mod action;
pub mod platform_specific;
pub use action::Action;
use crate::core::widget;
use crate::futures::futures;
use crate::futures::MaybeSend;
use futures::channel::mpsc;
use futures::Stream;
use std::fmt;
use std::future::Future;
#[must_use = "`Command` must be returned to runtime to take effect"]
pub struct Command<T>(Internal<Action<T>>);
#[derive(Debug)]
enum Internal<T> {
None,
Single(T),
Batch(Vec<T>),
}
impl<T> Command<T> {
pub const fn none() -> Self {
Self(Internal::None)
}
pub const fn single(action: Action<T>) -> Self {
Self(Internal::Single(action))
}
pub fn widget(operation: impl widget::Operation<T> + 'static) -> Self {
Self::single(Action::Widget(Box::new(operation)))
}
pub fn perform<A>(
future: impl Future<Output = A> + 'static + MaybeSend,
f: impl FnOnce(A) -> T + 'static + MaybeSend,
) -> Command<T> {
use futures::FutureExt;
Command::single(Action::Future(Box::pin(future.map(f))))
}
pub fn run<A>(
stream: impl Stream<Item = A> + 'static + MaybeSend,
f: impl Fn(A) -> T + 'static + MaybeSend,
) -> Command<T> {
use futures::StreamExt;
Command::single(Action::Stream(Box::pin(stream.map(f))))
}
pub fn batch(commands: impl IntoIterator<Item = Command<T>>) -> Self {
let mut batch = Vec::new();
for Command(command) in commands {
match command {
Internal::None => {}
Internal::Single(command) => batch.push(command),
Internal::Batch(commands) => batch.extend(commands),
}
}
Self(Internal::Batch(batch))
}
pub fn map<A>(
self,
f: impl Fn(T) -> A + 'static + MaybeSend + Sync + Clone,
) -> Command<A>
where
T: 'static,
A: 'static,
{
match self.0 {
Internal::None => Command::none(),
Internal::Single(action) => Command::single(action.map(f)),
Internal::Batch(batch) => Command(Internal::Batch(
batch
.into_iter()
.map(|action| action.map(f.clone()))
.collect(),
)),
}
}
pub fn actions(self) -> Vec<Action<T>> {
let Command(command) = self;
match command {
Internal::None => Vec::new(),
Internal::Single(action) => vec![action],
Internal::Batch(batch) => batch,
}
}
}
impl<T> fmt::Debug for Command<T> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
let Command(command) = self;
command.fmt(f)
}
}
pub fn channel<Fut, Message>(
size: usize,
f: impl FnOnce(mpsc::Sender<Message>) -> Fut + MaybeSend + 'static,
) -> Command<Message>
where
Fut: Future<Output = ()> + MaybeSend + 'static,
Message: 'static + MaybeSend,
{
use futures::future;
use futures::stream::{self, StreamExt};
let (sender, receiver) = mpsc::channel(size);
let runner = stream::once(f(sender)).filter_map(|_| future::ready(None));
Command::single(Action::Stream(Box::pin(stream::select(receiver, runner))))
}