final class King: Piece { override var unicodeRepresentation: String { return color == .Black ? "♛" : "♕" } override var pseudoLegalPositions: [Square.Position] { [ position + (1, 0), position + (1, 1), position + (0, 1), position + (-1, 1), position + (-1, 0), position + (-1, -1), position + (0, -1), position + (1, -1), ].filter { $0.index != nil } } 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 { // TODO: Notify board of check return false } } } return true } init(with color: Color, on position: Square.Position) { super.init(kind: .King, on: position, with: color) } }