Interface Iterator<T>
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- Type Parameters:
T
- Component type
- All Superinterfaces:
Foldable<T>
,Iterable<T>
,java.lang.Iterable<T>
,java.util.Iterator<T>
,Traversable<T>
,Value<T>
public interface Iterator<T> extends java.util.Iterator<T>, Traversable<T>
io.vavr.collection.Iterator
is a compositional replacement forjava.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, andnext
which removes the next element from the iterator and returns it. They can be called an arbitrary amount of times. IfhasNext
returns false, a call ofnext
will throw aNoSuchElementException
.Caution: Other methods than
hasNext
andnext
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.
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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 givenpartialFunction
by mapping the elements to typeR
.static <T> Iterator<T>
concat(java.lang.Iterable<? extends java.lang.Iterable<? extends T>> iterables)
Creates an Iterator which traverses along the concatenation of the given iterables.static <T> Iterator<T>
concat(java.lang.Iterable<? extends T>... iterables)
Creates an Iterator which traverses along the concatenation of the given iterables.default Iterator<T>
concat(java.util.Iterator<? extends T> that)
static <T> Iterator<T>
continually(java.util.function.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(java.util.Comparator<? super T> comparator)
Returns a new version of this which contains no duplicates.default <U> Iterator<T>
distinctBy(java.util.function.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(java.util.function.Predicate<? super T> predicate)
Drops elements until the predicate holds for the current element.default Iterator<T>
dropWhile(java.util.function.Predicate<? super T> predicate)
Drops elements while the predicate holds for the current element.static <T> Iterator<T>
empty()
Returns the singleton instance of the emptyIterator
.static <T> Iterator<T>
fill(int n, java.util.function.Supplier<? extends T> s)
Returns an Iterator on a sequence ofn
values supplied by a given Suppliers
.static <T> Iterator<T>
fill(int n, T element)
Returns a Iterator containingn
times the givenelement
default Iterator<T>
filter(java.util.function.Predicate<? super T> predicate)
Returns an Iterator that contains elements that satisfy the givenpredicate
.default Iterator<T>
filterNot(java.util.function.Predicate<? super T> predicate)
Returns an Iterator that contains elements that not satisfy the givenpredicate
.default Option<T>
findLast(java.util.function.Predicate<? super T> predicate)
Returns the last element of this which satisfies the given predicate.default <U> Iterator<U>
flatMap(java.util.function.Function<? super T,? extends java.lang.Iterable<? extends U>> mapper)
Maps the elements of this Iterator to Iterables and concats their iterators.default <U> U
foldRight(U zero, java.util.function.BiFunction<? super T,? super U,? extends U> f)
Folds this elements from the right, starting withzero
and successively callingcombine
.static Iterator<java.lang.Integer>
from(int value)
Returns an infinite iterator of int values starting fromvalue
.static Iterator<java.lang.Integer>
from(int value, int step)
Returns an infinite iterator of int values starting fromvalue
and spaced bystep
.static Iterator<java.lang.Long>
from(long value)
Returns an infinite iterator of long values starting fromvalue
.static Iterator<java.lang.Long>
from(long value, long step)
Returns an infinite iterator of long values starting fromvalue
and spaced bystep
.default T
get()
Gets the first value in iteration order if thisTraversable
is not empty, otherwise throws.default <C> Map<C,Iterator<T>>
groupBy(java.util.function.Function<? super T,? extends C> classifier)
Groups this elements by classifying the elements.default Iterator<Seq<T>>
grouped(int size)
Groups thisTraversable
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 asOption
.default Iterator<T>
intersperse(T element)
Inserts an element between all elements of this Iterator.default boolean
isAsync()
AnIterator
is computed synchronously.default boolean
isEmpty()
Checks if this Traversable is empty.default boolean
isLazy()
AnIterator
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(java.util.function.Supplier<? extends Option<? extends T>> supplier)
Creates an iterator that repeatedly invokes the supplier while it's aSome
and end on the firstNone
static <T> Iterator<T>
iterate(T seed, java.util.function.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(java.util.function.Function<? super T,? extends U> mapper)
Maps the elements of this Iterator lazily using the givenmapper
.static <T> Iterator<T>
narrow(Iterator<? extends T> iterator)
Narrows a widenedIterator<? extends T>
toIterator<T>
by performing a type-safe cast.default Option<T>
nextOption()
A safe alternative toIterator.next()
that is equivalent tostatic <T> Iterator<T>
of(T element)
Creates anIterator
which iterates over the given element.static <T> Iterator<T>
of(T... elements)
Creates anIterator
which iterates over the given elements.static Iterator<java.lang.Boolean>
ofAll(boolean... elements)
Creates an Iterator from boolean values.static Iterator<java.lang.Byte>
ofAll(byte... elements)
Creates an Iterator from byte values.static Iterator<java.lang.Character>
ofAll(char... elements)
Creates an Iterator from char values.static Iterator<java.lang.Double>
ofAll(double... elements)
