ScalaVersionSpecific.scala

/*
 * ScalaCheck
 * Copyright (c) 2007-2021 Rickard Nilsson. All rights reserved.
 * http://www.scalacheck.org
 *
 * This software is released under the terms of the Revised BSD License.
 * There is NO WARRANTY. See the file LICENSE for the full text.
 */

package org.scalacheck

import rng.Seed

private[scalacheck] object ScalaVersionSpecific {
  def toLazyList[T](i: IterableOnce[T]) = LazyList.from(i)
}

private[scalacheck] trait GenVersionSpecific {

  /** Generates an infinite lazy list. */
  def infiniteLazyList[T](g: => Gen[T]): Gen[LazyList[T]] = {
    def unfold[A, S](z: S)(f: S => Option[(A, S)]): LazyList[A] = f(z) match {
      case Some((h, s)) => h #:: unfold(s)(f)
      case None => LazyList.empty
    }
    Gen.gen { (p, seed0) =>
      new Gen.R[LazyList[T]] {
        val result: Option[LazyList[T]] = Some(unfold(seed0)(s => Some(g.pureApply(p, s) -> s.next)))
        val seed: Seed = seed0.next
      }
    }
  }
}

private[scalacheck] trait GenSpecificationVersionSpecific

private[scalacheck] trait CogenVersionSpecific {
  implicit def cogenLazyList[A: Cogen]: Cogen[LazyList[A]] =
    Cogen.it(_.iterator)
}

private[scalacheck] trait ShrinkVersionSpecific {

  /** Forward to Shrink instance factory */
  def withLazyList[T](s: T => LazyList[T]): Shrink[T] = Shrink(s.andThen(_.toStream))
}