1 use super::size_hint;
2
3 /// An iterator which iterates two other iterators simultaneously
4 ///
5 /// See [`.zip_eq()`](crate::Itertools::zip_eq) for more information.
6 #[derive(Clone, Debug)]
7 #[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
8 pub struct ZipEq<I, J> {
9 a: I,
10 b: J,
11 }
12
13 /// Iterate `i` and `j` in lock step.
14 ///
15 /// **Panics** if the iterators are not of the same length.
16 ///
17 /// [`IntoIterator`] enabled version of [`Itertools::zip_eq`](crate::Itertools::zip_eq).
18 ///
19 /// ```
20 /// use itertools::zip_eq;
21 ///
22 /// let data = [1, 2, 3, 4, 5];
23 /// for (a, b) in zip_eq(&data[..data.len() - 1], &data[1..]) {
24 /// /* loop body */
25 /// }
26 /// ```
zip_eq<I, J>(i: I, j: J) -> ZipEq<I::IntoIter, J::IntoIter> where I: IntoIterator, J: IntoIterator27 pub fn zip_eq<I, J>(i: I, j: J) -> ZipEq<I::IntoIter, J::IntoIter>
28 where I: IntoIterator,
29 J: IntoIterator
30 {
31 ZipEq {
32 a: i.into_iter(),
33 b: j.into_iter(),
34 }
35 }
36
37 impl<I, J> Iterator for ZipEq<I, J>
38 where I: Iterator,
39 J: Iterator
40 {
41 type Item = (I::Item, J::Item);
42
next(&mut self) -> Option<Self::Item>43 fn next(&mut self) -> Option<Self::Item> {
44 match (self.a.next(), self.b.next()) {
45 (None, None) => None,
46 (Some(a), Some(b)) => Some((a, b)),
47 (None, Some(_)) | (Some(_), None) =>
48 panic!("itertools: .zip_eq() reached end of one iterator before the other")
49 }
50 }
51
size_hint(&self) -> (usize, Option<usize>)52 fn size_hint(&self) -> (usize, Option<usize>) {
53 size_hint::min(self.a.size_hint(), self.b.size_hint())
54 }
55 }
56
57 impl<I, J> ExactSizeIterator for ZipEq<I, J>
58 where I: ExactSizeIterator,
59 J: ExactSizeIterator
60 {}
61