Package io.vavr.collection

Interface Iterator<T>

Type Parameters:

T - Component type

All Superinterfaces:

Foldable<T>, Iterable<T>, Iterator<T>, Traversable<T>, Value<T>

public interface Iterator<T>
extends Iterator<T>, Traversable<T>

io.vavr.collection.Iterator is a compositional replacement for java.util.Iterator whose purpose is to iterate once over a sequence of elements.

Note: Iterators encapsulate mutable state. They are not meant to be used concurrently by different threads. Do not reuse Iterators, e.g. after passing to List.ofAll(Iterable).

There are two abstract methods: hasNext for checking if there is a next element available, and next which removes the next element from the iterator and returns it. They can be called an arbitrary amount of times. If hasNext returns false, a call of next will throw a NoSuchElementException.

Caution: Other methods than hasNext and next can be called only once (exclusively). More specifically, after calling a method it cannot be guaranteed that the next call will succeed.

An Iterator that can be only used once because it is a traversal pointer into a collection, and not a collection itself.

Author:

Daniel Dietrich

Method Summary

Modifier and Type	Method	Description
default <R> Iterator<R>	collect(PartialFunction<? super T,? extends R> partialFunction)	Collects all elements that are in the domain of the given partialFunction by mapping the elements to type R.
static <T> Iterator<T>	concat(Iterable<? extends Iterable<? extends T>> iterables)	Creates an Iterator which traverses along the concatenation of the given iterables.
static <T> Iterator<T>	concat(Iterable<? extends T>... iterables)	Creates an Iterator which traverses along the concatenation of the given iterables.
default Iterator<T>	concat(Iterator<? extends T> that)
static <T> Iterator<T>	continually(Supplier<? extends T> supplier)	Generates an infinite iterator using a value Supplier.
static <T> Iterator<T>	continually(T t)	Creates an infinite iterator returning the given element.
default Iterator<T>	distinct()	Returns a new version of this which contains no duplicates.
default Iterator<T>	distinctBy(Comparator<? super T> comparator)	Returns a new version of this which contains no duplicates.
default <U> Iterator<T>	distinctBy(Function<? super T,? extends U> keyExtractor)	Returns a new version of this which contains no duplicates.
default Iterator<T>	drop(int n)	Removes up to n elements from this iterator.
default Iterator<T>	dropRight(int n)	Drops the last n elements of this or all elements, if this length < n.
default Iterator<T>	dropUntil(Predicate<? super T> predicate)	Drops elements until the predicate holds for the current element.
default Iterator<T>	dropWhile(Predicate<? super T> predicate)	Drops elements while the predicate holds for the current element.
static <T> Iterator<T>	empty()	Returns the empty Iterator.
static <T> Iterator<T>	fill(int n, Supplier<? extends T> s)	Returns an Iterator on a sequence of n values supplied by a given Supplier s.
static <T> Iterator<T>	fill(int n, T element)	Returns a Iterator containing n times the given element
default Iterator<T>	filter(Predicate<? super T> predicate)	Returns an Iterator that contains elements that satisfy the given predicate.
default Option<T>	findLast(Predicate<? super T> predicate)	Returns the last element of this which satisfies the given predicate.
default <U> Iterator<U>	flatMap(Function<? super T,? extends Iterable<? extends U>> mapper)	FlatMaps the elements of this Iterator to Iterables, which are iterated in the order of occurrence.
default <U> U	foldRight(U zero, BiFunction<? super T,? super U,? extends U> f)	Folds this elements from the right, starting with zero and successively calling combine.
static Iterator<Integer>	from(int value)	Returns an infinite iterator of int values starting from value.
static Iterator<Integer>	from(int value, int step)	Returns an infinite iterator of int values starting from value and spaced by step.
static Iterator<Long>	from(long value)	Returns an infinite iterator of long values starting from value.
static Iterator<Long>	from(long value, long step)	Returns an infinite iterator of long values starting from value and spaced by step.
default T	get()	Gets the first value in iteration order if this Traversable is not empty, otherwise throws.
default <C> Map<C,Iterator<T>>	groupBy(Function<? super T,? extends C> classifier)	Groups this elements by classifying the elements.
default Iterator<Seq<T>>	grouped(int size)	Groups this Traversable into fixed size blocks.
default boolean	hasDefiniteSize()	Checks if this Traversable is known to have a finite size.
default T	head()	Returns the first element of a non-empty Traversable.
default Iterator<T>	init()	Dual of Traversable.tail(), returning all elements except the last.
default Option<Iterator<T>>	initOption()	Dual of Traversable.tailOption(), returning all elements except the last as Option.
default Iterator<T>	intersperse(T element)	Inserts an element between all elements of this Iterator.
default boolean	isAsync()	An Iterator is computed synchronously.
default boolean	isEmpty()	Checks if this Traversable is empty.
default boolean	isLazy()	An Iterator is computed lazily.
default boolean	isSequential()	Checks if the elements of this Traversable appear in encounter order.
default boolean	isTraversableAgain()	Checks if this Traversable can be repeatedly traversed.
static <T> Iterator<T>	iterate(Supplier<? extends Option<? extends T>> supplier)	Creates an iterator that repeatedly invokes the supplier while it's a Some and end on the first None
static <T> Iterator<T>	iterate(T seed, Function<? super T,? extends T> f)	Generates an infinite iterator using a function to calculate the next value based on the previous.
default Iterator<T>	iterator()	An iterator by means of head() and tail().
default T	last()	Dual of Traversable.head(), returning the last element.
default int	length()	Computes the number of elements of this Traversable.
default <U> Iterator<U>	map(Function<? super T,? extends U> mapper)	Maps the elements of this Iterator lazily using the given mapper.
static <T> Iterator<T>	narrow(Iterator<? extends T> iterator)	Narrows a widened Iterator<? extends T> to Iterator<T> by performing a type-safe cast.
static <T> Iterator<T>	of(T element)	Creates an Iterator which traverses one element.
static <T> Iterator<T>	of(T... elements)	Creates an Iterator which traverses the given elements.
static Iterator<Boolean>	ofAll(boolean... elements)	Creates an Iterator from boolean values.
static Iterator<Byte>	ofAll(byte... elements)	Creates an Iterator from byte values.
static Iterator<Character>	ofAll(char... elements)	Creates an Iterator from char values.
static Iterator<Double>	ofAll(double... elements)	Creates ann Iterator from double values.
static Iterator<Float>	ofAll(float... elements)	Creates an Iterator from float values.
static Iterator<Integer>	ofAll(int... elements)	Creates an Iterator from int values.
static Iterator<Long>	ofAll(long... elements)	Creates an Iterator from long values.
static Iterator<Short>	ofAll(short... elements)	Creates an Iterator from short values.
static <T> Iterator<T>	ofAll(Iterable<? extends T> iterable)	Creates an Iterator based on the given Iterable.
static <T> Iterator<T>	ofAll(Iterator<? extends T> iterator)	Creates an Iterator based on the given Iterator by delegating calls of hasNext() and next() to it.
default Iterator<T>	orElse(Iterable<? extends T> other)	Returns this Traversable if it is nonempty, otherwise return the alternative.