Creates ann Iterator from double values.static Iterator<java.lang.Float>
ofAll(float... elements)
Creates an Iterator from float values.static Iterator<java.lang.Integer>
ofAll(int... elements)
Creates an Iterator from int values.static Iterator<java.lang.Long>
ofAll(long... elements)
Creates an Iterator from long values.static Iterator<java.lang.Short>
ofAll(short... elements)
Creates an Iterator from short values.static <T> Iterator<T>
ofAll(java.lang.Iterable<? extends T> iterable)
Creates aIterator
based on the givenIterable
.static <T> Iterator<T>
ofAll(java.util.Iterator<? extends T> iterator)
Creates an Iterator based on the given Iterator by delegating calls ofhasNext()
andnext()
to it.default Iterator<T>
orElse(java.lang.Iterable<? extends T> other)
Returns thisTraversable
if it is nonempty, otherwise return the alternative.default Iterator<T>
orElse(java.util.function.Supplier<? extends java.lang.Iterable<? extends T>> supplier)
Returns thisTraversable
if it is nonempty, otherwise return the result of evaluating supplier.default Tuple2<Iterator<T>,Iterator<T>>
partition(java.util.function.Predicate<? super T> predicate)
Creates a partition of thisTraversable
by splitting this elements in two in distinct traversables according to a predicate.default Iterator<T>
peek(java.util.function.Consumer<? super T> action)
Performs the givenaction
on the first element if this is an eager implementation.static Iterator<java.lang.Character>
range(char from, char toExclusive)
Creates an Iterator of characters starting fromfrom
, extending totoExclusive - 1
.static Iterator<java.lang.Integer>
range(int from, int toExclusive)
Creates an Iterator of int numbers starting fromfrom
, extending totoExclusive - 1
.static Iterator<java.lang.Long>
range(long from, long toExclusive)
Creates an Iterator of long numbers starting fromfrom
, extending totoExclusive - 1
.static Iterator<java.lang.Character>
rangeBy(char from, char toExclusive, int step)
Creates an Iterator of characters starting fromfrom
, extending totoExclusive - 1
, withstep
.static Iterator<java.lang.Double>
rangeBy(double from, double toExclusive, double step)
static Iterator<java.lang.Integer>
rangeBy(int from, int toExclusive, int step)
Creates an Iterator of int numbers starting fromfrom
, extending totoExclusive - 1
, withstep
.static Iterator<java.lang.Long>
rangeBy(long from, long toExclusive, long step)
Creates an Iterator of long numbers starting fromfrom
, extending totoExclusive - 1
, withstep
.static Iterator<java.math.BigDecimal>
rangeBy(java.math.BigDecimal from, java.math.BigDecimal toExclusive, java.math.BigDecimal step)
static Iterator<java.lang.Character>
rangeClosed(char from, char toInclusive)
Creates an Iterator of characters starting fromfrom
, extending totoInclusive
.static Iterator<java.lang.Integer>
rangeClosed(int from, int toInclusive)
Creates an Iterator of int numbers starting fromfrom
, extending totoInclusive
.static Iterator<java.lang.Long>
rangeClosed(long from, long toInclusive)
Creates an Iterator of long numbers starting fromfrom
, extending totoInclusive
.static Iterator<java.lang.Character>
rangeClosedBy(char from, char toInclusive, int step)
Creates an Iterator of characters starting fromfrom
, extending totoInclusive
, withstep
.static Iterator<java.lang.Double>
rangeClosedBy(double from, double toInclusive, double step)
static Iterator<java.lang.Integer>
rangeClosedBy(int from, int toInclusive, int step)
Creates an Iterator of int numbers starting fromfrom
, extending totoInclusive
, withstep
.static Iterator<java.lang.Long>
rangeClosedBy(long from, long toInclusive, long step)
Creates an Iterator of long numbers starting fromfrom
, extending totoInclusive
, withstep
.default T
reduceLeft(java.util.function.BiFunction<? super T,? super T,? extends T> op)
Accumulates the elements of this Traversable by successively calling the given operationop
from the left.default T
reduceRight(java.util.function.BiFunction<? super T,? super T,? extends T> op)
Accumulates the elements of this Traversable by successively calling the given operationop
from the right.default Iterator<T>
reject(java.util.function.Predicate<? super T> predicate)
Deprecated.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(java.lang.Iterable<? extends T> elements)
Keeps all occurrences of the given elements from this.default Traversable<T>
scan(T zero, java.util.function.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, java.util.function.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, java.util.function.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(java.util.function.Function<? super T,?> classifier)
Slides a non-overlapping window of a variable size over thisTraversable
.default Iterator<Seq<T>>
sliding(int size)
Slides a window of a specificsize
and step size 1 over thisTraversable
by callingTraversable.sliding(int, int)
.default Iterator<Seq<T>>
sliding(int size, int step)
Slides a window of a specificsize
andstep
size over thisTraversable
.default Tuple2<Iterator<T>,Iterator<T>>
span(java.util.function.Predicate<? super T> predicate)
Returns a tuple where the first element is the longest prefix of elements that satisfy the givenpredicate
and the second element is the remainder.default java.lang.String
stringPrefix()
Returns the name of this Value type, which is used by toString().static <T> Iterator<T>
tabulate(int n, java.util.function.Function<? super java.lang.Integer,? extends T> f)
Returns an Iterator on a sequence ofn
