriority = 1
|
||
/// - NormalPriority = 2
|
||
/// - UserBlocking = 3
|
||
/// - HighPriority = 4
|
||
/// - ImmediatePriority = 5
|
||
///
|
||
/// We still have a concept of discrete vs continuous though - discrete events won't be batched, but continuous events will.
|
||
/// This means that multiple "scroll" events will be processed in a single frame, but multiple "click" events will be
|
||
/// flushed before proceeding. Multiple discrete events is highly unlikely, though.
|
||
#[derive(Debug, PartialEq, Eq, Clone, Copy, Hash, PartialOrd, Ord)]
|
||
pub enum EventPriority {
|
||
/// Work that must be completed during the EventHandler phase.
|
||
///
|
||
/// Currently this is reserved for controlled inputs.
|
||
Immediate = 3,
|
||
|
||
/// "High Priority" work will not interrupt other high priority work, but will interrupt medium and low priority work.
|
||
///
|
||
/// This is typically reserved for things like user interaction.
|
||
///
|
||
/// React calls these "discrete" events, but with an extra category of "user-blocking" (Immediate).
|
||
High = 2,
|
||
|
||
/// "Medium priority" work is generated by page events not triggered by the user. These types of events are less important
|
||
/// than "High Priority" events and will take precedence over low priority events.
|
||
///
|
||
/// This is typically reserved for VirtualEvents that are not related to keyboard or mouse input.
|
||
///
|
||
/// React calls these "continuous" events (e.g. mouse move, mouse wheel, touch move, etc).
|
||
Medium = 1,
|
||
|
||
/// "Low Priority" work will always be preempted unless the work is significantly delayed, in which case it will be
|
||
/// advanced to the front of the work queue until completed.
|
||
///
|
||
/// The primary user of Low Priority work is the asynchronous work system (Suspense).
|
||
///
|
||
/// This is considered "idle" work or "background" work.
|
||
Low = 0,
|
||
}
|
||
|
||
struct PollTasks<'a>(&'a mut ScopeArena);
|
||
|
||
impl<'a> Future for PollTasks<'a> {
|
||
type Output = ();
|
||
|
||
fn poll(self: Pin<&mut Self>, cx: &mut std::task::Context<'_>) -> Poll<Self::Output> {
|
||
let mut all_pending = true;
|
||
|
||
let mut unfinished_tasks: SmallVec<[_; 10]> = smallvec::smallvec![];
|
||
let mut scopes_to_clear: SmallVec<[_; 10]> = smallvec::smallvec![];
|
||
|
||
// Poll every scope manually
|
||
for fut in self.0.pending_futures.borrow().iter().copied() {
|
||
let scope = self.0.get_scope(fut).expect("Scope should never be moved");
|
||
|
||
let mut items = scope.items.borrow_mut();
|
||
|
||
// really this should just be retain_mut but that doesn't exist yet
|
||
while let Some(mut task) = items.tasks.pop() {
|
||
if task.as_mut().poll(cx).is_ready() {
|
||
all_pending = false
|
||
} else {
|
||
unfinished_tasks.push(task);
|
||
}
|
||
}
|
||
|
||
if unfinished_tasks.is_empty() {
|
||
scopes_to_clear.push(fut);
|
||
}
|
||
|
||
items.tasks.extend(unfinished_tasks.drain(..));
|
||
}
|
||
|
||
for scope in scopes_to_clear {
|
||
self.0.pending_futures.borrow_mut().remove(&scope);
|
||
}
|
||
|
||
// Resolve the future if any singular task is ready
|
||
match all_pending {
|
||
true => Poll::Pending,
|
||
false => Poll::Ready(()),
|
||
}
|
||
}
|
||
}
|