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Reduce genericity in Scan

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This commit is contained in:
Josh Stone 2019-07-11 18:24:12 -07:00
parent 0f82c0c210
commit f1003546db
1 changed files with 17 additions and 8 deletions
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25
src/libcore/iter/adapters/mod.rs
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@ -1900,7 +1900,8 @@ impl<B, I, St, F> Iterator for Scan<I, St, F> where
#[inline]
fn next(&mut self) -> Option<B> {
self.iter.next().and_then(|a| (self.f)(&mut self.state, a))
let a = self.iter.next()?;
(self.f)(&mut self.state, a)
}
#[inline]
@ -1910,17 +1911,25 @@ impl<B, I, St, F> Iterator for Scan<I, St, F> where
}
#[inline]
fn try_fold<Acc, Fold, R>(&mut self, init: Acc, mut fold: Fold) -> R where
fn try_fold<Acc, Fold, R>(&mut self, init: Acc, fold: Fold) -> R where
Self: Sized, Fold: FnMut(Acc, Self::Item) -> R, R: Try<Ok=Acc>
{
fn scan<'a, T, St, B, Acc, R: Try<Ok = Acc>>(
state: &'a mut St,
f: &'a mut impl FnMut(&mut St, T) -> Option<B>,
mut fold: impl FnMut(Acc, B) -> R + 'a,
) -> impl FnMut(Acc, T) -> LoopState<Acc, R> + 'a {
move |acc, x| {
match f(state, x) {
None => LoopState::Break(Try::from_ok(acc)),
Some(x) => LoopState::from_try(fold(acc, x)),
}
}
}
let state = &mut self.state;
let f = &mut self.f;
self.iter.try_fold(init, move |acc, x| {
match f(state, x) {
None => LoopState::Break(Try::from_ok(acc)),
Some(x) => LoopState::from_try(fold(acc, x)),
}
}).into_try()
self.iter.try_fold(init, scan(state, f, fold)).into_try()
}
}