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use crate::binary::struct_trait::{recv::Recv, session::Session};
use crossbeam_channel::Select;
use std::boxed::Box;
use std::error::Error;
use std::fmt;
use std::marker;
#[derive(Debug)]
enum SelectError {
EmptyVec,
}
impl fmt::Display for SelectError {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
match *self {
SelectError::EmptyVec => {
write!(f, "please use a vector with at least one element")
}
}
}
}
impl Error for SelectError {
fn description(&self) -> &str {
match *self {
SelectError::EmptyVec => "empty vectors not allowed",
}
}
fn cause(&self) -> Option<&dyn Error> {
match *self {
SelectError::EmptyVec => None,
}
}
}
pub fn select_mut<T, S>(rs: &mut Vec<Recv<T, S>>) -> Result<(T, S), Box<dyn Error>>
where
T: marker::Send,
S: Session,
{
if rs.is_empty() {
Err(Box::new(SelectError::EmptyVec))
} else {
let (index, res) = {
let mut sel = Select::new();
let iter = rs.iter();
for r in iter {
sel.recv(&r.channel);
}
loop {
let index = sel.ready();
let res = rs[index].channel.try_recv();
if let Err(e) = res {
if e.is_empty() {
continue;
}
}
break (index, res);
}
};
let _ = rs.swap_remove(index);
match res {
Ok(res) => Ok(res),
Err(e) => Err(Box::new(e)),
}
}
}
type SelectType<T, S> = Result<(T, S), Box<dyn Error>>;
pub fn select<T, S>(rs: Vec<Recv<T, S>>) -> (SelectType<T, S>, Vec<Recv<T, S>>)
where
T: marker::Send,
S: Session,
{
let mut rs = rs;
let res = select_mut(&mut rs);
(res, rs)
}