61 lines
1.7 KiB
Rust
61 lines
1.7 KiB
Rust
// This does practically the same thing that TryFrom<&str> does.
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// Additionally, upon implementing FromStr, you can use the `parse` method
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// on strings to generate an object of the implementor type.
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// You can read more about it at https://doc.rust-lang.org/std/str/trait.FromStr.html
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use std::str::FromStr;
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#[derive(Debug)]
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struct Person {
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name: String,
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age: usize,
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}
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// Steps:
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// 1. If the length of the provided string is 0, then return an error
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// 2. Split the given string on the commas present in it
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// 3. Extract the first element from the split operation and use it as the name
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// 4. Extract the other element from the split operation and parse it into a `usize` as the age
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// If while parsing the age, something goes wrong, then return an error
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// Otherwise, then return a Result of a Person object
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impl FromStr for Person {
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type Err = String;
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fn from_str(s: &str) -> Result<Person, Self::Err> {
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if s.is_empty() {
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return Err("empty &str".to_string());
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}
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let splits: Vec<&str> = s.split(",").collect::<Vec<&str>>();
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let name = splits[0].to_string();
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let age_result = splits[1].parse::<usize>();
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match age_result {
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Ok(age) => Ok(Person { name, age }),
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Error => Err("incorrect age".to_string()),
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}
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}
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}
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fn main() {
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let p = "Mark,20".parse::<Person>().unwrap();
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println!("{:?}", p);
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}
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#[cfg(test)]
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mod tests {
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use super::*;
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#[test]
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fn empty_input() {
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assert!("".parse::<Person>().is_err());
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}
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#[test]
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fn good_input() {
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assert!("John,32".parse::<Person>().is_ok());
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}
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#[test]
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#[should_panic]
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fn missing_age() {
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"John".parse::<Person>().unwrap();
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}
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}
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