Scala Library
scala.collection.immutable

class Queue
[source: scala/collection/immutable/Queue.scala]
@serializable

@SerialVersionUID(-7622936493364270175L)

class Queue[+A](protected val in : List[A], protected val out : List[A])
extends Seq[A]
Queue objects implement data structures that allow to insert and retrieve elements in a first-in-first-out (FIFO) manner.
Author
Erik Stenman
Version
1.0, 08/07/2003
Since
1
Method Summary
def + [B >: A](iter : Iterable[B]) : Queue[B]
Returns a new queue with all all elements provided by an Iterable object added at the end of the queue. The elements are prepended in the order they are given out by the iterator.
def + [B >: A](elem : B) : Queue[B]
Creates a new queue with element added at the end of the old queue.
def apply (n : Int) : A
Returns the n-th element of this queue. The first element is at position 0.
def dequeue : (A, Queue[A])
Returns a tuple with the first element in the queue, and a new queue with this element removed.
def enqueue [B >: A](iter : Iterable[B]) : Queue[B]
Returns a new queue with all elements provided by an Iterable object added at the end of the queue. The elements are prepended in the order they are given out by the iterator.
def enqueue [B >: A](elem : B) : Queue[B]
Creates a new queue with element added at the end of the old queue.
def front : A
Returns the first element in the queue, or throws an error if there is no element contained in the queue.
override def isEmpty : Boolean
Checks if the queue is empty.
override def iterator : Iterator[A]
Returns the elements in the list as an iterator
def length : Int
Returns the length of the queue.
override def toString : java.lang.String
Returns a string representation of this queue.
Methods inherited from Seq
companion
Methods inherited from SeqLike
thisCollection, toCollection, lengthCompare, size, isDefinedAt, segmentLength, prefixLength, indexWhere, indexWhere, findIndexOf, indexOf, indexOf, lastIndexOf, lastIndexOf, lastIndexWhere, lastIndexWhere, reverse, reverseMap, reverseIterator, reversedElements, startsWith, startsWith, endsWith, indexOfSeq, indexOfSeq, lastIndexOfSeq, lastIndexOfSeq, contains, union, diff, intersect, removeDuplicates, patch, updated, +:, :+, padTo, sortWith, sortWith, sortBy, toSeq, indices, view, view, hashCode, equals, findLastIndexOf, equalsWith, containsSlice, projection
Methods inherited from PartialFunction
orElse, andThen
Methods inherited from Function1
compose
Methods inherited from IterableLike
elements, foreach, forall, exists, find, foldRight, reduceRight, toIterable, head, take, slice, takeWhile, takeRight, dropRight, copyToArray, zip, zipAll, zipWithIndex, sameElements, toStream, canEqual, first, firstOption
Methods inherited from GenericTraversableTemplate
newBuilder, genericBuilder, unzip, flatten, transpose
Methods inherited from TraversableLike
repr, nonEmpty, hasDefiniteSize, ++, ++, map, flatMap, filter, filterNot, partialMap, remove, partition, groupBy, count, foldLeft, /:, :\, reduceLeft, reduceLeftOption, reduceRightOption, sum, product, min, max, headOption, tail, last, lastOption, init, drop, dropWhile, span, splitAt, copyToBuffer, copyToArray, toArray, toList, toIndexedSeq, toSet, mkString, mkString, mkString, addString, addString, addString, stringPrefix, withFilter
Methods inherited from AnyRef
getClass, clone, notify, notifyAll, wait, wait, wait, finalize, ==, !=, eq, ne, synchronized
Methods inherited from Any
==, !=, isInstanceOf, asInstanceOf
Method Details
def apply(n : Int) : A
Returns the n-th element of this queue. The first element is at position 0.
Parameters
n - index of the element to return
Returns
the element at position n in this queue.
Throws
Predef.NoSuchElementException - if the queue is too short.
override def iterator : Iterator[A]
Returns the elements in the list as an iterator
override def isEmpty : Boolean
Checks if the queue is empty.
Returns
true, iff there is no element in the queue.
def length : Int
Returns the length of the queue.
@deprecated("Use the method <code>enqueue</code> from now on.")

def +[B >: A](elem : B) : Queue[B]
Creates a new queue with element added at the end of the old queue.
Parameters
elem - the element to insert
def enqueue[B >: A](elem : B) : Queue[B]
Creates a new queue with element added at the end of the old queue.
Parameters
elem - the element to insert
@deprecated("Use the method <code>enqueue</code> from now on.")

def +[B >: A](iter : Iterable[B]) : Queue[B]
Returns a new queue with all all elements provided by an Iterable object added at the end of the queue. The elements are prepended in the order they are given out by the iterator.
Parameters
iter - an iterable object
def enqueue[B >: A](iter : Iterable[B]) : Queue[B]
Returns a new queue with all elements provided by an Iterable object added at the end of the queue. The elements are prepended in the order they are given out by the iterator.
Parameters
iter - an iterable object
def dequeue : (A, Queue[A])
Returns a tuple with the first element in the queue, and a new queue with this element removed.
Throws
Predef.NoSuchElementException -
Returns
the first element of the queue.
def front : A
Returns the first element in the queue, or throws an error if there is no element contained in the queue.
Throws
Predef.NoSuchElementException -
Returns
the first element.
override def toString : java.lang.String
Returns a string representation of this queue.
Scala Library