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use super::size_hint;
/// An iterator which iterates two other iterators simultaneously
///
/// See [`.zip_eq()`](crate::Itertools::zip_eq) for more information.
#[derive(Clone, Debug)]
#[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
pub struct ZipEq<I, J> {
a: I,
b: J,
}
/// Iterate `i` and `j` in lock step.
///
/// **Panics** if the iterators are not of the same length.
///
/// [`IntoIterator`] enabled version of [`Itertools::zip_eq`](crate::Itertools::zip_eq).
///
/// ```
/// use itertools::zip_eq;
///
/// let data = [1, 2, 3, 4, 5];
/// for (a, b) in zip_eq(&data[..data.len() - 1], &data[1..]) {
/// /* loop body */
/// }
/// ```
pub fn zip_eq<I, J>(i: I, j: J) -> ZipEq<I::IntoIter, J::IntoIter>
where I: IntoIterator,
J: IntoIterator
{
ZipEq {
a: i.into_iter(),
b: j.into_iter(),
}
}
impl<I, J> Iterator for ZipEq<I, J>
where I: Iterator,
J: Iterator
{
type Item = (I::Item, J::Item);
fn next(&mut self) -> Option<Self::Item> {
match (self.a.next(), self.b.next()) {
(None, None) => None,
(Some(a), Some(b)) => Some((a, b)),
(None, Some(_)) | (Some(_), None) =>
panic!("itertools: .zip_eq() reached end of one iterator before the other")
}
}
fn size_hint(&self) -> (usize, Option<usize>) {
size_hint::min(self.a.size_hint(), self.b.size_hint())
}
}
impl<I, J> ExactSizeIterator for ZipEq<I, J>
where I: ExactSizeIterator,
J: ExactSizeIterator
{}
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