values of a given Functionf
over a range of integer values from 0 ton - 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 anOption
.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(java.util.function.Predicate<? super T> predicate)
Takes elements until the predicate holds for the current element.default Iterator<T>
takeWhile(java.util.function.Predicate<? super T> predicate)
Takes elements while the predicate holds for the current element.default <U> U
transform(java.util.function.Function<? super Iterator<T>,? extends U> f)
Transforms thisIterator
.static <T> Iterator<T>
unfold(T seed, java.util.function.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, java.util.function.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, java.util.function.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(java.util.function.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(java.util.function.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(java.lang.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(java.lang.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(java.lang.Iterable<? extends U> that, java.util.function.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,java.lang.Integer>>
zipWithIndex()
Zips this traversable with its indices.default <U> Iterator<U>
zipWithIndex(java.util.function.BiFunction<? super T,? super java.lang.Integer,? extends U> mapper)
Returns a traversable formed from this traversable and another Iterable collection by mapping elements.-
Methods inherited from interface io.vavr.collection.Traversable
arrangeBy, average, containsAll, count, equals, existsUnique, find, fold, foldLeft, forEachWithIndex, hashCode, headOption, isDistinct, isOrdered, isSingleValued, lastOption, max, maxBy, maxBy, min, minBy, minBy, mkCharSeq, mkCharSeq, mkCharSeq, mkString, mkString, mkString, nonEmpty, product, reduce, reduceLeftOption, reduceOption, reduceRightOption, single, singleOption, size, spliterator, sum
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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
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Method Detail
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concat
@SafeVarargs static <T> Iterator<T> concat(java.lang.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
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concat
static <T> Iterator<T> concat(java.lang.Iterable<? extends java.lang.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
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empty
static <T> Iterator<T> empty()
Returns the singleton instance of the emptyIterator
.A call to
Iterator.hasNext()
will always returnfalse
. A call toIterator.next()
will always throw aNoSuchElementException
.- Type Parameters:
T
- Element type- Returns:
- The empty
Iterator
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narrow
static <T> Iterator<T> narrow(Iterator<? extends T> iterator)
Narrows a widenedIterator<? extends T>
toIterator<T>
by performing a type-safe cast. This is eligible because immutable/read-only collections are covariant.- Type Parameters:
T
- Component type of theIterator
.- Parameters:
iterator
- AnIterator
.- Returns:
- the given
iterator
instance as narrowed typeIterator<T>
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of
static <T> Iterator<T> of(T element)
Creates anIterator
which iterates over the given element.- Type Parameters:
T
- Element type- Parameters:
element
- An element- Returns:
- A new
Iterator
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of
@SafeVarargs static <T> Iterator<T> of(T... elements)
Creates anIterator
which iterates over the given elements.Iterator<Integer> iterator = Iterator.of(1, 2, 3);
- Type Parameters:
T
- Element type- Parameters:
elements
- Zero or more elements- Returns:
- The singleton instance of the empty
Iterator
, ifelements.length == 0
, otherwise a newIterator
. - Throws:
java.lang.NullPointerException
- ifelements
is null
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ofAll
static <T> Iterator<T> ofAll(java.lang.Iterable<? extends T> iterable)
Creates aIterator
based on the givenIterable
. This is a convenience method forIterator.ofAll(iterable.iterator()
.- Type Parameters:
T
- Component type.- Parameters:
iterable
- AIterable
- Returns:
- A new
io.vavr.collection.Iterator
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ofAll
static <T> Iterator<T> ofAll(java.util.Iterator<? extends T> iterator)
Creates an Iterator based on the given Iterator by delegating calls ofhasNext()
andnext()
to it.- Type Parameters:
T
- Component type.- Parameters:
iterator
- AIterator
- Returns:
- A new
io.vavr.collection.Iterator
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ofAll
static Iterator<java.lang.Boolean> ofAll(boolean... elements)
Creates an Iterator from boolean values.- Parameters:
elements
- boolean values- Returns:
- A new Iterator of Boolean values
- Throws:
java.lang.NullPointerException
- if elements is null
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ofAll
static Iterator<java.lang.Byte> ofAll(byte... elements)
Creates an Iterator from byte values.- Parameters:
elements
- byte values- Returns:
- A new Iterator of Byte values
- Throws:
java.lang.NullPointerException
- if elements is null
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ofAll
static Iterator<java.lang.Character> ofAll(char... elements)
Creates an Iterator from char values.- Parameters:
