Interface Iterator<T>

  • 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 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.

    • 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​(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 empty Iterator.
      static <T> Iterator<T> fill​(int n, java.util.function.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​(java.util.function.Predicate<? super T> predicate)
      Returns an Iterator that contains elements that satisfy the given predicate.
      default Iterator<T> filterNot​(java.util.function.Predicate<? super T> predicate)
      Returns an Iterator that contains elements that not satisfy the given predicate.
      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 with zero and successively calling combine.
      static Iterator<java.lang.Integer> from​(int value)
      Returns an infinite iterator of int values starting from value.
      static Iterator<java.lang.Integer> from​(int value, int step)
      Returns an infinite iterator of int values starting from value and spaced by step.
      static Iterator<java.lang.Long> from​(long value)
      Returns an infinite iterator of long values starting from value.
      static Iterator<java.lang.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​(java.util.function.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​(java.util.function.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, 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 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.
      default Option<T> nextOption()
      A safe alternative to Iterator.next() that is equivalent to
      static <T> Iterator<T> of​(T element)
      Creates an Iterator which iterates over the given element.
      static <T> Iterator<T> of​(T... elements)
      Creates an Iterator 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 a Iterator based on the given Iterable.
      static <T> Iterator<T> ofAll​(java.util.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​(java.lang.Iterable<? extends T> other)
      Returns this Traversable if it is nonempty, otherwise return the alternative.
      default Iterator<T> orElse​(java.util.function.Supplier<? extends java.lang.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​(java.util.function.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​(java.util.function.Consumer<? super T> action)
      Performs the given action 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 from from, extending to toExclusive - 1.
      static Iterator<java.lang.Integer> range​(int from, int toExclusive)
      Creates an Iterator of int numbers starting from from, extending to toExclusive - 1.
      static Iterator<java.lang.Long> range​(long from, long toExclusive)
      Creates an Iterator of long numbers starting from from, extending to toExclusive - 1.
      static Iterator<java.lang.Character> rangeBy​(char from, char toExclusive, int step)
      Creates an Iterator of characters starting from from, extending to toExclusive - 1, with step.
      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 from from, extending to toExclusive - 1, with step.
      static Iterator<java.lang.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<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 from from, extending to toInclusive.
      static Iterator<java.lang.Integer> rangeClosed​(int from, int toInclusive)
      Creates an Iterator of int numbers starting from from, extending to toInclusive.
      static Iterator<java.lang.Long> rangeClosed​(long from, long toInclusive)
      Creates an Iterator of long numbers starting from from, extending to toInclusive.
      static Iterator<java.lang.Character> rangeClosedBy​(char from, char toInclusive, int step)
      Creates an Iterator of characters starting from from, extending to toInclusive, with step.
      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 from from, extending to toInclusive, with step.
      static Iterator<java.lang.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​(java.util.function.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​(java.util.function.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​(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 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​(java.util.function.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 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 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​(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 this Iterator.
      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.Iterable

        to
      • Methods inherited from interface java.util.Iterator

        forEachRemaining, hasNext, next, remove
    • Method Detail

      • 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
      • 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
      • empty

        static <T> Iterator<T> empty()
        Returns the singleton instance of the empty Iterator.

        A call to Iterator.hasNext() will always return false. A call to Iterator.next() will always throw a NoSuchElementException.

        Type Parameters:
        T - Element 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 iterates over the given element.
        Type Parameters:
        T - Element type
        Parameters:
        element - An element
        Returns:
        A new Iterator
      • of

        @SafeVarargs
        static <T> Iterator<T> of​(T... elements)
        Creates an Iterator 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, if elements.length == 0, otherwise a new Iterator.
        Throws:
        java.lang.NullPointerException - if elements is null
      • ofAll

        static <T> Iterator<T> ofAll​(java.lang.Iterable<? extends T> iterable)
        Creates a 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​(java.util.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<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
      • 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
      • 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
      • 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
      • 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
      • 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
      • 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
      • 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
      • 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 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:
        java.lang.NullPointerException - if f is null
      • fill

        static <T> Iterator<T> fill​(int n,
                                    java.util.function.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:
        java.lang.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<java.lang.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<java.lang.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:
        java.lang.IllegalArgumentException - if step is zero
      • rangeBy

        @GwtIncompatible("BigDecimalHelper is GwtIncompatible")
        static Iterator<java.lang.Double> rangeBy​(double from,
                                                  double toExclusive,
                                                  double step)
      • rangeBy

        static Iterator<java.math.BigDecimal> rangeBy​(java.math.BigDecimal from,
                                                      java.math.BigDecimal toExclusive,
                                                      java.math.BigDecimal step)
      • range

        static Iterator<java.lang.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<java.lang.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:
        java.lang.IllegalArgumentException - if step is zero
      • range

        static Iterator<java.lang.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<java.lang.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:
        java.lang.IllegalArgumentException - if step is zero
      • rangeClosed

        static Iterator<java.lang.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<java.lang.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:
        java.lang.IllegalArgumentException - if step 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 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<java.lang.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:
        java.lang.IllegalArgumentException - if step is zero
      • rangeClosed

        static Iterator<java.lang.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<java.lang.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:
        java.lang.IllegalArgumentException - if step is zero
      • from

        static Iterator<java.lang.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<java.lang.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<java.lang.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<java.lang.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​(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 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:
        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 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​(java.util.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​(java.util.function.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:
        java.lang.NullPointerException - if f 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 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​(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 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​(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 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,​java.lang.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​(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 interface Traversable<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 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​(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 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,
                                      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 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:
        java.lang.NullPointerException - if f 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 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:
        java.lang.NullPointerException - if f 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 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:
        java.lang.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​(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 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​(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 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​(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 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​(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 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​(java.util.function.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
      • filterNot

        default Iterator<T> filterNot​(java.util.function.Predicate<? super T> predicate)
        Returns an Iterator that contains elements that not satisfy the given predicate.
        Specified by:
        filterNot in interface Traversable<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 interface Traversable<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 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​(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 interface Traversable<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 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​(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 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.
      • 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 java.lang.Iterable<T>
        Specified by:
        iterator in interface Traversable<T>
        Specified by:
        iterator in interface Value<T>
        Returns:
        A new Iterator of this Traversable elements.
      • 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​(java.util.function.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
      • nextOption

        default Option<T> nextOption()
        A safe alternative to Iterator.next() that is equivalent to
        
         hasNext() ? Option.some(next()) : Option.none()
         
        Returns:
        a new instance of Option
      • orElse

        default Iterator<T> orElse​(java.lang.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​(java.util.function.Supplier<? extends java.lang.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​(java.util.function.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​(java.util.function.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​(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 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​(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 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​(java.lang.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,
                                    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 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,
                                         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 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,
                                          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 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​(java.util.function.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​(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 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 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 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​(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 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​(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 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.