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Trait scala.collection.IterableOnce

trait IterableOnce[+A] extends Any

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.

Source
IterableOnce.scala
Linear Supertypes
Any
Known Subclasses
ValueSet, None, Option, Some, AbstractIndexedSeqView, AbstractIterable, AbstractIterator, AbstractMap, AbstractMapView, AbstractSeq, AbstractSeqView, AbstractSet, AbstractView, BitSet, BitSetOps, BufferedIterator, EvidenceIterableFactoryDefaults, IndexedSeq, IndexedSeqOps, IndexedSeqView, Appended, Concat, Drop, DropRight, Id, Map, Prepended, Reverse, Slice, Take, TakeRight, Iterable, IterableFactoryDefaults, IterableOps, Iterator, GroupedIterator, LinearSeq, LinearSeqOps, Map, MapFactoryDefaults, MapOps, KeySet, MapView, Filter, FilterKeys, Id, MapValues, TapEach, Seq, SeqMap, SeqOps, SeqView, Appended, Concat, Drop, DropRight, Id, Map, Prepended, Reverse, Sorted, Take, TakeRight, Set, SetOps, SortedMap, SortedMapFactoryDefaults, SortedMapOps, KeySortedSet, SortedSet, SortedSetFactoryDefaults, SortedSetOps, StrictOptimizedIterableOps, StrictOptimizedLinearSeqOps, StrictOptimizedMapOps, StrictOptimizedSeqOps, StrictOptimizedSetOps, StrictOptimizedSortedMapOps, StrictOptimizedSortedSetOps, StringView, View, Appended, Collect, Concat, DistinctBy, Drop, DropRight, DropWhile, Elems, Empty, Fill, Filter, FlatMap, Iterate, LeftPartitionMapped, Map, PadTo, Prepended, RightPartitionMapped, ScanLeft, Single, Tabulate, Take, TakeRight, TakeWhile, Unfold, Updated, Zip, ZipAll, ZipWithIndex, Map, TrieMap, ::, AbstractMap, AbstractSeq, AbstractSet, ArraySeq, ofBoolean, ofByte, ofChar, ofDouble, ofFloat, ofInt, ofLong, ofRef, ofShort, ofUnit, BitSet, HashMap, HashSet, IndexedSeq, IndexedSeqOps, IntMap, Iterable, LazyList, LinearSeq, LinearSeqOps, List, ListMap, ListSet, Node, LongMap, Map, Map1, Map2, Map3, Map4, WithDefault, MapOps, ImmutableKeySet, Nil, NumericRange, Exclusive, Inclusive, Queue, Range, Exclusive, Inclusive, Seq, SeqMap, SeqOps, Set, Set1, Set2, Set3, Set4, SetOps, SortedMap, WithDefault, SortedMapOps, ImmutableKeySortedSet, SortedSet, SortedSetOps, Cons, Empty, StrictOptimizedMapOps, StrictOptimizedSeqOps, StrictOptimizedSetOps, StrictOptimizedSortedMapOps, StrictOptimizedSortedSetOps, TreeMap, TreeSeqMap, TreeSet, Vector, VectorMap, WrappedString, AbstractBuffer, AbstractIterable, AbstractMap, AbstractSeq, AbstractSet, AnyRefMap, ArrayBuffer, ArrayBufferView, ArrayDeque, ArrayDequeOps, ArraySeq, ofBoolean, ofByte, ofChar, ofDouble, ofFloat, ofInt, ofLong, ofRef, ofShort, ofUnit, BitSet, Buffer, CollisionProofHashMap, HashMap, HashSet, IndexedBuffer, IndexedSeq, IndexedSeqOps, Iterable, LinkedHashMap, LinkedKeySet, LinkedHashSet, ListBuffer, LongMap, Map, WithDefault, MapOps, MultiMap, PriorityQueue, Queue, Seq, SeqMap, SeqOps, Set, SetOps, SortedMap, WithDefault, SortedMapOps, SortedSet, SortedSetOps, Stack, StringBuilder, TreeMap, TreeSet, UnrolledBuffer, WeakHashMap, BufferedSource, BufferedLineIterator, Source, LineIterator, Accumulator, AnyAccumulator, DoubleAccumulator, IntAccumulator, LongAccumulator, SystemProperties, MatchIterator, DefaultMap, BitSet1, BitSet2, BitSetN, Stream, VectorIterator, ListMap, OpenHashMap

Abstract Value Members

abstract def getClass(): Class[_ <: AnyRef]

Returns the runtime class representation of the object.

returns

a class object corresponding to the runtime type of the receiver.

Definition Classes
Any

abstract def iterator: Iterator[A]

Concrete Value Members

final def !=(arg0: Any): Boolean

Test two objects for inequality.

returns

true if !(this == that), false otherwise.

