rust split option to result to value

from_str.rs

use std::num::ParseIntError;
use std::str::FromStr;

#[derive(Debug, PartialEq)]
enum ParsePersonError {
    // Empty input string
    Empty,
    // Incorrect number of fields
    BadLen,
    // Empty name field
    NoName,
    // Wrapped error from parse::<usize>()
    ParseInt(ParseIntError),
}

#[derive(Debug, PartialEq, Default)]
struct Person {
    name: String,
    age: usize,
}

impl FromStr for Person {
    type Err = ParsePersonError;
    fn from_str(s: &str) -> Result<Person, Self::Err> {
        if s.is_empty() {
            return Err(ParsePersonError::Empty);
        }
        let mut split = s.split(",").collect::<Vec<_>>();
        let mut person = Person::default();

        if split.len() != 2 {
            return Err(ParsePersonError::BadLen);
        }

        let mut split_iter = split.into_iter();
        person.name = split_iter
            .next()
            .filter(|s| s.len() > 0)
            .map(|s| s.to_string())
            .ok_or(ParsePersonError::NoName)?;

        person.age = split_iter
            .next()
            .ok_or(ParsePersonError::BadLen)?
            .parse::<usize>()
            .map_err(|e| {
                ParsePersonError::ParseInt(e)
            })?;

        Ok(person)
    }
}