elements
- char values- Returns:
- A new Iterator of Character values
- Throws:
java.lang.NullPointerException
- if elements is null
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ofAll
static Iterator<java.lang.Double> ofAll(double... elements)
Creates ann Iterator from double values.- Parameters:
elements
- double values- Returns:
- A new Iterator of Double values
- Throws:
java.lang.NullPointerException
- if elements is null
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ofAll
static Iterator<java.lang.Float> ofAll(float... elements)
Creates an Iterator from float values.- Parameters:
elements
- float values- Returns:
- A new Iterator of Float values
- Throws:
java.lang.NullPointerException
- if elements is null
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ofAll
static Iterator<java.lang.Integer> ofAll(int... elements)
Creates an Iterator from int values.- Parameters:
elements
- int values- Returns:
- A new Iterator of Integer values
- Throws:
java.lang.NullPointerException
- if elements is null
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ofAll
static Iterator<java.lang.Long> ofAll(long... elements)
Creates an Iterator from long values.- Parameters:
elements
- long values- Returns:
- A new Iterator of Long values
- Throws:
java.lang.NullPointerException
- if elements is null
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ofAll
static Iterator<java.lang.Short> ofAll(short... elements)
Creates an Iterator from short values.- Parameters:
elements
- short values- Returns:
- A new Iterator of Short values
- Throws:
java.lang.NullPointerException
- if elements is null
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tabulate
static <T> Iterator<T> tabulate(int n, java.util.function.Function<? super java.lang.Integer,? extends T> f)
Returns an Iterator on a sequence ofn
values of a given Functionf
over a range of integer values from 0 ton - 1
.- Type Parameters:
T
- Component type of the Iterator- Parameters:
n
- The number of elementsf
- The Function computing element values- Returns:
- An Iterator on a sequence of elements
f(0),f(1), ..., f(n - 1)
- Throws:
java.lang.NullPointerException
- iff
is null
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fill
static <T> Iterator<T> fill(int n, java.util.function.Supplier<? extends T> s)
Returns an Iterator on a sequence ofn
values supplied by a given Suppliers
.- Type Parameters:
T
- Component type of the Iterator- Parameters:
n
- The number of elementss
- The Supplier computing element values- Returns:
- An iterator on a sequence of
n
elements, where each element contains the result supplied bys
. - Throws:
java.lang.NullPointerException
- ifs
is null
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fill
static <T> Iterator<T> fill(int n, T element)
Returns a Iterator containingn
times the givenelement
- Type Parameters:
T
- Component type of the Iterator- Parameters:
n
- The number of elementselement
- The element- Returns:
- An iterator of
n
sequence elements, where each element is the givenelement
.
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range
static Iterator<java.lang.Character> range(char from, char toExclusive)
Creates an Iterator of characters starting fromfrom
, extending totoExclusive - 1
.Examples:
Iterator.range('a', 'c') // = ('a', 'b') Iterator.range('c', 'a') // = ()
- Parameters:
from
- the first charactertoExclusive
- the successor of the last character- Returns:
- a range of characters as specified or the empty range if
from >= toExclusive
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rangeBy
static Iterator<java.lang.Character> rangeBy(char from, char toExclusive, int step)
Creates an Iterator of characters starting fromfrom
, extending totoExclusive - 1
, withstep
.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 charactertoExclusive
- the successor of the last character if step > 0, the predecessor of the last character if step < 0step
- the step- Returns:
- a range of characters as specified or the empty range if
signum(step) == signum(from - toExclusive)
. - Throws:
java.lang.IllegalArgumentException
- ifstep
is zero
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rangeBy
@GwtIncompatible("BigDecimalHelper is GwtIncompatible") static Iterator<java.lang.Double> rangeBy(double from, double toExclusive, double step)
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rangeBy
static Iterator<java.math.BigDecimal> rangeBy(java.math.BigDecimal from, java.math.BigDecimal toExclusive, java.math.BigDecimal step)
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range
static Iterator<java.lang.Integer> range(int from, int toExclusive)
Creates an Iterator of int numbers starting fromfrom
, extending totoExclusive - 1
.Examples:
Iterator.range(0, 0) // = () Iterator.range(2, 0) // = () Iterator.range(-2, 2) // = (-2, -1, 0, 1)
- Parameters:
from
- the first numbertoExclusive
- the last number + 1- Returns:
- a range of int values as specified or the empty range if
from >= toExclusive
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rangeBy
static Iterator<java.lang.Integer> rangeBy(int from, int toExclusive, int step)
Creates an Iterator of int numbers starting fromfrom
, extending totoExclusive - 1
, withstep
.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 numbertoExclusive
- the last number + 1 if step > 0, the last number - 1 if step < 0step
- the step- Returns:
- a range of long values as specified or the empty range if
