Coderetreat2012 Lifegame実装例(Scala)

BoardTest.scala

package lifegame

import org.scalatest._
import junit.JUnitRunner
import org.junit.runner.RunWith

class Board(size: (Int, Int), alivePoints: Set[(Int, Int)]) {
  type Coordinate = (Int, Int)

  val allCoordinates = coordinates((0, 0), (size._1 - 1, size._2 - 1))

  def coordinates(begin: Coordinate, end: Coordinate): Seq[Seq[Coordinate]] =
    begin._2.to(end._2).map((col) => begin._1.to(end._1).map((_, col)))

  def neighbors(point: Coordinate) = coordinates((point._1 - 1, point._2 - 1), (point._1 + 1, point._2 + 1))

  def aliveNext(point: Coordinate): Boolean = {
    val aliveNeighborsCount = neighbors(point).flatten.filter((p) => p != point && alivePoints.contains(p)).size
    isAlive(point) match {
      case true => 1 < aliveNeighborsCount && aliveNeighborsCount < 4
      case false => aliveNeighborsCount == 3
    }
  }

  def isAlive(point: Coordinate): Boolean = point match {
    case p: (Int, Int) if alivePoints.contains(p) => true
    case _ => false
  }

  def next: Board = new Board(size, allCoordinates.flatten.filter((p) => aliveNext(p)).toSet)

  override def toString: String =
    allCoordinates.map((row) =>
      row.map((point) => if (isAlive(point)) "O" else "X").mkString
    ).mkString("\n")
}

@RunWith(classOf[JUnitRunner])
class BoardTest extends FunSuite {

  test("toString") {
    val sut = new Board((3, 3), Set((0, 0), (0, 1), (1, 0)))

    val expected = """OOX
                     |OXX
                     |XXX""".stripMargin

    assert(sut.toString === expected)
  }

  test("next generation") {
    val sut = new Board((3, 3), Set((0, 0), (0, 1), (1, 0)))

    val actual = sut.next

    val expected = """OOX
                     |OOX
                     |XXX""".stripMargin
    assert(actual.toString === expected)
  }

  test("next generation 2") {
    val sut = new Board((3,3), Set((0, 0), (0, 1), (0, 2)))

    val actual = sut.next

    val expected ="""XXX
                    |OOX
                    |XXX""".stripMargin
    assert(actual.toString === expected)
  }

  /*
   * 誕生：指定セル 死亡、隣接セル 生存数が3であった場合、次の世代では生存になる
   * 維持：指定セル 生存、隣接セル 2 <= 生存数 <= 3の場合、次の世代では生存
   * 過疎：指定セル 生存、隣接セル 生存数 < 2の場合、次の世代では死亡
   * 過密：指定セル 生存、隣接セル 3 < 生存数の場合、次の世代では死亡
   */
  test("セルが生存していて近傍セルの生存数が3の場合、次世代で生存") {
    val sut = new Board((3, 3), Set((0, 0), (0, 1), (1, 0), (1, 1)))

    assert(sut.aliveNext((0, 0)) === true)
  }

  test("セルが生存していて近傍セルの生存数が2の場合、次世代で生存") {
    val sut = new Board((3, 3), Set((0, 0), (0, 1), (1, 0)))

    assert(sut.aliveNext((0, 0)) === true)
  }

  test("セルが生存していて近傍セルの生存数が4以上の場合、次世代で死亡") {
    val sut = new Board((3, 3), Set((0, 0), (0, 1), (0, 2), (1, 0), (1, 1)))

    assert(sut.aliveNext((1, 1)) === false)
  }

  test("セルが死亡していて近傍セルの生存数が3以上の場合、次世代で生存") {
    val sut = new Board((3, 3), Set((0, 0), (0, 1), (1, 0)))

    assert(sut.aliveNext((1, 1)) === true)
  }

}