Solution to 5.6.1

exercises/clippy/clippy1.rs

@@ -9,12 +9,10 @@
 // Execute `rustlings hint clippy1` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 use std::f32;
 
 fn main() {
-    let pi = 3.14f32;
+    let pi = f32::consts::PI;
     let radius = 5.00f32;
 
     let area = pi * f32::powi(radius, 2);

exercises/clippy/clippy2.rs

@@ -3,12 +3,10 @@
 // Execute `rustlings hint clippy2` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 fn main() {
     let mut res = 42;
     let option = Some(12);
-    for x in option {
+    if let Option::Some(x) = option {
         res += x;
     }
     println!("{}", res);

exercises/clippy/clippy3.rs

@@ -3,28 +3,27 @@
 // Here's a couple more easy Clippy fixes, so you can see its utility.
 // No hints.
 
-// I AM NOT DONE
-
 #[allow(unused_variables, unused_assignments)]
 fn main() {
     let my_option: Option<()> = None;
     if my_option.is_none() {
-        my_option.unwrap();
+        // Do not access null content
+        // my_option.unwrap();
     }
 
     let my_arr = &[
-        -1, -2, -3
-        -4, -5, -6
+        -1, -2, -3,
+        -4, -5, -6,
     ];
     println!("My array! Here it is: {:?}", my_arr);
 
-    let my_empty_vec = vec![1, 2, 3, 4, 5].resize(0, 5);
+    let mut my_empty_vec = vec![1, 2, 3, 4, 5];
+    my_empty_vec.clear();
     println!("This Vec is empty, see? {:?}", my_empty_vec);
 
     let mut value_a = 45;
     let mut value_b = 66;
     // Let's swap these two!
-    value_a = value_b;
-    value_b = value_a;
+    std::mem::swap(&mut value_a, &mut value_b);
     println!("value a: {}; value b: {}", value_a, value_b);
 }

exercises/conversions/as_ref_mut.rs

@@ -7,25 +7,36 @@
 // Execute `rustlings hint as_ref_mut` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
+use std::ops::{Deref, Mul};
 
 // Obtain the number of bytes (not characters) in the given argument.
-// TODO: Add the AsRef trait appropriately as a trait bound.
-fn byte_counter<T>(arg: T) -> usize {
+// Add the AsRef trait appropriately as a trait bound.
+fn byte_counter<T>(arg: T) -> usize
+where
+    T: AsRef<str>,
+{
     arg.as_ref().as_bytes().len()
 }
 
 // Obtain the number of characters (not bytes) in the given argument.
-// TODO: Add the AsRef trait appropriately as a trait bound.
-fn char_counter<T>(arg: T) -> usize {
+// Add the AsRef trait appropriately as a trait bound.
+fn char_counter<T>(arg: T) -> usize
+where
+    T: AsRef<str>,
+{
     arg.as_ref().chars().count()
 }
 
 // Squares a number using as_mut().
-// TODO: Add the appropriate trait bound.
-fn num_sq<T>(arg: &mut T) {
-    // TODO: Implement the function body.
-    ???
+// Add the appropriate trait bound.
+fn num_sq<T, TValue>(arg: &mut T)
+where
+    T: AsMut<TValue>,
+    TValue: Mul<Output = TValue> + Copy,
+{
+    // Implement the function body.
+    let mut x = arg.as_mut();
+    *x = (*x) * (*x);
 }
 
 #[cfg(test)]

exercises/conversions/from_into.rs

@@ -40,10 +40,46 @@ impl Default for Person {
 // If while parsing the age, something goes wrong, then return the default of
 // Person Otherwise, then return an instantiated Person object with the results
 
-// I AM NOT DONE
-
 impl From<&str> for Person {
     fn from(s: &str) -> Person {
+        // Avoid using collect() to avoid unnecessary allocations
+        let mut it = s.split(',');
+
+        if let Some(name) = it.next().filter(|n| !n.is_empty()) {
+            if let Some(age) = it.next() {
+                if let Ok(age) = age.trim().parse::<usize>() {
+                    return Person {
+                        name: name.to_string(),
+                        age,
+                    };
+                }
+            }
+        }
+
+        Person::default()
+
+        // A common way with worse performance
+        // let splited: Vec<&str> = s.split(',').collect();
+
+        // if splited.len() < 2 {
+        //     return Person::default();
+        // }
+
+        // let age = match splited[1].trim().parse::<usize>() {
+        //     Ok(age) => age,
+        //     Err(_) => return Person::default(),
+        // };
+
+        // let name = splited[0].to_string();
+
+        // if name.is_empty() {
+        //     return Person::default();
+        // }
+
+        // Person {
+        //     name,
+        //     age,
+        // }
     }
 }
 

exercises/conversions/from_str.rs

@@ -31,8 +31,6 @@ enum ParsePersonError {
     ParseInt(ParseIntError),
 }
 
-// I AM NOT DONE
-
 // Steps:
 // 1. If the length of the provided string is 0, an error should be returned
 // 2. Split the given string on the commas present in it
@@ -52,6 +50,32 @@ enum ParsePersonError {
 impl FromStr for Person {
     type Err = ParsePersonError;
     fn from_str(s: &str) -> Result<Person, Self::Err> {
+        if s.is_empty() {
+            return Err(ParsePersonError::Empty);
+        }
+
+        let mut it = s.split(',');
+
+        if let Some(name) = it.next() {
+            if name.is_empty() {
+                return Err(ParsePersonError::NoName);
+            }
+
+            if let Some(age) = it.next() {
+                let age = age.trim().parse::<usize>().map_err(ParsePersonError::ParseInt)?;
+
+                if it.next().is_none() {
+                    return Ok(Person {
+                        name: name.to_string(),
+                        age,
+                    });
+                }
+            }
+
+            return Err(ParsePersonError::BadLen);
+        }
+
+        Err(ParsePersonError::BadLen)
     }
 }
 

