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use super::CliffSearch;
use core::borrow::Borrow;
#[derive(Debug, Clone)]
pub struct LoadIterator<I> {
max_in: core::ops::Range<usize>,
last: Option<usize>,
overloaded: bool,
iter: I,
}
impl<I, T> CliffSearch for LoadIterator<I>
where
I: Iterator<Item = T>,
T: Borrow<usize>,
{
fn overloaded(&mut self) {
self.overloaded = true;
}
fn estimate(&self) -> core::ops::Range<usize> {
self.max_in.clone()
}
}
impl<I, T> Iterator for LoadIterator<I>
where
I: Iterator<Item = T>,
T: Borrow<usize>,
{
type Item = usize;
fn next(&mut self) -> Option<Self::Item> {
if let Some(ref mut last) = self.last {
if self.overloaded {
self.max_in.end = *last;
} else {
self.max_in.start = *last;
}
}
if self.overloaded {
return None;
}
let next = *self.iter.next()?.borrow();
self.last = Some(next);
Some(next)
}
}
impl<I, T> From<I> for LoadIterator<I::IntoIter>
where
I: IntoIterator<Item = T>,
T: Borrow<usize>,
{
fn from(v: I) -> Self {
LoadIterator {
max_in: 0..usize::max_value(),
last: None,
overloaded: false,
iter: v.into_iter(),
}
}
}
#[test]
fn linear_nofail() {
let mut scale = LoadIterator::from(&[1, 2, 3, 4]);
assert_eq!(scale.next(), Some(1));
assert_eq!(scale.next(), Some(2));
assert_eq!(scale.next(), Some(3));
assert_eq!(scale.next(), Some(4));
assert_eq!(scale.next(), None);
assert_eq!(scale.estimate(), 4..usize::max_value());
assert_eq!(scale.next(), None);
scale.overloaded();
assert_eq!(scale.next(), None);
}
#[test]
fn linear_fail() {
let mut scale = LoadIterator::from(&[1, 2, 3, 4]);
assert_eq!(scale.next(), Some(1));
assert_eq!(scale.next(), Some(2));
scale.overloaded();
assert_eq!(scale.next(), None);
assert_eq!(scale.estimate(), 1..2);
assert_eq!(scale.next(), None);
scale.overloaded();
assert_eq!(scale.next(), None);
}