Class Queue<T>

java.lang.Object
io.vavr.collection.AbstractQueue<T,Queue<T>>
io.vavr.collection.Queue<T>
Type Parameters:
T - Component type of the Queue
All Implemented Interfaces:
Foldable<T>, LinearSeq<T>, Seq<T>, Traversable<T>, Function1<Integer,T>, PartialFunction<Integer,T>, Value<T>, Serializable, Iterable<T>, Function<Integer,T>
public final class Queue<T> extends AbstractQueue<T,Queue<T>> implements LinearSeq<T>
An immutable Queue stores elements allowing a first-in-first-out (FIFO) retrieval.

Queue API:

A Queue internally consists of a front List containing the front elements of the Queue in the correct order and a rear List containing the rear elements of the Queue in reverse order.

When the front list is empty, front and rear are swapped and rear is reversed. This implies the following queue invariant: front.isEmpty() => rear.isEmpty().

See Okasaki, Chris: Purely Functional Data Structures (p. 42 ff.). Cambridge, 2003.

See Also:

  • Field Details

    • serialVersionUID

      private static final long serialVersionUID
      See Also:

    • EMPTY

      private static final Queue<?> EMPTY

    • front

      private final List<T> front

    • rear

      private final List<T> rear

  • Constructor Details

    • Queue

      private Queue(List<T> front, List<T> rear)
      Creates a Queue consisting of a front List and a rear List.

      For a Queue(front, rear) the following invariant holds: Queue is empty <=> front is empty. In other words: If the Queue is not empty, the front List contains at least one element.

      Parameters:
      front - A List of front elements, in correct order.
      rear - A List of rear elements, in reverse order.

  • Method Details

    • collector

      public static <T> Collector<T, ArrayList<T>, Queue<T>> collector()
      Returns a Collector which may be used in conjunction with Stream.collect(java.util.stream.Collector) to obtain a Queue .
      Type Parameters:
      T - Component type of the Queue.
      Returns:
      A io.vavr.collection.Queue Collector.

    • empty

      public static <T> Queue<T> empty()
      Returns the empty Queue.
      Type Parameters:
      T - Component type
      Returns:
      The empty Queue.

    • narrow

      public static <T> Queue<T> narrow(Queue<? extends T> queue)
      Narrows a widened Queue<? extends T> to Queue<T> by performing a type-safe cast. This is eligible because immutable/read-only collections are covariant.
      Type Parameters:
      T - Component type of the Queue.
      Parameters:
      queue - An Queue.
      Returns:
      the given queue instance as narrowed type Queue<T>.

    • of

      public static <T> Queue<T> of(T element)
      Returns a singleton Queue, i.e. a Queue of one element.
      Type Parameters:
      T - The component type
      Parameters:
      element - An element.
      Returns:
      A new Queue instance containing the given element

    • of

      @SafeVarargs public static <T> Queue<T> of(T... elements)
      Creates a Queue of the given elements.
      Type Parameters:
      T - Component type of the Queue.
      Parameters:
      elements - Zero or more elements.
      Returns:
      A queue containing the given elements in the same order.
      Throws:
      NullPointerException - if elements is null

    • ofAll

      public static <T> Queue<T> ofAll(Iterable<? extends T> elements)
      Creates a Queue of the given elements.
      Type Parameters:
      T - Component type of the Queue.
      Parameters:
      elements - An Iterable of elements.
      Returns:
      A queue containing the given elements in the same order.
      Throws:
      NullPointerException - if elements is null

    • ofAll

      public static <T> Queue<T> ofAll(Stream<? extends T> javaStream)
      Creates a Queue that contains the elements of the given Stream.
      Type Parameters:
      T - Component type of the Stream.
      Parameters:
      javaStream - A Stream
      Returns:
      A Queue containing the given elements in the same order.

    • ofAll

      public static Queue<Boolean> ofAll(boolean... elements)
      Creates a Queue from boolean values.
      Parameters:
      elements - boolean values
      Returns:
      A new Queue of Boolean values
      Throws:
      NullPointerException - if elements is null

    • ofAll

      public static Queue<Byte> ofAll(byte... elements)
      Creates a Queue from byte values.
      Parameters:
      elements - byte values
      Returns:
      A new Queue of Byte values
      Throws:
      NullPointerException - if elements is null

    • ofAll

      public static Queue<Character> ofAll(char... elements)
      Creates a Queue from char values.
      Parameters:
      elements - char values
      Returns:
      A new Queue of Character values
      Throws:
      NullPointerException - if elements is null

    • ofAll

      public static Queue<Double> ofAll(double... elements)
      Creates a Queue from double values.
      Parameters:
      elements - double values
      Returns:
      A new Queue of Double values
      Throws:
      NullPointerException - if elements is null

    • ofAll

      public static Queue<Float> ofAll(float... elements)
      Creates a Queue from float values.
      Parameters:
      elements - float values
      Returns:
      A new Queue of Float values
      Throws:
      NullPointerException - if elements is null

    • ofAll

      public static Queue<Integer> ofAll(int... elements)
      Creates a Queue from int values.
      Parameters:
      elements - int values
      Returns:
      A new Queue of Integer values
      Throws:
      NullPointerException - if elements is null

    • ofAll

      public static Queue<Long> ofAll(long... elements)
      Creates a Queue from long values.
      Parameters:
      elements - long values
      Returns:
      A new Queue of Long values
      Throws:
      NullPointerException - if elements is null

    • ofAll

      public static Queue<Short> ofAll(short... elements)
      Creates a Queue from short values.
      Parameters:
      elements - short values
      Returns:
      A new Queue of Short values
      Throws:
      NullPointerException - if elements is null

    • tabulate

      public static <T> Queue<T> tabulate(int n, Function<? super Integer, ? extends T> f)
      Returns a Queue containing 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 Queue
      Parameters:
      n - The number of elements in the Queue
      f - The Function computing element values
      Returns:
      A Queue consisting of elements f(0),f(1), ..., f(n - 1)
      Throws:
      NullPointerException - if f is null

    • fill

      public static <T> Queue<T> fill(int n, Supplier<? extends T> s)
      Returns a Queue containing n values supplied by a given Supplier s.
      Type Parameters:
      T - Component type of the Queue
      Parameters:
      n - The number of elements in the Queue
      s - The Supplier computing element values
      Returns:
      An Queue of size n, where each element contains the result supplied by s.
      Throws:
      NullPointerException - if s is null

    • fill

      public static <T> Queue<T> fill(int n, T element)
      Returns a Queue containing n times the given element
      Type Parameters:
      T - Component type of the Queue
      Parameters:
      n - The number of elements in the Queue
      element - The element
      Returns:
      An Queue of size n, where each element is the given element.

    • range

      public static Queue<Character> range(char from, char toExclusive)

    • rangeBy

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

    • rangeBy

      @GwtIncompatible public static Queue<Double> rangeBy(double from, double toExclusive, double step)

    • range

      public static Queue<Integer> range(int from, int toExclusive)
      Creates a Queue of int numbers starting from from, extending to toExclusive - 1.