(from == toExclusive) || (step * (from - toExclusive) > 0)
. - Throws:
java.lang.IllegalArgumentException
- ifstep
is zero
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range
static Iterator<java.lang.Long> range(long from, long toExclusive)
Creates an Iterator of long numbers starting fromfrom
, extending totoExclusive - 1
.Examples:
Iterator.range(0L, 0L) // = () Iterator.range(2L, 0L) // = () Iterator.range(-2L, 2L) // = (-2L, -1L, 0L, 1L)
- Parameters:
from
- the first numbertoExclusive
- the last number + 1- Returns:
- a range of long values as specified or the empty range if
from >= toExclusive
-
rangeBy
static Iterator<java.lang.Long> rangeBy(long from, long toExclusive, long step)
Creates an Iterator of long numbers starting fromfrom
, extending totoExclusive - 1
, withstep
.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 numbertoExclusive
- the last number + 1 if step > 0, the last number - 1 if step < 0step
- the step- Returns:
- a range of long values as specified or the empty range if
(from == toExclusive) || (step * (from - toExclusive) > 0)
. - Throws:
java.lang.IllegalArgumentException
- ifstep
is zero
-
rangeClosed
static Iterator<java.lang.Character> rangeClosed(char from, char toInclusive)
Creates an Iterator of characters starting fromfrom
, extending totoInclusive
.Examples:
Iterator.rangeClosed('a', 'c') // = ('a', 'b', 'c') Iterator.rangeClosed('c', 'a') // = ()
- Parameters:
from
- the first charactertoInclusive
- the last character- Returns:
- a range of characters as specified or the empty range if
from > toInclusive
-
rangeClosedBy
static Iterator<java.lang.Character> rangeClosedBy(char from, char toInclusive, int step)
Creates an Iterator of characters starting fromfrom
, extending totoInclusive
, withstep
.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 charactertoInclusive
- the last characterstep
- the step- Returns:
- a range of characters as specified or the empty range if
signum(step) == signum(from - toInclusive)
. - Throws:
java.lang.IllegalArgumentException
- ifstep
is zero
-
rangeClosedBy
@GwtIncompatible static Iterator<java.lang.Double> rangeClosedBy(double from, double toInclusive, double step)
-
rangeClosed
static Iterator<java.lang.Integer> rangeClosed(int from, int toInclusive)
Creates an Iterator of int numbers starting fromfrom
, extending totoInclusive
.Examples:
Iterator.rangeClosed(0, 0) // = (0) Iterator.rangeClosed(2, 0) // = () Iterator.rangeClosed(-2, 2) // = (-2, -1, 0, 1, 2)
- Parameters:
from
- the first numbertoInclusive
- the last number- Returns:
- a range of int values as specified or the empty range if
from > toInclusive
-
rangeClosedBy
static Iterator<java.lang.Integer> rangeClosedBy(int from, int toInclusive, int step)
Creates an Iterator of int numbers starting fromfrom
, extending totoInclusive
, withstep
.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 numbertoInclusive
- the last numberstep
- the step- Returns:
- a range of int values as specified or the empty range if
signum(step) == signum(from - toInclusive)
. - Throws:
java.lang.IllegalArgumentException
- ifstep
is zero
-
rangeClosed
static Iterator<java.lang.Long> rangeClosed(long from, long toInclusive)
Creates an Iterator of long numbers starting fromfrom
, extending totoInclusive
.Examples:
Iterator.rangeClosed(0L, 0L) // = (0L) Iterator.rangeClosed(2L, 0L) // = () Iterator.rangeClosed(-2L, 2L) // = (-2L, -1L, 0L, 1L, 2L)
- Parameters:
from
- the first numbertoInclusive
- the last number- Returns:
- a range of long values as specified or the empty range if
from > toInclusive
-
rangeClosedBy
static Iterator<java.lang.Long> rangeClosedBy(long from, long toInclusive, long step)
Creates an Iterator of long numbers starting fromfrom
, extending totoInclusive
, withstep
.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 numbertoInclusive
- the last numberstep
- the step- Returns:
- a range of int values as specified or the empty range if
signum(step) == signum(from - toInclusive)
. - Throws:
java.lang.IllegalArgumentException
- ifstep
is zero
-
from
static Iterator<java.lang.Integer> from(int value)
Returns an infinite iterator of int values starting fromvalue
.The
Iterator
extends toInteger.MIN_VALUE
when passingInteger.MAX_VALUE
.- Parameters:
value
- a start int value- Returns:
- a new
Iterator
of int values starting fromfrom
-
from
static Iterator<java.lang.Integer> from(int value, int step)
Returns an infinite iterator of int values starting fromvalue
and spaced bystep
.The
Iterator
extends toInteger.MIN_VALUE
when passingInteger.MAX_VALUE
.- Parameters:
value
- a start int valuestep
- the step by which to advance on each iteration- Returns:
- a new
Iterator
of int values starting fromfrom
-
from
static Iterator<java.lang.Long> from(long value)
Returns an infinite iterator of long values starting fromvalue
.The
Iterator
extends toLong.MIN_VALUE
when passingLong.MAX_VALUE
.- Parameters:
value
- a start long value- Returns:
- a new
Iterator
of long values starting fromfrom
-
from
static Iterator<java.lang.Long> from(long value, long step)
Returns an infinite iterator of long values starting fromvalue
and spaced bystep
.The
Iterator
extends toLong.MIN_VALUE
when passingLong.MAX_VALUE
.- Parameters:
value
- a start long valuestep
- the step by which to advance on each iteration- Returns:
- a new
Iterator
of long values starting fromfrom
-
continually
