bloom_core/
render_stream.rs

1use std::{
2    any::{Any, TypeId},
3    collections::HashMap,
4    pin::Pin,
5    sync::Arc,
6    task::Poll,
7};
8
9use async_context::provide_async_context;
10use futures_util::{
11    future::{self},
12    stream::{once, FuturesOrdered},
13    task::Spawn,
14    Future, Stream, StreamExt,
15};
16
17use crate::{hook::Hook, Element};
18
19use pin_project::pin_project;
20
21type NodeStreamItem<N, E> = Result<(N, NodeStream<N, E>), E>;
22
23#[pin_project]
24pub struct NodeStream<N, E>(#[pin] Pin<Box<dyn Stream<Item = NodeStreamItem<N, E>> + Send>>);
25
26impl<N, E> Stream for NodeStream<N, E> {
27    type Item = NodeStreamItem<N, E>;
28
29    fn poll_next(
30        self: Pin<&mut Self>,
31        cx: &mut std::task::Context<'_>,
32    ) -> Poll<Option<Self::Item>> {
33        let projection = self.project();
34        projection.0.poll_next(cx)
35    }
36}
37
38impl<N, E> NodeStream<N, E>
39where
40    E: Send + 'static,
41    N: Send + 'static,
42{
43    fn from(stream: impl Stream<Item = NodeStreamItem<N, E>> + Send + 'static) -> Self {
44        Self(Box::pin(stream))
45    }
46
47    fn ready(item: NodeStreamItem<N, E>) -> Self {
48        Self::from(once(future::ready(item)))
49    }
50
51    fn wrap(inner: impl Future<Output = NodeStream<N, E>> + Send + 'static) -> Self {
52        Self(Box::pin(once(inner).flatten()))
53    }
54}
55
56#[derive(Clone)]
57struct RenderContext {
58    context: Arc<HashMap<TypeId, Arc<dyn Any + Send + Sync>>>,
59}
60
61impl RenderContext {
62    fn new() -> Self {
63        Self {
64            context: Arc::new(HashMap::new()),
65        }
66    }
67
68    fn with_context(&self, value: Arc<dyn Any + Send + Sync>) -> Self {
69        let mut new_context = self.context.as_ref().clone();
70        new_context.insert(value.type_id(), value);
71        Self {
72            context: Arc::new(new_context),
73        }
74    }
75}
76
77fn render_element<N, E, S>(
78    element: Element<N, E>,
79    spawner: S,
80    ctx: RenderContext,
81) -> Pin<Box<dyn Future<Output = NodeStream<N, E>> + Send>>
82where
83    N: From<String> + Send + 'static,
84    E: Send + 'static,
85    S: Spawn + Clone + Send + 'static,
86{
87    match element {
88        Element::Component(component) => Box::pin(async move {
89            match provide_async_context(Hook::from_context(ctx.context.clone()), component.render())
90                .await
91            {
92                (Ok(element), _) => render_element(element, spawner, ctx).await,
93                (Err(error), _) => NodeStream::ready(Err(error)),
94            }
95        }),
96        Element::Node(node, children) => Box::pin(future::ready(NodeStream::ready(Ok((
97            node,
98            render_children(children, spawner, ctx),
99        ))))),
100        Element::Fragment(children) => {
101            Box::pin(future::ready(render_children(children, spawner, ctx)))
102        }
103        Element::Provider(provider, children) => Box::pin(future::ready(render_children(
104            children,
105            spawner,
106            ctx.with_context(provider),
107        ))),
108    }
109}
110
111fn render_children<N, E, S>(
112    children: Vec<Element<N, E>>,
113    spawner: S,
114    ctx: RenderContext,
115) -> NodeStream<N, E>
116where
117    N: From<String> + Send + 'static,
118    E: Send + 'static,
119    S: Spawn + Clone + Send + 'static,
120{
121    let children = children
122        .into_iter()
123        .map(|child| render_element(child, spawner.clone(), ctx.clone()))
124        .collect::<FuturesOrdered<_>>()
125        .flatten();
126
127    NodeStream::from(children)
128}
129
130/// render_stream is the main way to render some bloom-based UI once.
131/// It takes an element and a spawner and returns a stream of nodes.
132/// Libraries like bloom-server use this to render the UI to
133/// a stream of serialized HTML to implement server-side rendering.
134pub fn render_stream<N, E, S>(element: Element<N, E>, spawner: S) -> NodeStream<N, E>
135where
136    N: From<String> + Send + Sync + 'static,
137    E: Send + 'static,
138    S: Spawn + Clone + Send + 'static,
139{
140    NodeStream::wrap(render_element(
141        element,
142        spawner.clone(),
143        RenderContext::new(),
144    ))
145}
bloom_core/render_stream.rs

bloom_core/
render_stream.rs