      Examples: 

      
Queue.range(0, 0)  // = Queue()
Queue.range(2, 0)  // = Queue()
Queue.range(-2, 2) // = Queue(-2, -1, 0, 1)
      Parameters:
      from - the first number
      toExclusive - the last number + 1
      Returns:
      a range of int values as specified or Nil if from >= toExclusive

    • rangeBy

      public static Queue<Integer> rangeBy(int from, int toExclusive, int step)
      Creates a Queue of int numbers starting from from, extending to toExclusive - 1, with step.

      Examples: 

      
Queue.rangeBy(1, 3, 1)  // = Queue(1, 2)
Queue.rangeBy(1, 4, 2)  // = Queue(1, 3)
Queue.rangeBy(4, 1, -2) // = Queue(4, 2)
Queue.rangeBy(4, 1, 2)  // = Queue()
      Parameters:
      from - the first number
      toExclusive - the last number + 1
      step - the step
      Returns:
      a range of long values as specified or Nil if
      from >= toInclusive and step > 0 or
      from <= toInclusive and step < 0
      Throws:
      IllegalArgumentException - if step is zero

    • range

      public static Queue<Long> range(long from, long toExclusive)
      Creates a Queue of long numbers starting from from, extending to toExclusive - 1.

      Examples: 

      
Queue.range(0L, 0L)  // = Queue()
Queue.range(2L, 0L)  // = Queue()
Queue.range(-2L, 2L) // = Queue(-2L, -1L, 0L, 1L)
      Parameters:
      from - the first number
      toExclusive - the last number + 1
      Returns:
      a range of long values as specified or Nil if from >= toExclusive

    • rangeBy

      public static Queue<Long> rangeBy(long from, long toExclusive, long step)
      Creates a Queue of long numbers starting from from, extending to toExclusive - 1, with step.

      Examples: 

      
Queue.rangeBy(1L, 3L, 1L)  // = Queue(1L, 2L)
Queue.rangeBy(1L, 4L, 2L)  // = Queue(1L, 3L)
Queue.rangeBy(4L, 1L, -2L) // = Queue(4L, 2L)
Queue.rangeBy(4L, 1L, 2L)  // = Queue()
      Parameters:
      from - the first number
      toExclusive - the last number + 1
      step - the step
      Returns:
      a range of long values as specified or Nil if
      from >= toInclusive and step > 0 or
      from <= toInclusive and step < 0
      Throws:
      IllegalArgumentException - if step is zero

    • rangeClosed

      public static Queue<Character> rangeClosed(char from, char toInclusive)

    • rangeClosedBy

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

    • rangeClosedBy

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

    • rangeClosed

      public static Queue<Integer> rangeClosed(int from, int toInclusive)
      Creates a Queue of int numbers starting from from, extending to toInclusive.

      Examples: 

      
Queue.rangeClosed(0, 0)  // = Queue(0)
Queue.rangeClosed(2, 0)  // = Queue()
Queue.rangeClosed(-2, 2) // = Queue(-2, -1, 0, 1, 2)
      Parameters:
      from - the first number
      toInclusive - the last number
      Returns:
      a range of int values as specified or Nil if from > toInclusive

    • rangeClosedBy

      public static Queue<Integer> rangeClosedBy(int from, int toInclusive, int step)
      Creates a Queue of int numbers starting from from, extending to toInclusive, with step.

      Examples: 

      
Queue.rangeClosedBy(1, 3, 1)  // = Queue(1, 2, 3)
Queue.rangeClosedBy(1, 4, 2)  // = Queue(1, 3)
Queue.rangeClosedBy(4, 1, -2) // = Queue(4, 2)
Queue.rangeClosedBy(4, 1, 2)  // = Queue()
      Parameters:
      from - the first number
      toInclusive - the last number
      step - the step
      Returns:
      a range of int values as specified or Nil if
      from > toInclusive and step > 0 or
      from < toInclusive and step < 0
      Throws:
      IllegalArgumentException - if step is zero

    • rangeClosed

      public static Queue<Long> rangeClosed(long from, long toInclusive)
      Creates a Queue of long numbers starting from from, extending to toInclusive.

      Examples: 

      
Queue.rangeClosed(0L, 0L)  // = Queue(0L)
Queue.rangeClosed(2L, 0L)  // = Queue()
Queue.rangeClosed(-2L, 2L) // = Queue(-2L, -1L, 0L, 1L, 2L)
      Parameters:
      from - the first number
      toInclusive - the last number
      Returns:
      a range of long values as specified or Nil if from > toInclusive

    • transpose

      public static <T> Queue<Queue<T>> transpose(Queue<Queue<T>> matrix)
      Transposes the rows and columns of a Queue matrix.
      Type Parameters:
      T - matrix element type
      Parameters:
      matrix - to be transposed.
      Returns:
      a transposed Queue matrix.
      Throws:
      IllegalArgumentException - if the row lengths of matrix differ.

      ex: Queue.transpose(Queue(Queue(1,2,3), Queue(4,5,6))) → Queue(Queue(1,4), Queue(2,5), Queue(3,6))

    • rangeClosedBy

      public static Queue<Long> rangeClosedBy(long from, long toInclusive, long step)
      Creates a Queue of long numbers starting from from, extending to toInclusive, with step.

      Examples: 

      
Queue.rangeClosedBy(1L, 3L, 1L)  // = Queue(1L, 2L, 3L)
Queue.rangeClosedBy(1L, 4L, 2L)  // = Queue(1L, 3L)
Queue.rangeClosedBy(4L, 1L, -2L) // = Queue(4L, 2L)
Queue.rangeClosedBy(4L, 1L, 2L)  // = Queue()
      Parameters:
      from - the first number
      toInclusive - the last number
      step - the step
      Returns:
      a range of int values as specified or Nil if
      from > toInclusive and step > 0 or
      from < toInclusive and step < 0
      Throws:
      IllegalArgumentException - if step is zero

    • unfoldRight

      public static <T,U> Queue<U> unfoldRight(T seed, Function<? super T, Option<Tuple2<? extends U, ? extends T>>> f)
      Creates a Queue from a seed value and a function. The function takes the seed at first. The function should return None when it's done generating the Queue, otherwise Some Tuple of the element for the next call and the value to add to the resulting Queue.

      Example: 

      
Queue.unfoldRight(10, x -> x == 0
            ? Option.none()
            : Option.of(new Tuple2<>(x, x-1)));
// Queue(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 Queue with the values built up by the iteration
      Throws:
      NullPointerException - if f is null

    • unfoldLeft

      public static <T,U> Queue<U> unfoldLeft(T seed, Function<? super T, Option<Tuple2<? extends T, ? extends U>>> f)
      Creates a Queue from a seed value and a function. The function takes the seed at first. The function should return None when it's done generating the Queue, otherwise Some Tuple of the value to add to the resulting Queue and the element for the next call.

