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scala.collection.immutable.Queue

class Queue

class Queue[+ A](elem : 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


Companion: Queue

Source: Queue.scala(28)

 Constructors

def this(elem : A*)

 Fields

elements override def elements
Returns the elements in the list as an iterator
Iterator[A]
first def first
Returns the first element of this list [details]
return
- the first element of the list.
throws
Predef.UnsupportedOperationException - if the list is empty.
 A Seq
firstOption def firstOption
Returns as an option the first element of this list or None if list is empty [details]
return
- the first element as an option.
 Option[A] Seq
front def front
Returns the first element in the queue, or throws an error if there is no element contained in the queue [details]
return
- the first element.
 A
hasDefiniteSize def hasDefiniteSize
returns true iff this collection has a bound size [details]
Many APIs in this trait will not work on collections of unbound sizes.
Boolean Iterable
headOption def headOption Option[A] Seq
in protected val in List[A]
isEmpty override def isEmpty
Checks if the queue is empty [details]
return
- true, iff there is no element in the queue.
 Boolean
last def last
Returns the last element of this list [details]
return
- the last element of the list.
throws
Predef.UnsupportedOperationException - if the list is empty.
 A Seq
lastOption def lastOption
Returns as an option the last element of this list or None if list is empty [details]
return
- the last element as an option.
 Option[A] Seq
length def length
Returns the length of the queue
Int
mkString def mkString
Converts a collection into a flat String by each element's toString method [details]
note
- Will not terminate for infinite-sized collections.
 String Iterable
out protected val out List[A]
projection override def projection
returns a projection that can be used to call non-strict filter, map, and flatMap methods that build projections of the collection
Projection[A] Seq
reverse def reverse
A sequence consisting of all elements of this sequence in reverse order
Seq[A] Seq
size def size
should always be length
Int Seq
stringPrefix protected def stringPrefix
Defines the prefix of this object's toString representation
String Collection
toList def toList
Returns a list containing all of the elements in this iterable object [details]
note
- Will not terminate for infinite-sized collections.
 List[A] Iterable
toSeq override def toSeq
Overridden for efficiency [details]
return
- the sequence itself
 Seq[A] Seq
toStream def toStream
Returns a stream containing all of the elements in this iterable object [details]
note
- consider using projection for lazy behavior.
 Stream[A] Iterable

