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// 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, PartialEq)]
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 to create an implementation for a tuple of three integers,
// an array of three integers and a slice of integers.
//
// Note that the implementation for tuple and array will be checked at compile time,
// but the slice implementation needs to check the slice length!
// Also note that correct RGB color values must be integers in the 0..=255 range.
// 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]
fn test_tuple_out_of_range_positive() {
assert!(Color::try_from((256, 1000, 10000)).is_err());
}
#[test]
fn test_tuple_out_of_range_negative() {
assert!(Color::try_from((-1, -10, -256)).is_err());
}
#[test]
fn test_tuple_sum() {
assert!(Color::try_from((-1, 255, 255)).is_err());
}
#[test]
fn test_tuple_correct() {
let c: Result<Color, String> = (183, 65, 14).try_into();
assert_eq!(
c,
Ok(Color {
red: 183,
green: 65,
blue: 14
})
);
}
#[test]
fn test_array_out_of_range_positive() {
let c: Color = [1000, 10000, 256].try_into();
assert!(c.is_err());
}
#[test]
fn test_array_out_of_range_negative() {
let c: Color = [-10, -256, -1].try_into();
assert!(c.is_err());
}
#[test]
fn test_array_sum() {
let c: Color = [-1, 255, 255].try_into();
assert!(c.is_err());
}
#[test]
#[test]
fn test_array_correct() {
let c: Result<Color, String> = [183, 65, 14].try_into();
assert_eq!(
c,
Ok(Color {
red: 183,
green: 65,
blue: 14
})
);
}
#[test]
fn test_slice_out_of_range_positive() {
let arr = [10000, 256, 1000];
assert!(Color::try_from(&arr[..]).is_err());
}
#[test]
fn test_slice_out_of_range_negative() {
let arr = [-256, -1, -10];
assert!(Color::try_from(&arr[..]).is_err());
}
#[test]
fn test_slice_sum() {
let arr = [-1, 255, 255];
assert!(Color::try_from(&arr[..]).is_err());
}
#[test]
fn test_slice_correct() {
let v = vec![183, 65, 14];
let c: Result<Color, String> = Color::try_from(&v[..]);
assert_eq!(
c,
Ok(Color {
red: 183,
green: 65,
blue: 14
})
);
}
#[test]
fn test_slice_excess_length() {
let v = vec![0, 0, 0, 0];
assert!(Color::try_from(&v[..]).is_err());
}
#[test]
fn test_slice_insufficient_length() {
let v = vec![0, 0];
assert!(Color::try_from(&v[..]).is_err());
}
}
|