      Example: 

      
Queue.unfoldLeft(10, x -> x == 0
            ? Option.none()
            : Option.of(new Tuple2<>(x-1, x)));
// Queue(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 Queue with the values built up by the iteration
      Throws:
      NullPointerException - if f is null

    • unfold

      public static <T> Queue<T> unfold(T seed, Function<? super T, Option<Tuple2<? extends T, ? extends T>>> f)
      Creates a Queue from a seed value and a function. The function takes the seed at first. The function should return None when it's done generating the Queue, otherwise Some Tuple of the value to add to the resulting Queue and the element for the next call.

      Example: 

      
Queue.unfold(10, x -> x == 0
            ? Option.none()
            : Option.of(new Tuple2<>(x-1, x)));
// Queue(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 Queue with the values built up by the iteration
      Throws:
      NullPointerException - if f is null

    • enqueue

      public Queue<T> enqueue(T element)
      Enqueues a new element.
      Specified by:
      enqueue in class AbstractQueue<T,Queue<T>>
      Parameters:
      element - The new element
      Returns:
      a new Queue instance, containing the new element

    • enqueueAll

      public Queue<T> enqueueAll(Iterable<? extends T> elements)
      Enqueues the given elements. A queue has FIFO order, i.e. the first of the given elements is the first which will be retrieved.
      Specified by:
      enqueueAll in class AbstractQueue<T,Queue<T>>
      Parameters:
      elements - An Iterable of elements, may be empty
      Returns:
      a new Queue instance, containing the new elements
      Throws:
      NullPointerException - if elements is null

    • append

      public Queue<T> append(T element)
      Description copied from interface: Seq
      Appends an element to this.
      Specified by:
      append in interface LinearSeq<T>
      Specified by:
      append in interface Seq<T>
      Parameters:
      element - An element
      Returns:
      A new Seq containing the given element appended to this elements

    • appendAll

      public Queue<T> appendAll(Iterable<? extends T> elements)
      Description copied from interface: Seq
      Appends all given elements to this.
      Specified by:
      appendAll in interface LinearSeq<T>
      Specified by:
      appendAll in interface Seq<T>
      Parameters:
      elements - An Iterable of elements
      Returns:
      A new Seq containing the given elements appended to this elements

    • asJava

      @GwtIncompatible public List<T> asJava()
      Description copied from interface: Seq
      Creates an immutable List view on top of this Seq, i.e. calling mutators will result in UnsupportedOperationException at runtime.

      The difference to conversion methods toJava*() is that

      • A view is created in O(1) (constant time) whereas conversion takes O(n) (linear time), with n = collection size.
      • The operations on a view have the same performance characteristics than the underlying persistent Vavr collection whereas the performance characteristics of a converted collection are those of the Java standard collections.
      Please note that our immutable java.util.List view throws UnsupportedOperationException before checking method arguments. Java does handle this case inconsistently.
      Specified by:
      asJava in interface Seq<T>
      Returns:
      A new immutable Collection view on this Traversable.

    • asJava

      @GwtIncompatible public Queue<T> asJava(Consumer<? super List<T>> action)
      Description copied from interface: Seq
      Creates an immutable List view on top of this Seq that is passed to the given action.
      Specified by:
      asJava in interface LinearSeq<T>
      Specified by:
      asJava in interface Seq<T>
      Parameters:
      action - A side-effecting unit of work that operates on an immutable java.util.List view.
      Returns:
      this instance
      See Also:

    • asJavaMutable

      @GwtIncompatible public List<T> asJavaMutable()
      Description copied from interface: Seq
      Creates a mutable List view on top of this Seq, i.e. all mutator methods of the List are implemented.
      Specified by:
      asJavaMutable in interface Seq<T>
      Returns:
      A new mutable Collection view on this Traversable.
      See Also:

    • asJavaMutable

      @GwtIncompatible public Queue<T> asJavaMutable(Consumer<? super List<T>> action)
      Description copied from interface: Seq
      Creates a mutable List view on top of this Seq that is passed to the given action.
      Specified by:
      asJavaMutable in interface LinearSeq<T>
      Specified by:
      asJavaMutable in interface Seq<T>
      Parameters:
      action - A side-effecting unit of work that operates on a mutable java.util.List view.
      Returns:
      this instance, if only read operations are performed on the java.util.List view or a new instance of this type, if write operations are performed on the java.util.List view.
      See Also:

    • collect

      public <R> Queue<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 LinearSeq<T>
      Specified by:
      collect in interface Seq<T>
      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

    • combinations

      public Queue<Queue<T>> combinations()
      Description copied from interface: Seq
      Returns the union of all combinations from k = 0 to length().

      Examples: 

      
[].combinations() = [[]]

[1,2,3].combinations() = [
  [],                  // k = 0
  [1], [2], [3],       // k = 1
  [1,2], [1,3], [2,3], // k = 2
  [1,2,3]              // k = 3
]
      Specified by:
      combinations in interface LinearSeq<T>
      Specified by:
      combinations in interface Seq<T>
      Returns:
      the combinations of this

    • combinations

      public Queue<Queue<T>> combinations(int k)
      Description copied from interface: Seq
      Returns the k-combination of this traversable, i.e. all subset of this of k distinct elements.
      Specified by:
      combinations in interface LinearSeq<T>
      Specified by:
      combinations in interface Seq<T>
      Parameters:
      k - Size of subsets
      Returns:
      the k-combination of this elements
      See Also:

    • crossProduct

      public Iterator<Queue<T>> crossProduct(int power)
      Description copied from interface: Seq
      Calculates the n-ary cartesian power (or cross product or simply product) of this.

      Example: 

      
// = ((A,A), (A,B), (A,C), ..., (B,A), (B,B), ..., (Z,Y), (Z,Z))
CharSeq.rangeClosed('A', 'Z').crossProduct(2);

      Cartesian power of negative value will return empty iterator.

      Example: 

      
// = ()
CharSeq.rangeClosed('A', 'Z').crossProduct(-1);
      Specified by:
      crossProduct in interface LinearSeq<T>
      Specified by:
      crossProduct in interface Seq<T>
      Parameters:
      power - the number of cartesian multiplications
      Returns:
      A new Iterator representing the n-ary cartesian power of this

    • distinct

      public Queue<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 LinearSeq<T>
      Specified by:
      distinct in interface Seq<T>
      Specified by:
      distinct in interface Traversable<T>
      Returns:
      a new Traversable containing this elements without duplicates

    • distinctBy

      public Queue<T> distinctBy(Comparator<? super T> comparator)
      Description copied from interface: Traversable
      Returns a new version of this which contains no duplicates. Elements are compared using the given comparator.
      Specified by:
      distinctBy in interface LinearSeq<T>
      Specified by:
      distinctBy in interface Seq<T>
      Specified by:
      distinctBy in interface Traversable<T>
      Parameters:
      comparator - A comparator
      Returns:
      a new Traversable containing this elements without duplicates

    • distinctBy

      public <U> Queue<T> distinctBy(Function<? super T, ? extends U> keyExtractor)
      Description copied from interface: Traversable
      Returns a new version of this which contains no duplicates. Elements mapped to keys which are compared using equals.

