Rust each_cons

each_cons.rs

#![feature(slicing_syntax)]

use std::collections::RingBuf;

fn main() {
    let xs = &[1i, 2i, 3i, 4i, 5i];
    let mut iter = EachCons { iter: xs.iter(), n: 3, buffer: RingBuf::new() };

    for x in iter {
        println!("{}", x);
    }
}

pub struct EachCons<A, T> where T: Iterator<A> {
    iter: T,
    n: uint,
    buffer: RingBuf<A>
}

impl<A: Clone, T: Iterator<A>> Iterator<Vec<A>> for EachCons<A, T> {
    fn next(&mut self) -> Option<Vec<A>> {
        for x in self.iter {
            self.buffer.push_back(x);

            if self.buffer.len() > self.n {
                self.buffer.pop_front();
            }

            if self.buffer.len() == self.n {
                let (slice, _) = self.buffer.as_slices();

                let mut v = Vec::new();
                v.push_all(slice);

                return Some(v);
            } else {
                continue
            }
        }

        None
    }
}