dioxus/packages/core/src/scope.rs
Jonathan Kelley 8814977eee wip: docs
2021-11-30 22:48:05 -05:00

483 lines
15 KiB
Rust

use crate::innerlude::*;
use futures_channel::mpsc::UnboundedSender;
use smallvec::SmallVec;
use std::{
any::{Any, TypeId},
cell::{Cell, RefCell},
collections::HashMap,
future::Future,
rc::Rc,
};
use bumpalo::{boxed::Box as BumpBox, Bump};
/// Components in Dioxus use the "Context" object to interact with their lifecycle.
///
/// This lets components access props, schedule updates, integrate hooks, and expose shared state.
///
/// For the most part, the only method you should be using regularly is `render`.
///
/// ## Example
///
/// ```ignore
/// #[derive(Props)]
/// struct ExampleProps {
/// name: String
/// }
///
/// fn Example(cx: Context, props: &ExampleProps) -> Element {
/// cx.render(rsx!{ div {"Hello, {props.name}"} })
/// }
/// ```
pub type Context<'a> = &'a Scope;
/// Every component in Dioxus is represented by a `Scope`.
///
/// Scopes contain the state for hooks, the component's props, and other lifecycle information.
///
/// Scopes are allocated in a generational arena. As components are mounted/unmounted, they will replace slots of dead components.
/// The actual contents of the hooks, though, will be allocated with the standard allocator. These should not allocate as frequently.
///
/// We expose the `Scope` type so downstream users can traverse the Dioxus VirtualDOM for whatever
/// use case they might have.
pub struct Scope {
pub(crate) parent_scope: Option<*mut Scope>,
// parent element I think?
pub(crate) container: ElementId,
pub(crate) our_arena_idx: ScopeId,
pub(crate) height: u32,
pub(crate) subtree: Cell<u32>,
pub(crate) is_subtree_root: Cell<bool>,
pub(crate) generation: Cell<u32>,
pub(crate) frames: [BumpFrame; 2],
pub(crate) caller: *const dyn Fn(&Scope) -> Element,
pub(crate) items: RefCell<SelfReferentialItems<'static>>,
pub(crate) hook_arena: Bump,
pub(crate) hook_vals: RefCell<SmallVec<[*mut dyn Any; 5]>>,
pub(crate) hook_idx: Cell<usize>,
pub(crate) shared_contexts: RefCell<HashMap<TypeId, Rc<dyn Any>>>,
pub(crate) sender: UnboundedSender<SchedulerMsg>,
}
pub struct SelfReferentialItems<'a> {
pub(crate) listeners: Vec<&'a Listener<'a>>,
pub(crate) borrowed_props: Vec<&'a VComponent<'a>>,
pub(crate) tasks: Vec<BumpBox<'a, dyn Future<Output = ()>>>,
}
/// A component's unique identifier.
///
/// `ScopeId` is a `usize` that is unique across the entire VirtualDOM and across time. ScopeIDs will never be reused
/// once a component has been unmounted.
#[cfg_attr(feature = "serialize", derive(serde::Serialize, serde::Deserialize))]
#[derive(Copy, Clone, PartialEq, Eq, Hash, Debug)]
pub struct ScopeId(pub usize);
// Public methods exposed to libraries and components
impl Scope {
/// Get the subtree ID that this scope belongs to.
///
/// Each component has its own subtree ID - the root subtree has an ID of 0. This ID is used by the renderer to route
/// the mutations to the correct window/portal/subtree.
///
///
/// # Example
///
/// ```rust, ignore
/// let mut dom = VirtualDom::new(|cx, props|cx.render(rsx!{ div {} }));
/// dom.rebuild();
///
/// let base = dom.base_scope();
///
/// assert_eq!(base.subtree(), 0);
/// ```
///
/// todo: enable
pub(crate) fn _subtree(&self) -> u32 {
self.subtree.get()
}
/// Create a new subtree with this scope as the root of the subtree.
