generator to iterator

generator.rs

#![feature(generators, generator_trait)]

use std::ops::GeneratorState;
use std::pin::Pin;

fn generator_to_iterator<G>(g: G) -> impl Iterator<Item = G::Yield>
where
    G: std::marker::Unpin + std::ops::Generator,
{
    struct GeneratorIter<G>(G);
    impl<G> Iterator for GeneratorIter<G>
    where
        G: std::marker::Unpin + std::ops::Generator,
    {
        type Item = G::Yield;
        fn next(&mut self) -> Option<Self::Item> {
            match Pin::new(&mut self.0).resume() {
                GeneratorState::Yielded(x) => return Some(x),
                _ => None,
            }
        }
    }
    GeneratorIter(g)
}

fn main() {
    let iter = generator_to_iterator(|| {
        for i in 0..10 {
            yield i*i;
        }
    });
    for i in iter {
        println!("{:?}", i);
    }
}