1use super::size_hint;
2
3/// An iterator which iterates two other iterators simultaneously
4/// and panic if they have different lengths.
5///
6/// See [`.zip_eq()`](crate::Itertools::zip_eq) for more information.
7#[derive(Clone, Debug)]
8#[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
9pub struct ZipEq<I, J> {
10 a: I,
11 b: J,
12}
13
14/// Zips two iterators but **panics** if they are not of the same length.
15///
16/// [`IntoIterator`] enabled version of [`Itertools::zip_eq`](crate::Itertools::zip_eq).
17///
18/// ```
19/// use itertools::zip_eq;
20///
21/// let data = [1, 2, 3, 4, 5];
22/// for (a, b) in zip_eq(&data[..data.len() - 1], &data[1..]) {
23/// /* loop body */
24/// }
25/// ```
26pub fn zip_eq<I, J>(i: I, j: J) -> ZipEq<I::IntoIter, J::IntoIter>
27where
28 I: IntoIterator,
29 J: IntoIterator,
30{
31 ZipEq {
32 a: i.into_iter(),
33 b: j.into_iter(),
34 }
35}
36
37impl<I, J> Iterator for ZipEq<I, J>
38where
39 I: Iterator,
40 J: Iterator,
41{
42 type Item = (I::Item, J::Item);
43
44 fn next(&mut self) -> Option<Self::Item> {
45 match (self.a.next(), self.b.next()) {
46 (None, None) => None,
47 (Some(a: ::Item), Some(b: ::Item)) => Some((a, b)),
48 (None, Some(_)) | (Some(_), None) => {
49 panic!("itertools: .zip_eq() reached end of one iterator before the other")
50 }
51 }
52 }
53
54 fn size_hint(&self) -> (usize, Option<usize>) {
55 size_hint::min(self.a.size_hint(), self.b.size_hint())
56 }
57}
58
59impl<I, J> ExactSizeIterator for ZipEq<I, J>
60where
61 I: ExactSizeIterator,
62 J: ExactSizeIterator,
63{
64}
65