object StreamConverters extends StreamExtensions with Priority1AccumulatorConverters
StreamConverters
provides extension methods and other functionality to
ease interoperability of Scala collections with java.util.stream
classes.
Scala collections gain extension methods seqStream
and
parStream
that allow them to be used as the source of a Stream
.
Some collections either intrinsically cannot be paralellized, or
could be but an efficient implementation is missing. It this case,
only seqStream
is provided. If a collection cannot be stepped over
at all (e.g. Traversable
), then it gains neither method.
Array
also gains seqStream
and parStream
methods, and calling those
on Array[Double]
, Array[Int]
, or Array[Long]
will produce the
corresponding primitive stream.
Streams gain accumulate
and toScala[_]
methods, which collect the stream
into a custom high-performance scala.collection.mutable.java8.Accumulator
,
which is not part of the standard collections hierarchy, or into a named
Scala collection, respectively.
Generic streams also gain an unboxed
method that will convert to the
corresponding unboxed primitive stream, if appropriate. Unboxed streams
have custom accumulators with improved performance.
Accumulators have toArray
, toList
, iterator
, and to[_]
methods
to convert to standard Scala collections. Note that if you wish to
create an array from a Stream
, going through an Accumulator
is
not the most efficient option: just create the Array
directly.
Internally, Scala collections implement a hybrid of Iterator
and
java.util.Spliterator
to implement Stream
compatibility; these
are called Stepper
s. In particular, they can test for the presence
of a next element using hasStep
, can retrieve the next value with
nextStep
, or can optionally retrieve and operate on a value if present
with tryStep
, which works like tryAdvance
in java.util.Spliterator
.
Every Scala collection that can be stepped
through has a stepper
method implicitly provided. In addition,
maps have keyStepper
and valueStepper
methods. A limited number
of collections operations are defined on Stepper
s, including conversion
to Scala collections with to
or accumulation via accumulate
.
Stepper
s also implement seqStream
and parStream
to generate Stream
s.
These are provided regardless of whether a Stepper
can efficiently
subdivide itself for parallel processing (though one can check for the
presence of the EfficientSubstep
trait to know that parallel execution will
not be limited by long sequential searching steps, and one can call
anticipateParallelism
to warn a Stepper
that it will be used in a parallel
context and thus may wish to make different tradeoffs).
Examples:
import scala.compat.java8.StreamConverters._ val s = Vector(1,2,3,4).parStream // Stream[Int] val si = s.unboxed // Stream.OfInt val ai = si.accumulate // IntAccumulator val v = ai.to[Vector] // Vector[Int] again val t = Array(2.0, 3.0, 4.0).parStream // DoubleStream val q = t.toScala[scala.collection.immutable.Queue] // Queue[Double] val x = List(1L, 2L, 3L, 4L).stepper.parStream.sum // 10, potentially computed in parallel
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- implicit class AnyArrayHasSeqParStream[A <: AnyRef] extends AnyRef
- Definition Classes
- StreamExtensions
- implicit class ByteArrayHasSeqParStream extends AnyRef
- Definition Classes
- StreamExtensions
- implicit class CharArrayHasSeqParStream extends AnyRef
- Definition Classes
- StreamExtensions
- implicit class DoubleArrayHasSeqParStream extends AnyRef
- Definition Classes
- StreamExtensions
- implicit class DoubleStreamHasToScala extends AnyRef
- Definition Classes
- StreamExtensions
- implicit class FloatArrayHasSeqParStream extends AnyRef
- Definition Classes
- StreamExtensions
- implicit class IntArrayHasSeqParStream extends AnyRef
- Definition Classes
- StreamExtensions
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- implicit class IterableHasSeqStream[A] extends AnyRef
- Definition Classes
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- implicit class IterableNonGenericHasParStream[A, C <: collection.IterableOnce[_]] extends AnyRef
- Definition Classes
- StreamExtensions
- implicit class LongArrayHasSeqParStream extends AnyRef
- Definition Classes
- StreamExtensions
- implicit class LongStreamHasToScala extends AnyRef
- Definition Classes
- StreamExtensions
- implicit class MapHasParKeyValueStream[K, V, CC[X, Y] <: MapOps[X, Y, Map, _]] extends AnyRef
- Definition Classes
- StreamExtensions
- implicit class MapHasSeqKeyValueStream[K, V, CC[X, Y] <: MapOps[X, Y, Map, _]] extends AnyRef
- Definition Classes
- StreamExtensions
- implicit class ShortArrayHasSeqParStream extends AnyRef
- Definition Classes
- StreamExtensions
- implicit class StepperHasParStream[A] extends AnyRef
- Definition Classes
- StreamExtensions
- implicit class StepperHasSeqStream[A] extends AnyRef
- Definition Classes
- StreamExtensions
- implicit class StreamDoubleHasAccumulatePrimitive extends AnyRef
- Definition Classes
- StreamExtensions
- implicit class StreamHasToScala[A] extends AnyRef
- Definition Classes
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- implicit class StreamIntHasAccumulatePrimitive extends AnyRef
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- implicit class StreamJDoubleHasAccumulatePrimitive extends AnyRef
- Definition Classes
- StreamExtensions
- implicit class StreamJIntegerHasAccumulatePrimitive extends AnyRef
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- StreamExtensions
- implicit class StreamJLongHasAccumulatePrimitive extends AnyRef
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- StreamExtensions
- implicit class StreamLongHasAccumulatePrimitive extends AnyRef
- Definition Classes
- StreamExtensions
Value Members
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- implicit def accumulateAnyArray[A](underlying: Array[A]): AccumulateAnyArray[A]
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- Priority2AccumulatorConverters
- implicit def accumulateDoubleArray(underlying: Array[Double]): AccumulateDoubleArray
- Definition Classes
- Priority1AccumulatorConverters
- implicit def accumulateDoubleCollection(underlying: IterableOnce[Double]): AccumulateDoubleCollection
- Definition Classes
- Priority2AccumulatorConverters
- implicit def accumulateIntArray(underlying: Array[Int]): AccumulateIntArray
- Definition Classes
- Priority1AccumulatorConverters
- implicit def accumulateIntCollection(underlying: IterableOnce[Int]): AccumulateIntCollection
- Definition Classes
- Priority2AccumulatorConverters
- implicit def accumulateLongArray(underlying: Array[Long]): AccumulateLongArray
- Definition Classes
- Priority1AccumulatorConverters
- implicit def accumulateLongCollection(underlying: IterableOnce[Long]): AccumulateLongCollection
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- implicit def collectionCanAccumulate[A](underlying: IterableOnce[A]): CollectionCanAccumulate[A]
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- implicit def richDoubleStepper(s: Stepper[Double]): StepperExtensions[Double]
- implicit def richIntStepper(s: Stepper[Int]): StepperExtensions[Int]
- implicit def richLongStepper(s: Stepper[Long]): StepperExtensions[Long]
- implicit def richStepper[A](s: Stepper[A]): StepperExtensions[A]
- Definition Classes
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