Scala 3/API/scala.collection/IterableOnce

IterableOnce

A template trait for collections which can be traversed either once only or one or more times.

Note: IterableOnce does not extend IterableOnceOps. This is different than the general design of the collections library, which uses the following pattern:

trait Seq extends Iterable with SeqOps
trait SeqOps extends IterableOps

trait IndexedSeq extends Seq with IndexedSeqOps
trait IndexedSeqOps extends SeqOps

The goal is to provide a minimal interface without any sequential operations. This allows third-party extension like Scala parallel collections to integrate at the level of IterableOnce without inheriting unwanted implementations.

Companion: object

class Any

trait Iterable[A]

class AbstractIterable[A]

class AbstractMap[K, V]

class HashMap[K, V]

class IntMap[T]

class ListMap[K, V]

class LongMap[T]

class WithDefault[K, V]

class Map1[K, V]

class Map2[K, V]

class Map3[K, V]

class Map4[K, V]

class TreeMap[K, V]

class TreeSeqMap[K, V]

class VectorMap[K, V]

class AbstractMap[K, V]

class TrieMap[K, V]

class AnyRefMap[K, V]

class CollisionProofHashMap[K, V]

class HashMap[K, V]

class LinkedHashMap[K, V]

class ListMap[K, V]

class LongMap[V]

class WithDefault[K, V]

class OpenHashMap[Key, Value]

class TreeMap[K, V]

class SystemProperties

class AbstractSeq[A]

class ArraySeq[A]

class ofRef[T]

class ofByte

class ofShort

class ofChar

class ofInt

class ofLong

class ofFloat

class ofDouble

class ofBoolean

class ofUnit

class LazyList[A]

class List[A]

class ::[A]

object Nil

class NumericRange[T]

class Inclusive[T]

class Exclusive[T]

class Queue[A]

class Range

class Inclusive

class Exclusive

class Stream[A]

object Empty

class Cons[A]

class Vector[A]

class WrappedString

class AbstractSeq[A]

class AbstractBuffer[A]

class ArrayBuffer[A]

class ArrayDeque[A]

class Queue[A]

class Stack[A]

class ListBuffer[A]

class UnrolledBuffer[T]

class ArraySeq[T]

class ofRef[T]

class ofByte

class ofShort

class ofChar

class ofInt

class ofLong

class ofFloat

class ofDouble

class ofBoolean

class ofUnit

class StringBuilder

class AbstractSet[A]

class ValueSet

class BitSet

class BitSet1

class BitSet2

class BitSetN

class HashSet[A]

class ListSet[A]

class ImmutableKeySet

class Set1[A]

class Set2[A]

class Set3[A]

class Set4[A]

class ImmutableKeySortedSet

class TreeSet[A]

class AbstractSet[A]

class BitSet

class HashSet[A]

class LinkedHashSet[A]

class TreeSet[A]

class AbstractView[A]

class AbstractMapView[K, V]

class Id[K, V]

class MapValues[K, V, W]

class FilterKeys[K, V]

class Filter[K, V]

class TapEach[K, V, U]

class AbstractSeqView[A]

class AbstractIndexedSeqView[A]

class Slice[A]

class StringView

class ArrayBufferView[A]

class Id[A]

class Reverse[A]

object Empty

class Single[A]

class Elems[A]

class Fill[A]

class Tabulate[A]

class Iterate[A]

class Unfold[A, S]

class Filter[A]

class DistinctBy[A, B]

class LeftPartitionMapped[A, A1, A2]

class RightPartitionMapped[A, A1, A2]

class Drop[A]

class DropRight[A]

class DropWhile[A]

class Take[A]

class TakeRight[A]

class TakeWhile[A]

class ScanLeft[A, B]

class Map[A, B]

class FlatMap[A, B]

class Collect[A, B]

class Concat[A]

class Zip[A, B]

class ZipAll[A, B]

class Appended[A]

class Prepended[A]

class Updated[A]

class ZipWithIndex[A]

class PadTo[A]

class AbstractIterable[A]

class PriorityQueue[A]

trait Map[K, V]

trait DefaultMap[K, V]

trait SeqMap[K, V]

trait SortedMap[K, V]

trait Map[K, V]

trait MultiMap[K, V]

trait Seq[A]

trait IndexedSeq[A]

trait IndexedSeq[T]

trait IndexedBuffer[A]

trait LinearSeq[A]

trait Seq[A]

trait Buffer[A]

class Accumulator[A, CC, C]

class AnyAccumulator[A]

class DoubleAccumulator

class IntAccumulator

class LongAccumulator

trait Set[A]

trait SortedSet[A]

trait BitSet

trait SortedSet[A]

trait Set[A]

trait View[A]

trait MapView[K, V]

trait SeqView[A]

trait IndexedSeqView[A]

class Sorted[A, B]

trait Iterable[A]

trait IterableOps[A, CC, C]

trait EvidenceIterableFactoryDefaults[A, CC, Ev]

trait IterableFactoryDefaults[A, CC]

trait MapFactoryDefaults[K, V, CC, WithFilterCC]

class WeakHashMap[K, V]

trait MapOps[K, V, CC, C]

trait SortedMapFactoryDefaults[K, V, CC, WithFilterCC, UnsortedCC]

trait SortedMapOps[K, V, CC, C]

trait StrictOptimizedSortedMapOps[K, V, CC, C]

trait SortedMapOps[K, V, CC, C]

trait StrictOptimizedMapOps[K, V, CC, C]

trait MapOps[K, V, CC, C]

trait SeqOps[A, CC, C]

trait IndexedSeqOps[A, CC, C]

trait LinearSeqOps[A, CC, C]

trait StrictOptimizedLinearSeqOps[A, CC, C]

trait LinearSeqOps[A, CC, C]

trait StrictOptimizedSeqOps[A, CC, C]

trait ArrayDequeOps[A, CC, C]

trait SeqOps[A, CC, C]

trait SetOps[A, CC, C]

trait SortedSetOps[A, CC, C]

trait BitSetOps[C]

trait SortedSetFactoryDefaults[A, CC, WithFilterCC]

trait StrictOptimizedSortedSetOps[A, CC, C]

trait SortedSetOps[A, CC, C]

trait StrictOptimizedSetOps[A, CC, C]

trait SetOps[A, CC, C]

trait StrictOptimizedIterableOps[A, CC, C]

trait Iterator[A]

class AbstractIterator[A]

class GroupedIterator[B]

class BufferedLineIterator

class LineIterator

class MatchIterator

trait BufferedIterator[A]

Value members

Abstract methods

Iterator can be used only once

Concrete methods

Returns: The number of elements in this collection, if it can be cheaply computed, -1 otherwise. Cheaply usually means: Not requiring a collection traversal.

Returns a scala.collection.Stepper for the elements of this collection.

The Stepper enables creating a Java stream to operate on the collection, see scala.jdk.StreamConverters. For collections holding primitive values, the Stepper can be used as an iterator which doesn't box the elements.

The implicit scala.collection.StepperShape parameter defines the resulting Stepper type according to the element type of this collection.

For collections of Int, Short, Byte or Char, an scala.collection.IntStepper is returned
For collections of Double or Float, a scala.collection.DoubleStepper is returned
For collections of Long a scala.collection.LongStepper is returned
For any other element type, an scala.collection.AnyStepper is returned

Note that this method is overridden in subclasses and the return type is refined to S with EfficientSplit, for example scala.collection.IndexedSeqOps.stepper. For Steppers marked with scala.collection.Stepper.EfficientSplit, the converters in scala.jdk.StreamConverters allow creating parallel streams, whereas bare Steppers can be converted only to sequential streams.