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

      Specified by:
      distinctBy in interface LinearSeq<T>
      Specified by:
      distinctBy in interface Seq<T>
      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

      public Queue<T> drop(int n)
      Description copied from interface: Traversable
      Drops the first n elements of this or all elements, if this length < n.
      Specified by:
      drop in interface LinearSeq<T>
      Specified by:
      drop in interface Seq<T>
      Specified by:
      drop in interface Traversable<T>
      Parameters:
      n - The number of elements to drop.
      Returns:
      a new instance consisting of all elements of this except the first n ones, or else the empty instance, if this has less than n elements.

    • dropWhile

      public Queue<T> dropWhile(Predicate<? super T> predicate)
      Description copied from interface: Traversable
      Drops elements while the predicate holds for the current element.

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

      Specified by:
      dropWhile in interface LinearSeq<T>
      Specified by:
      dropWhile in interface Seq<T>
      Specified by:
      dropWhile in interface Traversable<T>
      Specified by:
      dropWhile in class AbstractQueue<T,Queue<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.

    • dropRight

      public Queue<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 LinearSeq<T>
      Specified by:
      dropRight in interface Seq<T>
      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.

    • dropRightUntil

      public Queue<T> dropRightUntil(Predicate<? super T> predicate)
      Description copied from interface: Seq
      Drops elements until the predicate holds for the current element, starting from the end.
      Specified by:
      dropRightUntil in interface LinearSeq<T>
      Specified by:
      dropRightUntil in interface Seq<T>
      Parameters:
      predicate - A condition tested subsequently for this elements, starting from the end.
      Returns:
      a new instance consisting of all elements until and including the last one which does satisfy the given predicate.

    • dropRightWhile

      public Queue<T> dropRightWhile(Predicate<? super T> predicate)
      Description copied from interface: Seq
      Drops elements while the predicate holds for the current element, starting from the end.

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

      Specified by:
      dropRightWhile in interface LinearSeq<T>
      Specified by:
      dropRightWhile in interface Seq<T>
      Parameters:
      predicate - A condition tested subsequently for this elements, starting from the end.
      Returns:
      a new instance consisting of all elements until and including the last one which does not satisfy the given predicate.

    • filter

      public Queue<T> filter(Predicate<? super T> predicate)
      Description copied from interface: Traversable
      Returns a new traversable consisting of all elements which satisfy the given predicate.
      Specified by:
      filter in interface LinearSeq<T>
      Specified by:
      filter in interface Seq<T>
      Specified by:
      filter in interface Traversable<T>
      Parameters:
      predicate - A predicate
      Returns:
      a new traversable

    • flatMap

      public <U> Queue<U> flatMap(Function<? super T, ? extends Iterable<? extends U>> mapper)
      Description copied from interface: Traversable
      FlatMaps this Traversable.
      Specified by:
      flatMap in interface LinearSeq<T>
      Specified by:
      flatMap in interface Seq<T>
      Specified by:
      flatMap in interface Traversable<T>
      Type Parameters:
      U - The resulting component type.
      Parameters:
      mapper - A mapper
      Returns:
      A new Traversable instance.

    • get

      public T get(int index)
      Description copied from interface: Seq
      Returns the element at the specified index.
      Specified by:
      get in interface Seq<T>
      Parameters:
      index - an index
      Returns:
      the element at the given index

    • groupBy

      public <C> Map<C,Queue<T>> groupBy(Function<? super T, ? extends C> classifier)
      Description copied from interface: Traversable
      Groups this elements by classifying the elements.
      Specified by:
      groupBy in interface LinearSeq<T>
      Specified by:
      groupBy in interface Seq<T>
      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:

    • grouped

      public Iterator<Queue<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 LinearSeq<T>
      Specified by:
      grouped in interface Seq<T>
      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

      public 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

      public 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.

    • indexOf

      public int indexOf(T element, int from)
      Description copied from interface: Seq
      Returns the index of the first occurrence of the given element after or at some start index or -1 if this does not contain the given element.
      Specified by:
      indexOf in interface Seq<T>
      Parameters:
      element - an element
      from - start index
      Returns:
      the index of the first occurrence of the given element

    • init

      public Queue<T> init()
      Description copied from class: AbstractQueue
      Dual of AbstractQueue.tail(), returning all elements except the last.
      Specified by:
      init in interface LinearSeq<T>
      Specified by:
      init in interface Seq<T>
      Specified by:
      init in interface Traversable<T>
      Specified by:
      init in class AbstractQueue<T,Queue<T>>
      Returns:
      a new instance containing all elements except the last.

    • insert

      public Queue<T> insert(int index, T element)
      Description copied from interface: Seq
      Inserts the given element at the specified index.
      Specified by:
      insert in interface LinearSeq<T>
      Specified by:
      insert in interface Seq<T>
      Parameters:
      index - an index
      element - an element
      Returns:
      a new Seq, where the given element is inserted into this at the given index

    • insertAll

      public Queue<T> insertAll(int index, Iterable<? extends T> elements)
      Description copied from interface: Seq
      Inserts the given elements at the specified index.
      Specified by:
      insertAll in interface LinearSeq<T>
      Specified by:
      insertAll in interface Seq<T>
      Parameters:
      index - an index
      elements - An Iterable of elements
      Returns:
      a new Seq, where the given elements are inserted into this at the given index

    • intersperse

      public Queue<T> intersperse(T element)
      Description copied from interface: Seq
      Inserts an element between all elements of this Traversable.
      Specified by:
      intersperse in interface LinearSeq<T>
      Specified by:
      intersperse in interface Seq<T>
      Parameters:
      element - An element.
      Returns:
      an interspersed version of this

    • isAsync

      public boolean isAsync()
      A Queue is computed synchronously.
      Specified by:
      isAsync in interface Value<T>
      Returns:
      false

    • isEmpty

      public 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

      public boolean isLazy()
      A Queue is computed eagerly.
      Specified by:
      isLazy in interface Value<T>
      Returns:
      false

    • isTraversableAgain

      public 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.

    • last

      public T last()
      Description copied from interface: Traversable
      Dual of Traversable.head(), returning the last element.
      Specified by:
      last in interface Traversable<T>
      Returns:
      the last element.

