gistfile1.rs

/** An example statically-dispatched, trait-based recursive datastructure in Rust */

/**A master trait */
trait Link {
    fn value(&self) -> i32;
    fn next(&self) -> Option<&Link>;
    fn sumOfValue(&self)->i32 {
        let maybeNext = self.next();
        match maybeNext {
            Some(v) => {
                return self.value() + v.sumOfValue()
            }
            None => {
                return self.value()
            }
        }
    }
}

/**A specialization of Link with value = 1 */
struct OneLink<NEXT: Link> {
    next : NEXT
}
impl<NEXT : Link> Link for OneLink<NEXT> {
    fn value(&self) -> i32 { 1 }
    fn next(&self) -> Option<&Link> { Some(&self.next) }
}

/**another specialization of link with value = 2*/
struct TwoLink<NEXT: Link> {
    next: NEXT
}
impl<NEXT : Link> Link for TwoLink<NEXT> {
    fn value(&self) -> i32 { 2 }
    fn next(&self) -> Option<&Link> { Some(&self.next) }
}

/**Another specialization of link with value 0 and no next element */
struct NoLink;
impl Link for NoLink {
    fn value(&self) -> i32 { 0 }
    fn next(&self) -> Option<&Link> { None }
}



fn main() {
    /**A chain of One -> Two -> None, for a total value of 3*/
    let chain = OneLink{ next: TwoLink { next: NoLink } };
    /**Calculate the total value */
    println!("{}",chain.sumOfValue());
}