Shared via Rust Playground

playground.rs

// This code is editable and runnable!
fn main() {
    let s = "foo\"bar\"baz\"";

    //println!("{}", s.split('"').collect::<Vec<_>>().join("\\\""));
    let mut iter = s.split('"').peekable();
    loop {
        match (iter.next(), iter.peek()) {
            (Some(i), Some(_)) => print!("{}\\\"", i),
            (Some(i), None) => {
                print!("{}", i);
                break
            }
            _ => unreachable!()
        }
    }
    /*
    for i in iter {
        println!("{:?}", iter.peek());
        print!("{}\\\"", i);
    }
   */
 }