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|
//! Generate events asynchronously for you application.
/// An event subscription.
pub struct Subscription<Hasher, Input, Output> {
recipes: Vec<Box<dyn Recipe<Hasher, Input, Output = Output>>>,
}
impl<H, I, O> Subscription<H, I, O>
where
H: std::hash::Hasher,
{
pub fn none() -> Self {
Self {
recipes: Vec::new(),
}
}
pub fn from_recipe(
recipe: impl Recipe<H, I, Output = O> + 'static,
) -> Self {
Self {
recipes: vec![Box::new(recipe)],
}
}
pub fn batch(
subscriptions: impl Iterator<Item = Subscription<H, I, O>>,
) -> Self {
Self {
recipes: subscriptions
.flat_map(|subscription| subscription.recipes)
.collect(),
}
}
pub fn recipes(self) -> Vec<Box<dyn Recipe<H, I, Output = O>>> {
self.recipes
}
pub fn map<A>(
mut self,
f: impl Fn(O) -> A + Send + Sync + 'static,
) -> Subscription<H, I, A>
where
H: 'static,
I: 'static,
O: 'static,
A: 'static,
{
let function = std::sync::Arc::new(f);
Subscription {
recipes: self
.recipes
.drain(..)
.map(|recipe| {
Box::new(Map::new(recipe, function.clone()))
as Box<dyn Recipe<H, I, Output = A>>
})
.collect(),
}
}
}
impl<I, O, H> std::fmt::Debug for Subscription<I, O, H> {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
f.debug_struct("Subscription").finish()
}
}
/// The connection of an event subscription.
pub trait Recipe<Hasher: std::hash::Hasher, Input> {
type Output;
fn hash(&self, state: &mut Hasher);
fn stream(
&self,
input: Input,
) -> futures::stream::BoxStream<'static, Self::Output>;
}
struct Map<Hasher, Input, A, B> {
recipe: Box<dyn Recipe<Hasher, Input, Output = A>>,
mapper: std::sync::Arc<dyn Fn(A) -> B + Send + Sync>,
}
impl<H, I, A, B> Map<H, I, A, B> {
fn new(
recipe: Box<dyn Recipe<H, I, Output = A>>,
mapper: std::sync::Arc<dyn Fn(A) -> B + Send + Sync + 'static>,
) -> Self {
Map { recipe, mapper }
}
}
impl<H, I, A, B> Recipe<H, I> for Map<H, I, A, B>
where
A: 'static,
B: 'static,
H: std::hash::Hasher,
{
type Output = B;
fn hash(&self, state: &mut H) {
use std::hash::Hash;
std::any::TypeId::of::<B>().hash(state);
self.recipe.hash(state);
}
fn stream(
&self,
input: I,
) -> futures::stream::BoxStream<'static, Self::Output> {
use futures::StreamExt;
let mapper = self.mapper.clone();
self.recipe
.stream(input)
.map(move |element| mapper(element))
.boxed()
}
}
|
