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Add documentation for multi_cartesian_product when iterator is empty #834

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Merged
Philippe-Cholet merged 1 commit into from
Jan 30, 2024
Merged

Add documentation for multi_cartesian_product when iterator is empty #834

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10 changes: 10 additions & 0 deletions src/lib.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -1181,6 +1181,16 @@ pub trait Itertools: Iterator {
/// assert_eq!(multi_prod.next(), Some(vec![1, 3, 5]));
/// assert_eq!(multi_prod.next(), None);
/// ```
///
/// If the adapted iterator is empty, the result is an iterator yielding a single empty vector.
/// This is known as the [nullary cartesian product](https://en.wikipedia.org/wiki/Empty_product#Nullary_Cartesian_product).
///
/// ```
/// use itertools::Itertools;
/// let mut nullary_cartesian_product = (0..0).map(|i| (i * 2)..(i * 2 + 2)).multi_cartesian_product();
/// assert_eq!(nullary_cartesian_product.next(), Some(vec![]));
/// assert_eq!(nullary_cartesian_product.next(), None);
/// ```
#[cfg(feature = "use_alloc")]
fn multi_cartesian_product(self) -> MultiProduct<<Self::Item as IntoIterator>::IntoIter>
where
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