    • lastIndexOf

      public int lastIndexOf(T element, int end)
      Description copied from interface: Seq
      Returns the index of the last occurrence of the given element before or at a given end index or -1 if this does not contain the given element.
      Specified by:
      lastIndexOf in interface Seq<T>
      Parameters:
      element - an element
      end - the end index
      Returns:
      the index of the last occurrence of the given element

    • length

      public 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

      public <U> Queue<U> map(Function<? super T, ? extends U> mapper)
      Description copied from interface: Traversable
      Maps the elements of this Traversable to elements of a new type preserving their order, if any.
      Specified by:
      map in interface LinearSeq<T>
      Specified by:
      map in interface Seq<T>
      Specified by:
      map in interface Traversable<T>
      Specified by:
      map in interface Value<T>
      Type Parameters:
      U - Component type of the target Traversable
      Parameters:
      mapper - A mapper.
      Returns:
      a mapped Traversable

    • orElse

      public Queue<T> orElse(Iterable<? extends T> other)
      Description copied from interface: Traversable
      Returns this Traversable if it is nonempty, otherwise return the alternative.
      Specified by:
      orElse in interface LinearSeq<T>
      Specified by:
      orElse in interface Seq<T>
      Specified by:
      orElse in interface Traversable<T>
      Parameters:
      other - An alternative Traversable
      Returns:
      this Traversable if it is nonempty, otherwise return the alternative.

    • orElse

      public Queue<T> orElse(Supplier<? extends Iterable<? extends T>> supplier)
      Description copied from interface: Traversable
      Returns this Traversable if it is nonempty, otherwise return the result of evaluating supplier.
      Specified by:
      orElse in interface LinearSeq<T>
      Specified by:
      orElse in interface Seq<T>
      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.

    • padTo

      public Queue<T> padTo(int length, T element)
      Description copied from interface: Seq
      A copy of this sequence with an element appended until a given target length is reached.

      Note: lazily-evaluated Seq implementations need to process all elements in order to gather the overall length.

      Specified by:
      padTo in interface LinearSeq<T>
      Specified by:
      padTo in interface Seq<T>
      Parameters:
      length - the target length
      element - the padding element
      Returns:
      a new sequence consisting of all elements of this sequence followed by the minimal number of occurrences of element so that the resulting sequence has a length of at least length.

    • leftPadTo

      public Queue<T> leftPadTo(int length, T element)
      Description copied from interface: Seq
      A copy of this sequence with an element prepended until a given target length is reached.

      Note: lazily-evaluated Seq implementations need to process all elements in order to gather the overall length.

      Specified by:
      leftPadTo in interface Seq<T>
      Parameters:
      length - the target length
      element - the padding element
      Returns:
      a new sequence consisting of all elements of this sequence prepended by the minimal number of occurrences of element so that the resulting sequence has a length of at least length.

    • patch

      public Queue<T> patch(int from, Iterable<? extends T> that, int replaced)
      Description copied from interface: Seq
      Produces a new list where a slice of elements in this list is replaced by another sequence.
      Specified by:
      patch in interface LinearSeq<T>
      Specified by:
      patch in interface Seq<T>
      Parameters:
      from - the index of the first replaced element
      that - sequence for replacement
      replaced - the number of elements to drop in the original list
      Returns:
      a new sequence.

    • partition

      public Tuple2<Queue<T>,Queue<T>> partition(Predicate<? super T> predicate)
      Description copied from interface: Traversable
      Creates a partition of this Traversable by splitting this elements in two in distinct traversables according to a predicate.
      Specified by:
      partition in interface LinearSeq<T>
      Specified by:
      partition in interface Seq<T>
      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.

    • permutations

      public Queue<Queue<T>> permutations()
      Description copied from interface: Seq
      Computes all unique permutations.

      Example: 

      
[].permutations() = []

[1,2,3].permutations() = [
  [1,2,3],
  [1,3,2],
  [2,1,3],
  [2,3,1],
  [3,1,2],
  [3,2,1]
]
      Specified by:
      permutations in interface LinearSeq<T>
      Specified by:
      permutations in interface Seq<T>
      Returns:
      this unique permutations

    • prepend

      public Queue<T> prepend(T element)
      Description copied from interface: Seq
      Prepends an element to this.
      Specified by:
      prepend in interface LinearSeq<T>
      Specified by:
      prepend in interface Seq<T>
      Parameters:
      element - An element
      Returns:
      A new Seq containing the given element prepended to this elements

    • prependAll

      public Queue<T> prependAll(Iterable<? extends T> elements)
      Description copied from interface: Seq
      Prepends all given elements to this.
      Specified by:
      prependAll in interface LinearSeq<T>
      Specified by:
      prependAll in interface Seq<T>
      Parameters:
      elements - An Iterable of elements
      Returns:
      A new Seq containing the given elements prepended to this elements

    • remove

      public Queue<T> remove(T element)
      Description copied from interface: Seq
      Removes the first occurrence of the given element.
      Specified by:
      remove in interface LinearSeq<T>
      Specified by:
      remove in interface Seq<T>
      Parameters:
      element - An element to be removed from this Seq.
      Returns:
      a Seq containing all elements of this without the first occurrence of the given element.

    • removeFirst

      public Queue<T> removeFirst(Predicate<T> predicate)
      Description copied from interface: Seq
      Removes the first occurrence that satisfy predicate
      Specified by:
      removeFirst in interface LinearSeq<T>
      Specified by:
      removeFirst in interface Seq<T>
      Parameters:
      predicate - an predicate
      Returns:
      a new Seq

    • removeLast

      public Queue<T> removeLast(Predicate<T> predicate)
      Description copied from interface: Seq
      Removes the last occurrence that satisfy predicate
      Specified by:
      removeLast in interface LinearSeq<T>
      Specified by:
      removeLast in interface Seq<T>
      Parameters:
      predicate - an predicate
      Returns:
      a new Seq

    • removeAt

      public Queue<T> removeAt(int index)
      Description copied from interface: Seq
      Removes the element at the specified position in this sequence. Shifts any subsequent elements to the left (subtracts one from their indices).
      Specified by:
      removeAt in interface LinearSeq<T>
      Specified by:
      removeAt in interface Seq<T>
      Parameters:
      index - position of element to remove
      Returns:
      a sequence containing all elements of this without the element at the specified position.

    • removeAll

      public Queue<T> removeAll(T element)
      Description copied from interface: Seq
      Removes all occurrences of the given element.
      Specified by:
      removeAll in interface LinearSeq<T>
      Specified by:
      removeAll in interface Seq<T>
      Parameters:
      element - An element to be removed from this Seq.
      Returns:
      a Seq containing all elements of this but not the given element.

    • replace

      public Queue<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 LinearSeq<T>
      Specified by:
      replace in interface Seq<T>
      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

      public Queue<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 LinearSeq<T>
      Specified by:
      replaceAll in interface Seq<T>
      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.

    • reverse

      public Queue<T> reverse()
      Description copied from interface: Seq
      Reverses the order of elements.
      Specified by:
      reverse in interface LinearSeq<T>
      Specified by:
      reverse in interface Seq<T>
      Returns:
      the reversed elements.

