scala.collection.mutable

class Queue

[source: scala/collection/mutable/Queue.scala]

@serializable

@cloneable

class Queue[A]
extends MutableList[A] with CloneableCollection
Queue objects implement data structures that allow to insert and retrieve elements in a first-in-first-out (FIFO) manner.
Author
Matthias Zenger
Version
1.1, 03/05/2004
Direct Known Subclasses:
QueueProxy, SynchronizedQueue

Values and Variables inherited from MutableList
first0, last0, len
Method Summary
def ++= (it : Iterator[A]) : Unit
Adds all elements provided by an iterator at the end of the queue. The elements are prepended in the order they are given out by the iterator.
def ++= (iter : Iterable[A]) : Unit
Adds all elements provided by an Iterable object at the end of the queue. The elements are prepended in the order they are given out by the iterator.
def += (elem : A) : Unit
Inserts a single element at the end of the queue.
def clear : Unit
Removes all elements from the queue. After this operation is completed, the queue will be empty.
override def clone : Queue[A]
This method clones the queue.
def dequeue : A
Returns the first element in the queue, and removes this element from the queue.
def dequeueAll (p : (A) => Boolean) : Seq[A]
Returns all elements in the queue which satisfy the given predicate, and removes those elements from the queue.
def dequeueFirst (p : (A) => Boolean) : Option[A]
Returns the first element in the queue which satisfies the given predicate, and removes this element from the queue.
def enqueue (elems : A*) : Unit
Adds all elements to the queue.
override def equals (obj : Any) : Boolean
Checks if two queues are structurally identical.
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 hashCode : Int
The hashCode method always yields an error, since it is not safe to use mutable queues as keys in hash tables.
override def isEmpty : Boolean
Checks if the queue is empty.
override def toString : String
Returns a textual representation of a queue as a string.
Methods inherited from MutableList
length, apply, get, prependElem, appendElem, reset, elements, last, toList, stringPrefix
Methods inherited from Seq
lengthCompare, size, concat, lastOption, headOption, ++, isDefinedAt, lastIndexOf, map, flatMap, filter, take, drop, slice, takeWhile, dropWhile, reverse, contains, subseq, toArray, projection, equalsWith, startsWith, endsWith, indexOf, containsSlice
Methods inherited from Iterable
foreach, forall, exists, find, findIndexOf, indexOf, foldLeft, foldRight, /:, :\, reduceLeft, reduceRight, copyToBuffer, sameElements, toStream, mkString, mkString, mkString, addString, addString, copyToArray, hasDefiniteSize
Methods inherited from PartialFunction
orElse, andThen
Methods inherited from Function1
compose
Methods inherited from AnyRef
getClass, notify, notifyAll, wait, wait, wait, finalize, ==, !=, eq, ne, synchronized
Methods inherited from Any
==, !=, isInstanceOf, asInstanceOf
Method Details
override def isEmpty : Boolean
Checks if the queue is empty.
Returns
true, iff there is no element in the queue.

def +=(elem : A) : Unit
Inserts a single element at the end of the queue.
Parameters
elem - the element to insert

def ++=(iter : Iterable[A]) : Unit
Adds all elements provided by an Iterable object 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 ++=(it : Iterator[A]) : Unit
Adds all elements provided by an iterator at the end of the queue. The elements are prepended in the order they are given out by the iterator.
Parameters
it - an iterator

def enqueue(elems : A*) : Unit
Adds all elements to the queue.
Parameters
elems - the elements to add.

def dequeue : A
Returns the first element in the queue, and removes this element from the queue.
Throws
Predef.NoSuchElementException -
Returns
the first element of the queue.

def dequeueFirst(p : (A) => Boolean) : Option[A]
Returns the first element in the queue which satisfies the given predicate, and removes this element from the queue.
Parameters
p - the predicate used for choosing the first element
Returns
the first element of the queue for which p yields true

def dequeueAll(p : (A) => Boolean) : Seq[A]
Returns all elements in the queue which satisfy the given predicate, and removes those elements from the queue.
Parameters
p - the predicate used for choosing elements
Returns
a sequence of all elements in the queue for which p yields true.

def front : A
Returns the first element in the queue, or throws an error if there is no element contained in the queue.
Returns
the first element.

def clear : Unit
Removes all elements from the queue. After this operation is completed, the queue will be empty.

override def equals(obj : Any) : Boolean
Checks if two queues are structurally identical.
Returns
true, iff both queues contain the same sequence of elements.

override def hashCode : Int
The hashCode method always yields an error, since it is not safe to use mutable queues as keys in hash tables.
Throws
Predef.UnsupportedOperationException -
Returns
never.

override def toString : String
Returns a textual representation of a queue as a string.
Returns
the string representation of this queue.

override def clone : Queue[A]
This method clones the queue.
Returns
a queue with the same elements.
Overrides
CloneableCollection.clone