gistfile1.rs

use std::hash::Hash;
use std::collections::HashMap;

pub struct Hashing<K: Eq + Hash, V: Eq + Hash> {
    x: HashMap<K, V>
}

impl<'a, K: Eq + Hash + Clone, V: Eq + Hash + Clone> Hashing<K, V> {
    pub fn new(h: HashMap<K, V>) -> Hashing<K, V> {
        Hashing { x: h }
    }

    pub fn pick(self, keys: Vec<K>) -> HashMap<K, V> {
        let mut picked = HashMap::new();
        for element in keys.iter() {
            if self.x.contains_key(element) {
                // ここで新しい lifetime を作る
                let e = element.clone();
                let a = self.x.get_copy(element);
                picked.insert(e, a);
            }
        }

        return picked;
    }
}

fn main() {
    let mut h = HashMap::new();
    h.insert(1i, 2u);
    h.insert(2i, 3u);
    h.insert(3i, 4u);

    Hashing::new(h).pick(vec!(1i, 2i));
}