1 use 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"]
9 pub 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 /// # let _ = (a, b);
25 /// }
26 /// ```
zip_eq<I, J>(i: I, j: J) -> ZipEq<I::IntoIter, J::IntoIter> where I: IntoIterator, J: IntoIterator,27 pub fn zip_eq<I, J>(i: I, j: J) -> ZipEq<I::IntoIter, J::IntoIter>
28 where
29 I: IntoIterator,
30 J: IntoIterator,
31 {
32 ZipEq {
33 a: i.into_iter(),
34 b: j.into_iter(),
35 }
36 }
37
38 impl<I, J> Iterator for ZipEq<I, J>
39 where
40 I: Iterator,
41 J: Iterator,
42 {
43 type Item = (I::Item, J::Item);
44
next(&mut self) -> Option<Self::Item>45 fn next(&mut self) -> Option<Self::Item> {
46 match (self.a.next(), self.b.next()) {
47 (None, None) => None,
48 (Some(a), Some(b)) => Some((a, b)),
49 (None, Some(_)) | (Some(_), None) => {
50 panic!("itertools: .zip_eq() reached end of one iterator before the other")
51 }
52 }
53 }
54
size_hint(&self) -> (usize, Option<usize>)55 fn size_hint(&self) -> (usize, Option<usize>) {
56 size_hint::min(self.a.size_hint(), self.b.size_hint())
57 }
58 }
59
60 impl<I, J> ExactSizeIterator for ZipEq<I, J>
61 where
62 I: ExactSizeIterator,
63 J: ExactSizeIterator,
64 {
65 }
66