random.scala

JAVA 语言的函数式编程扩展

/*                     __                                               *\
**     ________ ___   / /  ___     Scala API                            **
**    / __/ __// _ | / /  / _ |    (c) 2006-2007, LAMP/EPFL             **
**  __\ \/ /__/ __ |/ /__/ __ |    http://scala-lang.org/               **
** /____/\___/_/ |_/____/_/ | |                                         **
**                          |/                                          **
\*                                                                      */

// $Id: Random.scala 14498 2008-04-04 12:12:27Z washburn $


package scala

/**
 *  @author Stephane Micheloud
 */
class Random(self0: System.Random) {
  private var rnd = self0 // see setSeed(seed)
  def self = rnd

  /** Creates a new random number generator using a single long seed. */
  def this(seed: Long) = this(new System.Random(seed.toInt))

  /** Creates a new random number generator using a single integer seed. */
  def this(seed: Int) = this(new System.Random(seed))

  /** Creates a new random number generator. */
  def this() = this(new System.Random(System.Environment.TickCount))

  /** Returns the next pseudorandom, uniformly distributed boolean value
   *  from this random number generator's sequence.
   */
  def nextBoolean(): Boolean = (nextInt() & 0x1) == 1

  /** Generates random bytes and places them into a user-supplied byte
   *  array.
   */
  def nextBytes(bytes: Array[Byte]) { rnd.NextBytes(bytes) }

  /** Returns the next pseudorandom, uniformly distributed double value
   *  between 0.0 and 1.0 from this random number generator's sequence.
   */
  def nextDouble(): Double = rnd.NextDouble()

  /** Returns the next pseudorandom, uniformly distributed float value
   *  between 0.0 and 1.0 from this random number generator's sequence.
   */
  def nextFloat(): Float = nextDouble().toFloat

  /** Returns the next pseudorandom, Gaussian ("normally") distributed
   *  double value with mean 0.0 and standard deviation 1.0 from this
   *  random number generator's sequence.
   */
  //def nextGaussian(): Double

  /** Returns the next pseudorandom, uniformly distributed int value
   *  from this random number generator's sequence.
   */
  def nextInt(): Int = rnd.Next()

  /** Returns a pseudorandom, uniformly distributed int value between 0
   *  (inclusive) and the specified value (exclusive), drawn from this
   *  random number generator's sequence.
   */
  def nextInt(n: Int): Int = rnd.Next(0, n)

  /** Returns the next pseudorandom, uniformly distributed long value
   *  from this random number generator's sequence.
   */
  def nextLong(): Long = nextInt().toLong // 2x nextInt() ?!

  def setSeed(seed: Long) { rnd = new System.Random(seed.toInt) }

}