perf: use iterator in bitboard serialization

1 files changed, 16 insertions, 8 deletions

diff --git a/src/bitboard.rs b/src/bitboard.rs
index 056822b..48a60d8 100644
--- a/src/bitboard.rs
+++ b/src/bitboard.rs
@@ -28,7 +28,7 @@ pub trait BitboardFns {
     fn bitscan_and_reset(&mut self) -> Square;
 
     /// Convert bitboard into the list of squares
-    fn serialize(self) -> Vec<Square>;
+    fn serialize(self) -> SquareIterator;
 
     /// Return bitboard shifted nort, no wrap occurs
     fn nort_one(self) -> Self;
@@ -109,12 +109,8 @@ impl BitboardFns for Bitboard {
         square
     }
 
-    fn serialize(mut self) -> Vec<Square> {
-        let mut serialized = Vec::with_capacity(64);
-        while self > 0 {
-            serialized.push(self.bitscan_and_reset());
-        }
-        serialized
+    fn serialize(self) -> SquareIterator {
+        SquareIterator(self)
     }
 
     fn nort_one(self) -> Self {
@@ -150,6 +146,18 @@ impl BitboardFns for Bitboard {
     }
 }
 
+pub struct SquareIterator (Bitboard);
+impl Iterator for SquareIterator {
+    type Item = Square;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        if self.0 > 0 {
+            return Some(self.0.bitscan_and_reset());
+        }
+        None
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;
@@ -184,7 +192,7 @@ mod tests {
     #[test]
     fn test_serialize_bitboard() {
         let bb = 1 << 4 | 1 << 15 | 1 << 60;
-        let serialized = bb.serialize();
+        let serialized = bb.serialize().collect::<Vec<_>>();
         assert_eq!(serialized[0], Square::from(4));
         assert_eq!(serialized[1], Square::from(15));
         assert_eq!(serialized[2], Square::from(60));