Protocol std::iter::Iterator

protocol Iterator<Self, T> { ... }

source

Iterators.

See module-level documentation for more details.

Implementing an iterator

Types that have Iterator semantics should implement next at a minimum. When the iterator can cheaply determine the number of remaining elements, it should also implement size_hint. This enables the collections constructed from iterators to efficiently reserve space for the elements and avoid reallocations. If size_hint returns a value, it should be exact.

All types implementing Iterator should also mix in IteratorExt, which provides a number of useful extension methods.

See also DoubleEndedIterator for iterators that can be iterated in reverse order.

Example

struct Countdown { counter: i32 }

impl Countdown {
    use std::cmp::max;
    use std::iter::{Iterator, IteratorExt};

    fn next(self: &mut Countdown) -> Option<i32> {
        if self.counter <= 0 {
            Option::none()
        } else {
            let ret = Option::some(self.counter);
            self.counter -= 1;
            ret
        }
    }

    fn size_hint(self: &Countdown) -> Option<usize> {
        Option::some(max(0, self.counter) as usize)
    }

    mixin Iterator<Countdown, i32>;
    mixin IteratorExt<Countdown, i32>;
}

// use `(1..=5).rev()` in real code
let countdown = Countdown { counter: 5 };

for i in countdown {
    println!("{}", i);
}
println!("Ignition and Liftoff!");
Run this example

Required methods

Provided methods