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use std::fmt::Display;
use log::error;
pub trait Listener<M>: Send {
fn notify(&self, msg: M) -> Result<(), NotifyError>;
}
pub enum NotifyError {
Unsubscribe,
Full,
Other(Box<dyn Display>),
}
pub struct Listeners<M> {
pub(crate) listeners: Vec<Box<dyn Listener<M>>>,
}
impl<M: Clone> Listeners<M> {
pub fn add_with_initial_msg(&mut self, listener: Box<dyn Listener<M>>, initial: Option<M>) {
if let Some(initial) = initial {
if listener.notify(initial).is_ok() {
self.add(listener);
}
} else {
self.add(listener);
}
}
pub fn add(&mut self, listener: Box<dyn Listener<M>>) {
self.listeners.push(listener);
}
pub fn emit(&mut self, msg: M) {
self.listeners
.retain(|listener| match listener.notify(msg.clone()) {
Ok(()) => true,
Err(NotifyError::Full) => true,
Err(NotifyError::Unsubscribe) => false,
Err(NotifyError::Other(err)) => {
error!("Error in listener {}", err);
true
}
});
}
}
impl<M> Default for Listeners<M> {
fn default() -> Self {
Self {
listeners: Vec::new(),
}
}
}
impl <M: 'static + Send> Listener<M> for futures::channel::mpsc::UnboundedSender<M> {
fn notify(&self, msg: M) -> Result<(), NotifyError> {
self.unbounded_send(msg).map_err(|err| if err.is_full() {
NotifyError::Full
} else if err.is_disconnected() {
NotifyError::Unsubscribe
} else {
unreachable!()
})
}
}