 Methods

!= final def !=(arg0 : Object) Boolean AnyRef
!= final def !=(arg0 : Any) Boolean Any
+ def +[B >: A](iter : Iterable[B])
Returns a new queue with all all elements provided by an Iterable object added at the end of the queue [details]
The elements are prepended in the order they are given out by the iterator.
param
iter - an iterable object
 Queue[B]
+ def +[B >: A](elem : B)
Creates a new queue with element added at the end of the old queue [details]
param
elem - the element to insert
 Queue[B]
++ override def ++[B >: A](that : Iterable[B])
Appends two iterable objects
Seq[B] Seq
/: def /:[B](z : B)(op : (B, A) => B)
Similar to foldLeft but can be used as an operator with the order of list and zero arguments reversed [details]
That is, z /: xs is the same as xs foldLeft z
note
- Will not terminate for infinite-sized collections.
 B Iterable
:\ def :\[B](z : B)(op : (A, B) => B)
An alias for foldRight [details]
That is, xs :\ z is the same as xs foldRight z
note
- Will not terminate for infinite-sized collections.
 B Iterable
== final def ==(arg0 : Any) Boolean Any
== final def ==(arg0 : Object) Boolean AnyRef
addString def addString(buf : StringBuilder, sep : String) StringBuilder Iterable
addString def addString(buf : StringBuilder, start : String, sep : String, end : String)
Write all elements of this string into given string builder [details]
note
- Will not terminate for infinite-sized collections.
param
buf - ...
return
- ...
 StringBuilder Iterable
andThen override def andThen[C](k : (B) => C)
(f andThen g)(x) == g(f(x))
PartialFunction[A, C] PartialFunction
apply def apply(n : Int)
Returns the n-th element of this queue [details]
The first element is at position 0.
param
n - index of the element to return
return
- the element at position n in this queue.
throws
Predef.NoSuchElementException - if the queue is too short.
 A
asInstanceOf final def asInstanceOf[T0] T0 Any
clone protected def clone Object AnyRef
compose def compose[A](g : (A) => T1)
(f compose g)(x) == f(g(x))
(A) => R Function1
concat override def concat[B >: A](that : Iterable[B])
Appends two iterable objects [details]
deprecated
- use ++ instead
return
- the new iterable object
 Seq[B] Seq
contains def contains(elem : Any)
Tests if the given value elem is a member of this sequence [details]
param
elem - element whose membership has to be tested.
return
- true iff there is an element of this sequence which is equal (w.r.t. ==) to elem.
Boolean Seq
containsSlice def containsSlice[B](that : Seq[B])
Is that a slice in this?
Boolean Seq
copyToArray def copyToArray[B >: A](xs : Array[B], start : Int)
Fills the given array xs with the elements of this sequence starting at position start [details]
note
- Will not terminate for infinite-sized collections.
param
xs - the array to fill.
start - starting index.
pre
- the array must be large enough to hold all elements.
 Unit Iterable
copyToBuffer def copyToBuffer[B >: A](dest : Buffer[B])
Copy all elements to a given buffer [details]
note
- Will not terminate if not finite.
- Will not terminate for infinite-sized collections.
param
dest - The buffer to which elements are copied
 Unit Iterable
dequeue def dequeue
Returns a tuple with the first element in the queue, and a new queue with this element removed [details]
return
- the first element of the queue.
 (A, Queue[A])
drop override def drop(n : Int)
Returns this sequence without its n first elements If this sequence has less than n elements, the empty sequence is returned [details]
(non-strict)
param
n - the number of elements to drop
return
- the new sequence
 Seq[A] Seq
dropWhile override def dropWhile(p : (A) => Boolean)
Returns the longest suffix of this sequence whose first element does not satisfy the predicate p [details]
param
p - the test predicate.
return
- the longest suffix of the sequence whose first element does not satisfy the predicate p.
Seq[A] Seq
endsWith def endsWith[B](that : Seq[B])
[details]
return
- true if this sequence end with that sequence
see
- String.endsWith
 Boolean Seq
enqueue def enqueue[B >: A](elems : B*)
Returns a new queue with all elements added [details]
param
elems - the elements to add.
 Queue[B]
eq final def eq(arg0 : Object) Boolean AnyRef
equals override def equals(o : Any)
Compares two queues for equality by comparing each element in the queues [details]
return
- true, iff the two queues are structurally equal.
 Boolean
equalsWith def equalsWith[B](that : Seq[B])(f : (A, B) => Boolean) Boolean Seq
exists def exists(p : (A) => Boolean)
Apply a predicate p to all elements of this iterable object and return true, iff there is at least one element for which p yields true [details]
note
- May not terminate for infinite-sized collections.
param
p - the predicate
return
- true, iff the predicate yields true for at least one element.
 Boolean Iterable
filter override def filter(p : (A) => Boolean)
Returns all the elements of this sequence that satisfy the predicate p [details]
The order of the elements is preserved.
param
p - the predicate used to filter the list.
return
- the elements of this list satisfying p.
 Seq[A] Seq
finalize protected def finalize Unit AnyRef
find def find(p : (A) => Boolean)
Find and return the first element of the iterable object satisfying a predicate, if any [details]
note
- may not terminate for infinite-sized collections.
param
p - the predicate
return
- the first element in the iterable object satisfying p, or None if none exists.
Option[A] Iterable
findIndexOf def findIndexOf(p : (A) => Boolean)
Returns index of the first element satisying a predicate, or -1 [details]
note
- may not terminate for infinite-sized collections.
param
p - the predicate
return
- the index of the first element satisfying p, or -1 if such an element does not exist
Int Iterable
flatMap override def flatMap[B](f : (A) => Iterable[B])
Applies the given function f to each element of this sequence, then concatenates the results [details]
param
f - the function to apply on each element.
return
- f(a0) ::: ... ::: f(an) if this sequence is a0, ..., an.
Seq[B] Seq
foldLeft def foldLeft[B](z : B)(op : (B, A) => B)
Combines the elements of this iterable object together using the binary function f, from left to right, and starting with the value z [details]
note
- Will not terminate for infinite-sized collections.
return
- f(... (f(f(z, a0), a1) ...), an) if the list is [a0, a1, ..., an].
B Iterable
foldRight def foldRight[B](z : B)(op : (A, B) => B)
Combines the elements of this list together using the binary function f, from right to left, and starting with the value z [details]
note
- Will not terminate for infinite-sized collections.
return
- f(a0, f(a1, f(..., f(an, z)...))) if the list is [a0, a1, ..., an].
B Iterable
forall def forall(p : (A) => Boolean)
Apply a predicate p to all elements of this iterable object and return true, iff the predicate yields true for all elements [details]
