September Morn Update

Task/Fibonacci-sequence/Rust/fibonacci-sequence-5.rust

@@ -0,0 +1,29 @@
+use std::mem;
+
+struct Fib {
+    prev: usize,
+    curr: usize,
+}
+
+impl Fib {
+    fn new() -> Self {
+        Fib {prev: 0, curr: 1}
+    }
+}
+
+impl Iterator for Fib {
+    type Item = usize;
+    fn next(&mut self) -> Option<Self::Item>{
+        mem::swap(&mut self.curr, &mut self.prev);
+        self.curr.checked_add(self.prev).map(|n| {
+            self.curr = n;
+            n
+        })
+    }
+}
+
+fn main() {
+    for num in Fib::new() {
+        println!("{}", num);
+    }
+}