feat: finish with errors & options

exercises/error_handling/errors1.rs

@@ -5,14 +5,12 @@
 // construct to `Option` that can be used to express error conditions. Let's use it!
 // 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
+        Err("`name` was empty; it must be nonempty.".into())
     } else {
-        Some(format!("Hi! My name is {}", name))
+        Ok(format!("Hi! My name is {}", name))
     }
 }
 

exercises/error_handling/errors2.rs

@@ -17,14 +17,12 @@
 // one is a lot shorter!
 // 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>();
+    let qty = item_quantity.parse::<i32>()?;
 
     Ok(qty * cost_per_item + processing_fee)
 }

exercises/error_handling/errors3.rs

@@ -4,15 +4,13 @@
 // Why not? What should we do to fix it?
 // Execute `rustlings hint errors3` or use the `hint` watch subcommand for a hint.
 
-// I AM NOT DONE
-
 use std::num::ParseIntError;
 
 fn main() {
     let mut tokens = 100;
     let pretend_user_input = "8";
 
-    let cost = total_cost(pretend_user_input)?;
+    let cost = total_cost(pretend_user_input).expect("some error accrue");
 
     if cost > tokens {
         println!("You can't afford that many!");

exercises/error_handling/errors4.rs

@@ -1,7 +1,6 @@
 // errors4.rs
 // Execute `rustlings hint errors4` or use the `hint` watch subcommand for a hint.
 
-// I AM NOT DONE
 
 #[derive(PartialEq, Debug)]
 struct PositiveNonzeroInteger(u64);
@@ -15,6 +14,14 @@ enum CreationError {
 impl PositiveNonzeroInteger {
     fn new(value: i64) -> Result<PositiveNonzeroInteger, CreationError> {
         // Hmm...? Why is this only returning an Ok value?
+        if value == 0 {
+            return Err(CreationError::Zero);
+        }
+
+        if value < 0 {
+            return Err(CreationError::Negative);
+        }
+
         Ok(PositiveNonzeroInteger(value as u64))
     }
 }

exercises/error_handling/errors5.rs

@@ -16,14 +16,12 @@
 
 // Execute `rustlings hint errors5` or use the `hint` watch subcommand for a hint.
 
-// I AM NOT DONE
-
 use std::error;
 use std::fmt;
 use std::num::ParseIntError;
 
 // TODO: update the return type of `main()` to make this compile.
-fn main() -> Result<(), Box<dyn ???>> {
+fn main() -> Result<(), Box<dyn error::Error>> {
     let pretend_user_input = "42";
     let x: i64 = pretend_user_input.parse()?;
     println!("output={:?}", PositiveNonzeroInteger::new(x)?);

exercises/error_handling/errors6.rs

@@ -8,8 +8,6 @@
 
 // Execute `rustlings hint errors6` or use the `hint` watch subcommand for a hint.
 
-// I AM NOT DONE
-
 use std::num::ParseIntError;
 
 // This is a custom error type that we will be using in `parse_pos_nonzero()`.
@@ -24,13 +22,15 @@ impl ParsePosNonzeroError {
         ParsePosNonzeroError::Creation(err)
     }
     // TODO: add another error conversion function here.
-    // fn from_parseint...
+    fn from_parseint(err: ParseIntError) -> ParsePosNonzeroError {
+        ParsePosNonzeroError::ParseInt(err)
+    }
 }
 
 fn parse_pos_nonzero(s: &str) -> Result<PositiveNonzeroInteger, ParsePosNonzeroError> {
     // TODO: change this to return an appropriate error instead of panicking
     // when `parse()` returns an error.
-    let x: i64 = s.parse().unwrap();
+    let x: i64 = s.parse().map_err(ParsePosNonzeroError::from_parseint)?;
     PositiveNonzeroInteger::new(x).map_err(ParsePosNonzeroError::from_creation)
 }
 

exercises/options/options1.rs

@@ -1,8 +1,6 @@
 // options1.rs
 // Execute `rustlings hint options1` or use the `hint` watch subcommand for a hint.
 
-// I AM NOT DONE
-
 // This function returns how much icecream there is left in the fridge.
 // If it's before 10PM, there's 5 pieces left. At 10PM, someone eats them
 // all, so there'll be no more left :(
@@ -10,7 +8,15 @@ fn maybe_icecream(time_of_day: u16) -> Option<u16> {
     // We use the 24-hour system here, so 10PM is a value of 22 and 12AM is a value of 0
     // The Option output should gracefully handle cases where time_of_day > 23.
     // TODO: Complete the function body - remember to return an Option!
-    ???
+    if time_of_day > 23 {
+        return None;
+    }
+
+    if time_of_day >= 22 {
+        return Some(0);
+    }
+
+    return Some(5);
 }
 
 #[cfg(test)]
@@ -30,6 +36,6 @@ mod tests {
     fn raw_value() {
         // TODO: Fix this test. How do you get at the value contained in the Option?
         let icecreams = maybe_icecream(12);
-        assert_eq!(icecreams, 5);
+        assert_eq!(icecreams.unwrap(), 5);
     }
 }

exercises/options/options2.rs

@@ -1,8 +1,6 @@
 // options2.rs
 // Execute `rustlings hint options2` or use the `hint` watch subcommand for a hint.
 
-// I AM NOT DONE
-
 #[cfg(test)]
 mod tests {
     #[test]
@@ -11,7 +9,7 @@ mod tests {
         let optional_target = Some(target);
 
         // TODO: Make this an if let statement whose value is "Some" type
-        word = optional_target {
+        if let Some(word) = optional_target {
             assert_eq!(word, target);
         }
     }
@@ -26,7 +24,7 @@ mod tests {
 
         // TODO: make this a while let statement - remember that vector.pop also adds another layer of Option<T>
         // You can stack `Option<T>`'s into while let and if let
-        integer = optional_integers.pop() {
+        while let Some(Some(integer)) = optional_integers.pop() {
             assert_eq!(integer, range);
             range -= 1;
         }

exercises/options/options3.rs

@@ -1,8 +1,6 @@
 // options3.rs
 // Execute `rustlings hint options3` or use the `hint` watch subcommand for a hint.
 
-// I AM NOT DONE
-
 struct Point {
     x: i32,
     y: i32,
@@ -12,7 +10,7 @@ fn main() {
     let y: Option<Point> = Some(Point { x: 100, y: 200 });
 
     match y {
-        Some(p) => println!("Co-ordinates are {},{} ", p.x, p.y),
+        Some(ref p) => println!("Co-ordinates are {},{} ", p.x, p.y),
         _ => println!("no match"),
     }
     y; // Fix without deleting this line.

exercises/quiz2.rs

@@ -18,8 +18,6 @@
 // - The output element is going to be a Vector of strings.
 // No hints this time!
 
-// I AM NOT DONE
-
 pub enum Command {
     Uppercase,
     Trim,