static <T> Iterator<T> continually(java.util.function.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(java.util.function.Supplier<? extends Option<? extends T>> supplier)
Creates an iterator that repeatedly invokes the supplier while it's aSome
and end on the firstNone
- Type Parameters:
T
- value type- Parameters:
supplier
- A Supplier of iterator values- Returns:
- A new
Iterator
- Throws:
java.lang.NullPointerException
- if supplier produces null value
-
iterate
static <T> Iterator<T> iterate(T seed, java.util.function.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 iteratorf
- 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 givenpartialFunction
by mapping the elements to typeR
.More specifically, for each of this elements in iteration order first it is checked
If the elements makes it through that filter, the mapped instance is added to the result collectionpartialFunction.isDefinedAt(element)
Note:If thisR newElement = partialFunction.apply(element)
Traversable
is ordered (i.e. extendsOrdered
, the caller ofcollect
has to ensure that the elements are comparable (i.e. extendComparable
).- Specified by:
collect
in interfaceTraversable<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 typeR
-
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(java.util.function.Function<? super Iterator<T>,? extends U> f)
Transforms thisIterator
.- Type Parameters:
U
- Type of transformation result- Parameters:
f
- A transformation- Returns:
- An instance of type
U
- Throws:
java.lang.NullPointerException
- iff
is null
-
zip
default <U> Iterator<Tuple2<T,U>> zip(java.lang.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 interfaceTraversable<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(java.lang.Iterable<? extends U> that, java.util.function.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 interfaceTraversable<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(java.lang.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 interfaceTraversable<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,java.lang.Integer>> zipWithIndex()
Description copied from interface:Traversable
Zips this traversable with its indices.- Specified by:
zipWithIndex
in interfaceTraversable<T>
- Returns:
- A new traversable containing all elements of this traversable paired with their index, starting with 0.
-
zipWithIndex
default <U> Iterator<U> zipWithIndex(java.util.function.BiFunction<? super T,? super java.lang.Integer,? extends U> 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:
zipWithIndex
in interfaceTraversable<T>
- Type Parameters:
U
- The type of the mapped elements.- Parameters:
mapper
- a mapper.- Returns:
- a new traversable containing mapped elements of this traversable and
that
iterable.
-
unzip
default <T1,T2> Tuple2<Iterator<T1>,Iterator<T2>> unzip(java.util.function.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 interfaceTraversable<T>
- Type Parameters:
T1
- 1st element type of a pair returned by unzipperT2
- 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(java.util.function.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 interfaceTraversable<T>
- Type Parameters:
T1
- 1st element type of a triplet returned by unzipperT2
- 2nd element type of a triplet returned by unzipperT3
- 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, java.util.function.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 returnNone
when it's done generating elements, otherwiseSome
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 iterationf
- the function to get the next step of the iteration- Returns:
- a list with the values built up by the iteration
- Throws:
java.lang.NullPointerException
- iff
is null
-
unfoldLeft
static <T,U> Iterator<U> unfoldLeft(T seed, java.util.function.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 returnNone
when it's done generating elements, otherwiseSome
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 seedsU
- type of unfolded values- Parameters:
seed
- the start value for the iterationf
- the function to get the next step of the iteration- Returns:
- a list with the values built up by the iteration
- Throws:
java.lang.NullPointerException
- iff
is null
-
unfoldRight
static <T,U> Iterator<U> unfoldRight(T seed, java.util.function.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 returnNone
when it's done generating elements, otherwiseSome
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 seedsU
- type of unfolded values- Parameters:
seed
- the start value for the iterationf
- the function to get the next step of the iteration- Returns:
- a list with the values built up by the iteration
- Throws:
java.lang.NullPointerException
- iff
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 usingequals
.- Specified by:
distinct
in interfaceTraversable<T>
- Returns:
- a new
Traversable
containing this elements without duplicates
-
distinctBy
default Iterator<T> distinctBy(java.util.Comparator<? super T> comparator)
Description copied from interface:Traversable
Returns a new version of this which contains no duplicates. Elements are compared using the givencomparator
.- Specified by:
distinctBy
in interfaceTraversable<T>
- Parameters:
comparator
- A comparator- Returns:
- a new
Traversable
containing this elements without duplicates
-
distinctBy
default <U> Iterator<T> distinctBy(java.util.function.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 usingequals
.The elements of the result are determined in the order of their occurrence - first match wins.