///
/// Each component has its own subtree ID - the root subtree has an ID of 0. This ID is used by the renderer to route
/// the mutations to the correct window/portal/subtree.
///
/// This method
///
/// # Example
///
/// ```rust, ignore
/// fn App(cx: Context, props: &()) -> Element {
/// todo!();
/// rsx!(cx, div { "Subtree {id}"})
/// };
/// ```
///
/// todo: enable subtree
pub(crate) fn _create_subtree(&self) -> Option<u32> {
if self.is_subtree_root.get() {
None
} else {
todo!()
}
}
/// Get the height of this Scope - IE the number of scopes above it.
///
/// A Scope with a height of `0` is the root scope - there are no other scopes above it.
///
/// # Example
///
/// ```rust, ignore
/// let mut dom = VirtualDom::new(|cx, props| cx.render(rsx!{ div {} }));
/// dom.rebuild();
///
/// let base = dom.base_scope();
///
/// assert_eq!(base.height(), 0);
/// ```
pub fn height(&self) -> u32 {
self.height
}
/// Get the Parent of this Scope within this Dioxus VirtualDOM.
///
/// This ID is not unique across Dioxus VirtualDOMs or across time. IDs will be reused when components are unmounted.
///
/// The base component will not have a parent, and will return `None`.
///
/// # Example
///
/// ```rust, ignore
/// let mut dom = VirtualDom::new(|cx, props| cx.render(rsx!{ div {} }));
/// dom.rebuild();
///
/// let base = dom.base_scope();
///
/// assert_eq!(base.parent(), None);
/// ```
pub fn parent(&self) -> Option<ScopeId> {
// safety: the pointer to our parent is *always* valid thanks to the bump arena
self.parent_scope.map(|p| unsafe { &*p }.our_arena_idx)
}
/// Get the ID of this Scope within this Dioxus VirtualDOM.
///
/// This ID is not unique across Dioxus VirtualDOMs or across time. IDs will be reused when components are unmounted.
///
/// # Example
///
/// ```rust, ignore
/// let mut dom = VirtualDom::new(|cx, props| cx.render(rsx!{ div {} }));
/// dom.rebuild();
/// let base = dom.base_scope();
///
/// assert_eq!(base.scope_id(), 0);
/// ```
pub fn scope_id(&self) -> ScopeId {
self.our_arena_idx
}
/// Create a subscription that schedules a future render for the reference component
///
/// ## Notice: you should prefer using prepare_update and get_scope_id
pub fn schedule_update(&self) -> Rc<dyn Fn() + 'static> {
let (chan, id) = (self.sender.clone(), self.scope_id());
Rc::new(move || {
let _ = chan.unbounded_send(SchedulerMsg::Immediate(id));
})
}
/// Schedule an update for any component given its ScopeId.
///
/// A component's ScopeId can be obtained from `use_hook` or the [`Context::scope_id`] method.
///
/// This method should be used when you want to schedule an update for a component
pub fn schedule_update_any(&self) -> Rc<dyn Fn(ScopeId)> {
let chan = self.sender.clone();
Rc::new(move |id| {
let _ = chan.unbounded_send(SchedulerMsg::Immediate(id));
})
}
/// Get the [`ScopeId`] of a mounted component.
///
/// `ScopeId` is not unique for the lifetime of the VirtualDom - a ScopeId will be reused if a component is unmounted.
pub fn needs_update(&self) {
self.needs_update_any(self.scope_id())
}
/// Get the [`ScopeId`] of a mounted component.
///
/// `ScopeId` is not unique for the lifetime of the VirtualDom - a ScopeId will be reused if a component is unmounted.
pub fn needs_update_any(&self, id: ScopeId) {
let _ = self.sender.unbounded_send(SchedulerMsg::Immediate(id));
}
/// Get the [`ScopeId`] of a mounted component.
