Trait example

sublist.rs

#[derive(Debug, PartialEq)]
pub enum Comparison {
    Equal,
    Sublist,
    Superlist,
    Unequal,
}

trait IncludedIn {
    fn included_in(&self, rhs: Self) -> bool;
}

impl<T: PartialEq> IncludedIn for &[T] {
    fn included_in(&self, rhs: Self) -> bool {
        if self.is_empty() && !rhs.is_empty() {
            return true;
        }
        for window in rhs.windows(self.len()) {
            if &window == self {
                return true;
            }
        }
        false
    }
}

pub fn sublist<T: PartialEq>(first_list: &[T], second_list: &[T]) -> Comparison {
    if first_list == second_list {
        Comparison::Equal
    } else if first_list.included_in(second_list) {
        Comparison::Sublist
    } else if second_list.included_in(first_list) {
        Comparison::Superlist
    } else {
        Comparison::Unequal
    }
}