Refactoring, cleanup, improve modularity

Chess/nimfish/nimfishpkg/position.nim

@@ -0,0 +1,68 @@
+import std/strutils
+import std/strformat
+
+
+import bitboards
+import magics
+import pieces
+import moves
+
+
+
+type 
+
+    Position* = object
+        ## A chess position
+        
+        # Castling metadata. Updated on every move
+        castlingRights*: array[64, uint8]
+        # Number of half-moves that were performed
+        # to reach this position starting from the
+        # root of the tree
+        plyFromRoot*: int8
+        # Number of half moves since
+        # last piece capture or pawn movement.
+        # Used for the 50-move rule
+        halfMoveClock*: int8
+        # Full move counter. Increments
+        # every 2 ply (half-moves)
+        fullMoveCount*: int8
+        # En passant target square (see https://en.wikipedia.org/wiki/En_passant)
+        enPassantSquare*: Square
+
+        # The side to move
+        sideToMove*: PieceColor
+        # Positional bitboards for all pieces
+        pieces*: array[2, array[6, Bitboard]]
+        # Pieces pinned for the current side to move
+        diagonalPins*: Bitboard    # Pinned diagonally (by a queen or bishop)
+        orthogonalPins*: Bitboard  # Pinned orthogonally (by a queen or rook)
+        # Pieces checking the current side to move
+        checkers*: Bitboard
+
+
+func getKingStartingSquare*(color: PieceColor): Square {.inline.} =
+    ## Retrieves the starting square of the king
+    ## for the given color
+    case color:
+        of White:
+            return "e1".toSquare()
+        of Black:
+            return "e8".toSquare()
+        else:
+            discard
+
+
+func `[]`*(self: array[2, array[6, Bitboard]], color: PieceColor): ptr array[6, Bitboard] {.inline.} = addr self[color.int]
+func `[]`*(self: array[6, Bitboard], kind: PieceKind): ptr Bitboard {.inline.} = addr self[kind.int]
+func `[]=`*(self: var array[6, Bitboard], kind: PieceKind, bitboard: Bitboard) {.inline.} = self[kind.int] = bitboard
+
+
+func getBitboard*(self: Position, kind: PieceKind, color: PieceColor): Bitboard =
+    ## Returns the positional bitboard for the given piece kind and color
+    return self.pieces[color.int][kind.int]
+
+
+func getBitboard*(self: Position, piece: Piece): Bitboard =
+    ## Returns the positional bitboard for the given piece type
+    return self.getBitboard(piece.kind, piece.color)