1 #[cfg(doc)]
2 use crate::Itertools;
3
4 /// An iterator that produces only the `T` values as long as the
5 /// inner iterator produces `Ok(T)`.
6 ///
7 /// Used by [`process_results`](crate::process_results), see its docs
8 /// for more information.
9 #[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
10 #[derive(Debug)]
11 pub struct ProcessResults<'a, I, E: 'a> {
12 error: &'a mut Result<(), E>,
13 iter: I,
14 }
15
16 impl<'a, I, T, E> Iterator for ProcessResults<'a, I, E>
17 where I: Iterator<Item = Result<T, E>>
18 {
19 type Item = T;
20
next(&mut self) -> Option<Self::Item>21 fn next(&mut self) -> Option<Self::Item> {
22 match self.iter.next() {
23 Some(Ok(x)) => Some(x),
24 Some(Err(e)) => {
25 *self.error = Err(e);
26 None
27 }
28 None => None,
29 }
30 }
31
size_hint(&self) -> (usize, Option<usize>)32 fn size_hint(&self) -> (usize, Option<usize>) {
33 (0, self.iter.size_hint().1)
34 }
35
fold<B, F>(mut self, init: B, mut f: F) -> B where Self: Sized, F: FnMut(B, Self::Item) -> B,36 fn fold<B, F>(mut self, init: B, mut f: F) -> B
37 where
38 Self: Sized,
39 F: FnMut(B, Self::Item) -> B,
40 {
41 let error = self.error;
42 self.iter
43 .try_fold(init, |acc, opt| match opt {
44 Ok(x) => Ok(f(acc, x)),
45 Err(e) => {
46 *error = Err(e);
47 Err(acc)
48 }
49 })
50 .unwrap_or_else(|e| e)
51 }
52 }
53
54 /// “Lift” a function of the values of an iterator so that it can process
55 /// an iterator of `Result` values instead.
56 ///
57 /// [`IntoIterator`] enabled version of [`Itertools::process_results`].
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>) -> R58 pub fn process_results<I, F, T, E, R>(iterable: I, processor: F) -> Result<R, E>
59 where I: IntoIterator<Item = Result<T, E>>,
60 F: FnOnce(ProcessResults<I::IntoIter, E>) -> R
61 {
62 let iter = iterable.into_iter();
63 let mut error = Ok(());
64
65 let result = processor(ProcessResults { error: &mut error, iter });
66
67 error.map(|_| result)
68 }
69