rustlings: complete 12

7 files changed, 113 insertions, 13 deletions

diff --git a/rustlings/.rustlings-state.txt b/rustlings/.rustlings-state.txt
index 8b4959e..dac5f44 100644
--- a/rustlings/.rustlings-state.txt
+++ b/rustlings/.rustlings-state.txt
@@ -1,6 +1,6 @@
 DON'T EDIT THIS FILE!
 
-options1
+errors1
 
 intro1
 intro2
@@ -48,4 +48,7 @@ modules3
 hashmaps1
 hashmaps2
 hashmaps3
-quiz2
\ No newline at end of file
+quiz2
+options1
+options2
+options3
\ No newline at end of file
diff --git a/rustlings/exercises/12_options/options1.rs b/rustlings/exercises/12_options/options1.rs
index d0c412a..be97952 100644
--- a/rustlings/exercises/12_options/options1.rs
+++ b/rustlings/exercises/12_options/options1.rs
@@ -3,7 +3,13 @@
 // someone eats it all, so no ice cream is left (value 0). Return `None` if
 // `hour_of_day` is higher than 23.
 fn maybe_ice_cream(hour_of_day: u16) -> Option<u16> {
-    // TODO: Complete the function body.
+    if hour_of_day >= 24 {
+        return None;
+    }
+    if hour_of_day >= 22 {
+        return Some(0);
+    }
+    Some(5)
 }
 
 fn main() {
@@ -18,7 +24,7 @@ mod tests {
     fn raw_value() {
         // TODO: Fix this test. How do you get the value contained in the
         // Option?
-        let ice_creams = maybe_ice_cream(12);
+        let ice_creams = maybe_ice_cream(12).unwrap();
 
         assert_eq!(ice_creams, 5); // Don't change this line.
     }
diff --git a/rustlings/exercises/12_options/options2.rs b/rustlings/exercises/12_options/options2.rs
index 07c27c6..1039d61 100644
--- a/rustlings/exercises/12_options/options2.rs
+++ b/rustlings/exercises/12_options/options2.rs
@@ -10,7 +10,7 @@ mod tests {
         let optional_target = Some(target);
 
         // TODO: Make this an if-let statement whose value is `Some`.
-        word = optional_target {
+        if let Some(word) = optional_target {
             assert_eq!(word, target);
         }
     }
@@ -29,7 +29,7 @@ mod tests {
         // TODO: Make this a while-let statement. Remember that `Vec::pop()`
         // adds another layer of `Option`. You can do nested pattern matching
         // in if-let and while-let statements.
-        integer = optional_integers.pop() {
+        while let Some(Some(integer)) = optional_integers.pop() {
             assert_eq!(integer, cursor);
             cursor -= 1;
         }
diff --git a/rustlings/exercises/12_options/options3.rs b/rustlings/exercises/12_options/options3.rs
index c97b1d3..aecb7a5 100644
--- a/rustlings/exercises/12_options/options3.rs
+++ b/rustlings/exercises/12_options/options3.rs
@@ -9,7 +9,7 @@ fn main() {
 
     // TODO: Fix the compiler error by adding something to this match statement.
     match optional_point {
-        Some(p) => println!("Coordinates are {},{}", p.x, p.y),
+        Some(ref p) => println!("Coordinates are {},{}", p.x, p.y),
         _ => panic!("No match!"),
     }
 
diff --git a/rustlings/solutions/12_options/options1.rs b/rustlings/solutions/12_options/options1.rs
index dcf2377..4d615dd 100644
--- a/rustlings/solutions/12_options/options1.rs
+++ b/rustlings/solutions/12_options/options1.rs
@@ -1,4 +1,39 @@
+// This function returns how much icecream there is left in the fridge.
+// If it's before 22:00 (24-hour system), then 5 scoops are left. At 22:00,
+// someone eats it all, so no icecream is left (value 0). Return `None` if
+// `hour_of_day` is higher than 23.
+fn maybe_icecream(hour_of_day: u16) -> Option<u16> {
+    match hour_of_day {
+        0..=21 => Some(5),
+        22..=23 => Some(0),
+        _ => None,
+    }
+}
+
 fn main() {
-    // DON'T EDIT THIS SOLUTION FILE!
-    // It will be automatically filled after you finish the exercise.
+    // You can optionally experiment here.
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn raw_value() {
+        // Using `unwrap` is fine in a test.
+        let icecreams = maybe_icecream(12).unwrap();
+
+        assert_eq!(icecreams, 5);
+    }
+
+    #[test]
+    fn check_icecream() {
+        assert_eq!(maybe_icecream(0), Some(5));
+        assert_eq!(maybe_icecream(9), Some(5));
+        assert_eq!(maybe_icecream(18), Some(5));
+        assert_eq!(maybe_icecream(22), Some(0));
+        assert_eq!(maybe_icecream(23), Some(0));
+        assert_eq!(maybe_icecream(24), None);
+        assert_eq!(maybe_icecream(25), None);
+    }
 }
diff --git a/rustlings/solutions/12_options/options2.rs b/rustlings/solutions/12_options/options2.rs
index dcf2377..0f24665 100644
--- a/rustlings/solutions/12_options/options2.rs
+++ b/rustlings/solutions/12_options/options2.rs
@@ -1,4 +1,37 @@
 fn main() {
-    // DON'T EDIT THIS SOLUTION FILE!
-    // It will be automatically filled after you finish the exercise.
+    // You can optionally experiment here.
+}
+
+#[cfg(test)]
+mod tests {
+    #[test]
+    fn simple_option() {
+        let target = "rustlings";
+        let optional_target = Some(target);
+
+        // if-let
+        if let Some(word) = optional_target {
+            assert_eq!(word, target);
+        }
+    }
+
+    #[test]
+    fn layered_option() {
+        let range = 10;
+        let mut optional_integers: Vec<Option<i8>> = vec![None];
+
+        for i in 1..=range {
+            optional_integers.push(Some(i));
+        }
+
+        let mut cursor = range;
+
+        // while-let with nested pattern matching
+        while let Some(Some(integer)) = optional_integers.pop() {
+            assert_eq!(integer, cursor);
+            cursor -= 1;
+        }
+
+        assert_eq!(cursor, 0);
+    }
 }
diff --git a/rustlings/solutions/12_options/options3.rs b/rustlings/solutions/12_options/options3.rs
index dcf2377..c918f71 100644
--- a/rustlings/solutions/12_options/options3.rs
+++ b/rustlings/solutions/12_options/options3.rs
@@ -1,4 +1,27 @@
+#[derive(Debug)]
+struct Point {
+    x: i32,
+    y: i32,
+}
+
 fn main() {
-    // DON'T EDIT THIS SOLUTION FILE!
-    // It will be automatically filled after you finish the exercise.
+    let optional_point = Some(Point { x: 100, y: 200 });
+
+    // Solution 1: Matching over the `Option` (not `&Option`) but without moving
+    // out of the `Some` variant.
+    match optional_point {
+        Some(ref p) => println!("Coordinates are {},{}", p.x, p.y),
+        //   ^^^ added
+        _ => panic!("No match!"),
+    }
+
+    // Solution 2: Matching over a reference (`&Option`) by added `&` before
+    // `optional_point`.
+    match &optional_point {
+        //^ added
+        Some(p) => println!("Coordinates are {},{}", p.x, p.y),
+        _ => panic!("No match!"),
+    }
+
+    println!("{optional_point:?}");
 }