Function array_tools::try_init_with_iter[−][src]

pub fn try_init_with_iter<T, A, I, E>(iter: I) -> Result<Option<A>, E> where
    A: FixedSizeArray<T>,
    I: Iterator<Item = Result<T, E>>,

Attempts to initialize array of T with iterator over Result<T, E> values.

This function behaves much like init_with_iter does.

If iterator yields not enough items, this function returns Ok(None).
If iterator yields enough items items to fill array, this function returns Ok(Some(array)).
If iterator yields excessive items, this function only takes required number of items and returns Ok(Some(array)).
If iterator yields Err before array is fully initialized, this function stops immediately and returns Err obtained from iterator.

Panics

Only if iterator's next method does.

Examples

use array_tools as art;

#[derive(Debug, Clone, Copy, PartialEq, Eq)]
struct MyErr;

let mut iter = [Ok(3i32), Ok(2), Ok(1), Ok(0)].iter().copied();
let result: Result<Option<[i32; 5]>, MyErr> = art::try_init_with_iter(iter.by_ref());

assert_eq!(result, Ok(None));
assert_eq!(iter.next(), None);

let mut iter = [Ok(4i32), Ok(3), Ok(2), Ok(1), Ok(0)].iter().copied();
let result: Result<Option<[i32; 5]>, MyErr> = art::try_init_with_iter(iter.by_ref());

assert_eq!(result, Ok(Some([4i32, 3, 2, 1, 0])));
assert_eq!(iter.next(), None);

let mut iter = [Ok(5i32), Ok(4), Ok(3), Ok(2), Ok(1), Ok(0)].iter().copied();
let result: Result<Option<[i32; 5]>, MyErr> = art::try_init_with_iter(iter.by_ref());

assert_eq!(result, Ok(Some([5i32, 4, 3, 2, 1])));
assert_eq!(iter.next(), Some(Ok(0)));
assert_eq!(iter.next(), None);



let mut iter = [Ok(3i32), Ok(2), Ok(1), Err(MyErr)].iter().copied();
let result: Result<Option<[i32; 5]>, MyErr> = art::try_init_with_iter(iter.by_ref());

assert_eq!(result, Err(MyErr));
assert_eq!(iter.next(), None);

let mut iter = [Ok(4i32), Ok(3), Ok(2), Ok(1), Err(MyErr)].iter().copied();
let result: Result<Option<[i32; 5]>, MyErr> = art::try_init_with_iter(iter.by_ref());

assert_eq!(result, Err(MyErr));
assert_eq!(iter.next(), None);

let mut iter = [Ok(5i32), Ok(4), Ok(3), Ok(2), Ok(1), Err(MyErr)].iter().copied();
let result: Result<Option<[i32; 5]>, MyErr> = art::try_init_with_iter(iter.by_ref());

assert_eq!(result, Ok(Some([5i32, 4, 3, 2, 1])));
assert_eq!(iter.next(), Some(Err(MyErr)));
assert_eq!(iter.next(), None);