Owned Chars

Chars but keeping a strong reference (Rc) to the string.

#![allow(unused)]
fn main() {
mod rcchars { pub struct RcChars { rc: std::rc::Rc<String>, index: usize }
impl Iterator for RcChars { type Item = char; fn next(&mut self) -> Option<Self::Item> {
let s = self.rc.get(self.index..)?; let c = s.chars().next()?; self.index += c.len_utf8(); Some(c)
} } impl RcChars { pub fn from_rc(rc: std::rc::Rc<String>) -> Self { Self { rc, index: 0 } } }
impl From<std::rc::Rc<String>> for RcChars { fn from(value: std::rc::Rc<String>) -> Self { Self::from_rc(value) } }
} use {std::rc::Rc, rcchars::RcChars};
{
    let rc = Rc::new("abc".to_string());
    let rcc = RcChars::from(rc.clone());
    drop(rc);
    assert_eq!(rcc.collect::<Vec<_>>(), ['a', 'b', 'c']);
}
{
    let rc = Rc::new("abc".to_string());
    let rcc = RcChars::from(rc);
    let rcc = Box::new(rcc);
    assert_eq!(rcc.collect::<Vec<_>>(), ['a', 'b', 'c']);
}
}

Solutions

• The one in hidden code (slightly compacted).
• Implementation used in rattlescript.
• Same solution but with some extra comments.
• Another solution. I prefer this one.
• There's an even simpler version that even an AI can generate (don't do that for unsafe code in production), but I dislike it for several reasons, even though it's mostly sound.