    • rotateLeft

      public Queue<T> rotateLeft(int n)
      Description copied from interface: Seq
      Circular rotates the elements by the specified distance to the left direction. 
      // = List(3, 4, 5, 1, 2)
List.of(1, 2, 3, 4, 5).rotateLeft(2);
      Specified by:
      rotateLeft in interface LinearSeq<T>
      Specified by:
      rotateLeft in interface Seq<T>
      Parameters:
      n - distance of left rotation
      Returns:
      the rotated elements.

    • rotateRight

      public Queue<T> rotateRight(int n)
      Description copied from interface: Seq
      Circular rotates the elements by the specified distance to the right direction. 
      // = List(4, 5, 1, 2, 3)
List.of(1, 2, 3, 4, 5).rotateRight(2);
      Specified by:
      rotateRight in interface LinearSeq<T>
      Specified by:
      rotateRight in interface Seq<T>
      Parameters:
      n - distance of right rotation
      Returns:
      the rotated elements.

    • scan

      public Queue<T> scan(T zero, BiFunction<? super T, ? super T, ? extends T> operation)
      Description copied from interface: Traversable
      Computes a prefix scan of the elements of the collection. Note: The neutral element z may be applied more than once.
      Specified by:
      scan in interface LinearSeq<T>
      Specified by:
      scan in interface Seq<T>
      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

      public <U> Queue<U> scanLeft(U zero, BiFunction<? super U, ? super T, ? extends U> operation)
      Description copied from interface: Traversable
      Produces a collection containing cumulative results of applying the operator going left to right. Note: will not terminate for infinite-sized collections. Note: might return different results for different runs, unless the underlying collection type is ordered.
      Specified by:
      scanLeft in interface LinearSeq<T>
      Specified by:
      scanLeft in interface Seq<T>
      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

      public <U> Queue<U> scanRight(U zero, BiFunction<? super T, ? super U, ? extends U> operation)
      Description copied from interface: Traversable
      Produces a collection containing cumulative results of applying the operator going right to left. The head of the collection is the last cumulative result. Note: will not terminate for infinite-sized collections. Note: might return different results for different runs, unless the underlying collection type is ordered.
      Specified by:
      scanRight in interface LinearSeq<T>
      Specified by:
      scanRight in interface Seq<T>
      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

    • shuffle

      public Queue<T> shuffle()
      Description copied from interface: Seq
      Randomize the order of the elements in the current sequence.
      Specified by:
      shuffle in interface LinearSeq<T>
      Specified by:
      shuffle in interface Seq<T>
      Returns:
      a sequence with the same elements as the current sequence in a random order.

    • slice

      public Queue<T> slice(int beginIndex, int endIndex)
      Description copied from interface: Seq
      Returns a Seq that is a slice of this. The slice begins with the element at the specified beginIndex and extends to the element at index endIndex - 1.

      Examples: 

      
List.of(1, 2, 3, 4).slice(1, 3); // = (2, 3)
List.of(1, 2, 3, 4).slice(0, 4); // = (1, 2, 3, 4)
List.of(1, 2, 3, 4).slice(2, 2); // = ()
List.of(1, 2).slice(1, 0);       // = ()
List.of(1, 2).slice(-10, 10);    // = (1, 2)
      See also Seq.subSequence(int, int) which throws in some cases instead of returning a sequence.
      Specified by:
      slice in interface LinearSeq<T>
      Specified by:
      slice in interface Seq<T>
      Parameters:
      beginIndex - the beginning index, inclusive
      endIndex - the end index, exclusive
      Returns:
      the specified slice

    • slideBy

      public Iterator<Queue<T>> slideBy(Function<? super T, ?> classifier)
      Description copied from interface: Traversable
      Slides a non-overlapping window of a variable size over this Traversable.

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

      Examples: 

      [].slideBy(Function.identity()) = []
[1,2,3,4,4,5].slideBy(Function.identity()) = [[1],[2],[3],[4,4],[5]]
[1,2,3,10,12,5,7,20,29].slideBy(x -> x/10) = [[1,2,3],[10,12],[5,7],[20,29]]
      Specified by:
      slideBy in interface LinearSeq<T>
      Specified by:
      slideBy in interface Seq<T>
      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

      public Iterator<Queue<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 LinearSeq<T>
      Specified by:
      sliding in interface Seq<T>
      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

      public Iterator<Queue<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 LinearSeq<T>
      Specified by:
      sliding in interface Seq<T>
      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

    • sorted

      public Queue<T> sorted()
      Description copied from interface: Seq
      Sorts this elements according to their natural order. If this elements are not Comparable, a java.lang.ClassCastException may be thrown.
      Specified by:
      sorted in interface LinearSeq<T>
      Specified by:
      sorted in interface Seq<T>
      Returns:
      A sorted version of this

    • sorted

      public Queue<T> sorted(Comparator<? super T> comparator)
      Description copied from interface: Seq
      Sorts this elements according to the provided Comparator. If this elements are not Comparable, a java.lang.ClassCastException may be thrown.
      Specified by:
      sorted in interface LinearSeq<T>
      Specified by:
      sorted in interface Seq<T>
      Parameters:
      comparator - A comparator
      Returns:
      a sorted version of this

    • sortBy

      public <U extends Comparable<? super U>> Queue<T> sortBy(Function<? super T, ? extends U> mapper)
      Description copied from interface: Seq
      Sorts this elements by comparing the elements in a different domain, using the given mapper.
      Specified by:
      sortBy in interface LinearSeq<T>
      Specified by:
      sortBy in interface Seq<T>
      Type Parameters:
      U - The domain where elements are compared
      Parameters:
      mapper - A mapper
      Returns:
      a sorted version of this

    • sortBy

      public <U> Queue<T> sortBy(Comparator<? super U> comparator, Function<? super T, ? extends U> mapper)
      Description copied from interface: Seq
      Sorts this elements by comparing the elements in a different domain, using the given mapper.
      Specified by:
      sortBy in interface LinearSeq<T>
      Specified by:
      sortBy in interface Seq<T>
      Type Parameters:
      U - The domain where elements are compared
      Parameters:
      comparator - A comparator
      mapper - A mapper
      Returns:
      a sorted version of this

    • span

      public Tuple2<Queue<T>,Queue<T>> span(Predicate<? super T> predicate)
      Description copied from interface: Traversable
      Returns a tuple where the first element is the longest prefix of elements that satisfy the given predicate and the second element is the remainder.
      Specified by:
      span in interface LinearSeq<T>
      Specified by:
      span in interface Seq<T>
      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.

    • splitAt

      public Tuple2<Queue<T>,Queue<T>> splitAt(int n)
      Description copied from interface: Seq
      Splits a Seq at the specified index. The result of splitAt(n) is equivalent to Tuple.of(take(n), drop(n)).
      Specified by:
      splitAt in interface Seq<T>
      Parameters:
      n - An index.
      Returns:
      A Tuple containing the first n and the remaining elements.

