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Compute each key only once in position_{min,max,minmax}_by_key #1136

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Merged
phimuemue merged 1 commit into from
Oct 21, 2026
Merged

Compute each key only once in position_{min,max,minmax}_by_key #1136

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15 changes: 3 additions & 12 deletions src/lib.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -4622,9 +4622,7 @@ pub trait Itertools: Iterator {
K: Ord,
F: FnMut(&Self::Item) -> K,
{
self.enumerate()
.max_by(|x, y| Ord::cmp(&key(&x.1), &key(&y.1)))
.map(|x| x.0)
self.map(|item| key(&item)).position_max()
}

/// Return the position of the maximum element in the iterator, as
Expand Down Expand Up @@ -4712,9 +4710,7 @@ pub trait Itertools: Iterator {
K: Ord,
F: FnMut(&Self::Item) -> K,
{
self.enumerate()
.min_by(|x, y| Ord::cmp(&key(&x.1), &key(&y.1)))
.map(|x| x.0)
self.map(|item| key(&item)).position_min()
}

/// Return the position of the minimum element in the iterator, as
Expand Down Expand Up @@ -4842,12 +4838,7 @@ pub trait Itertools: Iterator {
K: PartialOrd,
F: FnMut(&Self::Item) -> K,
{
use crate::MinMaxResult::{MinMax, NoElements, OneElement};
match self.enumerate().minmax_by_key(|e| key(&e.1)) {
NoElements => NoElements,
OneElement(x) => OneElement(x.0),
MinMax(x, y) => MinMax(x.0, y.0),
}
self.map(|item| key(&item)).position_minmax()
}

/// Return the positions of the minimum and maximum elements of an
Expand Down
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