default Iterator<T>	orElse(Supplier<? extends Iterable<? extends T>> supplier)	Returns this Traversable if it is nonempty, otherwise return the result of evaluating supplier.
default Tuple2<Iterator<T>,Iterator<T>>	partition(Predicate<? super T> predicate)	Creates a partition of this Traversable by splitting this elements in two in distinct traversables according to a predicate.
default Iterator<T>	peek(Consumer<? super T> action)	Performs the given action on the first element if this is an eager implementation.
static Iterator<Character>	range(char from, char toExclusive)	Creates an Iterator of characters starting from from, extending to toExclusive - 1.
static Iterator<Integer>	range(int from, int toExclusive)	Creates an Iterator of int numbers starting from from, extending to toExclusive - 1.
static Iterator<Long>	range(long from, long toExclusive)	Creates an Iterator of long numbers starting from from, extending to toExclusive - 1.
static Iterator<Character>	rangeBy(char from, char toExclusive, int step)	Creates an Iterator of characters starting from from, extending to toExclusive - 1, with step.
static Iterator<Double>	rangeBy(double from, double toExclusive, double step)
static Iterator<Integer>	rangeBy(int from, int toExclusive, int step)	Creates an Iterator of int numbers starting from from, extending to toExclusive - 1, with step.
static Iterator<Long>	rangeBy(long from, long toExclusive, long step)	Creates an Iterator of long numbers starting from from, extending to toExclusive - 1, with step.
static Iterator<BigDecimal>	rangeBy(BigDecimal from, BigDecimal toExclusive, BigDecimal step)
static Iterator<Character>	rangeClosed(char from, char toInclusive)	Creates an Iterator of characters starting from from, extending to toInclusive.
static Iterator<Integer>	rangeClosed(int from, int toInclusive)	Creates an Iterator of int numbers starting from from, extending to toInclusive.
static Iterator<Long>	rangeClosed(long from, long toInclusive)	Creates an Iterator of long numbers starting from from, extending to toInclusive.
static Iterator<Character>	rangeClosedBy(char from, char toInclusive, int step)	Creates an Iterator of characters starting from from, extending to toInclusive, with step.
static Iterator<Double>	rangeClosedBy(double from, double toInclusive, double step)
static Iterator<Integer>	rangeClosedBy(int from, int toInclusive, int step)	Creates an Iterator of int numbers starting from from, extending to toInclusive, with step.
static Iterator<Long>	rangeClosedBy(long from, long toInclusive, long step)	Creates an Iterator of long numbers starting from from, extending to toInclusive, with step.
default T	reduceLeft(BiFunction<? super T,? super T,? extends T> op)	Accumulates the elements of this Traversable by successively calling the given operation op from the left.
default T	reduceRight(BiFunction<? super T,? super T,? extends T> op)	Accumulates the elements of this Traversable by successively calling the given operation op from the right.
default Iterator<T>	reject(Predicate<? super T> predicate)	Returns a new traversable consisting of all elements which do not satisfy the given predicate.
default Iterator<T>	replace(T currentElement, T newElement)	Replaces the first occurrence (if exists) of the given currentElement with newElement.
default Iterator<T>	replaceAll(T currentElement, T newElement)	Replaces all occurrences of the given currentElement with newElement.
default Iterator<T>	retainAll(Iterable<? extends T> elements)	Keeps all occurrences of the given elements from this.
default Traversable<T>	scan(T zero, BiFunction<? super T,? super T,? extends T> operation)	Computes a prefix scan of the elements of the collection.
default <U> Iterator<U>	scanLeft(U zero, BiFunction<? super U,? super T,? extends U> operation)	Produces a collection containing cumulative results of applying the operator going left to right.
default <U> Iterator<U>	scanRight(U zero, BiFunction<? super T,? super U,? extends U> operation)	Produces a collection containing cumulative results of applying the operator going right to left.
default Iterator<Seq<T>>	slideBy(Function<? super T,?> classifier)	Slides a non-overlapping window of a variable size over this Traversable.
default Iterator<Seq<T>>	sliding(int size)	Slides a window of a specific size and step size 1 over this Traversable by calling Traversable.sliding(int, int).
default Iterator<Seq<T>>	sliding(int size, int step)	Slides a window of a specific size and step size over this Traversable.
default Tuple2<Iterator<T>,Iterator<T>>	span(Predicate<? super T> predicate)	Returns a tuple where the first element is the longest prefix of elements that satisfy the given predicate and the second element is the remainder.
default String	stringPrefix()	Returns the name of this Value type, which is used by toString().
static <T> Iterator<T>	tabulate(int n, Function<? super Integer,? extends T> f)	Returns an Iterator on a sequence of n values of a given Function f over a range of integer values from 0 to n - 1.
default Iterator<T>	tail()	Drops the first element of a non-empty Traversable.
default Option<Iterator<T>>	tailOption()	Drops the first element of a non-empty Traversable and returns an Option.
default Iterator<T>	take(int n)	Take the first n elements from this iterator.
default Iterator<T>	takeRight(int n)	Takes the last n elements of this or all elements, if this length < n.
default Iterator<T>	takeUntil(Predicate<? super T> predicate)	Takes elements until the predicate holds for the current element.
default Iterator<T>	takeWhile(Predicate<? super T> predicate)	Takes elements while the predicate holds for the current element.
default <U> U	transform(Function<? super Iterator<T>,? extends U> f)	Transforms this Iterator.
static <T> Iterator<T>	unfold(T seed, Function<? super T,Option<Tuple2<? extends T,? extends T>>> f)	Creates an iterator from a seed value and a function.
static <T, U> Iterator<U>	unfoldLeft(T seed, Function<? super T,Option<Tuple2<? extends T,? extends U>>> f)	Creates an iterator from a seed value and a function.
static <T, U> Iterator<U>	unfoldRight(T seed, Function<? super T,Option<Tuple2<? extends U,? extends T>>> f)	Creates an iterator from a seed value and a function.
default <T1, T2> Tuple2<Iterator<T1>,Iterator<T2>>	unzip(Function<? super T,Tuple2<? extends T1,? extends T2>> unzipper)	Unzips this elements by mapping this elements to pairs which are subsequently split into two distinct sets.
default <T1, T2, T3> Tuple3<Iterator<T1>,Iterator<T2>,Iterator<T3>>	unzip3(Function<? super T,Tuple3<? extends T1,? extends T2,? extends T3>> unzipper)	Unzips this elements by mapping this elements to triples which are subsequently split into three distinct sets.
default <U> Iterator<Tuple2<T,U>>	zip(Iterable<? extends U> that)	Returns a traversable formed from this traversable and another Iterable collection by combining corresponding elements in pairs.
default <U> Iterator<Tuple2<T,U>>	zipAll(Iterable<? extends U> that, T thisElem, U thatElem)	Returns a traversable formed from this traversable and another Iterable by combining corresponding elements in pairs.
default <U, R> Iterator<R>	zipWith(Iterable<? extends U> that, BiFunction<? super T,? super U,? extends R> mapper)	Returns a traversable formed from this traversable and another Iterable collection by mapping elements.
default Iterator<Tuple2<T,Integer>>	zipWithIndex()	Zips this traversable with its indices.
default <U> Iterator<U>	zipWithIndex(BiFunction<? super T,? super Integer,? extends U> mapper)	Zips this traversable with its indices by applying mapper provided.

