rustlings/exercises/conversions/try_from_into.rs
2020-08-10 10:24:21 -04:00

136 lines
3.8 KiB
Rust

// TryFrom is a simple and safe type conversion that may fail in a controlled way under some circumstances.
// Basically, this is the same as From. The main difference is that this should return a Result type
// instead of the target type itself.
// You can read more about it at https://doc.rust-lang.org/std/convert/trait.TryFrom.html
use std::convert::{TryFrom, TryInto};
#[derive(Debug)]
struct Color {
red: u8,
green: u8,
blue: u8,
}
// I AM NOT DONE
// Your task is to complete this implementation
// 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.
//
// 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(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 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]
#[should_panic]
fn test_tuple_out_of_range_positive() {
let _ = Color::try_from((256, 1000, 10000)).unwrap();
}
#[test]
#[should_panic]
fn test_tuple_out_of_range_negative() {
let _ = Color::try_from((-1, -10, -256)).unwrap();
}
#[test]
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_array_out_of_range_positive() {
let _: Color = [1000, 10000, 256].try_into().unwrap();
}
#[test]
#[should_panic]
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_slice_out_of_range_positive() {
let arr = [10000, 256, 1000];
let _ = Color::try_from(&arr[..]).unwrap();
}
#[test]
#[should_panic]
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_slice_excess_length() {
let v = vec![0, 0, 0, 0];
let _ = Color::try_from(&v[..]).unwrap();
}
#[test]
#[should_panic]
fn test_slice_insufficient_length() {
let v = vec![0, 0];
let _ = Color::try_from(&v[..]).unwrap();
}
}