Improve list by adding iterator trait

src/utility/list.rs

@@ -77,7 +77,7 @@ impl<T> DoublyLinkedList<T> {
         }
     }
     
-    /// Remove the item at the end of the list
+    /// Retrieve and remove the item at the end of the list
     pub fn pop_back(&mut self) -> Option<T> {
         self.tail.take().map(|prev_tail| {
             self.size -= 1;
@@ -94,7 +94,7 @@ impl<T> DoublyLinkedList<T> {
         })
     }
 
-    /// Remove the item at the start of the list
+    /// Retrieve and remove the item at the start of the list
     pub fn pop_front(&mut self) -> Option<T> {
         self.head.take().map(|prev_head| {
             self.size -= 1;
@@ -124,6 +124,43 @@ impl<T> Drop for DoublyLinkedList<T> {
     }
 }
 
+impl<T> IntoIterator for DoublyLinkedList<T> {
+    type Item = <ListIterator<T> as Iterator>::Item;
+
+    type IntoIter = ListIterator<T>;
+
+    fn into_iter(self) -> Self::IntoIter {
+        Self::IntoIter::new(self)
+    }
+}
+
+pub struct ListIterator<T> {
+    list: DoublyLinkedList<T>,
+}
+
+impl<T> ListIterator<T> {
+    fn new(list: DoublyLinkedList<T>) -> Self {
+        Self { list }
+    }
+}
+
+impl<T> Iterator for ListIterator<T> {
+    type Item = T;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        self.list.pop_front()
+    }
+}
+
+impl<T> DoubleEndedIterator for ListIterator<T> {
+    fn next_back(&mut self) -> Option<Self::Item> {
+        self.list.pop_back()
+    }
+}
+
+pub type List<T> = DoublyLinkedList<T>;
+pub type ListInt = List<i32>;
+
 #[cfg(test)]
 mod test {
 
@@ -138,5 +175,4 @@ mod test {
         assert_eq!(list.pop_front().unwrap(), 5);
     }
 
-
 }