Methods inherited from interface io.vavr.collection.Foldable

fold, reduce, reduceOption

Methods inherited from interface java.util.Iterator

forEachRemaining, hasNext, next, remove

Methods inherited from interface io.vavr.collection.Traversable

arrangeBy, average, containsAll, count, equals, existsUnique, find, foldLeft, forEachWithIndex, hashCode, headOption, isDistinct, isOrdered, isSingleValued, lastOption, max, maxBy, maxBy, min, minBy, minBy, mkCharSeq, mkCharSeq, mkCharSeq, mkString, mkString, mkString, nonEmpty, product, reduceLeftOption, reduceRightOption, single, singleOption, size, spliterator, sum

Methods inherited from interface io.vavr.Value

collect, collect, contains, corresponds, eq, exists, forAll, forEach, getOrElse, getOrElse, getOrElseThrow, getOrElseTry, getOrNull, out, out, stderr, stdout, toArray, toCharSeq, toCompletableFuture, toEither, toEither, toInvalid, toInvalid, toJavaArray, toJavaArray, toJavaArray, toJavaCollection, toJavaList, toJavaList, toJavaMap, toJavaMap, toJavaMap, toJavaOptional, toJavaParallelStream, toJavaSet, toJavaSet, toJavaStream, toLeft, toLeft, toLinkedMap, toLinkedMap, toLinkedSet, toList, toMap, toMap, toOption, toPriorityQueue, toPriorityQueue, toQueue, toRight, toRight, toSet, toSortedMap, toSortedMap, toSortedMap, toSortedMap, toSortedSet, toSortedSet, toStream, toString, toTree, toTree, toTry, toTry, toValid, toValid, toValidation, toValidation, toVector

Method Details

concat

@SafeVarargs
static <T> Iterator<T> concat(Iterable<? extends T>... iterables)

Creates an Iterator which traverses along the concatenation of the given iterables.

Type Parameters:

T - Component type.

Parameters:

iterables - The iterables

Returns:

A new io.vavr.collection.Iterator

concat

static <T> Iterator<T> concat(Iterable<? extends Iterable<? extends T>> iterables)

Creates an Iterator which traverses along the concatenation of the given iterables.

Type Parameters:

T - Component type.

Parameters:

iterables - The iterable of iterables

Returns:

A new io.vavr.collection.Iterator

empty

static <T> Iterator<T> empty()

Returns the empty Iterator.

Type Parameters:

T - Component type

Returns:

The empty Iterator

narrow

static <T> Iterator<T> narrow(Iterator<? extends T> iterator)

Narrows a widened Iterator<? extends T> to Iterator<T> by performing a type-safe cast. This is eligible because immutable/read-only collections are covariant.

Type Parameters:

T - Component type of the Iterator.

Parameters:

iterator - An Iterator.

Returns:

the given iterator instance as narrowed type Iterator<T>.

of

static <T> Iterator<T> of(T element)

Creates an Iterator which traverses one element.

Type Parameters:

T - Component type.

Parameters:

element - An element

Returns:

A new Iterator

of

@SafeVarargs
static <T> Iterator<T> of(T... elements)

Creates an Iterator which traverses the given elements.

Type Parameters:

T - Component type

Parameters:

elements - Zero or more elements

Returns:

A new Iterator

ofAll

static <T> Iterator<T> ofAll(Iterable<? extends T> iterable)

Creates an Iterator based on the given Iterable. This is a convenience method for Iterator.ofAll(iterable.iterator().

Type Parameters:

T - Component type.

Parameters:

iterable - A Iterable

Returns:

A new io.vavr.collection.Iterator

ofAll

static <T> Iterator<T> ofAll(Iterator<? extends T> iterator)

Creates an Iterator based on the given Iterator by delegating calls of hasNext() and next() to it.

Type Parameters:

T - Component type.

Parameters:

iterator - A Iterator

Returns:

A new io.vavr.collection.Iterator

ofAll

static Iterator<Boolean> ofAll(boolean... elements)

Creates an Iterator from boolean values.

Parameters:

elements - boolean values

Returns:

A new Iterator of Boolean values

Throws:

NullPointerException - if elements is null

ofAll

static Iterator<Byte> ofAll(byte... elements)

Creates an Iterator from byte values.

Parameters:

elements - byte values

Returns:

A new Iterator of Byte values

Throws:

NullPointerException - if elements is null

ofAll

static Iterator<Character> ofAll(char... elements)

Creates an Iterator from char values.

Parameters:

elements - char values

Returns:

A new Iterator of Character values

Throws:

NullPointerException - if elements is null

ofAll

static Iterator<Double> ofAll(double... elements)

Creates ann Iterator from double values.

Parameters:

elements - double values

Returns:

A new Iterator of Double values

Throws:

NullPointerException - if elements is null

ofAll

static Iterator<Float> ofAll(float... elements)

Creates an Iterator from float values.

Parameters:

elements - float values

Returns:

A new Iterator of Float values

Throws:

NullPointerException - if elements is null

ofAll

static Iterator<Integer> ofAll(int... elements)

Creates an Iterator from int values.

Parameters:

elements - int values

Returns:

A new Iterator of Integer values

Throws:

NullPointerException - if elements is null

ofAll

static Iterator<Long> ofAll(long... elements)

Creates an Iterator from long values.

Parameters:

elements - long values

Returns:

A new Iterator of Long values

Throws:

NullPointerException - if elements is null

ofAll

static Iterator<Short> ofAll(short... elements)

Creates an Iterator from short values.

Parameters:

elements - short values

Returns:

A new Iterator of Short values

Throws:

NullPointerException - if elements is null

tabulate

static <T> Iterator<T> tabulate(int n,
 Function<? super Integer,? extends T> f)

Returns an Iterator on a sequence of n values of a given Function f over a range of integer values from 0 to n - 1.

Type Parameters:

T - Component type of the Iterator

Parameters:

n - The number of elements

f - The Function computing element values

Returns:

An Iterator on a sequence of elements f(0),f(1), ..., f(n - 1)

Throws:

NullPointerException - if f is null

fill

static <T> Iterator<T> fill(int n,
 Supplier<? extends T> s)

Returns an Iterator on a sequence of n values supplied by a given Supplier s.

Type Parameters:

T - Component type of the Iterator

Parameters:

n - The number of elements

s - The Supplier computing element values

Returns:

An iterator on a sequence of n elements, where each element contains the result supplied by s.

Throws:

NullPointerException - if s is null

fill

static <T> Iterator<T> fill(int n,
 T element)

Returns a Iterator containing n times the given element

Type Parameters:

T - Component type of the Iterator

Parameters:

n - The number of elements

element - The element

Returns:

An iterator of n sequence elements, where each element is the given element.

range

static Iterator<Character> range(char from,
 char toExclusive)

Creates an Iterator of characters starting from from, extending to toExclusive - 1.

Examples:

 
 Iterator.range('a', 'c')  // = ('a', 'b')
 Iterator.range('c', 'a')  // = ()
 
 

Parameters:

from - the first character

toExclusive - the successor of the last character

Returns:

a range of characters as specified or the empty range if from >= toExclusive

rangeBy

static Iterator<Character> rangeBy(char from,
 char toExclusive,
 int step)

Creates an Iterator of characters starting from from, extending to toExclusive - 1, with step.

Examples:

 
 Iterator.rangeBy('a', 'c', 1)  // = ('a', 'b')
 Iterator.rangeBy('a', 'd', 2)  // = ('a', 'c')
 Iterator.rangeBy('d', 'a', -2) // = ('d', 'b')
 Iterator.rangeBy('d', 'a', 2)  // = ()
 
 

Parameters:

from - the first character

toExclusive - the successor of the last character if step > 0, the predecessor of the last character if step < 0

step - the step

Returns:

a range of characters as specified or the empty range if signum(step) == signum(from - toExclusive).

