Stepper

Steppers exist to enable creating Java streams over Scala collections, see scala.jdk.StreamConverters. Besides that use case, they allow iterating over collections holding unboxed primitives (e.g., Array[Int]) without boxing the elements.

Steppers have an iterator-like interface with methods hasStep and nextStep(). The difference to iterators - and the reason Stepper is not a subtype of Iterator - is that there are hand-specialized variants of Stepper for Int, Long and Double (IntStepper, etc.). These enable iterating over collections holding unboxed primitives (e.g., Arrays, scala.jdk.Accumulators) without boxing the elements.

The selection of primitive types (Int, Long and Double) matches the hand-specialized variants of Java Streams (java.util.stream.Stream, java.util.stream.IntStream, etc.) and the corresponding Java Spliterators (java.util.Spliterator, java.util.Spliterator.OfInt, etc.).

Steppers can be converted to Scala Iterators, Java Iterators and Java Spliterators. Primitive Steppers are converted to the corresponding primitive Java Iterators and Spliterators.

Type Params
A

the element type of the Stepper

Companion
object
Source
Stepper.scala
class Object
trait Matchable
class Any

Value members

Abstract methods

Returns a set of characteristics of this Stepper and its elements. See method characteristics in java.util.Spliterator.

Returns an estimate of the number of elements of this Stepper, or Long.MaxValue. See method estimateSize in java.util.Spliterator.

Check if there's an element available.

def javaIterator[B >: A]: Iterator[_]

Returns a Java java.util.Iterator corresponding to this Stepper.

Note that the return type is Iterator[_] instead of Iterator[A] to allow returning a java.util.PrimitiveIterator.OfInt (which is a Iterator[Integer]) in the subclass IntStepper (which is a Stepper[Int]).

def nextStep(): A

Return the next element and advance the stepper

def spliterator[B >: A]: Spliterator[_]

Returns a java.util.Spliterator corresponding to this Stepper.

Note that the return type is Spliterator[_] instead of Spliterator[A] to allow returning a java.util.Spliterator.OfInt (which is a Spliterator[Integer]) in the subclass IntStepper (which is a Stepper[Int]).

def trySplit(): Stepper[A]

Split this stepper, if applicable. The elements of the current Stepper are split up between the resulting Stepper and the current stepper.

May return null, in which case the current Stepper yields the same elements as before.

See method trySplit in java.util.Spliterator.

Concrete methods

Returns an Iterator corresponding to this Stepper. Note that Iterators corresponding to primitive Steppers box the elements.