note
- May not terminate for infinite-sized collections.
param
p - the predicate
return
- true, iff the predicate yields true for all elements.
 Boolean Iterable
foreach def foreach(f : (A) => Unit)
Apply a function f to all elements of this iterable object [details]
note
- Will not terminate for infinite-sized collections.
param
f - a function that is applied to every element.
 Unit Iterable
getClass final def getClass Class[Any] AnyRef
hashCode override def hashCode Int
indexOf def indexOf[B >: A](that : Seq[B])
[details]
return
- -1 if that not contained in this, otherwise the index where that is contained
see
- String.indexOf
 Int Seq
indexOf def indexOf[B >: A](elem : B)
Returns the index of the first occurence of the specified object in this iterable object [details]
note
- may not terminate for infinite-sized collections.
param
elem - element to search for.
return
- the index in this sequence of the first occurence of the specified element, or -1 if the sequence does not contain this element.
Int Iterable
isDefinedAt def isDefinedAt(x : Int)
Is this partial function defined for the index x? [details]
param
x - ..
return
- true, iff x is a legal sequence index.
 Boolean Seq
isInstanceOf final def isInstanceOf[T0] Boolean Any
lastIndexOf def lastIndexOf[B >: A](elem : B)
Returns the index of the last occurence of the specified element in this sequence, or -1 if the sequence does not contain this element [details]
param
elem - element to search for.
return
- the index in this sequence of the last occurence of the specified element, or -1 if the sequence does not contain this element.
Int Seq
lengthCompare def lengthCompare(l : Int)
Returns length - l [details]
This method is used by matching streams against right-ignoring (...,_) patterns. Lazy sequences should override this method if length forces evaluation of the stream.
Int Seq
map override def map[B](f : (A) => B)
Returns the sequence resulting from applying the given function f to each element of this sequence [details]
param
f - function to apply to each element.
return
- f(a0), ..., f(an) if this sequence is a0, ..., an.
Seq[B] Seq
mkQueue protected def mkQueue[A](i : List[A], o : List[A]) Queue[A]
mkString def mkString(sep : String)
Returns a string representation of this iterable object [details]
The string representations of elements (w.r.t. the method toString()) are separated by the string sep.
note
- Will not terminate for infinite-sized collections.
param
sep - separator string.
return
- a string representation of this iterable object.
 String Iterable
mkString def mkString(start : String, sep : String, end : String)
Returns a string representation of this iterable object [details]
The resulting string begins with the string start and is finished by the string end. Inside, the string representations of elements (w.r.t. the method toString()) are separated by the string sep.
ex
- List(1, 2, 3).mkString("(", "; ", ")") = "(1; 2; 3)"
note
- Will not terminate for infinite-sized collections.
param
sep - separator string.
start - starting string.
end - ending string.
return
- a string representation of this iterable object.
 String Iterable
ne final def ne(arg0 : Object) Boolean AnyRef
notify final def notify Unit AnyRef
notifyAll final def notifyAll Unit AnyRef
orElse def orElse[A1 <: A, B1 >: B](that : PartialFunction[A1, B1]) PartialFunction[A1, B1] PartialFunction
partition def partition(p : (A) => Boolean)
Partitions this iterable in two iterables according to a predicate [details]
param
p - the predicate on which to partition
return
- a pair of iterables: the iterable that satisfy the predicate p and the iterable that do not. The relative order of the elements in the resulting iterables is the same as in the original iterable.
(Iterable[A], Iterable[A]) Iterable
reduceLeft def reduceLeft[B >: A](op : (B, A) => B)
Combines the elements of this iterable object together using the binary operator op, from left to right [details]
note
- Will not terminate for infinite-sized collections.
param
op - The operator to apply
return
- op(... op(a0,a1), ..., an) if the iterable object has elements a0, a1, ..., an.
throws
Predef.UnsupportedOperationException - if the iterable object is empty.
 B Iterable
reduceRight def reduceRight[B >: A](op : (A, B) => B)
Combines the elements of this iterable object together using the binary operator op, from right to left [details]
note
- Will not terminate for infinite-sized collections.
param
op - The operator to apply
return
- a0 op (... op (an-1 op an)...) if the iterable object has elements a0, a1, ..., an.
throws
Predef.UnsupportedOperationException - if the iterator is empty.
 B Iterable
sameElements def sameElements[B >: A](that : Iterable[B])
Checks if the other iterable object contains the same elements [details]
note
- will not terminate for infinite-sized collections.
param
that - the other iterable object
return
- true, iff both iterable objects contain the same elements.
 Boolean Iterable
slice def slice(from : Int, until : Int)
A sub-sequence starting at index from and ending (non-inclusive) at index until (non-strict) [details]
param
until - The index of the element following the slice
from - The index of the first element of the slice
throws
IndexOutOfBoundsException - if from < 0 or length < from + len
Seq[A] Seq
slice def slice(from : Int)
A sub-sequence starting at index from and extending up to the length of the current sequence (non-strict) [details]
param
from - The index of the first element of the slice
throws
IndexOutOfBoundsException - if from < 0
 Seq[A] Seq
startsWith def startsWith[B](that : Seq[B])
[details]
return
- true if this sequence start with that sequences
see
- String.startsWith
 Boolean Seq
subseq def subseq(from : Int, end : Int)
Returns a subsequence starting from index from consisting of len elements [details]
deprecated
- use slice instead
 Seq[A] Seq
synchronized final def synchronized[T0](arg0 : T0) T0 AnyRef
take override def take(n : Int)
Returns a sequence consisting only over the first n elements of this sequence, or else the whole sequence, if it has less than n elements [details]
(non-strict)
param
n - the number of elements to take
return
- a possibly projected sequence
 Seq[A] Seq
takeWhile override def takeWhile(p : (A) => Boolean)
Returns the longest prefix of this sequence whose elements satisfy the predicate p [details]
param
p - the test predicate.
return
- the longest prefix of this sequence whose elements satisfy the predicate p.
Seq[A] Seq
toArray override def toArray[B >: A]
Converts this sequence to a fresh Array with length elements
Array[B] Seq
toString override def toString
Returns a string representation of this queue
String
wait final def wait(arg0 : Long, arg1 : Int) Unit AnyRef
wait final def wait(arg0 : Long) Unit AnyRef
wait final def wait Unit AnyRef
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