Trait try_all::TryMapAllOption

pub trait TryMapAllOption {
    type Item;
    fn try_map_all_opt<T>(
        self, 
        f: impl Fn(Self::Item) -> Option<T>
    ) -> Option<IntoIter<T>>;
}

Trait providing try map (option) extensions to Iterators.

See TryMapAllOption::try_map_all_opt.

Once Try (#42327) is stabilized, hopefully the Result and Option variants can be merged and generalized.

Associated Types

type Item

Required methods

fn try_map_all_opt<T>(
    self,
    f: impl Fn(Self::Item) -> Option<T>
) -> Option<IntoIter<T>>

Applies a closure on all items of the iterator until one fails (or all succeed).

This is TryMapAll::try_map_all - Option edition.

Arguments

• f: fallible mapping function

Returns

The iterator of all successes, or the first failure.

Examples

Useful for propagating failures from within closures with ? operator:

fn not_zero(is: Vec<u64>) -> Option<Vec<u64>> {
	Some(is.into_iter().try_map_all_opt(|i| if i > 0 { Some(i) } else { None })?.collect())
}

Due to the nature of operation, the function has to collect intermediate results. In other words, if f has side effects, expect them for all applications until [including] first failure. Additionally, this won’t work on infinite sequences :o.

Implementors

impl<I: Iterator> TryMapAllOption for I

type Item = I::Item

fn try_map_all_opt<T>(
    self,
    f: impl Fn(Self::Item) -> Option<T>
) -> Option<IntoIter<T>>