Definition Classes
Any

final def ##(): Int

Equivalent to x.hashCode except for boxed numeric types and null. For numerics, it returns a hash value which is consistent with value equality: if two value type instances compare as true, then ## will produce the same hash value for each of them. For null returns a hashcode where null.hashCode throws a NullPointerException.

returns

a hash value consistent with ==

Definition Classes
Any

def +(other: String): String

Implicit
This member is added by an implicit conversion from IterableOnce[A] toany2stringadd[IterableOnce[A]] performed by method any2stringadd in scala.Predef.
Definition Classes
any2stringadd

def ->[B](y: B): (IterableOnce[A], B)

Implicit
This member is added by an implicit conversion from IterableOnce[A] toArrowAssoc[IterableOnce[A]] performed by method ArrowAssoc in scala.Predef.
Definition Classes
ArrowAssoc
Annotations
@inline()

final def ==(arg0: Any): Boolean

Test two objects for equality. The expression x == that is equivalent to if (x eq null) that eq null else x.equals(that).

returns

true if the receiver object is equivalent to the argument; false otherwise.

Definition Classes
Any

final def asInstanceOf[T0]: T0

Cast the receiver object to be of type T0.

Note that the success of a cast at runtime is modulo Scala's erasure semantics. Therefore the expression 1.asInstanceOf[String] will throw a ClassCastException at runtime, while the expression List(1).asInstanceOf[List[String]] will not. In the latter example, because the type argument is erased as part of compilation it is not possible to check whether the contents of the list are of the requested type.

returns

the receiver object.

Definition Classes
Any
Exceptions thrown

ClassCastException if the receiver object is not an instance of the erasure of type T0.

def ensuring(cond: (IterableOnce[A]) => Boolean, msg: => Any): IterableOnce[A]

Implicit
This member is added by an implicit conversion from IterableOnce[A] toEnsuring[IterableOnce[A]] performed by method Ensuring in scala.Predef.
Definition Classes
Ensuring

def ensuring(cond: (IterableOnce[A]) => Boolean): IterableOnce[A]

Implicit
This member is added by an implicit conversion from IterableOnce[A] toEnsuring[IterableOnce[A]] performed by method Ensuring in scala.Predef.
Definition Classes
Ensuring

def ensuring(cond: Boolean, msg: => Any): IterableOnce[A]

Implicit
This member is added by an implicit conversion from IterableOnce[A] toEnsuring[IterableOnce[A]] performed by method Ensuring in scala.Predef.
Definition Classes
Ensuring

def ensuring(cond: Boolean): IterableOnce[A]

Implicit
This member is added by an implicit conversion from IterableOnce[A] toEnsuring[IterableOnce[A]] performed by method Ensuring in scala.Predef.
Definition Classes
Ensuring

def equals(arg0: Any): Boolean

Compares the receiver object (this) with the argument object (that) for equivalence.

Any implementation of this method should be an equivalence relation:

    It is reflexive: for any instance x of type Any, x.equals(x) should return true.It is symmetric: for any instances x and y of type Any, x.equals(y) should return true if and only if y.equals(x) returns true.It is transitive: for any instances x, y, and z of type Any if x.equals(y) returns true and y.equals(z) returns true, then x.equals(z) should return true.

If you override this method, you should verify that your implementation remains an equivalence relation. Additionally, when overriding this method it is usually necessary to override hashCode to ensure that objects which are "equal" (o1.equals(o2) returns true) hash to the same scala.Int. (o1.hashCode.equals(o2.hashCode)).

returns

true if the receiver object is equivalent to the argument; false otherwise.

Definition Classes
Any

def formatted(fmtstr: String): String

Returns string formatted according to given format string. Format strings are as for String.format (@see java.lang.String.format).

Implicit
This member is added by an implicit conversion from IterableOnce[A] toStringFormat[IterableOnce[A]] performed by method StringFormat in scala.Predef.
Definition Classes
StringFormat
Annotations
@inline()

def hashCode(): Int

Calculate a hash code value for the object.

The default hashing algorithm is platform dependent.

Note that it is allowed for two objects to have identical hash codes (o1.hashCode.equals(o2.hashCode)) yet not be equal (o1.equals(o2) returns false). A degenerate implementation could always return 0. However, it is required that if two objects are equal (o1.equals(o2) returns true) that they have identical hash codes (o1.hashCode.equals(o2.hashCode)). Therefore, when overriding this method, be sure to verify that the behavior is consistent with the equals method.

returns

the hash code value for this object.

Definition Classes
Any

final def isInstanceOf[T0]: Boolean

Test whether the dynamic type of the receiver object is T0.

Note that the result of the test is modulo Scala's erasure semantics. Therefore the expression 1.isInstanceOf[String] will return false, while the expression List(1).isInstanceOf[List[String]] will return true. In the latter example, because the type argument is erased as part of compilation it is not possible to check whether the contents of the list are of the specified type.

returns

true if the receiver object is an instance of erasure of type T0; false otherwise.

Definition Classes
Any

def knownSize: Int

returns

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

def stepper[S <: Stepper[_]](implicit shape: StepperShape[A, S]): S

Returns a 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 StepperShape parameter defines the resulting Stepper type according to the element type of this collection.

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

Note that this method is overridden in subclasses and the return type is refined to S with EfficientSplit, for example 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.

def toString(): String

Returns a string representation of the object.

The default representation is platform dependent.

returns

a string representation of the object.

Definition Classes
Any

© 2002-2019 EPFL, with contributions from Lightbend.
Licensed under the Apache License, Version 2.0.
https://www.scala-lang.org/api/2.13.0/scala/collection/IterableOnce.html