day(07): don't implement Ord

Makes it easier to implement a function that generates comparator based
on the card ranking and the hand type deduction.

Signed-off-by: Matej Focko <mfocko@redhat.com>

src/bin/day07.rs

@@ -20,7 +20,7 @@ enum HandType {
 }
 
 lazy_static! {
-    static ref CARDS: Vec<char> =
+    static ref CARDS_1: Vec<char> =
         vec!['2', '3', '4', '5', '6', '7', '8', '9', 'T', 'J', 'Q', 'K', 'A',];
     static ref CARDS_2: Vec<char> =
         vec!['J', '2', '3', '4', '5', '6', '7', '8', '9', 'T', 'Q', 'K', 'A',];
@@ -45,10 +45,14 @@ impl FromStr for Hand {
     }
 }
 
-impl Ord for Hand {
+impl Hand {
-    fn cmp(&self, other: &Self) -> cmp::Ordering {
+    fn make_comparator<'a>(
-        let my_type = self.hand_type();
+        card_ordering: &'a [char],
-        let other_type = other.hand_type();
+        hand_type_getter: &'a dyn Fn(&Self) -> HandType,
+    ) -> impl Fn(&Hand, &Hand) -> cmp::Ordering + 'a {
+        |x: &Self, y: &Self| {
+            let my_type = hand_type_getter(x);
+            let other_type = hand_type_getter(y);
 
             match my_type.partial_cmp(&other_type) {
                 Some(cmp::Ordering::Equal) => {}
@@ -56,13 +60,13 @@ impl Ord for Hand {
                 _ => {}
             }
 
-        for (my, other) in self.cards.iter().zip(other.cards.iter()) {
+            for (my, other) in x.cards.iter().zip(y.cards.iter()) {
-            let l = CARDS
+                let l = card_ordering
                     .iter()
                     .enumerate()
                     .find_map(|(i, c)| if c == my { Some(i) } else { None })
                     .unwrap();
-            let r = CARDS
+                let r = card_ordering
                     .iter()
                     .enumerate()
                     .find_map(|(i, c)| if c == other { Some(i) } else { None })
@@ -79,14 +83,7 @@ impl Ord for Hand {
         }
     }
 
-impl PartialOrd for Hand {
+    fn hand_type_no_joker(&self) -> HandType {
-    fn partial_cmp(&self, other: &Self) -> Option<cmp::Ordering> {
-        Some(self.cmp(other))
-    }
-}
-
-impl Hand {
-    fn hand_type(&self) -> HandType {
         let freqs = self.cards.iter().counts();
 
         let mut pairs = 0;
@@ -154,6 +151,23 @@ impl Hand {
 struct Day07 {
     hands: Vec<Hand>,
 }
+
+impl Day07 {
+    fn solve(
+        &mut self,
+        card_ordering: &[char],
+        hand_type_getter: &dyn Fn(&Hand) -> HandType,
+    ) -> i32 {
+        self.hands
+            .sort_by(Hand::make_comparator(card_ordering, hand_type_getter));
+        self.hands
+            .iter()
+            .enumerate()
+            .map(|(r, h)| (r as i32 + 1) * h.bid)
+            .sum()
+    }
+}
+
 impl Solution<Output1, Output2> for Day07 {
     fn new<P: AsRef<Path>>(pathname: P) -> Self {
         let hands = file_to_structs(pathname);
@@ -162,49 +176,11 @@ impl Solution<Output1, Output2> for Day07 {
     }
 
     fn part_1(&mut self) -> Output1 {
-        self.hands.sort();
+        self.solve(&CARDS_1, &Hand::hand_type_no_joker)
-        self.hands
-            .iter()
-            .enumerate()
-            .map(|(r, h)| (r as i32 + 1) * h.bid)
-            .sum()
     }
 
     fn part_2(&mut self) -> Output2 {
-        self.hands.sort_by(|x, y| {
+        self.solve(&CARDS_2, &Hand::hand_type_with_joker)
-            let my_type = x.hand_type_with_joker();
-            let other_type = y.hand_type_with_joker();
-
-            match my_type.partial_cmp(&other_type) {
-                Some(core::cmp::Ordering::Equal) => {}
-                ord => return ord.unwrap(),
-            }
-
-            for (my, other) in x.cards.iter().zip(y.cards.iter()) {
-                let l = CARDS_2
-                    .iter()
-                    .enumerate()
-                    .find_map(|(i, c)| if c == my { Some(i) } else { None })
-                    .unwrap();
-                let r = CARDS_2
-                    .iter()
-                    .enumerate()
-                    .find_map(|(i, c)| if c == other { Some(i) } else { None })
-                    .unwrap();
-
-                match l.partial_cmp(&r) {
-                    Some(core::cmp::Ordering::Equal) => {}
-                    ord => return ord.unwrap(),
-                }
-            }
-
-            unreachable!()
-        });
-        self.hands
-            .iter()
-            .enumerate()
-            .map(|(r, h)| (r as i32 + 1) * h.bid)
-            .sum()
     }
 }