Throws:

IllegalArgumentException - if step is zero

rangeBy

@GwtIncompatible("BigDecimalHelper is GwtIncompatible")
static Iterator<Double> rangeBy(double from,
 double toExclusive,
 double step)

rangeBy

static Iterator<BigDecimal> rangeBy(BigDecimal from,
 BigDecimal toExclusive,
 BigDecimal step)

range

static Iterator<Integer> range(int from,
 int toExclusive)

Creates an Iterator of int numbers starting from from, extending to toExclusive - 1.

Examples:

 
 Iterator.range(0, 0)  // = ()
 Iterator.range(2, 0)  // = ()
 Iterator.range(-2, 2) // = (-2, -1, 0, 1)
 
 

Parameters:

from - the first number

toExclusive - the last number + 1

Returns:

a range of int values as specified or the empty range if from >= toExclusive

rangeBy

static Iterator<Integer> rangeBy(int from,
 int toExclusive,
 int step)

Creates an Iterator of int numbers starting from from, extending to toExclusive - 1, with step.

Examples:

 
 Iterator.rangeBy(1, 3, 1)  // = (1, 2)
 Iterator.rangeBy(1, 4, 2)  // = (1, 3)
 Iterator.rangeBy(4, 1, -2) // = (4, 2)
 Iterator.rangeBy(4, 1, 2)  // = ()
 
 

Parameters:

from - the first number

toExclusive - the last number + 1 if step > 0, the last number - 1 if step < 0

step - the step

Returns:

a range of long values as specified or the empty range if (from == toExclusive) || (step * (from - toExclusive) > 0).

Throws:

IllegalArgumentException - if step is zero

range

static Iterator<Long> range(long from,
 long toExclusive)

Creates an Iterator of long numbers starting from from, extending to toExclusive - 1.

Examples:

 
 Iterator.range(0L, 0L)  // = ()
 Iterator.range(2L, 0L)  // = ()
 Iterator.range(-2L, 2L) // = (-2L, -1L, 0L, 1L)
 
 

Parameters:

from - the first number

toExclusive - the last number + 1

Returns:

a range of long values as specified or the empty range if from >= toExclusive

rangeBy

static Iterator<Long> rangeBy(long from,
 long toExclusive,
 long step)

Creates an Iterator of long numbers starting from from, extending to toExclusive - 1, with step.

Examples:

 
 Iterator.rangeBy(1L, 3L, 1L)  // = (1L, 2L)
 Iterator.rangeBy(1L, 4L, 2L)  // = (1L, 3L)
 Iterator.rangeBy(4L, 1L, -2L) // = (4L, 2L)
 Iterator.rangeBy(4L, 1L, 2L)  // = ()
 
 

Parameters:

from - the first number

toExclusive - the last number + 1 if step > 0, the last number - 1 if step < 0

step - the step

Returns:

a range of long values as specified or the empty range if (from == toExclusive) || (step * (from - toExclusive) > 0).

Throws:

IllegalArgumentException - if step is zero

rangeClosed

static Iterator<Character> rangeClosed(char from,
 char toInclusive)

Creates an Iterator of characters starting from from, extending to toInclusive.

Examples:

 
 Iterator.rangeClosed('a', 'c')  // = ('a', 'b', 'c')
 Iterator.rangeClosed('c', 'a')  // = ()
 
 

Parameters:

from - the first character

toInclusive - the last character

Returns:

a range of characters as specified or the empty range if from > toInclusive

rangeClosedBy

static Iterator<Character> rangeClosedBy(char from,
 char toInclusive,
 int step)

Creates an Iterator of characters starting from from, extending to toInclusive, with step.

Examples:

 
 Iterator.rangeClosedBy('a', 'c', 1)  // = ('a', 'b', 'c')
 Iterator.rangeClosedBy('a', 'd', 2)  // = ('a', 'c')
 Iterator.rangeClosedBy('d', 'a', -2) // = ('d', 'b')
 Iterator.rangeClosedBy('d', 'a', 2)  // = ()
 
 

Parameters:

from - the first character

toInclusive - the last character

step - the step

Returns:

a range of characters as specified or the empty range if signum(step) == signum(from - toInclusive).

Throws:

IllegalArgumentException - if step is zero

rangeClosedBy

@GwtIncompatible
static Iterator<Double> rangeClosedBy(double from,
 double toInclusive,
 double step)

rangeClosed

static Iterator<Integer> rangeClosed(int from,
 int toInclusive)

Creates an Iterator of int numbers starting from from, extending to toInclusive.

Examples:

 
 Iterator.rangeClosed(0, 0)  // = (0)
 Iterator.rangeClosed(2, 0)  // = ()
 Iterator.rangeClosed(-2, 2) // = (-2, -1, 0, 1, 2)
 
 

Parameters:

from - the first number

toInclusive - the last number

Returns:

a range of int values as specified or the empty range if from > toInclusive

rangeClosedBy

static Iterator<Integer> rangeClosedBy(int from,
 int toInclusive,
 int step)

Creates an Iterator of int numbers starting from from, extending to toInclusive, with step.

Examples:

 
 Iterator.rangeClosedBy(1, 3, 1)  // = (1, 2, 3)
 Iterator.rangeClosedBy(1, 4, 2)  // = (1, 3)
 Iterator.rangeClosedBy(4, 1, -2) // = (4, 2)
 Iterator.rangeClosedBy(4, 1, 2)  // = ()
 
 

Parameters:

from - the first number

toInclusive - the last number

step - the step

Returns:

a range of int values as specified or the empty range if signum(step) == signum(from - toInclusive).

Throws:

IllegalArgumentException - if step is zero

rangeClosed

static Iterator<Long> rangeClosed(long from,
 long toInclusive)

Creates an Iterator of long numbers starting from from, extending to toInclusive.

Examples:

 
 Iterator.rangeClosed(0L, 0L)  // = (0L)
 Iterator.rangeClosed(2L, 0L)  // = ()
 Iterator.rangeClosed(-2L, 2L) // = (-2L, -1L, 0L, 1L, 2L)
 
 

Parameters:

from - the first number

toInclusive - the last number

Returns:

a range of long values as specified or the empty range if from > toInclusive

rangeClosedBy

static Iterator<Long> rangeClosedBy(long from,
 long toInclusive,
 long step)

Creates an Iterator of long numbers starting from from, extending to toInclusive, with step.

Examples:

 
 Iterator.rangeClosedBy(1L, 3L, 1L)  // = (1L, 2L, 3L)
 Iterator.rangeClosedBy(1L, 4L, 2L)  // = (1L, 3L)
 Iterator.rangeClosedBy(4L, 1L, -2L) // = (4L, 2L)
 Iterator.rangeClosedBy(4L, 1L, 2L)  // = ()
 
 

Parameters:

from - the first number

toInclusive - the last number

step - the step

Returns:

a range of int values as specified or the empty range if signum(step) == signum(from - toInclusive).

Throws:

IllegalArgumentException - if step is zero

from

static Iterator<Integer> from(int value)

Returns an infinite iterator of int values starting from value.

The Iterator extends to Integer.MIN_VALUE when passing Integer.MAX_VALUE.