///
/// `ScopeId` is not unique for the lifetime of the VirtualDom - a ScopeId will be reused if a component is unmounted.
pub fn bump(&self) -> &Bump {
&self.wip_frame().bump
}
/// This method enables the ability to expose state to children further down the VirtualDOM Tree.
///
/// This is a "fundamental" operation and should only be called during initialization of a hook.
///
/// For a hook that provides the same functionality, use `use_provide_state` and `use_consume_state` instead.
///
/// When the component is dropped, so is the context. Be aware of this behavior when consuming
/// the context via Rc/Weak.
///
/// # Example
///
/// ```rust, ignore
/// struct SharedState(&'static str);
///
/// static App: FC<()> = |cx, props|{
/// cx.use_hook(|_| cx.provide_state(SharedState("world")), |_| {}, |_| {});
/// rsx!(cx, Child {})
/// }
///
/// static Child: FC<()> = |cx, props| {
/// let state = cx.consume_state::<SharedState>();
/// rsx!(cx, div { "hello {state.0}" })
/// }
/// ```
pub fn provide_state<T: 'static>(&self, value: T) {
self.shared_contexts
.borrow_mut()
.insert(TypeId::of::<T>(), Rc::new(value))
.map(|f| f.downcast::<T>().ok())
.flatten();
}
/// Try to retrieve a SharedState with type T from the any parent Scope.
pub fn consume_state<T: 'static>(&self) -> Option<Rc<T>> {
if let Some(shared) = self.shared_contexts.borrow().get(&TypeId::of::<T>()) {
Some(shared.clone().downcast::<T>().unwrap())
} else {
let mut search_parent = self.parent_scope;
while let Some(parent_ptr) = search_parent {
let parent = unsafe { &*parent_ptr };
if let Some(shared) = parent.shared_contexts.borrow().get(&TypeId::of::<T>()) {
return Some(shared.clone().downcast::<T>().unwrap());
}
search_parent = parent.parent_scope;
}
None
}
}
/// Pushes the future onto the poll queue to be polled after the component renders.
///
///
///
///
/// The future is forcibly dropped if the component is not ready by the next render
pub fn push_task<'src, F: Future<Output = ()>>(
&'src self,
fut: impl FnOnce() -> F + 'src,
) -> usize
where
F::Output: 'src,
F: 'src,
{
self.sender
.unbounded_send(SchedulerMsg::NewTask(self.our_arena_idx))
.unwrap();
// allocate the future
let fut = fut();
let fut: &mut dyn Future<Output = ()> = self.bump().alloc(fut);
// wrap it in a type that will actually drop the contents
let boxed_fut: BumpBox<dyn Future<Output = ()>> = unsafe { BumpBox::from_raw(fut) };
// erase the 'src lifetime for self-referential storage
let self_ref_fut = unsafe { std::mem::transmute(boxed_fut) };
let mut items = self.items.borrow_mut();
items.tasks.push(self_ref_fut);
items.tasks.len() - 1
}
/// Take a lazy VNode structure and actually build it with the context of the VDom's efficient VNode allocator.
///
/// This function consumes the context and absorb the lifetime, so these VNodes *must* be returned.
///
/// ## Example
///
/// ```ignore
/// fn Component(cx: Scope, props: &Props) -> Element {
/// // Lazy assemble the VNode tree
/// let lazy_nodes = rsx!("hello world");
///
/// // Actually build the tree and allocate it
/// cx.render(lazy_tree)
/// }
///```
pub fn render<'src>(&'src self, rsx: Option<LazyNodes<'src, '_>>) -> Option<VPortal> {
let frame = self.wip_frame();
let bump = &frame.bump;
let factory = NodeFactory { bump };
let node = rsx.map(|f| f.call(factory))?;
let node = bump.alloc(node);
let node_ptr = node as *mut _;
let node_ptr = unsafe { std::mem::transmute(node_ptr) };
let link = VPortal {
scope_id: Cell::new(Some(self.our_arena_idx)),
link_idx: Cell::new(0),
node: node_ptr,
};
Some(link)
}
/// Store a value between renders
///
/// This is *the* foundational hook for all other hooks.