    • splitAt

      public Tuple2<Queue<T>,Queue<T>> splitAt(Predicate<? super T> predicate)
      Description copied from interface: Seq
      Splits a sequence at the first element which satisfies the Predicate, e.g. Tuple(init, element+tail).
      Specified by:
      splitAt in interface Seq<T>
      Parameters:
      predicate - An predicate
      Returns:
      A Tuple containing divided sequences

    • splitAtInclusive

      public Tuple2<Queue<T>,Queue<T>> splitAtInclusive(Predicate<? super T> predicate)
      Description copied from interface: Seq
      Splits a sequence at the first element which satisfies the Predicate, e.g. Tuple(init+element, tail).
      Specified by:
      splitAtInclusive in interface Seq<T>
      Parameters:
      predicate - An predicate
      Returns:
      A Tuple containing divided sequences

    • startsWith

      public boolean startsWith(Iterable<? extends T> that, int offset)
      Description copied from interface: Seq
      Tests whether this list contains the given sequence at a given index.

      Note: If the both the receiver object this and the argument that are infinite sequences this method may not terminate.

      Specified by:
      startsWith in interface Seq<T>
      Parameters:
      that - the sequence to test
      offset - the index where the sequence is searched.
      Returns:
      true if that is empty or that is prefix of this collection starting from the given offset, false otherwise.

    • subSequence

      public Queue<T> subSequence(int beginIndex)
      Description copied from interface: Seq
      Returns a Seq that is a subsequence of this. The subsequence begins with the element at the specified beginIndex and extends to the end of this Seq.

      Examples: 

      
List.of(1, 2).subSequence(0);     // = (1, 2)
List.of(1, 2).subSequence(1);     // = (2)
List.of(1, 2).subSequence(2);     // = ()
List.of(1, 2).subSequence(10);    // throws IndexOutOfBoundsException
List.of(1, 2).subSequence(-10);   // throws IndexOutOfBoundsException
      See also Seq.drop(int) which is similar but does not throw.
      Specified by:
      subSequence in interface LinearSeq<T>
      Specified by:
      subSequence in interface Seq<T>
      Parameters:
      beginIndex - the beginning index, inclusive
      Returns:
      the specified subsequence

    • subSequence

      public Queue<T> subSequence(int beginIndex, int endIndex)
      Description copied from interface: Seq
      Returns a Seq that is a subsequence of this. The subsequence begins with the element at the specified beginIndex and extends to the element at index endIndex - 1.

      Examples: 

      
List.of(1, 2, 3, 4).subSequence(1, 3); // = (2, 3)
List.of(1, 2, 3, 4).subSequence(0, 4); // = (1, 2, 3, 4)
List.of(1, 2, 3, 4).subSequence(2, 2); // = ()
List.of(1, 2).subSequence(1, 0);       // throws IndexOutOfBoundsException
List.of(1, 2).subSequence(-10, 1);     // throws IndexOutOfBoundsException
List.of(1, 2).subSequence(0, 10);      // throws IndexOutOfBoundsException
      See also Seq.slice(int, int) which returns an empty sequence instead of throwing.
      Specified by:
      subSequence in interface LinearSeq<T>
      Specified by:
      subSequence in interface Seq<T>
      Parameters:
      beginIndex - the beginning index, inclusive
      endIndex - the end index, exclusive
      Returns:
      the specified subsequence

    • tail

      public Queue<T> tail()
      Description copied from class: AbstractQueue
      Drops the first element of a non-empty Traversable.
      Specified by:
      tail in interface LinearSeq<T>
      Specified by:
      tail in interface Seq<T>
      Specified by:
      tail in interface Traversable<T>
      Specified by:
      tail in class AbstractQueue<T,Queue<T>>
      Returns:
      A new instance of Traversable containing all elements except the first.

    • take

      public Queue<T> take(int n)
      Description copied from interface: Traversable
      Takes the first n elements of this or all elements, if this length < n.

      The result is equivalent to sublist(0, max(0, min(length(), n))) but does 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:
      take in interface LinearSeq<T>
      Specified by:
      take in interface Seq<T>
      Specified by:
      take in interface Traversable<T>
      Parameters:
      n - The number of elements to take.
      Returns:
      A new instance consisting of the first n elements of this or all elements, if this has less than n elements.

    • takeUntil

      public Queue<T> takeUntil(Predicate<? super T> predicate)
      Description copied from interface: Traversable
      Takes elements until the predicate holds for the current element.

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

      Specified by:
      takeUntil in interface LinearSeq<T>
      Specified by:
      takeUntil in interface Seq<T>
      Specified by:
      takeUntil in interface Traversable<T>
      Specified by:
      takeUntil in class AbstractQueue<T,Queue<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.

    • takeRight

      public Queue<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 LinearSeq<T>
      Specified by:
      takeRight in interface Seq<T>
      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.

    • takeRightUntil

      public Queue<T> takeRightUntil(Predicate<? super T> predicate)
      Description copied from interface: Seq
      Takes elements until the predicate holds for the current element, starting from the end.
      Specified by:
      takeRightUntil in interface LinearSeq<T>
      Specified by:
      takeRightUntil in interface Seq<T>
      Parameters:
      predicate - A condition tested subsequently for this elements, starting from the end.
      Returns:
      a new instance consisting of all elements after the last one which does satisfy the given predicate.

    • takeRightWhile

      public Queue<T> takeRightWhile(Predicate<? super T> predicate)
      Description copied from interface: Seq
      Takes elements while the predicate holds for the current element, starting from the end.

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

      Specified by:
      takeRightWhile in interface LinearSeq<T>
      Specified by:
      takeRightWhile in interface Seq<T>
      Parameters:
      predicate - A condition tested subsequently for this elements, starting from the end.
      Returns:
      a new instance consisting of all elements after the last one which does not satisfy the given predicate.

    • transform

      public <U> U transform(Function<? super Queue<T>, ? extends U> f)
      Transforms this Queue.
      Type Parameters:
      U - Type of transformation result
      Parameters:
      f - A transformation
      Returns:
      An instance of type U
      Throws:
      NullPointerException - if f is null

    • unzip

      public <T1,T2> Tuple2<Queue<T1>, Queue<T2>> unzip(Function<? super T, Tuple2<? extends T1, ? extends T2>> unzipper)
      Description copied from interface: Traversable
      Unzips this elements by mapping this elements to pairs which are subsequently split into two distinct sets.
      Specified by:
      unzip in interface LinearSeq<T>
      Specified by:
      unzip in interface Seq<T>
      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

      public <T1,T2,T3> Tuple3<Queue<T1>, Queue<T2>, Queue<T3>> unzip3(Function<? super T, Tuple3<? extends T1, ? extends T2, ? extends T3>> unzipper)
      Description copied from interface: Traversable
      Unzips this elements by mapping this elements to triples which are subsequently split into three distinct sets.
      Specified by:
      unzip3 in interface Seq<T>
      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

    • update

      public Queue<T> update(int index, T element)
      Description copied from interface: Seq
      Updates the given element at the specified index.
      Specified by:
      update in interface LinearSeq<T>
      Specified by:
      update in interface Seq<T>
      Parameters:
      index - an index
      element - an element
      Returns:
      a new Seq consisting of all previous elements, with a single one (at the given index), changed to the new value.

