card: excessively simple card iterator

src/card/iters.rs

@@ -0,0 +1,51 @@
+use crate::card::{Card, PlayingCard, Rank, Suit};
+
+pub struct CardIterator(Card);
+
+impl Iterator for CardIterator {
+    type Item = Card;
+
+    fn next(&mut self) -> Option<Card> {
+        match self.0 {
+            Card::Joker(_) => None,
+            Card::PlayingCard(PlayingCard {
+                rank: Rank::Two,
+                suit: Suit::Spade,
+                deck,
+            }) => {
+                self.0 = Card::Joker((deck + 1) * -1);
+                None
+            }
+            Card::PlayingCard(pc) => {
+                self.0 = Card::from(i64::from(pc) + 1);
+                Some(self.0)
+            }
+        }
+    }
+}
+
+impl DoubleEndedIterator for CardIterator {
+    fn next_back(&mut self) -> Option<<Self as Iterator>::Item> {
+        match self.0 {
+            Card::Joker(_) => None,
+            Card::PlayingCard(PlayingCard {
+                rank: Rank::Three,
+                suit: Suit::Diamond,
+                deck,
+            }) => {
+                self.0 = Card::Joker((deck + 1) * -1);
+                None
+            }
+            Card::PlayingCard(pc) => {
+                self.0 = Card::from(i64::from(pc) - 1);
+                Some(self.0)
+            }
+        }
+    }
+}
+
+impl Card {
+    pub fn into_iter(self) -> CardIterator {
+        CardIterator(self)
+    }
+}

src/card/mod.rs

@@ -2,6 +2,7 @@ mod default;
 mod display;
 mod hash;
 mod impls;
+mod iters;
 mod numerics;
 mod ord;