# Queue

Queue objects implement data structures that allow to insert and retrieve elements in a first-in-first-out (FIFO) manner.

Queue is implemented as a pair of Lists, one containing the in elements and the other the out elements. Elements are added to the in list and removed from the out list. When the out list runs dry, the queue is pivoted by replacing the out list by in.reverse, and in by Nil.

Adding items to the queue always has cost O(1). Removing items has cost O(1), except in the case where a pivot is required, in which case, a cost of O(n) is incurred, where n is the number of elements in the queue. When this happens, n remove operations with O(1) cost are guaranteed. Removing an item is on average O(1).

Companion:
object
Source:
Queue.scala
trait LinearSeq[A]
trait LinearSeqOps[A, Queue, Queue[A]]
trait LinearSeq[A]
trait LinearSeqOps[A, Queue, Queue[A]]
class AbstractSeq[A]
trait Seq[A]
trait SeqOps[A, Queue, Queue[A]]
trait Iterable[A]
class AbstractSeq[A]
trait Seq[A]
trait Equals
trait SeqOps[A, Queue, Queue[A]]
trait Int => A
trait Iterable[A]
trait IterableOps[A, Queue, Queue[A]]
trait IterableOnce[A]
class Object
trait Matchable
class Any

## Value members

### Concrete methods

override def appended[B >: A](elem: B): Queue[B]
Definition Classes
Source:
Queue.scala
override def appendedAll[B >: A](that: IterableOnce[B]): Queue[B]
Definition Classes
Source:
Queue.scala
override def apply(n: Int): A

Returns the n-th element of this queue.

Returns the n-th element of this queue. The first element is at position 0.

Value parameters:
n

index of the element to return

Returns:

the element at position n in this queue.

Throws:
NoSuchElementException

if the queue is too short.

Definition Classes
Source:
Queue.scala
def dequeue: (A, Queue[A])

Returns a tuple with the first element in the queue, and a new queue with this element removed.

Returns a tuple with the first element in the queue, and a new queue with this element removed.

Returns:

the first element of the queue.

Source:
Queue.scala
def dequeueOption: Option[(A, Queue[A])]

Optionally retrieves the first element and a queue of the remaining elements.

Optionally retrieves the first element and a queue of the remaining elements.

Returns:

A tuple of the first element of the queue, and a new queue with this element removed. If the queue is empty, None is returned.

Source:
Queue.scala
def enqueue[B >: A](elem: B): Queue[B]

Creates a new queue with element added at the end of the old queue.

Creates a new queue with element added at the end of the old queue.

Value parameters:
elem

the element to insert

Source:
Queue.scala
def enqueueAll[B >: A](iter: Iterable[B]): Queue[B]

Creates a new queue with all elements provided by an Iterable object added at the end of the old queue.

Creates a new queue with all elements provided by an Iterable object added at the end of the old queue.

The elements are appended in the order they are given out by the iterator.

Value parameters:
iter

an iterable object

Source:
Queue.scala
override def exists(p: A => Boolean): Boolean
Definition Classes
Source:
Queue.scala
override def forall(p: A => Boolean): Boolean
Definition Classes
Source:
Queue.scala
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 in the queue, or throws an error if there is no element contained in the queue.

Returns:

the first element.

Source:
Queue.scala
Definition Classes
Source:
Queue.scala
override def isEmpty

Checks if the queue is empty.

Checks if the queue is empty.

Returns:

true, iff there is no element in the queue.

Definition Classes
Source:
Queue.scala
override def iterableFactory
Definition Classes
Source:
Queue.scala
override def iterator: Iterator[A]

Returns the elements in the list as an iterator

Returns the elements in the list as an iterator

Definition Classes
Source:
Queue.scala
override def last: A
Definition Classes
Source:
Queue.scala
override def length: Int

Returns the length of the queue.

Returns the length of the queue.

Definition Classes
Source:
Queue.scala
override def prepended[B >: A](elem: B): Queue[B]
Definition Classes
Source:
Queue.scala
override def tail: Queue[A]
Definition Classes
Source:
Queue.scala
override def toString(): String

Returns a string representation of this queue.

Returns a string representation of this queue.

Definition Classes
Source:
Queue.scala

### Deprecated methods

@deprecated("Use `enqueueAll` instead of `enqueue` to enqueue a collection of elements", "2.13.0") @inline
final def enqueue[B >: A](iter: Iterable[B]): Queue[B]

Creates a new queue with all elements provided by an Iterable object added at the end of the old queue.

Creates a new queue with all elements provided by an Iterable object added at the end of the old queue.

The elements are appended in the order they are given out by the iterator.

Value parameters:
iter

an iterable object

Deprecated
Source:
Queue.scala

### Inherited methods

final def ++[B >: A](suffix: IterableOnce[B]): Queue[B]

Alias for concat

Alias for concat

Inherited from:
IterableOps
Source:
Iterable.scala
final override def ++:[B >: A](prefix: IterableOnce[B]): Queue[B]

Alias for prependedAll

Alias for prependedAll

Definition Classes
Inherited from:
SeqOps
Source:
Seq.scala
final def +:[B >: A](elem: B): Queue[B]

Alias for prepended.

Alias for prepended.

Note that :-ending operators are right associative (see example). A mnemonic for +: vs. :+ is: the COLon goes on the COLlection side.

