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@OlegIlyenko
Created January 9, 2011 17:41
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import io.Source
import scala.util.control.Breaks._
/**
* Scala TicTacToe game without any side effects
*
* Written in response to following post (which also contains task description):
* http://blog.tmorris.net/scala-exercise-with-types-and-abstraction/
*/
object TicTacToe {
val WinCount = 3
sealed trait Move
case object O extends Move
case object X extends Move
sealed abstract class Game[T](val board: T)
case class InProgress[T](override val board: T) extends Game[T](board)
case class Finished[T](override val board: T) extends Game[T](board)
case class Broken[T](override val board: T, val problem: String) extends Game[T](board)
case class Position(x: Int, y: Int)
type Board = Seq[Seq[Option[Move]]]
def createGame(width: Int, height: Int): InProgress[Board] =
InProgress(for (x <- 0 until width) yield for(y <- 0 until height) yield None)
def move(game: InProgress[Board], p: Position): Game[Board] =
(game.board(p.x)(p.y), placeMove(game.board, p, whoseTurn(game))) match {
case (Some(move), board) => Broken(board, "Position was already taken by " + move)
case (None, board) if finished_?(board) => Finished(board)
case (None, board) => InProgress(board)
}
def whoseTurn(game: InProgress[Board]): Move =
game.board.flatMap(_.flatten).foldLeft((0, 0)) {
case ((x, o), X) => (x + 1, o)
case ((x, o), O) => (x, o + 1)
} match {
case (x, o) if x - o <= 0 => X
case _ => O
}
def whoWon(game: Finished[Board]): Option[Move] =
(for {
x <- 0 until game.board.size
y <- 0 until game.board(0).size
curr <- game.board(x)(y)
if won_?(game.board, curr, x, y)
} yield Some(curr)) find (_.isDefined) getOrElse None
def playerAt(game: Game[Board], p: Position): Option[Move] = game.board(p.x)(p.y)
def draw(game: Game[Board]) = (for (y <- 0 until game.board(0).size) yield horizMoves(game.board, 0, y) map {
case Some(m) => m.toString
case None => " "
} mkString " | ") mkString ("\n" + ("-" * game.board.size).mkString("-+-") + "\n")
private def won_?(board: Board, m: Move, x: Int, y: Int): Boolean =
won_?(horizMoves(board, x, y), m) || won_?(vertMoves(board, x, y), m) ||
won_?(diagRightMoves(board, x, y), m) || won_?(diagRightMoves(board, x, y), m)
private def won_?(moves: Seq[Option[Move]], m: Move): Boolean = moves.foldLeft(List(0)) {
case (count :: rest, Some(`m`)) => count + 1 :: rest
case (counts, _) => 0 :: counts
}.max >= WinCount
private def horizMoves(board: Board, x: Int, y: Int) = for (xx <- x until board.size) yield board(xx)(y)
private def vertMoves(board: Board, x: Int, y: Int) = for (yy <- y until board(x).size) yield board(x)(yy)
private def diagRightMoves(board: Board, x: Int, y: Int) =
for ((xx, yy) <- (x until board.size) zip (y until board(x).size)) yield board(xx)(yy)
private def diagLeftMoves(board: Board, x: Int, y: Int) =
for ((xx, yy) <- (0 to x by -1) zip (y until board(x).size)) yield board(xx)(yy)
private def placeMove(board: Board, p: Position, m: Move) =
board.updated(p.x, board(p.x).updated(p.y, Some(m)))
private def finished_?(board: Board) =
board.flatMap(_.flatten).size == board.size * board(0).size || whoWon(Finished(board)).isDefined
}
object Int {
def unapply(s: String): Option[Int] = try {
Some(s.toInt)
} catch {
case _ : java.lang.NumberFormatException => None
}
}
object TicTacToeGame extends Application {
import TicTacToe._
val game = createGame(3, 3)
println("Welcome to Tic Tac Toe!")
prompt(game)
breakable {
Source.stdin.getLines.map(_.split("\\s*,\\s*").toList match {
case List(Int(x), Int(y)) if x < 3 && y < 3 => Some(Position(x, y))
case _ => println("Invalid position, should be: x, y"); None
}).filter(_.isDefined).map(_.get).foldLeft(game: Game[Board]) {
case (g @ InProgress(_), p) =>
move(g, p) match {
case game @ InProgress(_) => prompt(game)
case game @ Broken(_, problem) => print("Problem: " + problem); prompt(g)
case game @ Finished(_) =>
println(draw(game) + "\n" + "Game finished, " + whoWon(game) + " won!"); break; game
}
case _ => println("Wrong state!"); game
}
}
println("Bye!")
def prompt(game: InProgress[Board]): InProgress[Board] = {
print("\n" + draw(game) + "\n" + whoseTurn(game) + "> ");
game
}
}
@annoynimouse
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также думаю, в комментарии стоит включить ссылку на http://blog.tmorris.net/scala-exercise-with-types-and-abstraction/ и формулировку задачи

@wmhtet
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wmhtet commented Nov 5, 2011

I have studied and blogged about this project here http://blog.aunndroid.com/2011/11/chewy-code-scala-tictactoe-part-1.html

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