#[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
#[derive(Debug)]
pub struct ProcessResults<'a, I, E: 'a> {
error: &'a mut Result<(), E>,
iter: I,
}
impl<'a, I, T, E> Iterator for ProcessResults<'a, I, E>
where I: Iterator<Item = Result<T, E>>
{
type Item = T;
fn next(&mut self) -> Option<Self::Item> {
match self.iter.next() {
Some(Ok(x)) => Some(x),
Some(Err(e)) => {
*self.error = Err(e);
None
}
None => None,
}
}
fn size_hint(&self) -> (usize, Option<usize>) {
let (_, hi) = self.iter.size_hint();
(0, hi)
}
}
pub fn process_results<I, F, T, E, R>(iterable: I, processor: F) -> Result<R, E>
where I: IntoIterator<Item = Result<T, E>>,
F: FnOnce(ProcessResults<I::IntoIter, E>) -> R
{
let iter = iterable.into_iter();
let mut error = Ok(());
let result = processor(ProcessResults { error: &mut error, iter: iter });
error.map(|_| result)
}