    • update

      public Queue<T> update(int index, Function<? super T, ? extends T> updater)
      Description copied from interface: Seq
      Updates the given element at the specified index using the specified function.
      Specified by:
      update in interface LinearSeq<T>
      Specified by:
      update in interface Seq<T>
      Parameters:
      index - an index
      updater - a function transforming the previous value
      Returns:
      a new Seq consisting of all previous elements, with a single one (at the given index), changed to the new value.

    • zip

      public <U> Queue<Tuple2<T,U>> zip(Iterable<? extends U> that)
      Description copied from interface: Traversable
      Returns a traversable formed from this traversable and another Iterable collection by combining corresponding elements in pairs. If one of the two iterables is longer than the other, its remaining elements are ignored.

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

      Specified by:
      zip in interface LinearSeq<T>
      Specified by:
      zip in interface Seq<T>
      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

      public <U,R> Queue<R> zipWith(Iterable<? extends U> that, BiFunction<? super T, ? super U, ? extends R> mapper)
      Description copied from interface: Traversable
      Returns a traversable formed from this traversable and another Iterable collection by mapping elements. If one of the two iterables is longer than the other, its remaining elements are ignored.

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

      Specified by:
      zipWith in interface LinearSeq<T>
      Specified by:
      zipWith in interface Seq<T>
      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

      public <U> Queue<Tuple2<T,U>> zipAll(Iterable<? extends U> that, T thisElem, U thatElem)
      Description copied from interface: Traversable
      Returns a traversable formed from this traversable and another Iterable by combining corresponding elements in pairs. If one of the two collections is shorter than the other, placeholder elements are used to extend the shorter collection to the length of the longer.

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

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

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

      Specified by:
      zipAll in interface LinearSeq<T>
      Specified by:
      zipAll in interface Seq<T>
      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

      public Queue<Tuple2<T,Integer>> zipWithIndex()
      Description copied from interface: Traversable
      Zips this traversable with its indices.
      Specified by:
      zipWithIndex in interface LinearSeq<T>
      Specified by:
      zipWithIndex in interface Seq<T>
      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

      public <U> Queue<U> zipWithIndex(BiFunction<? super T, ? super Integer, ? extends U> mapper)
      Description copied from interface: Traversable
      Zips this traversable with its indices by applying mapper provided.
      Specified by:
      zipWithIndex in interface LinearSeq<T>
      Specified by:
      zipWithIndex in interface Seq<T>
      Specified by:
      zipWithIndex in interface Traversable<T>
      Type Parameters:
      U - The type of the mapped elements.
      Parameters:
      mapper - a mapper.
      Returns:
      a new traversable containing elements of this traversable, zipped with indices, and mapped with mapper provided.

    • readResolve

      private Object readResolve()

    • stringPrefix

      public 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.

    • equals

      public boolean equals(Object o)
      Description copied from interface: Traversable
      In Vavr there are four basic classes of collections:
      • Seq (sequential elements)
      • Set (distinct elements)
      • Map (indexed elements)
      • Multimap (indexed collections)
      Two collection instances of these classes are equal if and only if both collections
      • belong to the same basic collection class (Seq, Set, Map or Multimap)
      • contain the same elements
      • have the same element order, if the collections are of type Seq
      Two Map/Multimap elements, resp. entries, (key1, value1) and (key2, value2) are equal, if the keys are equal and the values are equal.

      Notes:

      • No collection instance equals null, e.g. Queue(1) not equals null.
      • Nulls are allowed and handled as expected, e.g. List(null, 1) equals Stream(null, 1) and HashMap((null, 1)) equals LinkedHashMap((null, 1)).
      • The element order is taken into account for Seq only. E.g. List(null, 1) not equals Stream(1, null) and HashMap((null, 1), ("a", null)) equals LinkedHashMap(("a", null), (null, 1)). The reason is, that we do not know which implementations we compare when having two instances of type Map, Multimap or Set (see Liskov Substitution Principle).
      • Other collection classes are equal if their types are equal and their elements are equal (in iteration order).
      • Iterator equality is defined to be object reference equality.
      Specified by:
      equals in interface Traversable<T>
      Specified by:
      equals in interface Value<T>
      Overrides:
      equals in class Object
      Parameters:
      o - an object, may be null
      Returns:
      true, if this collection equals the given object according to the rules described above, false otherwise.

    • hashCode

      public int hashCode()
      Description copied from interface: Traversable
      Returns the hash code of this collection.
      We distinguish between two types of hashes, those for collections with predictable iteration order (like Seq) and those with arbitrary iteration order (like Set, Map and Multimap).
      In all cases the hash of an empty collection is defined to be 1.
      Collections with predictable iteration order are hashed as follows: 
      int hash = 1;
for (T t : this) { hash = hash * 31 + Objects.hashCode(t); }
      Collections with arbitrary iteration order are hashed in a way such that the hash of a fixed number of elements is independent of their iteration order. 
      int hash = 1;
for (T t : this) { hash += Objects.hashCode(t); }
      Please note that the particular hashing algorithms may change in a future version of Vavr.
      Generally, hash codes of collections aren't cached in Vavr (opposed to the size/length). Storing hash codes in order to reduce the time complexity would increase the memory footprint. Persistent collections are built upon tree structures, it allows us to implement efficient memory sharing. A drawback of tree structures is that they make it necessary to store collection attributes at each tree node (read: element).
      The computation of the hash code is linear in time, i.e. O(n). If the hash code of a collection is re-calculated often, e.g. when using a List as HashMap key, we might want to cache the hash code. This can be achieved by simply using a wrapper class, which is not included in Vavr but could be implemented like this: 
      public final class Hashed<K> {

    private final K key;
    private final Lazy<Integer> hashCode;

    public Hashed(K key) {
        this.key = key;
        this.hashCode = Lazy.of(() -> Objects.hashCode(key));
    }

    public K key() {
        return key;
    }

    &#64;Override
    public boolean equals(Object o) {
        if (o == key) {
            return true;
        } else if (key != null && o instanceof Hashed) {
            final Hashed that = (Hashed) o;
            return key.equals(that.key);
        } else {
            return false;
        }
    }

    &#64;Override
    public int hashCode() {
        return hashCode.get();
    }

    &#64;Override
    public String toString() {
        return "Hashed(" + (key == null ? "null" : key.toString()) + ")";
    }
}
      Specified by:
      hashCode in interface Traversable<T>
      Specified by:
      hashCode in interface Value<T>
      Overrides:
      hashCode in class Object
      Returns:
      The hash code of this collection