- Specified by:
distinctBy
in interfaceTraversable<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 interfaceTraversable<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 interfaceTraversable<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(java.util.function.Predicate<? super T> predicate)
Description copied from interface:Traversable
Drops elements until the predicate holds for the current element.- Specified by:
dropUntil
in interfaceTraversable<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(java.util.function.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 interfaceTraversable<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(java.util.function.Predicate<? super T> predicate)
Returns an Iterator that contains elements that satisfy the givenpredicate
.- Specified by:
filter
in interfaceTraversable<T>
- Parameters:
predicate
- A predicate- Returns:
- A new Iterator
-
filterNot
default Iterator<T> filterNot(java.util.function.Predicate<? super T> predicate)
Returns an Iterator that contains elements that not satisfy the givenpredicate
.- Specified by:
filterNot
in interfaceTraversable<T>
- Parameters:
predicate
- A predicate- Returns:
- A new Iterator
-
reject
@Deprecated default Iterator<T> reject(java.util.function.Predicate<? super T> predicate)
Deprecated.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 interfaceTraversable<T>
- Parameters:
predicate
- A predicate- Returns:
- a new traversable
-
findLast
default Option<T> findLast(java.util.function.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 interfaceTraversable<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(java.util.function.Function<? super T,? extends java.lang.Iterable<? extends U>> mapper)
Maps the elements of this Iterator to Iterables and concats their iterators.- Specified by:
flatMap
in interfaceTraversable<T>
- Type Parameters:
U
- Component type of the resulting Iterator- Parameters:
mapper
- A mapper- Returns:
- A new Iterator
-
foldRight
default <U> U foldRight(U zero, java.util.function.BiFunction<? super T,? super U,? extends U> f)
Description copied from interface:Traversable
Folds this elements from the right, starting withzero
and successively callingcombine
.Example:
// = "!cba" List("a", "b", "c").foldRight("!", (x, xs) -> xs + x)
-
get
default T get()
Description copied from interface:Traversable
Gets the first value in iteration order if thisTraversable
is not empty, otherwise throws.
-
groupBy
default <C> Map<C,Iterator<T>> groupBy(java.util.function.Function<? super T,? extends C> classifier)
Description copied from interface:Traversable
Groups this elements by classifying the elements.- Specified by:
groupBy
in interfaceTraversable<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 thisTraversable
into fixed size blocks.Let length be the length of this Iterable. Then grouped is defined as follows:
- If
this.isEmpty()
, the resultingIterator
is empty. - If
size <= length
, the resultingIterator
will containlength / size
blocks of sizesize
and maybe a non-empty block of sizelength % size
, if there are remaining elements. - If
size > length
, the resultingIterator
will contain one block of sizelength
.
[].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]]
grouped(int)
is a special case of Traversable.sliding(int, int), i.e.grouped(size)
is the same assliding(size, size)
.- Specified by:
grouped
in interfaceTraversable<T>
- Parameters:
size
- a positive block size- Returns:
- A new Iterator of grouped blocks of the given size
- If
-
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 interfaceTraversable<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 interfaceTraversable<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 interfaceTraversable<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 asOption
.- Specified by:
initOption
in interfaceTraversable<T>
- Returns:
Some(traversable)
orNone
if this is empty.
-
isAsync
default boolean isAsync()
AnIterator
is computed synchronously.
-
isEmpty
default boolean isEmpty()
Description copied from interface:Traversable
Checks if this Traversable is empty.
-
isLazy
default boolean isLazy()
AnIterator
is computed lazily.
-
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 interfaceTraversable<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 interfaceTraversable<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.
-
last
default T last()
Description copied from interface:Traversable
Dual of Traversable.head(), returning the last element.- Specified by:
last
in interfaceTraversable<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 interfaceTraversable<T>
- Returns:
- the number of elements
-
map
default <U> Iterator<U> map(java.util.function.Function<? super T,? extends U> mapper)
Maps the elements of this Iterator lazily using the givenmapper
.
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nextOption
default Option<T> nextOption()
A safe alternative toIterator.next()
that is equivalent tohasNext() ? Option.some(next()) : Option.none()
- Returns:
- a new instance of
Option
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orElse
default Iterator<T> orElse(java.lang.Iterable<? extends T> other)
Description copied from interface:Traversable
Returns thisTraversable
if it is nonempty, otherwise return the alternative.- Specified by:
orElse
in interfaceTraversable<T>
- Parameters:
other
- An alternativeTraversable
- Returns:
- this
Traversable
if it is nonempty, otherwise return the alternative.
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orElse
default Iterator<T> orElse(java.util.function.Supplier<? extends java.lang.Iterable<? extends T>> supplier)
Description copied from interface:Traversable
Returns thisTraversable
if it is nonempty, otherwise return the result of evaluating supplier.- Specified by:
orElse
in interfaceTraversable<T>
- Parameters:
supplier
- An alternativeTraversable
supplier- Returns:
- this
Traversable
if it is nonempty, otherwise return the result of evaluating supplier.
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partition
default Tuple2<Iterator<T>,Iterator<T>> partition(java.util.function.Predicate<? super T> predicate)
Description copied from interface:Traversable
Creates a partition of thisTraversable
by splitting this elements in two in distinct traversables according to a predicate.- Specified by:
partition
in interfaceTraversable<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 givenpredicate
, the secondTraversable
contains all elements that don't. The original order of elements is preserved.
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peek
default Iterator<T> peek(java.util.function.Consumer<? super T> action)
Description copied from interface:Value
Performs the givenaction
on the first element if this is an eager implementation. Performs the givenaction
on all elements (the first immediately, successive deferred), if this is a lazy implementation.