Parameters:

value - a start int value

Returns:

a new Iterator of int values starting from from

from

static Iterator<Integer> from(int value,
 int step)

Returns an infinite iterator of int values starting from value and spaced by step.

The Iterator extends to Integer.MIN_VALUE when passing Integer.MAX_VALUE.

Parameters:

value - a start int value

step - the step by which to advance on each iteration

Returns:

a new Iterator of int values starting from from

from

static Iterator<Long> from(long value)

Returns an infinite iterator of long values starting from value.

The Iterator extends to Long.MIN_VALUE when passing Long.MAX_VALUE.

Parameters:

value - a start long value

Returns:

a new Iterator of long values starting from from

from

static Iterator<Long> from(long value,
 long step)

Returns an infinite iterator of long values starting from value and spaced by step.

The Iterator extends to Long.MIN_VALUE when passing Long.MAX_VALUE.

Parameters:

value - a start long value

step - the step by which to advance on each iteration

Returns:

a new Iterator of long values starting from from

continually

static <T> Iterator<T> continually(Supplier<? extends T> supplier)

Generates an infinite iterator using a value Supplier.

Type Parameters:

T - value type

Parameters:

supplier - A Supplier of iterator values

Returns:

A new Iterator

iterate

static <T> Iterator<T> iterate(Supplier<? extends Option<? extends T>> supplier)

Creates an iterator that repeatedly invokes the supplier while it's a Some and end on the first None

Type Parameters:

T - value type

Parameters:

supplier - A Supplier of iterator values

Returns:

A new Iterator

Throws:

NullPointerException - if supplier produces null value

iterate

static <T> Iterator<T> iterate(T seed,
 Function<? super T,? extends T> f)

Generates an infinite iterator using a function to calculate the next value based on the previous.

Type Parameters:

T - value type

Parameters:

seed - The first value in the iterator

f - A function to calculate the next value based on the previous

Returns:

A new Iterator

continually

static <T> Iterator<T> continually(T t)

Creates an infinite iterator returning the given element.

Type Parameters:

T - Element type

Parameters:

t - An element

Returns:

A new Iterator containing infinite t's.

collect

default <R> Iterator<R> collect(PartialFunction<? super T,? extends R> partialFunction)

Description copied from interface: Traversable

Collects all elements that are in the domain of the given partialFunction by mapping the elements to type R.

More specifically, for each of this elements in iteration order first it is checked

 partialFunction.isDefinedAt(element)
 

If the elements makes it through that filter, the mapped instance is added to the result collection

 R newElement = partialFunction.apply(element)
 

Note:If this Traversable is ordered (i.e. extends Ordered, the caller of collect has to ensure that the elements are comparable (i.e. extend Comparable).

Specified by:

collect in interface Traversable<T>

Type Parameters:

R - The new element type

Parameters:

partialFunction - A function that is not necessarily defined of all elements of this traversable.

Returns:

A new Traversable instance containing elements of type R

concat

default Iterator<T> concat(Iterator<? extends T> that)

intersperse

default Iterator<T> intersperse(T element)

Inserts an element between all elements of this Iterator.

Parameters:

element - An element.

Returns:

an interspersed version of this

transform

default <U> U transform(Function<? super Iterator<T>,? extends U> f)

Transforms this Iterator.

Type Parameters:

U - Type of transformation result

Parameters:

f - A transformation

Returns:

An instance of type U

Throws:

NullPointerException - if f is null

zip

default <U> Iterator<Tuple2<T,U>> zip(Iterable<? extends U> that)

Description copied from interface: Traversable

Returns a traversable formed from this traversable and another Iterable collection by combining corresponding elements in pairs. If one of the two iterables is longer than the other, its remaining elements are ignored.

The length of the returned traversable is the minimum of the lengths of this traversable and that iterable.

Specified by:

zip in interface Traversable<T>

Type Parameters:

U - The type of the second half of the returned pairs.

Parameters:

that - The Iterable providing the second half of each result pair.

Returns:

a new traversable containing pairs consisting of corresponding elements of this traversable and that iterable.

zipWith

default <U,
R> Iterator<R> zipWith(Iterable<? extends U> that,
 BiFunction<? super T,? super U,? extends R> mapper)

Description copied from interface: Traversable

Returns a traversable formed from this traversable and another Iterable collection by mapping elements. If one of the two iterables is longer than the other, its remaining elements are ignored.

The length of the returned traversable is the minimum of the lengths of this traversable and that iterable.

Specified by:

zipWith in interface Traversable<T>

Type Parameters:

U - The type of the second parameter of the mapper.

R - The type of the mapped elements.

Parameters:

that - The Iterable providing the second parameter of the mapper.

mapper - a mapper.

Returns:

a new traversable containing mapped elements of this traversable and that iterable.

zipAll

default <U> Iterator<Tuple2<T,U>> zipAll(Iterable<? extends U> that,
 T thisElem,
 U thatElem)

Description copied from interface: Traversable

Returns a traversable formed from this traversable and another Iterable by combining corresponding elements in pairs. If one of the two collections is shorter than the other, placeholder elements are used to extend the shorter collection to the length of the longer.

The length of the returned traversable is the maximum of the lengths of this traversable and that iterable.

Special case: if this traversable is shorter than that elements, and that elements contains duplicates, the resulting traversable may be shorter than the maximum of the lengths of this and that because a traversable contains an element at most once.

If this Traversable is shorter than that, thisElem values are used to fill the result. If that is shorter than this Traversable, thatElem values are used to fill the result.

Specified by:

zipAll in interface Traversable<T>

Type Parameters:

U - The type of the second half of the returned pairs.

Parameters:

that - The Iterable providing the second half of each result pair.

thisElem - The element to be used to fill up the result if this traversable is shorter than that.

thatElem - The element to be used to fill up the result if that is shorter than this traversable.

Returns:

A new traversable containing pairs consisting of corresponding elements of this traversable and that.

zipWithIndex

default Iterator<Tuple2<T,Integer>> zipWithIndex()

Description copied from interface: Traversable

Zips this traversable with its indices.

Specified by:

zipWithIndex in interface Traversable<T>

Returns:

A new traversable containing all elements of this traversable paired with their index, starting with 0.

zipWithIndex

default <U> Iterator<U> zipWithIndex(BiFunction<? super T,? super Integer,? extends U> mapper)

Description copied from interface: Traversable

Zips this traversable with its indices by applying mapper provided.

Specified by:

zipWithIndex in interface Traversable<T>

Type Parameters:

U - The type of the mapped elements.

Parameters:

mapper - a mapper.

Returns:

a new traversable containing elements of this traversable, zipped with indices, and mapped with mapper provided.

unzip

default <T1,
T2> Tuple2<Iterator<T1>,Iterator<T2>> unzip(Function<? super T,Tuple2<? extends T1,? extends T2>> unzipper)

Description copied from interface: Traversable

Unzips this elements by mapping this elements to pairs which are subsequently split into two distinct sets.

Specified by:

unzip in interface Traversable<T>

Type Parameters:

T1 - 1st element type of a pair returned by unzipper

T2 - 2nd element type of a pair returned by unzipper

Parameters:

unzipper - a function which converts elements of this to pairs

Returns:

A pair of set containing elements split by unzipper

unzip3

default <T1,
T2,
T3>
Tuple3<Iterator<T1>,Iterator<T2>,Iterator<T3>> unzip3(Function<? super T,Tuple3<? extends T1,? extends T2,? extends T3>> unzipper)

Description copied from interface: Traversable

Unzips this elements by mapping this elements to triples which are subsequently split into three distinct sets.

