feat: Rewrite try_from_into (#393)

Author: ikar49

exercises/conversions/from_str.rs

@@ -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 {
@@ -82,4 +83,4 @@ mod tests {
         ",one".parse::<Person>().unwrap();
     }
 
-}
+}

exercises/conversions/try_from_into.rs

@@ -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();
     }
-}
+}

info.toml

@@ -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."""