///
/// - Initializer: closure used to create the initial hook state
/// - Runner: closure used to output a value every time the hook is used
///
/// To "cleanup" the hook, implement `Drop` on the stored hook value. Whenever the component is dropped, the hook
/// will be dropped as well.
///
/// # Example
///
/// ```ignore
/// // use_ref is the simplest way of storing a value between renders
/// fn use_ref<T: 'static>(initial_value: impl FnOnce() -> T) -> &RefCell<T> {
/// use_hook(
/// || Rc::new(RefCell::new(initial_value())),
/// |state| state,
/// )
/// }
/// ```
pub fn use_hook<'src, State: 'static, Output: 'src>(
&'src self,
initializer: impl FnOnce(usize) -> State,
runner: impl FnOnce(&'src mut State) -> Output,
) -> Output {
let mut vals = self.hook_vals.borrow_mut();
let hook_len = vals.len();
let cur_idx = self.hook_idx.get();
if cur_idx >= hook_len {
let val = self.hook_arena.alloc(initializer(hook_len));
vals.push(val);
}
let state = vals
.get(cur_idx)
.and_then(|inn| {
self.hook_idx.set(cur_idx + 1);
let raw_box = unsafe { &mut **inn };
raw_box.downcast_mut::<State>()
})
.expect(
r###"
Unable to retrieve the hook that was initialized at this index.
Consult the `rules of hooks` to understand how to use hooks properly.
You likely used the hook in a conditional. Hooks rely on consistent ordering between renders.
Functions prefixed with "use" should never be called conditionally.
"###,
);
runner(state)
}
/// The "work in progress frame" represents the frame that is currently being worked on.
pub(crate) fn wip_frame(&self) -> &BumpFrame {
match self.generation.get() & 1 == 0 {
true => &self.frames[0],
false => &self.frames[1],
}
}
pub(crate) fn wip_frame_mut(&mut self) -> &mut BumpFrame {
match self.generation.get() & 1 == 0 {
true => &mut self.frames[0],
false => &mut self.frames[1],
}
}
pub(crate) fn fin_frame(&self) -> &BumpFrame {
match self.generation.get() & 1 == 1 {
true => &self.frames[0],
false => &self.frames[1],
}
}
/// Reset this component's frame
///
/// # Safety:
/// This method breaks every reference of VNodes in the current frame.
pub(crate) unsafe fn reset_wip_frame(&mut self) {
// todo: unsafecell or something
let bump = self.wip_frame_mut();
bump.bump.reset();
}
pub(crate) fn cycle_frame(&self) {
self.generation.set(self.generation.get() + 1);
}
pub fn root_node(&self) -> &VNode {
let node = *self.wip_frame().nodes.borrow().get(0).unwrap();
unsafe { std::mem::transmute(&*node) }
}
}
pub(crate) struct BumpFrame {
pub bump: Bump,
pub nodes: RefCell<Vec<*const VNode<'static>>>,
}
impl BumpFrame {
pub fn new(capacity: usize) -> Self {
let bump = Bump::with_capacity(capacity);
let node = &*bump.alloc(VText {
text: "asd",
dom_id: Default::default(),
is_static: false,
});
let node = bump.alloc(VNode::Text(unsafe { std::mem::transmute(node) }));
let nodes = RefCell::new(vec![node as *const _]);
Self { bump, nodes }
}
pub fn assign_nodelink(&self, node: &VPortal) {
let mut nodes = self.nodes.borrow_mut();
let len = nodes.len();
nodes.push(node.node);
node.link_idx.set(len);
}
}
#[test]
fn sizeof() {
dbg!(std::mem::size_of::<Scope>());
}