Specified by:

unzip3 in interface Traversable<T>

Type Parameters:

T1 - 1st element type of a triplet returned by unzipper

T2 - 2nd element type of a triplet returned by unzipper

T3 - 3rd element type of a triplet returned by unzipper

Parameters:

unzipper - a function which converts elements of this to pairs

Returns:

A triplet of set containing elements split by unzipper

unfold

static <T> Iterator<T> unfold(T seed,
 Function<? super T,Option<Tuple2<? extends T,? extends T>>> f)

Creates an iterator from a seed value and a function. The function takes the seed at first. The function should return None when it's done generating elements, otherwise Some Tuple of the value to add to the resulting iterator and the element for the next call.

Example:

 
 Iterator.unfold(10, x -> x == 0
                 ? Option.none()
                 : Option.of(new Tuple2<>(x-1, x)));
 // List(1, 2, 3, 4, 5, 6, 7, 8, 9, 10))
 
 

Type Parameters:

T - type of seeds and unfolded values

Parameters:

seed - the start value for the iteration

f - the function to get the next step of the iteration

Returns:

a list with the values built up by the iteration

Throws:

NullPointerException - if f is null

unfoldLeft

static <T,
U> Iterator<U> unfoldLeft(T seed,
 Function<? super T,Option<Tuple2<? extends T,? extends U>>> f)

Creates an iterator from a seed value and a function. The function takes the seed at first. The function should return None when it's done generating elements, otherwise Some Tuple of the value to add to the resulting iterator and the element for the next call.

Example:

 
 Iterator.unfoldLeft(10, x -> x == 0
                    ? Option.none()
                    : Option.of(new Tuple2<>(x-1, x)));
 // List(1, 2, 3, 4, 5, 6, 7, 8, 9, 10))
 
 

Type Parameters:

T - type of seeds

U - type of unfolded values

Parameters:

seed - the start value for the iteration

f - the function to get the next step of the iteration

Returns:

a list with the values built up by the iteration

Throws:

NullPointerException - if f is null

unfoldRight

static <T,
U> Iterator<U> unfoldRight(T seed,
 Function<? super T,Option<Tuple2<? extends U,? extends T>>> f)

Creates an iterator from a seed value and a function. The function takes the seed at first. The function should return None when it's done generating elements, otherwise Some Tuple of the element for the next call and the value to add to the resulting iterator.

Example:

 
 Iterator.unfoldRight(10, x -> x == 0
             ? Option.none()
             : Option.of(new Tuple2<>(x, x-1)));
 // List(10, 9, 8, 7, 6, 5, 4, 3, 2, 1))
 
 

Type Parameters:

T - type of seeds

U - type of unfolded values

Parameters:

seed - the start value for the iteration

f - the function to get the next step of the iteration

Returns:

a list with the values built up by the iteration

Throws:

NullPointerException - if f is null

distinct

default Iterator<T> distinct()

Description copied from interface: Traversable

Returns a new version of this which contains no duplicates. Elements are compared using equals.

Specified by:

distinct in interface Traversable<T>

Returns:

a new Traversable containing this elements without duplicates

distinctBy

default Iterator<T> distinctBy(Comparator<? super T> comparator)

Description copied from interface: Traversable

Returns a new version of this which contains no duplicates. Elements are compared using the given comparator.

Specified by:

distinctBy in interface Traversable<T>

Parameters:

comparator - A comparator

Returns:

a new Traversable containing this elements without duplicates

distinctBy

default <U> Iterator<T> distinctBy(Function<? super T,? extends U> keyExtractor)

Description copied from interface: Traversable

Returns a new version of this which contains no duplicates. Elements mapped to keys which are compared using equals.

The elements of the result are determined in the order of their occurrence - first match wins.

Specified by:

distinctBy in interface Traversable<T>

Type Parameters:

U - key type

Parameters:

keyExtractor - A key extractor

Returns:

a new Traversable containing this elements without duplicates

drop

default Iterator<T> drop(int n)

Removes up to n elements from this iterator.

Specified by:

drop in interface Traversable<T>

Parameters:

n - A number

Returns:

The empty iterator, if n <= 0 or this is empty, otherwise a new iterator without the first n elements.

dropRight

default Iterator<T> dropRight(int n)

Description copied from interface: Traversable

Drops the last n elements of this or all elements, if this length < n.

Specified by:

dropRight in interface Traversable<T>

Parameters:

n - The number of elements to drop.

Returns:

a new instance consisting of all elements of this except the last n ones, or else the empty instance, if this has less than n elements.

dropUntil

default Iterator<T> dropUntil(Predicate<? super T> predicate)

Description copied from interface: Traversable

Drops elements until the predicate holds for the current element.

Specified by:

dropUntil in interface Traversable<T>

Parameters:

predicate - A condition tested subsequently for this elements.

Returns:

a new instance consisting of all elements starting from the first one which does satisfy the given predicate.

dropWhile

default Iterator<T> dropWhile(Predicate<? super T> predicate)

Description copied from interface: Traversable

Drops elements while the predicate holds for the current element.

Note: This is essentially the same as dropUntil(predicate.negate()). It is intended to be used with method references, which cannot be negated directly.

Specified by:

dropWhile in interface Traversable<T>

Parameters:

predicate - A condition tested subsequently for this elements.

Returns:

a new instance consisting of all elements starting from the first one which does not satisfy the given predicate.

filter

default Iterator<T> filter(Predicate<? super T> predicate)

Returns an Iterator that contains elements that satisfy the given predicate.

Specified by:

filter in interface Traversable<T>

Parameters:

predicate - A predicate

Returns:

A new Iterator

reject

default Iterator<T> reject(Predicate<? super T> predicate)

Description copied from interface: Traversable

Returns a new traversable consisting of all elements which do not satisfy the given predicate.

The default implementation is equivalent to

filter(predicate.negate()

Specified by:

reject in interface Traversable<T>

Parameters:

predicate - A predicate

Returns:

a new traversable

findLast

default Option<T> findLast(Predicate<? super T> predicate)

Description copied from interface: Traversable

Returns the last element of this which satisfies the given predicate.

Same as reverse().find(predicate).

Specified by:

findLast in interface Traversable<T>

Parameters:

predicate - A predicate.

Returns:

Some(element) or None, where element may be null (i.e. List.of(null).find(e -> e == null)).

flatMap

default <U> Iterator<U> flatMap(Function<? super T,? extends Iterable<? extends U>> mapper)

FlatMaps the elements of this Iterator to Iterables, which are iterated in the order of occurrence.

Specified by:

flatMap in interface Traversable<T>

Type Parameters:

U - Component type

Parameters:

mapper - A mapper

Returns:

A new Iterable

foldRight

default <U> U foldRight(U zero,
 BiFunction<? super T,? super U,? extends U> f)

Description copied from interface: Foldable

Folds this elements from the right, starting with zero and successively calling combine.

Example:

 
 // = "!cba"
 List("a", "b", "c").foldRight("!", (x, xs) -> xs + x)
  

Specified by:

foldRight in interface Foldable<T>

Specified by:

foldRight in interface Traversable<T>

Type Parameters:

U - the type of the folded value

Parameters:

zero - A zero element to start with.

f - A function which combines elements.

