3f9b26dc64
The `advance_by(n)` docs state that in the error case `Err(k)` that k is always less than n. It also states that `advance_by(0)` may return `Err(0)` to indicate an exhausted iterator. These statements are inconsistent. Since only one implementation (Skip) actually made use of that I changed it to return Ok(()) in that case too. While adding some tests I also found a bug in `Take::advance_back_by`.
149 lines
4.1 KiB
Rust
149 lines
4.1 KiB
Rust
use core::iter::*;
|
|
|
|
#[test]
|
|
fn test_iterator_take() {
|
|
let xs = [0, 1, 2, 3, 5, 13, 15, 16, 17, 19];
|
|
let ys = [0, 1, 2, 3, 5];
|
|
|
|
let mut it = xs.iter().take(ys.len());
|
|
let mut i = 0;
|
|
assert_eq!(it.len(), ys.len());
|
|
while let Some(&x) = it.next() {
|
|
assert_eq!(x, ys[i]);
|
|
i += 1;
|
|
assert_eq!(it.len(), ys.len() - i);
|
|
}
|
|
assert_eq!(i, ys.len());
|
|
assert_eq!(it.len(), 0);
|
|
|
|
let mut it = xs.iter().take(ys.len());
|
|
let mut i = 0;
|
|
assert_eq!(it.len(), ys.len());
|
|
while let Some(&x) = it.next_back() {
|
|
i += 1;
|
|
assert_eq!(x, ys[ys.len() - i]);
|
|
assert_eq!(it.len(), ys.len() - i);
|
|
}
|
|
assert_eq!(i, ys.len());
|
|
assert_eq!(it.len(), 0);
|
|
}
|
|
|
|
#[test]
|
|
fn test_iterator_take_nth() {
|
|
let xs = [0, 1, 2, 4, 5];
|
|
let mut it = xs.iter();
|
|
{
|
|
let mut take = it.by_ref().take(3);
|
|
let mut i = 0;
|
|
while let Some(&x) = take.nth(0) {
|
|
assert_eq!(x, i);
|
|
i += 1;
|
|
}
|
|
}
|
|
assert_eq!(it.nth(1), Some(&5));
|
|
assert_eq!(it.nth(0), None);
|
|
|
|
let xs = [0, 1, 2, 3, 4];
|
|
let mut it = xs.iter().take(7);
|
|
let mut i = 1;
|
|
while let Some(&x) = it.nth(1) {
|
|
assert_eq!(x, i);
|
|
i += 2;
|
|
}
|
|
}
|
|
|
|
#[test]
|
|
fn test_iterator_take_nth_back() {
|
|
let xs = [0, 1, 2, 4, 5];
|
|
let mut it = xs.iter();
|
|
{
|
|
let mut take = it.by_ref().take(3);
|
|
let mut i = 0;
|
|
while let Some(&x) = take.nth_back(0) {
|
|
i += 1;
|
|
assert_eq!(x, 3 - i);
|
|
}
|
|
}
|
|
assert_eq!(it.nth_back(0), None);
|
|
|
|
let xs = [0, 1, 2, 3, 4];
|
|
let mut it = xs.iter().take(7);
|
|
assert_eq!(it.nth_back(1), Some(&3));
|
|
assert_eq!(it.nth_back(1), Some(&1));
|
|
assert_eq!(it.nth_back(1), None);
|
|
}
|
|
|
|
#[test]
|
|
fn test_take_advance_by() {
|
|
let mut take = (0..10).take(3);
|
|
assert_eq!(take.advance_by(2), Ok(()));
|
|
assert_eq!(take.next(), Some(2));
|
|
assert_eq!(take.advance_by(1), Err(0));
|
|
|
|
assert_eq!((0..0).take(10).advance_by(0), Ok(()));
|
|
assert_eq!((0..0).take(10).advance_by(1), Err(0));
|
|
assert_eq!((0..10).take(4).advance_by(5), Err(4));
|
|
|
|
let mut take = (0..10).take(3);
|
|
assert_eq!(take.advance_back_by(2), Ok(()));
|
|
assert_eq!(take.next(), Some(0));
|
|
assert_eq!(take.advance_back_by(1), Err(0));
|
|
|
|
assert_eq!((0..2).take(1).advance_back_by(10), Err(1));
|
|
assert_eq!((0..0).take(1).advance_back_by(1), Err(0));
|
|
assert_eq!((0..0).take(1).advance_back_by(0), Ok(()));
|
|
assert_eq!((0..usize::MAX).take(100).advance_back_by(usize::MAX), Err(100));
|
|
}
|
|
|
|
#[test]
|
|
fn test_iterator_take_short() {
|
|
let xs = [0, 1, 2, 3];
|
|
|
|
let mut it = xs.iter().take(5);
|
|
let mut i = 0;
|
|
assert_eq!(it.len(), xs.len());
|
|
while let Some(&x) = it.next() {
|
|
assert_eq!(x, xs[i]);
|
|
i += 1;
|
|
assert_eq!(it.len(), xs.len() - i);
|
|
}
|
|
assert_eq!(i, xs.len());
|
|
assert_eq!(it.len(), 0);
|
|
|
|
let mut it = xs.iter().take(5);
|
|
let mut i = 0;
|
|
assert_eq!(it.len(), xs.len());
|
|
while let Some(&x) = it.next_back() {
|
|
i += 1;
|
|
assert_eq!(x, xs[xs.len() - i]);
|
|
assert_eq!(it.len(), xs.len() - i);
|
|
}
|
|
assert_eq!(i, xs.len());
|
|
assert_eq!(it.len(), 0);
|
|
}
|
|
|
|
#[test]
|
|
fn test_take_try_folds() {
|
|
let f = &|acc, x| i32::checked_add(2 * acc, x);
|
|
assert_eq!((10..30).take(10).try_fold(7, f), (10..20).try_fold(7, f));
|
|
assert_eq!((10..30).take(10).try_rfold(7, f), (10..20).try_rfold(7, f));
|
|
|
|
let mut iter = (10..30).take(20);
|
|
assert_eq!(iter.try_fold(0, i8::checked_add), None);
|
|
assert_eq!(iter.next(), Some(20));
|
|
assert_eq!(iter.try_rfold(0, i8::checked_add), None);
|
|
assert_eq!(iter.next_back(), Some(24));
|
|
|
|
let mut iter = (2..20).take(3);
|
|
assert_eq!(iter.try_for_each(Err), Err(2));
|
|
assert_eq!(iter.try_for_each(Err), Err(3));
|
|
assert_eq!(iter.try_for_each(Err), Err(4));
|
|
assert_eq!(iter.try_for_each(Err), Ok(()));
|
|
|
|
let mut iter = (2..20).take(3).rev();
|
|
assert_eq!(iter.try_for_each(Err), Err(4));
|
|
assert_eq!(iter.try_for_each(Err), Err(3));
|
|
assert_eq!(iter.try_for_each(Err), Err(2));
|
|
assert_eq!(iter.try_for_each(Err), Ok(()));
|
|
}
|