Bad Safe Deque--Iteration

src/fourth.rs

@@ -162,11 +162,48 @@ impl<T> Drop for List<T> {
     }
 }
 
+pub struct IntoIter<T>(List<T>);
+
+impl<T> List<T> {
+    pub fn into_iter(self) -> IntoIter<T> {
+        IntoIter(self)
+    }
+}
+
+impl<T> Iterator for IntoIter<T> {
+    type Item = T;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        self.0.pop_front()
+    }
+}
+
+impl<T> DoubleEndedIterator for IntoIter<T> {
+    fn next_back(&mut self) -> Option<Self::Item> {
+        self.0.pop_back()
+    }
+}
+
 #[cfg(test)]
 mod test {
     use super::List;
 
     #[test]
+    fn into_iter() {
+        let mut list = List::new();
+        list.push_front(1);
+        list.push_front(2);
+        list.push_front(3);
+
+        let mut iter = list.into_iter();
+        assert_eq!(iter.next(), Some(3));
+        assert_eq!(iter.next_back(), Some(1));
+        assert_eq!(iter.next(), Some(2));
+        assert_eq!(iter.next_back(), None);
+        assert_eq!(iter.next(), None);
+    }
+
+    #[test]
     fn basics() {
         let mut list = List::new();