Returns:

a folded value

get

default T get()

Description copied from interface: Traversable

Gets the first value in iteration order if this Traversable is not empty, otherwise throws.

Specified by:

get in interface Traversable<T>

Specified by:

get in interface Value<T>

Returns:

the first value

groupBy

default <C> Map<C,Iterator<T>> groupBy(Function<? super T,? extends C> classifier)

Description copied from interface: Traversable

Groups this elements by classifying the elements.

Specified by:

groupBy in interface Traversable<T>

Type Parameters:

C - classified class type

Parameters:

classifier - A function which classifies elements into classes

Returns:

A Map containing the grouped elements

See Also:

• Traversable.arrangeBy(Function)

grouped

default Iterator<Seq<T>> grouped(int size)

Description copied from interface: Traversable

Groups this Traversable into fixed size blocks.

Let length be the length of this Iterable. Then grouped is defined as follows:

• If this.isEmpty(), the resulting Iterator is empty.
• If size <= length, the resulting Iterator will contain length / size blocks of size size and maybe a non-empty block of size length % size, if there are remaining elements.
• If size > length, the resulting Iterator will contain one block of size length.

Examples:

 
 [].grouped(1) = []
 [].grouped(0) throws
 [].grouped(-1) throws
 [1,2,3,4].grouped(2) = [[1,2],[3,4]]
 [1,2,3,4,5].grouped(2) = [[1,2],[3,4],[5]]
 [1,2,3,4].grouped(5) = [[1,2,3,4]]
 
 

Please note that grouped(int) is a special case of Traversable.sliding(int, int), i.e. grouped(size) is the same as sliding(size, size).

Specified by:

grouped in interface Traversable<T>

Parameters:

size - a positive block size

Returns:

A new Iterator of grouped blocks of the given size

hasDefiniteSize

default boolean hasDefiniteSize()

Description copied from interface: Traversable

Checks if this Traversable is known to have a finite size.

This method should be implemented by classes only, i.e. not by interfaces.

Specified by:

hasDefiniteSize in interface Traversable<T>

Returns:

true, if this Traversable is known to have a finite size, false otherwise.

head

default T head()

Description copied from interface: Traversable

Returns the first element of a non-empty Traversable.

Specified by:

head in interface Traversable<T>

Returns:

The first element of this Traversable.

init

default Iterator<T> init()

Description copied from interface: Traversable

Dual of Traversable.tail(), returning all elements except the last.

Specified by:

init in interface Traversable<T>

Returns:

a new instance containing all elements except the last.

initOption

default Option<Iterator<T>> initOption()

Description copied from interface: Traversable

Dual of Traversable.tailOption(), returning all elements except the last as Option.

Specified by:

initOption in interface Traversable<T>

Returns:

Some(traversable) or None if this is empty.

isAsync

default boolean isAsync()

An Iterator is computed synchronously.

Specified by:

isAsync in interface Value<T>

Returns:

false

isEmpty

default boolean isEmpty()

Description copied from interface: Traversable

Checks if this Traversable is empty.

Specified by:

isEmpty in interface Traversable<T>

Specified by:

isEmpty in interface Value<T>

Returns:

true, if this Traversable contains no elements, false otherwise.

isLazy

default boolean isLazy()

An Iterator is computed lazily.

Specified by:

isLazy in interface Value<T>

Returns:

true

isTraversableAgain

default boolean isTraversableAgain()

Description copied from interface: Traversable

Checks if this Traversable can be repeatedly traversed.

This method should be implemented by classes only, i.e. not by interfaces.

Specified by:

isTraversableAgain in interface Traversable<T>

Returns:

true, if this Traversable is known to be traversable repeatedly, false otherwise.

isSequential

default boolean isSequential()

Description copied from interface: Traversable

Checks if the elements of this Traversable appear in encounter order.

Specified by:

isSequential in interface Traversable<T>

Returns:

true, if the insertion order of elements is preserved, false otherwise.

iterator

default Iterator<T> iterator()

Description copied from interface: Traversable

An iterator by means of head() and tail(). Subclasses may want to override this method.

Specified by:

iterator in interface Iterable<T>

Specified by:

iterator in interface Traversable<T>

Specified by:

iterator in interface Value<T>

Returns:

A new Iterator of this Traversable elements.

last

default T last()

Description copied from interface: Traversable

Dual of Traversable.head(), returning the last element.

Specified by:

last in interface Traversable<T>

Returns:

the last element.

length

default int length()

Description copied from interface: Traversable

Computes the number of elements of this Traversable.

Same as Traversable.size().

Specified by:

length in interface Traversable<T>

Returns:

the number of elements

map

default <U> Iterator<U> map(Function<? super T,? extends U> mapper)

Maps the elements of this Iterator lazily using the given mapper.

Specified by:

map in interface Traversable<T>

Specified by:

map in interface Value<T>

Type Parameters:

U - Component type

Parameters:

mapper - A mapper.

Returns:

A new Iterator

orElse

default Iterator<T> orElse(Iterable<? extends T> other)

Description copied from interface: Traversable

Returns this Traversable if it is nonempty, otherwise return the alternative.

Specified by:

orElse in interface Traversable<T>

Parameters:

other - An alternative Traversable

Returns:

this Traversable if it is nonempty, otherwise return the alternative.

orElse

default Iterator<T> orElse(Supplier<? extends Iterable<? extends T>> supplier)

Description copied from interface: Traversable

Returns this Traversable if it is nonempty, otherwise return the result of evaluating supplier.

Specified by:

orElse in interface Traversable<T>

Parameters:

supplier - An alternative Traversable supplier

Returns:

this Traversable if it is nonempty, otherwise return the result of evaluating supplier.

partition

default Tuple2<Iterator<T>,Iterator<T>> partition(Predicate<? super T> predicate)

Description copied from interface: Traversable

Creates a partition of this Traversable by splitting this elements in two in distinct traversables according to a predicate.

Specified by:

partition in interface Traversable<T>

Parameters:

predicate - A predicate which classifies an element if it is in the first or the second traversable.

Returns:

A disjoint union of two traversables. The first Traversable contains all elements that satisfy the given predicate, the second Traversable contains all elements that don't. The original order of elements is preserved.

peek

default Iterator<T> peek(Consumer<? super T> action)

Description copied from interface: Value

Performs the given action on the first element if this is an eager implementation. Performs the given action on all elements (the first immediately, successive deferred), if this is a lazy implementation.

Specified by:

peek in interface Traversable<T>

Specified by:

peek in interface Value<T>

Parameters:

action - The action that will be performed on the element(s).

Returns:

this instance

reduceLeft

default T reduceLeft(BiFunction<? super T,? super T,? extends T> op)

Description copied from interface: Traversable

Accumulates the elements of this Traversable by successively calling the given operation op from the left.

Specified by:

reduceLeft in interface Foldable<T>

Specified by:

reduceLeft in interface Traversable<T>

Parameters:

op - A BiFunction of type T

Returns:

the reduced value.

reduceRight

default T reduceRight(BiFunction<? super T,? super T,? extends T> op)

Description copied from interface: Traversable

Accumulates the elements of this Traversable by successively calling the given operation op from the right.