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reduceLeft
default T reduceLeft(java.util.function.BiFunction<? super T,? super T,? extends T> op)
Description copied from interface:Traversable
Accumulates the elements of this Traversable by successively calling the given operationop
from the left.- Specified by:
reduceLeft
in interfaceFoldable<T>
- Specified by:
reduceLeft
in interfaceTraversable<T>
- Parameters:
op
- A BiFunction of type T- Returns:
- the reduced value.
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reduceRight
default T reduceRight(java.util.function.BiFunction<? super T,? super T,? extends T> op)
Description copied from interface:Traversable
Accumulates the elements of this Traversable by successively calling the given operationop
from the right.- Specified by:
reduceRight
in interfaceFoldable<T>
- Specified by:
reduceRight
in interfaceTraversable<T>
- Parameters:
op
- An operation of type T- Returns:
- the reduced value.
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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 interfaceTraversable<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.
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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 interfaceTraversable<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.
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retainAll
default Iterator<T> retainAll(java.lang.Iterable<? extends T> elements)
Description copied from interface:Traversable
Keeps all occurrences of the given elements from this.- Specified by:
retainAll
in interfaceTraversable<T>
- Parameters:
elements
- Elements to be kept.- Returns:
- a Traversable containing all occurrences of the given elements.
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scan
default Traversable<T> scan(T zero, java.util.function.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 interfaceTraversable<T>
- Parameters:
zero
- neutral element for the operator opoperation
- the associative operator for the scan- Returns:
- a new traversable collection containing the prefix scan of the elements in this traversable collection
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scanLeft
default <U> Iterator<U> scanLeft(U zero, java.util.function.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 interfaceTraversable<T>
- Type Parameters:
U
- the type of the elements in the resulting collection- Parameters:
zero
- the initial valueoperation
- the binary operator applied to the intermediate result and the element- Returns:
- collection with intermediate results
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scanRight
default <U> Iterator<U> scanRight(U zero, java.util.function.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 interfaceTraversable<T>
- Type Parameters:
U
- the type of the elements in the resulting collection- Parameters:
zero
- the initial valueoperation
- the binary operator applied to the intermediate result and the element- Returns:
- collection with intermediate results
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slideBy
default Iterator<Seq<T>> slideBy(java.util.function.Function<? super T,?> classifier)
Description copied from interface:Traversable
Slides a non-overlapping window of a variable size over thisTraversable
.Each window contains elements with the same class, as determined by
classifier
. Two consecutive values in thisTraversable
will be in the same window only ifclassifier
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 interfaceTraversable<T>
- Parameters:
classifier
- A function which classifies elements into classes- Returns:
- A new Iterator of windows of the grouped elements
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sliding
default Iterator<Seq<T>> sliding(int size)
Description copied from interface:Traversable
Slides a window of a specificsize
and step size 1 over thisTraversable
by callingTraversable.sliding(int, int)
.- Specified by:
sliding
in interfaceTraversable<T>
- Parameters:
size
- a positive window size- Returns:
- a new Iterator of windows of a specific size using step size 1
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sliding
default Iterator<Seq<T>> sliding(int size, int step)
Description copied from interface:Traversable
Slides a window of a specificsize
andstep
size over thisTraversable
.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 interfaceTraversable<T>
- Parameters:
size
- a positive window sizestep
- a positive step size- Returns:
- a new Iterator of windows of a specific size using a specific step size
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span
default Tuple2<Iterator<T>,Iterator<T>> span(java.util.function.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 givenpredicate
and the second element is the remainder.- Specified by:
span
in interfaceTraversable<T>
- Parameters:
predicate
- A predicate.- Returns:
- a
Tuple
containing the longest prefix of elements that satisfy p and the remainder.
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stringPrefix
default java.lang.String stringPrefix()
Description copied from interface:Value
Returns the name of this Value type, which is used by toString().- Specified by:
stringPrefix
in interfaceValue<T>
- Returns:
- This type name.
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tail
default Iterator<T> tail()
Description copied from interface:Traversable
Drops the first element of a non-empty Traversable.- Specified by:
tail
in interfaceTraversable<T>
- Returns:
- A new instance of Traversable containing all elements except the first.
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tailOption
default Option<Iterator<T>> tailOption()
Description copied from interface:Traversable
Drops the first element of a non-empty Traversable and returns anOption
.- Specified by:
tailOption
in interfaceTraversable<T>
- Returns:
Some(traversable)
orNone
if this is empty.
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take
default Iterator<T> take(int n)
Take the first n elements from this iterator.- Specified by:
take
in interfaceTraversable<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.
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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 ifn < 0
orn > length()
.In the case of
n < 0
the empty instance is returned, in the case ofn > length()
this is returned.- Specified by:
takeRight
in interfaceTraversable<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.
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takeUntil
default Iterator<T> takeUntil(java.util.function.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 interfaceTraversable<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.
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takeWhile
default Iterator<T> takeWhile(java.util.function.Predicate<? super T> predicate)
Description copied from interface:Traversable
Takes elements while the predicate holds for the current element.- Specified by:
takeWhile
in interfaceTraversable<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.
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