Function ustr::existing_ustr

pub fn existing_ustr(s: &str) -> Option<Ustr>

Create a new Ustr from the given &str but only if it already exists in the string cache.

use ustr::{ustr, existing_ustr};

let u1 = existing_ustr("the quick brown fox");
let u2 = ustr("the quick brown fox");
let u3 = existing_ustr("the quick brown fox");
assert_eq!(u1, None);
assert_eq!(u3, Some(u2));