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Test with non-fused iterators

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This commit is contained in:
Tim Vermeulen 2020-10-06 00:48:34 +02:00
parent bcacfe1dbf
commit 1d27a508d1
1 changed files with 41 additions and 4 deletions
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45
library/core/tests/iter.rs
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@ -4,6 +4,43 @@ use core::cell::Cell;
use core::convert::TryFrom;
use core::iter::*;
/// An iterator wrapper that panics whenever `next` or `next_back` is called
/// after `None` has been returned.
struct Unfuse<I> {
iter: I,
exhausted: bool,
}
fn unfuse<I: IntoIterator>(iter: I) -> Unfuse<I::IntoIter> {
Unfuse { iter: iter.into_iter(), exhausted: false }
}
impl<I> Iterator for Unfuse<I>
where
I: Iterator,
{
type Item = I::Item;
fn next(&mut self) -> Option<Self::Item> {
assert!(!self.exhausted);
let next = self.iter.next();
self.exhausted = next.is_none();
next
}
}
impl<I> DoubleEndedIterator for Unfuse<I>
where
I: DoubleEndedIterator,
{
fn next_back(&mut self) -> Option<Self::Item> {
assert!(!self.exhausted);
let next = self.iter.next_back();
self.exhausted = next.is_none();
next
}
}
#[test]
fn test_lt() {
let empty: [isize; 0] = [];
@ -148,14 +185,14 @@ fn test_iterator_chain_advance_by() {
let len = xs.len() + ys.len();
for i in 0..xs.len() {
let mut iter = xs.iter().chain(ys);
let mut iter = unfuse(xs).chain(unfuse(ys));
iter.advance_by(i).unwrap();
assert_eq!(iter.next(), Some(&xs[i]));
assert_eq!(iter.advance_by(100), Err(len - i - 1));
}
for i in 0..ys.len() {
let mut iter = xs.iter().chain(ys);
let mut iter = unfuse(xs).chain(unfuse(ys));
iter.advance_by(xs.len() + i).unwrap();
assert_eq!(iter.next(), Some(&ys[i]));
assert_eq!(iter.advance_by(100), Err(ys.len() - i - 1));
@ -181,14 +218,14 @@ fn test_iterator_chain_advance_back_by() {
let len = xs.len() + ys.len();
for i in 0..ys.len() {
let mut iter = xs.iter().chain(ys);
let mut iter = unfuse(xs).chain(unfuse(ys));
iter.advance_back_by(i).unwrap();
assert_eq!(iter.next_back(), Some(&ys[ys.len() - i - 1]));
assert_eq!(iter.advance_back_by(100), Err(len - i - 1));
}
for i in 0..xs.len() {
let mut iter = xs.iter().chain(ys);
let mut iter = unfuse(xs).chain(unfuse(ys));
iter.advance_back_by(ys.len() + i).unwrap();
assert_eq!(iter.next_back(), Some(&xs[xs.len() - i - 1]));
assert_eq!(iter.advance_back_by(100), Err(xs.len() - i - 1));