Merge pull request #438 from lenguyenthanh/which-pieceMap-is-better

Implement faster pieceMap

src/main/scala/ByColor.scala

@@ -44,6 +44,10 @@ case class ByColor[A](white: A, black: A):
     f(white)
     f(black)
 
+  def foreach[U](f: (Color, A) => U): Unit =
+    f(White, white)
+    f(Black, black)
+
   def forall(pred: A => Boolean) = pred(white) && pred(black)
 
   def exists(pred: A => Boolean) = pred(white) || pred(black)

src/main/scala/Role.scala

@@ -96,6 +96,22 @@ case class ByRole[A](pawn: A, knight: A, bishop: A, rook: A, queen: A, king: A):
   def fold[B](z: B)(f: (B, Role, A) => B): B =
     f(f(f(f(f(f(z, Pawn, pawn), Knight, knight), Bishop, bishop), Rook, rook), Queen, queen), King, king)
 
+  def foreach[U](f: A => U): Unit =
+    f(pawn)
+    f(knight)
+    f(bishop)
+    f(rook)
+    f(queen)
+    f(king)
+
+  def foreach[U](f: (Role, A) => U): Unit =
+    f(Pawn, pawn)
+    f(Knight, knight)
+    f(Bishop, bishop)
+    f(Rook, rook)
+    f(Queen, queen)
+    f(King, king)
+
   def findRole(f: A => Boolean): Option[Role] =
     if f(pawn) then Some(Pawn)
     else if f(knight) then Some(Knight)

src/main/scala/bitboard/Board.scala

@@ -145,9 +145,15 @@ case class Board(
   inline def isOccupied(inline p: Piece) =
     piece(p).nonEmpty
 
-  // TODO remove unsafe get
+  // benchmarked: https://github.com/lichess-org/scalachess/pull/438
   lazy val pieceMap: Map[Square, Piece] =
-    occupied.squares.view.map(s => (s, pieceAt(s).get)).toMap
+    val m = Map.newBuilder[Square, Piece]
+    byColor.foreach: (color, c) =>
+      byRole.foreach: (role, r) =>
+        val piece = color - role
+        (c & r).foreach: s =>
+          m += s -> piece
+    m.result
 
   def piecesOf(c: Color): Map[Square, Piece] =
     pieceMap.filter((_, p) => p.color == c)