card: split up into its own module.

src/card/ord.rs

@@ -0,0 +1,46 @@
+use crate::card::{Card, PlayingCard};
+use std::cmp::Ordering;
+
+impl Ord for PlayingCard {
+    fn cmp(&self, other: &Self) -> Ordering {
+        self.abs().cmp(&other.abs())
+    }
+}
+
+impl Ord for Card {
+    fn cmp(&self, other: &Self) -> Ordering {
+        match (self, other) {
+            (Self::PlayingCard(c1), Self::PlayingCard(c2)) => c1.cmp(c2),
+            // Jokers should not really care about internal ordering.
+            (Self::Joker(_), Self::Joker(_)) => Ordering::Equal,
+            // Jokers are the lowest possible card so any Playing Cards are
+            // better than them.
+            (Self::Joker(_), _) => Ordering::Less,
+            (_, Self::Joker(_)) => Ordering::Greater,
+        }
+    }
+}
+
+impl PartialEq for PlayingCard {
+    fn eq(&self, other: &Self) -> bool {
+        self.cmp(other) == Ordering::Equal
+    }
+}
+
+impl PartialEq for Card {
+    fn eq(&self, other: &Self) -> bool {
+        self.cmp(other) == Ordering::Equal
+    }
+}
+
+impl PartialOrd for PlayingCard {
+    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
+        Some(self.cmp(other))
+    }
+}
+
+impl PartialOrd for Card {
+    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
+        Some(self.cmp(other))
+    }
+}