What's the most efficient way to reuse an iterator in Rust?

Question

I\'d like to reuse an iterator I made, so as to avoid paying to recreate it from scratch. But iterators don\'t seem to be cloneable and collect mov

Answer 1

You may use closure to get identical iterators:

#[derive(Debug)]
struct MyStruct{
    one:Vec,
    two:Vec,
    three:String
}

fn main() {
    let my_string:String = "ABCD1234absd".into();
    let my_iter = || my_string.chars();
    let my_struct = MyStruct{
        one: my_iter().collect(),
        two: my_iter().filter(|x| x.is_numeric()).collect(),
        three: my_iter().filter(|x| x.is_lowercase()).collect()
    };
    println!("{:?}", my_struct);
}

See also this Correct way to return an Iterator? question.

Also you may clone iterator (see @Paolo Falabella answer about iterators cloneability):

fn main() {
    let v = vec![1,2,3,4,5,6,7,8,9]; 
    let mut i = v.iter().skip(2);
    let mut j = i.clone();
    println!("{:?}", i.take(3).collect::>());
    println!("{:?}", j.filter(|&x| x%2==0).collect::>());
}

Unfortunately I can't tell which way is more effective