trait Stepper[+A] extends AnyRef
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.
- A
the element type of the Stepper
- Source
- Stepper.scala
- Alphabetic
- By Inheritance
- Stepper
- AnyRef
- Any
- by any2stringadd
- by StringFormat
- by Ensuring
- by ArrowAssoc
- Hide All
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- Public
- Protected
Abstract Value Members
- abstract def characteristics: Int
Returns a set of characteristics of this Stepper and its elements.
Returns a set of characteristics of this Stepper and its elements. See method
characteristics
in java.util.Spliterator. - abstract def estimateSize: Long
Returns an estimate of the number of elements of this Stepper, or Long.MaxValue.
Returns an estimate of the number of elements of this Stepper, or Long.MaxValue. See method
estimateSize
in java.util.Spliterator. - abstract def hasStep: Boolean
Check if there's an element available.
- abstract def javaIterator[B >: A]: java.util.Iterator[_]
Returns a Java java.util.Iterator corresponding to this Stepper.
Returns a Java java.util.Iterator corresponding to this Stepper.
Note that the return type is
Iterator[_]
instead ofIterator[A]
to allow returning a java.util.PrimitiveIterator.OfInt (which is aIterator[Integer]
) in the subclass IntStepper (which is aStepper[Int]
). - abstract def nextStep(): A
Return the next element and advance the stepper
- abstract def spliterator[B >: A]: Spliterator[_]
Returns a java.util.Spliterator corresponding to this Stepper.
Returns a java.util.Spliterator corresponding to this Stepper.
Note that the return type is
Spliterator[_]
instead ofSpliterator[A]
to allow returning a java.util.Spliterator.OfInt (which is aSpliterator[Integer]
) in the subclass IntStepper (which is aStepper[Int]
). - abstract def trySplit(): Stepper[A]
Split this stepper, if applicable.
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 Value Members
- final def !=(arg0: Any): Boolean
Test two objects for inequality.
Test two objects for inequality.
- returns
true
if !(this == that), false otherwise.
- Definition Classes
- AnyRef → Any
- final def ##: Int
Equivalent to
x.hashCode
except for boxed numeric types andnull
.Equivalent to
x.hashCode
except for boxed numeric types andnull
. 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. Fornull
returns a hashcode wherenull.hashCode
throws aNullPointerException
.- returns
a hash value consistent with ==
- Definition Classes
- AnyRef → Any
- def +(other: String): String
- Implicit
- This member is added by an implicit conversion from Stepper[A] toany2stringadd[Stepper[A]] performed by method any2stringadd in scala.Predef.
- Definition Classes
- any2stringadd
- def ->[B](y: B): (Stepper[A], B)
- Implicit
- This member is added by an implicit conversion from Stepper[A] toArrowAssoc[Stepper[A]] performed by method ArrowAssoc in scala.Predef.
- Definition Classes
- ArrowAssoc
- Annotations
- @inline()
- final def ==(arg0: Any): Boolean
The expression
x == that
is equivalent toif (x eq null) that eq null else x.equals(that)
.The expression
x == that
is equivalent toif (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
- AnyRef → Any
- final def asInstanceOf[T0]: T0
Cast the receiver object to be of type
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 aClassCastException
at runtime, while the expressionList(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 typeT0
.
- def clone(): AnyRef
Create a copy of the receiver object.
Create a copy of the receiver object.
The default implementation of the
clone
method is platform dependent.- returns
a copy of the receiver object.
- def ensuring(cond: (Stepper[A]) => Boolean, msg: => Any): Stepper[A]
- Implicit
- This member is added by an implicit conversion from Stepper[A] toEnsuring[Stepper[A]] performed by method Ensuring in scala.Predef.
- Definition Classes
- Ensuring
- def ensuring(cond: (Stepper[A]) => Boolean): Stepper[A]
- Implicit
- This member is added by an implicit conversion from Stepper[A] toEnsuring[Stepper[A]] performed by method Ensuring in scala.Predef.
- Definition Classes
- Ensuring
- def ensuring(cond: Boolean, msg: => Any): Stepper[A]
- Implicit
- This member is added by an implicit conversion from Stepper[A] toEnsuring[Stepper[A]] performed by method Ensuring in scala.Predef.
- Definition Classes
- Ensuring
- def ensuring(cond: Boolean): Stepper[A]
- Implicit
- This member is added by an implicit conversion from Stepper[A] toEnsuring[Stepper[A]] performed by method Ensuring in scala.Predef.
- Definition Classes
- Ensuring
- final def eq(arg0: AnyRef): Boolean
Tests whether the argument (
that
) is a reference to the receiver object (this
).Tests whether the argument (
that
) is a reference to the receiver object (this
).The
eq
method implements an equivalence relation on non-null instances ofAnyRef
, and has three additional properties:- It is consistent: for any non-null instances
x
andy
of typeAnyRef
, multiple invocations ofx.eq(y)
consistently returnstrue
or consistently returnsfalse
. - For any non-null instance
x
of typeAnyRef
,x.eq(null)
andnull.eq(x)
returnsfalse
. null.eq(null)
returnstrue
.
When overriding the
equals
orhashCode
methods, it is important to ensure that their behavior is consistent with reference equality. Therefore, if two objects are references to each other (o1 eq o2
), they should be equal to each other (o1 == o2
) and they should hash to the same value (o1.hashCode == o2.hashCode
).- returns
true
if the argument is a reference to the receiver object;false
otherwise.
- Definition Classes
- AnyRef
- It is consistent: for any non-null instances
- def equals(arg0: AnyRef): Boolean
The equality method for reference types.
- def finalize(): Unit
Called by the garbage collector on the receiver object when there are no more references to the object.
