Scala example source code file (Tuple2Zipped.scala)

This example Scala source code file (Tuple2Zipped.scala) is included in my "Source Code Warehouse" project. The intent of this project is to help you more easily find Scala source code examples by using tags.

All credit for the original source code belongs to scala-lang.org; I'm just trying to make examples easier to find. (For my Scala work, see my Scala examples and tutorials.)

Scala tags/keywords

boolean, cbf, collection, el1, el2, generics, repr1, repr2, t2, that, to, zippedtraversable2

The Tuple2Zipped.scala Scala example source code

/*                     __                                               *\
**     ________ ___   / /  ___     Scala API                            **
**    / __/ __// _ | / /  / _ |    (c) 2002-2013, LAMP/EPFL             **
**  __\ \/ /__/ __ |/ /__/ __ |    http://scala-lang.org/               **
** /____/\___/_/ |_/____/_/ | |                                         **
**                          |/                                          **
\*                                                                      */

package scala
package runtime


import scala.collection.{ TraversableLike, IterableLike }
import scala.collection.generic.{ CanBuildFrom => CBF }
import scala.language.{ higherKinds, implicitConversions }

/** This interface is intended as a minimal interface, not complicated
 *  by the requirement to resolve type constructors, for implicit search (which only
 *  needs to find an implicit conversion to Traversable for our purposes.)
 */
trait ZippedTraversable2[+El1, +El2] extends Any {
  def foreach[U](f: (El1, El2) => U): Unit
}
object ZippedTraversable2 {
  implicit def zippedTraversable2ToTraversable[El1, El2](zz: ZippedTraversable2[El1, El2]): Traversable[(El1, El2)] = {
    new scala.collection.AbstractTraversable[(El1, El2)] {
      def foreach[U](f: ((El1, El2)) => U): Unit = zz foreach Function.untupled(f)
    }
  }
}

final class Tuple2Zipped[El1, Repr1, El2, Repr2](val colls: (TraversableLike[El1, Repr1], IterableLike[El2, Repr2])) extends AnyVal with ZippedTraversable2[El1, El2] {
  // This would be better as "private def coll1 = colls._1" but
  // SI-6215 precludes private methods in value classes.
  def map[B, To](f: (El1, El2) => B)(implicit cbf: CBF[Repr1, B, To]): To = {
    val b = cbf(colls._1.repr)
    b.sizeHint(colls._1)
    val elems2 = colls._2.iterator

    for (el1 <- colls._1) {
      if (elems2.hasNext)
        b += f(el1, elems2.next())
      else
        return b.result()
    }

    b.result()
  }

  def flatMap[B, To](f: (El1, El2) => TraversableOnce[B])(implicit cbf: CBF[Repr1, B, To]): To = {
    val b = cbf(colls._1.repr)
    val elems2 = colls._2.iterator

    for (el1 <- colls._1) {
      if (elems2.hasNext)
        b ++= f(el1, elems2.next())
      else
        return b.result()
    }

    b.result()
  }

  def filter[To1, To2](f: (El1, El2) => Boolean)(implicit cbf1: CBF[Repr1, El1, To1], cbf2: CBF[Repr2, El2, To2]): (To1, To2) = {
    val b1 = cbf1(colls._1.repr)
    val b2 = cbf2(colls._2.repr)
    val elems2 = colls._2.iterator

    for (el1 <- colls._1) {
      if (elems2.hasNext) {
        val el2 = elems2.next()
        if (f(el1, el2)) {
          b1 += el1
          b2 += el2
        }
      }
      else return (b1.result(), b2.result())
    }

    (b1.result(), b2.result())
  }

  def exists(f: (El1, El2) => Boolean): Boolean = {
    val elems2 = colls._2.iterator

    for (el1 <- colls._1) {
      if (elems2.hasNext) {
        if (f(el1, elems2.next()))
          return true
      }
      else return false
    }
    false
  }

  def forall(f: (El1, El2) => Boolean): Boolean =
    !exists((x, y) => !f(x, y))

  def foreach[U](f: (El1, El2) => U): Unit = {
    val elems2 = colls._2.iterator

    for (el1 <- colls._1) {
      if (elems2.hasNext)
        f(el1, elems2.next())
      else
        return
    }
  }
}

object Tuple2Zipped {
  final class Ops[T1, T2](val x: (T1, T2)) extends AnyVal {
    def invert[El1, CC1[X] <: TraversableOnce[X], El2, CC2[X] <: TraversableOnce[X], That]
      (implicit w1: T1 <:< CC1[El1],
                w2: T2 <:< CC2[El2],
                bf: scala.collection.generic.CanBuildFrom[CC1[_], (El1, El2), That]
      ): That = {
        val buf = bf(x._1)
        val it1 = x._1.toIterator
        val it2 = x._2.toIterator
        while (it1.hasNext && it2.hasNext)
          buf += ((it1.next(), it2.next()))

        buf.result()
      }

    def zipped[El1, Repr1, El2, Repr2]
      (implicit w1: T1 => TraversableLike[El1, Repr1],
                w2: T2 => IterableLike[El2, Repr2]
      ): Tuple2Zipped[El1, Repr1, El2, Repr2] = new Tuple2Zipped((x._1, x._2))
  }
}