sec.rs

use std::marker::PhantomData;
use std::convert::From;

#[derive(Debug, Clone, Copy)]
struct H;
#[derive(Debug, Clone, Copy)]
struct L;

#[derive(Debug, Clone, Copy)]
struct Sec<S, A> {
    _security_level: PhantomData<S>,
    data: A,
}

impl<S, A> Sec<S, A> {
    fn new(data: A) -> Sec<S, A> {
        Sec { data, _security_level: PhantomData }
    }
    
    fn open(self, _s: S) -> A {
        self.data
    }
    
    fn map<B, F>(self, f: F) -> Sec<S, B> where F: FnOnce(A) -> B {
        let data = f(self.data);
        Sec::new(data)
    }
    
    fn and_then<B, F>(self, f: F) -> Sec<S, B> where F: FnOnce(A) -> Sec<S, B> {
        f(self.data)
    }
}

impl<S, A> From<A> for Sec<S, A> {
    fn from(data: A) -> Sec<S, A> {
        Sec::new(data)
    }
}

fn main() {
    let a: Sec<H, i32> = Sec::new(12);
    println!("{:?}", a);
    let b = a.map(|x| x + 3);
    println!("{:?}", b);
    let c = b.and_then(|x| Sec::new(x + 3));
    println!("{:?}", c);
    let d = c.open(H);
    println!("{:?}", d);
}