Trait ForwardIterExt

pub trait ForwardIterExt: Iterator + Sized {
    // Provided method
    fn forward(self) -> ForwardIter<Self>  { ... }
}

Ensure that side effects in iterators always run forward

Provided Methods

fn forward(self) -> ForwardIter<Self>

Ensure that side effects in iterators always run forward

Space complexity

• call Iterator methods: O(1)
• call DoubleEndedIterator methods: O(n)

Examples

Fail case:

let mut i = 0;
let x: Vec<_> = (0..4).map(|_| { i += 1; i }).rev().collect();
assert_eq!(x, [4, 3, 2, 1]); // fail!

Rewrite to:

let mut i = 0;
let x: Vec<_> = (0..4).map(|_| { i += 1; i }).forward().rev().collect();
assert_eq!(x, [4, 3, 2, 1]); // success!

Dyn Compatibility

This trait is not dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety", so this trait is not object safe.

Implementors

impl<I: Iterator> ForwardIterExt for I