general code improvements

src/board.rs

@@ -68,12 +68,10 @@ impl Board {
         self
     }
 
-    pub fn possible_moves(&self, color: Piece) -> Box<dyn Iterator<Item = (usize, usize)> + '_> {
-        Box::new(
-            (0..BOARD_SIZE)
-                .flat_map(|i| (0..BOARD_SIZE).map(move |j| (i, j)))
-                .filter(move |(i, j)| self.would_prop(*i, *j, color)),
-        )
+    pub fn possible_moves(&self, color: Piece) -> impl Iterator<Item = (usize, usize)> + use<'_> {
+        (0..BOARD_SIZE)
+            .flat_map(|i| (0..BOARD_SIZE).map(move |j| (i, j)))
+            .filter(move |(i, j)| self.would_prop(*i, *j, color))
     }
 
     /// Returns a mutable reference to a place on the [`Board`]
@@ -137,8 +135,8 @@ impl Board {
     /// DO NOT USE THIS ALONE, this should be called as a part of
     /// [`Board::place`] or [`Board::place_and_prop_unchecked`]
     // TODO! this function is responsible for approx 64% of the time spent computing moves in `ComplexAgent`
-    // IDEAS: early-exit from each chain so we don't have to call `diag` (which allocs a lot and uses a lot of cycles)
     // NOTE! got it down to 24.86% (61.1% decrease) with allocator optimizations
+    // IDEAS: early-exit from each chain so we don't have to call `diag` (which allocs a lot and uses a lot of cycles)
     fn propegate_from_dry(&self, i: usize, j: usize, starting_color: Piece) -> Vec<(usize, usize)> {
         // Create all chains from the piece being propegated from in `i` and `j` coordinates
         let (i_chain, j_chain) = (