use crate::common::*;
#[derive(Debug)]
pub struct TryScan<I, St, F> {
pub(super) iter: Option<I>,
pub(super) state: St,
pub(super) f: F,
}
impl<I, St, F, T, U, E> Iterator for TryScan<I, St, F>
where
I: Iterator<Item = Result<T, E>>,
F: FnMut(&mut St, T) -> Result<Option<U>, E>,
{
type Item = Result<U, E>;
fn next(&mut self) -> Option<Self::Item> {
let mut iter = match self.iter.take() {
Some(iter) => iter,
None => return None,
};
let input_item = match iter.next() {
Some(Ok(item)) => item,
Some(Err(err)) => {
return Some(Err(err));
}
None => {
return None;
}
};
let output_item = match (self.f)(&mut self.state, input_item) {
Ok(Some(item)) => item,
Ok(None) => return None,
Err(err) => return Some(Err(err)),
};
self.iter = Some(iter);
Some(Ok(output_item))
}
}