Specified by:

reduceRight in interface Foldable<T>

Specified by:

reduceRight in interface Traversable<T>

Parameters:

op - An operation of type T

Returns:

the reduced value.

replace

default Iterator<T> replace(T currentElement,
 T newElement)

Description copied from interface: Traversable

Replaces the first occurrence (if exists) of the given currentElement with newElement.

Specified by:

replace in interface Traversable<T>

Parameters:

currentElement - An element to be substituted.

newElement - A replacement for currentElement.

Returns:

a Traversable containing all elements of this where the first occurrence of currentElement is replaced with newElement.

replaceAll

default Iterator<T> replaceAll(T currentElement,
 T newElement)

Description copied from interface: Traversable

Replaces all occurrences of the given currentElement with newElement.

Specified by:

replaceAll in interface Traversable<T>

Parameters:

currentElement - An element to be substituted.

newElement - A replacement for currentElement.

Returns:

a Traversable containing all elements of this where all occurrences of currentElement are replaced with newElement.

retainAll

default Iterator<T> retainAll(Iterable<? extends T> elements)

Description copied from interface: Traversable

Keeps all occurrences of the given elements from this.

Specified by:

retainAll in interface Traversable<T>

Parameters:

elements - Elements to be kept.

Returns:

a Traversable containing all occurrences of the given elements.

scan

default Traversable<T> scan(T zero,
 BiFunction<? super T,? super T,? extends T> operation)

Description copied from interface: Traversable

Computes a prefix scan of the elements of the collection. Note: The neutral element z may be applied more than once.

Specified by:

scan in interface Traversable<T>

Parameters:

zero - neutral element for the operator op

operation - the associative operator for the scan

Returns:

a new traversable collection containing the prefix scan of the elements in this traversable collection

scanLeft

default <U> Iterator<U> scanLeft(U zero,
 BiFunction<? super U,? super T,? extends U> operation)

Description copied from interface: Traversable

Produces a collection containing cumulative results of applying the operator going left to right. Note: will not terminate for infinite-sized collections. Note: might return different results for different runs, unless the underlying collection type is ordered.

Specified by:

scanLeft in interface Traversable<T>

Type Parameters:

U - the type of the elements in the resulting collection

Parameters:

zero - the initial value

operation - the binary operator applied to the intermediate result and the element

Returns:

collection with intermediate results

scanRight

default <U> Iterator<U> scanRight(U zero,
 BiFunction<? super T,? super U,? extends U> operation)

Description copied from interface: Traversable

Produces a collection containing cumulative results of applying the operator going right to left. The head of the collection is the last cumulative result. Note: will not terminate for infinite-sized collections. Note: might return different results for different runs, unless the underlying collection type is ordered.

Specified by:

scanRight in interface Traversable<T>

Type Parameters:

U - the type of the elements in the resulting collection

Parameters:

zero - the initial value

operation - the binary operator applied to the intermediate result and the element

Returns:

collection with intermediate results

slideBy

default Iterator<Seq<T>> slideBy(Function<? super T,?> classifier)

Description copied from interface: Traversable

Slides a non-overlapping window of a variable size over this Traversable.

Each window contains elements with the same class, as determined by classifier. Two consecutive values in this Traversable will be in the same window only if classifier returns equal values for them. Otherwise, the values will constitute the last element of the previous window and the first element of the next window.

Examples:

 [].slideBy(Function.identity()) = []
 [1,2,3,4,4,5].slideBy(Function.identity()) = [[1],[2],[3],[4,4],[5]]
 [1,2,3,10,12,5,7,20,29].slideBy(x -> x/10) = [[1,2,3],[10,12],[5,7],[20,29]]
 

Specified by:

slideBy in interface Traversable<T>

Parameters:

classifier - A function which classifies elements into classes

Returns:

A new Iterator of windows of the grouped elements

sliding

default Iterator<Seq<T>> sliding(int size)

Description copied from interface: Traversable

Slides a window of a specific size and step size 1 over this Traversable by calling Traversable.sliding(int, int).

Specified by:

sliding in interface Traversable<T>

Parameters:

size - a positive window size

Returns:

a new Iterator of windows of a specific size using step size 1

sliding

default Iterator<Seq<T>> sliding(int size,
 int step)

Description copied from interface: Traversable

Slides a window of a specific size and step size over this Traversable.

Examples:

 
 [].sliding(1,1) = []
 [1,2,3,4,5].sliding(2,3) = [[1,2],[4,5]]
 [1,2,3,4,5].sliding(2,4) = [[1,2],[5]]
 [1,2,3,4,5].sliding(2,5) = [[1,2]]
 [1,2,3,4].sliding(5,3) = [[1,2,3,4],[4]]
 
 

Specified by:

sliding in interface Traversable<T>

Parameters:

size - a positive window size

step - a positive step size

Returns:

a new Iterator of windows of a specific size using a specific step size

span

default Tuple2<Iterator<T>,Iterator<T>> span(Predicate<? super T> predicate)

Description copied from interface: Traversable

Returns a tuple where the first element is the longest prefix of elements that satisfy the given predicate and the second element is the remainder.

Specified by:

span in interface Traversable<T>

Parameters:

predicate - A predicate.

Returns:

a Tuple containing the longest prefix of elements that satisfy p and the remainder.

stringPrefix

default String stringPrefix()

Description copied from interface: Value

Returns the name of this Value type, which is used by toString().

Specified by:

stringPrefix in interface Value<T>

Returns:

This type name.

tail

default Iterator<T> tail()

Description copied from interface: Traversable

Drops the first element of a non-empty Traversable.

Specified by:

tail in interface Traversable<T>

Returns:

A new instance of Traversable containing all elements except the first.

tailOption

default Option<Iterator<T>> tailOption()

Description copied from interface: Traversable

Drops the first element of a non-empty Traversable and returns an Option.

Specified by:

tailOption in interface Traversable<T>

Returns:

Some(traversable) or None if this is empty.

take

default Iterator<T> take(int n)

Take the first n elements from this iterator.

Specified by:

take in interface Traversable<T>

Parameters:

n - A number

Returns:

The empty iterator, if n <= 0 or this is empty, otherwise a new iterator without the first n elements.

takeRight

default Iterator<T> takeRight(int n)

Description copied from interface: Traversable

Takes the last n elements of this or all elements, if this length < n.

The result is equivalent to sublist(max(0, min(length(), length() - n)), n), i.e. takeRight will not throw if n < 0 or n > length().

In the case of n < 0 the empty instance is returned, in the case of n > length() this is returned.

Specified by:

takeRight in interface Traversable<T>

Parameters:

n - The number of elements to take.

Returns:

A new instance consisting of the last n elements of this or all elements, if this has less than n elements.

takeUntil

default Iterator<T> takeUntil(Predicate<? super T> predicate)

Description copied from interface: Traversable

Takes elements until the predicate holds for the current element.

Note: This is essentially the same as takeWhile(predicate.negate()). It is intended to be used with method references, which cannot be negated directly.

Specified by:

takeUntil in interface Traversable<T>

Parameters:

predicate - A condition tested subsequently for this elements.

Returns:

a new instance consisting of all elements before the first one which does satisfy the given predicate.

takeWhile

default Iterator<T> takeWhile(Predicate<? super T> predicate)

Description copied from interface: Traversable

Takes elements while the predicate holds for the current element.

Specified by:

takeWhile in interface Traversable<T>

Parameters:

predicate - A condition tested subsequently for the contained elements.

Returns:

a new instance consisting of all elements before the first one which does not satisfy the given predicate.