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feat: Rewrite try_from_into (#393)
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ikar49 authored May 15, 2020
1 parent d6c0a68 commit 763aa6e
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3 changes: 2 additions & 1 deletion exercises/conversions/from_str.rs
Original file line number Diff line number Diff line change
Expand Up @@ -17,6 +17,7 @@ struct Person {
// 3. Extract the first element from the split operation and use it as the name
// 4. If the name is empty, then return an error
// 5. Extract the other element from the split operation and parse it into a `usize` as the age
// with something like `"4".parse::<usize>()`.
// If while parsing the age, something goes wrong, then return an error
// Otherwise, then return a Result of a Person object
impl FromStr for Person {
Expand Down Expand Up @@ -82,4 +83,4 @@ mod tests {
",one".parse::<Person>().unwrap();
}

}
}
138 changes: 83 additions & 55 deletions exercises/conversions/try_from_into.rs
Original file line number Diff line number Diff line change
Expand Up @@ -5,98 +5,126 @@
use std::convert::{TryInto, TryFrom};

#[derive(Debug)]
struct Person {
name: String,
age: usize,
struct Color {
red: u8,
green: u8,
blue: u8,
}

// I AM NOT DONE

// Your task is to complete this implementation
// in order for the line `let p = Person::try_from("Mark,20")` to compile
// and return an Ok result of inner type Person.
// Please note that you'll need to parse the age component into a `usize`
// with something like `"4".parse::<usize>()`. The outcome of this needs to
// be handled appropriately.
// and return an Ok result of inner type Color.
// You need create implementation for a tuple of three integer,
// an array of three integer and slice of integer.
//
// Steps:
// 1. If the length of the provided string is 0, then return an error
// 2. Split the given string on the commas present in it
// 3. Extract the first element from the split operation and use it as the name
// 4. If the name is empty, then return an error.
// 5. Extract the other element from the split operation and parse it into a `usize` as the age
// If while parsing the age, something goes wrong, then return an error
// Otherwise, then return a Result of a Person object
impl TryFrom<&str> for Person {
// Note, that implementation for tuple and array will be checked at compile-time,
// but slice implementation need check slice length!
// Also note, that chunk of correct rgb color must be integer in range 0..=255.

// Tuple implementation
impl TryFrom<(i16, i16, i16)> for Color {
type Error = String;
fn try_from(s: &str) -> Result<Self, Self::Error> {
fn try_from(tuple: (i16, i16, i16)) -> Result<Self, Self::Error> {
}
}

// Array implementation
impl TryFrom<[i16; 3]> for Color {
type Error = String;
fn try_from(arr: [i16; 3]) -> Result<Self, Self::Error> {
}
}

// Slice implementation
impl TryFrom<&[i16]> for Color {
type Error = String;
fn try_from(slice: &[i16]) -> Result<Self, Self::Error> {
}
}

fn main() {
// Use the `from` function
let p1 = Person::try_from("Mark,20");
// Since From is implemented for Person, we should be able to use Into
let p2: Result<Person, _> = "Gerald,70".try_into();
println!("{:?}", p1);
println!("{:?}", p2);
let c1 = Color::try_from((183, 65, 14));
println!("{:?}", c1);

// Since From is implemented for Color, we should be able to use Into
let c2: Result<Color, _> = [183, 65, 14].try_into();
println!("{:?}", c2);

let v = vec![183, 65, 14];
// With slice we should use `from` function
let c3 = Color::try_from(&v[..]);
println!("{:?}", c3);
// or take slice within round brackets and use Into
let c4: Result<Color, _> = (&v[..]).try_into();
println!("{:?}", c4);
}

#[cfg(test)]
mod tests {
use super::*;

#[test]
fn test_bad_convert() {
// Test that error is returned when bad string is provided
let p = Person::try_from("");
assert!(p.is_err());
}
#[test]
fn test_good_convert() {
// Test that "Mark,20" works
let p = Person::try_from("Mark,20");
assert!(p.is_ok());
let p = p.unwrap();
assert_eq!(p.name, "Mark");
assert_eq!(p.age, 20);
#[should_panic]
fn test_tuple_out_of_range_positive() {
let _ = Color::try_from((256, 1000, 10000)).unwrap();
}
#[test]
#[should_panic]
fn test_panic_empty_input() {
let p: Person = "".try_into().unwrap();
fn test_tuple_out_of_range_negative() {
let _ = Color::try_from((-1, -10, -256)).unwrap();
}
#[test]
#[should_panic]
fn test_panic_bad_age() {
let p = Person::try_from("Mark,twenty").unwrap();
fn test_tuple_correct() {
let c: Color = (183, 65, 14).try_into().unwrap();
assert_eq!(c.red, 183);
assert_eq!(c.green, 65);
assert_eq!(c.blue, 14);
}

#[test]
#[should_panic]
fn test_missing_comma_and_age() {
let _: Person = "Mark".try_into().unwrap();
fn test_array_out_of_range_positive() {
let _: Color = [1000, 10000, 256].try_into().unwrap();
}

#[test]
#[should_panic]
fn test_missing_age() {
let _: Person = "Mark,".try_into().unwrap();
fn test_array_out_of_range_negative() {
let _: Color = [-10, -256, -1].try_into().unwrap();
}
#[test]
fn test_array_correct() {
let c: Color = [183, 65, 14].try_into().unwrap();
assert_eq!(c.red, 183);
assert_eq!(c.green, 65);
assert_eq!(c.blue, 14);
}

#[test]
#[should_panic]
fn test_missing_name() {
let _ : Person = ",1".try_into().unwrap();
fn test_slice_out_of_range_positive() {
let arr = [10000, 256, 1000];
let _ = Color::try_from(&arr[..]).unwrap();
}

#[test]
#[should_panic]
fn test_missing_name_and_age() {
let _: Person = ",".try_into().unwrap();
fn test_slice_out_of_range_negative() {
let arr = [-256, -1, -10];
let _ = Color::try_from(&arr[..]).unwrap();
}
#[test]
fn test_slice_correct() {
let v = vec![183, 65, 14];
let c = Color::try_from(&v[..]).unwrap();
assert_eq!(c.red, 183);
assert_eq!(c.green, 65);
assert_eq!(c.blue, 14);
}

#[test]
#[should_panic]
fn test_missing_name_and_invalid_age() {
let _: Person = ",one".try_into().unwrap();
fn test_slice_excess_length() {
let v = vec![0, 0, 0, 0];
let _ = Color::try_from(&v[..]).unwrap();
}
}
}
5 changes: 3 additions & 2 deletions info.toml
Original file line number Diff line number Diff line change
Expand Up @@ -799,5 +799,6 @@ name = "from_str"
path = "exercises/conversions/from_str.rs"
mode = "test"
hint = """
If you've already solved try_from_into.rs, then this is almost a copy-paste.
Otherwise, go ahead and solve try_from_into.rs first."""
The implementation of FromStr should return an Ok with a Person object,
or an Err with a string if the string is not valid.
This is a some like an `try_from_into` exercise."""

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