FromStr is not implemented for char

[oli-obk]

I'm not sure if this is an oversight. But the implementation should be trivial. I'll add tests and implement it, if it is fine.

enum ParseCharError { EmptyString, TooManyChars }
impl FromStr for char {
    type Err = ParseCharError;
    #[inline]
    fn from_str(s: &str) -> Result<char, ParseCharError> {
        match s.len() {
            0 => Err(ParseCharError::EmptyString),
            1 => Ok(s[0]),
            _ => Err(ParseCharError::TooManyChars),
        }
    }
}

[bluss]

Strings aren't indexable and .len() doesn't count the number of chars. 😄

What comes to mind first is an iterator inspecting the two first chars:

let mut chars = s.chars();
match (chars.next(), chars.next()) {
    (None, None) => // empty
    (Some(c), None) => Ok(c),
    _  => // Too many
}

[oli-obk]

xD I didn't test my code, but you get the gist.
I had a chars() impl at first, but then edited it

[steveklabnik]

cc @aturon

[steveklabnik]

Triage: this has not been added.

fn main() {
    let c = String::from("c");
    let c: char = c.parse().unwrap();
}

[aturon]

PRs welcome!

[tinaun]

I can take this.

I was also thinking of adding a FromStr impl for &'a str, but unsure if it would be better to wait for never_type to get closer to stabilization and use that instead of adding another empty enum to std

[tinaun]

wait, that wouldn't work bc of lifetime issues regardless, right? :(