modes:triple: ordering done

big-c.org

@@ -5,7 +5,7 @@ Model the concept of a triple (three cards of similar rank).
 ** DONE Triple::new
 ** TODO Hand
 ** TODO Display
-** TODO Ord
+** DONE Ord
 ** TODO Hash
 ** TODO Testing
 * Backlog :backlog:

src/modes/mod.rs

@@ -1,5 +1,6 @@
 pub mod pair;
 pub mod single;
+pub mod triple;
 
 #[derive(Eq, Ord, PartialEq, PartialOrd, Debug, Copy, Clone)]
 pub enum Footstool {

src/modes/triple.rs

@@ -3,7 +3,7 @@ use crate::{
     helper::ordered,
 };
 
-#[derive(Debug, Copy, Clone)]
+#[derive(Eq, Debug, Copy, Clone)]
 pub struct Triple(Card, Card, Card);
 
 impl Triple {
@@ -30,3 +30,41 @@ impl Triple {
         }
     }
 }
+
+use std::cmp::Ordering;
+
+impl Ord for Triple {
+    fn cmp(&self, other: &Self) -> Ordering {
+        /*
+        Like pairs, we'll do a high-to-low comparison.  Since we're dealing with
+        3 items we'll need to compute potentially 3 comparisons.
+        */
+        let Triple(s1, s2, s3) = self;
+        let Triple(o1, o2, o3) = other;
+
+        let cmp = s3.cmp(o3);
+        if cmp != Ordering::Equal {
+            cmp
+        } else {
+            let cmp = s2.cmp(o2);
+            if cmp != Ordering::Equal {
+                cmp
+            } else {
+                s1.cmp(o1)
+            }
+        }
+    }
+}
+
+impl PartialEq for Triple {
+    fn eq(&self, other: &Self) -> bool {
+        self.cmp(other) == Ordering::Equal
+    }
+}
+
+impl PartialOrd for Triple {
+    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
+        Some(self.cmp(other))
+    }
+}
+