Called by the garbage collector on the receiver object when there are no more references to the object.
The details of when and if the
finalize
method is invoked, as well as the interaction betweenfinalize
and non-local returns and exceptions, are all platform dependent.- Attributes
- protected[lang]
- Definition Classes
- AnyRef
- Annotations
- @throws(classOf[java.lang.Throwable])
- Note
not specified by SLS as a member of AnyRef
- def formatted(fmtstr: String): String
Returns string formatted according to given
format
string.Returns string formatted according to given
format
string. Format strings are as forString.format
(@see java.lang.String.format).- Implicit
- This member is added by an implicit conversion from Stepper[A] toStringFormat[Stepper[A]] performed by method StringFormat in scala.Predef.
- Definition Classes
- StringFormat
- Annotations
- @inline()
- final def getClass(): Class[_ <: AnyRef]
Returns the runtime class representation of the object.
- def hashCode(): Int
The hashCode method for reference types.
- final def isInstanceOf[T0]: Boolean
Test whether the dynamic type of the receiver object is
T0
.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 returnfalse
, while the expressionList(1).isInstanceOf[List[String]]
will returntrue
. 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 typeT0
;false
otherwise.
- Definition Classes
- Any
- def iterator: Iterator[A]
Returns an Iterator corresponding to this Stepper.
Returns an Iterator corresponding to this Stepper. Note that Iterators corresponding to primitive Steppers box the elements.
- final def ne(arg0: AnyRef): Boolean
Equivalent to
!(this eq that)
.Equivalent to
!(this eq that)
.- returns
true
if the argument is not a reference to the receiver object;false
otherwise.
- Definition Classes
- AnyRef
- final def notify(): Unit
Wakes up a single thread that is waiting on the receiver object's monitor.
Wakes up a single thread that is waiting on the receiver object's monitor.
- Definition Classes
- AnyRef
- Annotations
- @native()
- Note
not specified by SLS as a member of AnyRef
- final def notifyAll(): Unit
Wakes up all threads that are waiting on the receiver object's monitor.
Wakes up all threads that are waiting on the receiver object's monitor.
- Definition Classes
- AnyRef
- Annotations
- @native()
- Note
not specified by SLS as a member of AnyRef
- final def synchronized[T0](arg0: => T0): T0
Executes the code in
body
with an exclusive lock onthis
.Executes the code in
body
with an exclusive lock onthis
.- returns
the result of
body
- Definition Classes
- AnyRef
- def toString(): String
Creates a String representation of this object.
Creates a String representation of this object. The default representation is platform dependent. On the java platform it is the concatenation of the class name, "@", and the object's hashcode in hexadecimal.
- returns
a String representation of the object.
- Definition Classes
- AnyRef → Any
- final def wait(): Unit
See https://docs.oracle.com/javase/8/docs/api/java/lang/Object.html#wait--.
- Definition Classes
- AnyRef
- Annotations
- @throws(classOf[java.lang.InterruptedException])
- Note
not specified by SLS as a member of AnyRef
- final def wait(arg0: Long, arg1: Int): Unit
See https://docs.oracle.com/javase/8/docs/api/java/lang/Object.html#wait-long-int-
- Definition Classes
- AnyRef
- Annotations
- @throws(classOf[java.lang.InterruptedException])
- Note
not specified by SLS as a member of AnyRef
- final def wait(arg0: Long): Unit
See https://docs.oracle.com/javase/8/docs/api/java/lang/Object.html#wait-long-.
Deprecated Value Members
- def →[B](y: B): (Stepper[A], B)
- Implicit
- This member is added by an implicit conversion from Stepper[A] toArrowAssoc[Stepper[A]] performed by method ArrowAssoc in scala.Predef.
- Definition Classes
- ArrowAssoc
- Annotations
- @deprecated
- Deprecated
(Since version 2.13.0) Use
->
instead. If you still wish to display it as one character, consider using a font with programming ligatures such as Fira Code.
This is the documentation for the Scala standard library.
Package structure
The scala package contains core types like
Int
,Float
,Array
orOption
which are accessible in all Scala compilation units without explicit qualification or imports.Notable packages include:
scala.collection
and its sub-packages contain Scala's collections frameworkscala.collection.immutable
- Immutable, sequential data-structures such asVector
,List
,Range
,HashMap
orHashSet
scala.collection.mutable
- Mutable, sequential data-structures such asArrayBuffer
,StringBuilder
,HashMap
orHashSet
scala.collection.concurrent
- Mutable, concurrent data-structures such asTrieMap
scala.concurrent
- Primitives for concurrent programming such asFutures
andPromises
scala.io
- Input and output operationsscala.math
- Basic math functions and additional numeric types likeBigInt
andBigDecimal
scala.sys
- Interaction with other processes and the operating systemscala.util.matching
- Regular expressionsOther packages exist. See the complete list on the right.
Additional parts of the standard library are shipped as separate libraries. These include:
scala.reflect
- Scala's reflection API (scala-reflect.jar)scala.xml
- XML parsing, manipulation, and serialization (scala-xml.jar)scala.collection.parallel
- Parallel collections (scala-parallel-collections.jar)scala.util.parsing
- Parser combinators (scala-parser-combinators.jar)scala.swing
- A convenient wrapper around Java's GUI framework called Swing (scala-swing.jar)Automatic imports
Identifiers in the scala package and the
scala.Predef
object are always in scope by default.Some of these identifiers are type aliases provided as shortcuts to commonly used classes. For example,
List
is an alias forscala.collection.immutable.List
.Other aliases refer to classes provided by the underlying platform. For example, on the JVM,
String
is an alias forjava.lang.String
.