exercises/conversions/try_from_into.rs

@@ -27,8 +27,6 @@ enum IntoColorError {
     IntConversion,
 }
 
-// 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.
@@ -41,20 +39,39 @@ enum IntoColorError {
 impl TryFrom<(i16, i16, i16)> for Color {
     type Error = IntoColorError;
     fn try_from(tuple: (i16, i16, i16)) -> Result<Self, Self::Error> {
+        let (r, g, b) = tuple;
+
+        let r: u8 = r.try_into().map_err(|_| IntoColorError::IntConversion)?;
+        let g: u8 = g.try_into().map_err(|_| IntoColorError::IntConversion)?;
+        let b: u8 = b.try_into().map_err(|_| IntoColorError::IntConversion)?;
+
+        Ok(Color {
+            red: r,
+            green: g,
+            blue: b,
+        })
     }
 }
 
 // Array implementation
 impl TryFrom<[i16; 3]> for Color {
     type Error = IntoColorError;
     fn try_from(arr: [i16; 3]) -> Result<Self, Self::Error> {
+        let [r, g, b] = arr;
+
+        Color::try_from((r, g, b))
     }
 }
 
 // Slice implementation
 impl TryFrom<&[i16]> for Color {
     type Error = IntoColorError;
     fn try_from(slice: &[i16]) -> Result<Self, Self::Error> {
+        if slice.len() != 3 {
+            return Err(IntoColorError::BadLen);
+        }
+
+        Color::try_from((slice[0], slice[1], slice[2]))
     }
 }
 

exercises/conversions/using_as.rs

@@ -10,11 +10,9 @@
 // Execute `rustlings hint using_as` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 fn average(values: &[f64]) -> f64 {
     let total = values.iter().sum::<f64>();
-    total / values.len()
+    total / (values.len() as f64)
 }
 
 fn main() {

exercises/enums/enums1.rs

@@ -2,11 +2,13 @@
 //
 // No hints this time! ;)
 
-// I AM NOT DONE
-
 #[derive(Debug)]
 enum Message {
-    // TODO: define a few types of messages as used below
+    // define a few types of messages as used below
+    Quit,
+    Echo,
+    Move,
+    ChangeColor,
 }
 
 fn main() {

exercises/enums/enums2.rs

@@ -3,11 +3,12 @@
 // Execute `rustlings hint enums2` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 #[derive(Debug)]
 enum Message {
-    // TODO: define the different variants used below
+    Move { x: i32, y: i32 },
+    Echo(String),
+    ChangeColor(u8, u8, u8),
+    Quit,
 }
 
 impl Message {

exercises/enums/enums3.rs

@@ -5,10 +5,12 @@
 // Execute `rustlings hint enums3` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 enum Message {
-    // TODO: implement the message variant types based on their usage below
+    // implement the message variant types based on their usage below
+    ChangeColor(u8, u8, u8),
+    Echo(String),
+    Move(Point),
+    Quit,
 }
 
 struct Point {
@@ -45,6 +47,12 @@ impl State {
         // variants
         // Remember: When passing a tuple as a function argument, you'll need
         // extra parentheses: fn function((t, u, p, l, e))
+        match message {
+            Message::Quit => self.quit(),
+            Message::ChangeColor(r, g, b) => self.change_color((r, g, b)),
+            Message::Move(p) => self.move_position(p),
+            Message::Echo(msg) => self.echo(msg),
+        }
     }
 }
 

exercises/error_handling/errors1.rs

@@ -9,14 +9,12 @@
 // Execute `rustlings hint errors1` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
-pub fn generate_nametag_text(name: String) -> Option<String> {
+pub fn generate_nametag_text(name: String) -> Result<String, String> {
     if name.is_empty() {
         // Empty names aren't allowed.
-        None
+        Result::Err(String::from("`name` was empty; it must be nonempty."))
     } else {
-        Some(format!("Hi! My name is {}", name))
+        Result::Ok(format!("Hi! My name is {}", name))
     }
 }
 

exercises/error_handling/errors2.rs

@@ -19,16 +19,49 @@
 // Execute `rustlings hint errors2` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 use std::num::ParseIntError;
 
 pub fn total_cost(item_quantity: &str) -> Result<i32, ParseIntError> {
     let processing_fee = 1;
     let cost_per_item = 5;
-    let qty = item_quantity.parse::<i32>();
 
-    Ok(qty * cost_per_item + processing_fee)
+    {
+        // let qty = item_quantity.parse::<i32>();
+
+        // Ok(qty * cost_per_item + processing_fee)
+
+        // match qty {
+        //     Result::Err(err) => Err(err),
+        //     Result::Ok(qty) => Ok(qty * cost_per_item + processing_fee)
+        // }
+
+        // if let Result::Ok(qty) = qty {
+        //     Ok(qty * cost_per_item + processing_fee)
+        // }
+        // else {
+        //     qty
+        // }
+    }
+
+    // Original try! was discarded
+    {
+        // let qty = try!(item_quantity.parse::<i32>());
+
+        // Ok(qty * cost_per_item + processing_fee)
+    }
+
+    {
+        let qty = item_quantity.parse::<i32>()?;
+
+        Ok(qty * cost_per_item + processing_fee)
+    }
+
+    // I prefer this
+    // {
+    //     let qty = item_quantity.parse::<i32>();
+
+    //     qty.map(|qty| qty * cost_per_item + processing_fee)
+    // }
 }
 
 #[cfg(test)]