final class Bishop: Piece, DiagonalMoves { override var unicodeRepresentation: String { return color == .Black ? "♝" : "♗" } override var pseudoLegalPositions: [Square.Position] { return getDiagonalMoves(from: position) } override var legalPositions: [Square.Position] { return pseudoLegalPositions.filter { isLegal(on: $0) } } override func move(to dst: Square.Position) { } override func isLegal(on pos: Square.Position) -> Bool { if let board = board, let s = board[pos] { if let p = s.piece { if p.color == color { return false } if p.kind == .King { delegate?.notify(.kingInCheck(self)) return false } } } return true } init(with color: Color, on position: Square.Position) { super.init(kind: .Bishop, on: position, with: color) } }