Inherited from:
SeqOps
Source:
Seq.scala
final def :+[B >: A](elem: B): Queue[B]

Alias for appended

Alias for appended

Note that :-ending operators are right associative (see example). A mnemonic for +: vs. :+ is: the COLon goes on the COLlection side.

Inherited from:
SeqOps
Source:
Seq.scala
final def :++[B >: A](suffix: IterableOnce[B]): Queue[B]

Alias for appendedAll

Alias for appendedAll

Inherited from:
SeqOps
Source:
Seq.scala

Appends all elements of this collection to a string builder.

Appends all elements of this collection to a string builder. The written text consists of the string representations (w.r.t. the method toString) of all elements of this collection without any separator string.

Example:

scala> val a = List(1,2,3,4)
a: List[Int] = List(1, 2, 3, 4)

scala> val b = new StringBuilder()
b: StringBuilder =

h: StringBuilder = 1234
Value parameters:
b

the string builder to which elements are appended.

Returns:

the string builder b to which elements were appended.

Inherited from:
IterableOnceOps
Source:
IterableOnce.scala

Appends all elements of this collection to a string builder using a separator string.

Appends all elements of this collection to a string builder using a separator string. The written text consists of the string representations (w.r.t. the method toString) of all elements of this collection, separated by the string sep.

Example:

scala> val a = List(1,2,3,4)
a: List[Int] = List(1, 2, 3, 4)

scala> val b = new StringBuilder()
b: StringBuilder =

res0: StringBuilder = 1, 2, 3, 4
Value parameters:
b

the string builder to which elements are appended.

sep

the separator string.

Returns:

the string builder b to which elements were appended.

Inherited from:
IterableOnceOps
Source:
IterableOnce.scala

Appends all elements of this collection to a string builder using start, end, and separator strings.

Appends all elements of this collection to a string builder using start, end, and separator strings. The written text begins with the string start and ends with the string end. Inside, the string representations (w.r.t. the method toString) of all elements of this collection are separated by the string sep.

Example:

scala> val a = List(1,2,3,4)
a: List[Int] = List(1, 2, 3, 4)

scala> val b = new StringBuilder()
b: StringBuilder =

scala> a.addString(b , "List(" , ", " , ")")
res5: StringBuilder = List(1, 2, 3, 4)
Value parameters:
b

the string builder to which elements are appended.

end

the ending string.

sep

the separator string.

start

the starting string.

Returns:

the string builder b to which elements were appended.

Inherited from:
IterableOnceOps
Source:
IterableOnce.scala

Composes this partial function with another partial function that gets applied to results of this partial function.

Composes this partial function with another partial function that gets applied to results of this partial function.

Note that calling isDefinedAt on the resulting partial function may apply the first partial function and execute its side effect. For efficiency, it is recommended to call applyOrElse instead of isDefinedAt or apply.

Type parameters:
C

the result type of the transformation function.

Value parameters:
k

the transformation function

Returns:

a partial function with the domain of this partial function narrowed by other partial function, which maps arguments x to k(this(x)).

Inherited from:
PartialFunction
Source:
PartialFunction.scala
override def andThen[C](k: A => C): PartialFunction[Int, C]

Composes this partial function with a transformation function that gets applied to results of this partial function.

Composes this partial function with a transformation function that gets applied to results of this partial function.

If the runtime type of the function is a PartialFunction then the other andThen method is used (note its cautions).

Type parameters:
C

the result type of the transformation function.

Value parameters:
k

the transformation function

Returns:

a partial function with the domain of this partial function, possibly narrowed by the specified function, which maps arguments x to k(this(x)).

Definition Classes
Inherited from:
PartialFunction
Source:
PartialFunction.scala
def applyOrElse[A1 <: Int, B1 >: A](x: A1, default: A1 => B1): B1

Applies this partial function to the given argument when it is contained in the function domain.

Applies this partial function to the given argument when it is contained in the function domain. Applies fallback function where this partial function is not defined.

Note that expression pf.applyOrElse(x, default) is equivalent to

if(pf isDefinedAt x) pf(x) else default(x)

except that applyOrElse method can be implemented more efficiently. For all partial function literals the compiler generates an applyOrElse implementation which avoids double evaluation of pattern matchers and guards. This makes applyOrElse the basis for the efficient implementation for many operations and scenarios, such as:

- combining partial functions into orElse/andThen chains does not lead to excessive apply/isDefinedAt evaluation - lift and unlift do not evaluate source functions twice on each invocation - runWith allows efficient imperative-style combining of partial functions with conditionally applied actions

For non-literal partial function classes with nontrivial isDefinedAt method it is recommended to override applyOrElse with custom implementation that avoids double isDefinedAt evaluation. This may result in better performance and more predictable behavior w.r.t. side effects.

Value parameters:
default

the fallback function

x

the function argument

Returns:

the result of this function or fallback function application.

Inherited from:
PartialFunction
Source:
PartialFunction.scala
def canEqual(that: Any): Boolean
Inherited from:
Seq
Source:
Seq.scala
override def collect[B](pf: PartialFunction[A, B]): Queue[B]
Definition Classes
Inherited from:
StrictOptimizedIterableOps
Source:
StrictOptimizedIterableOps.scala
def collectFirst[B](pf: PartialFunction[A, B]): Option[B]

Finds the first element of the collection for which the given partial function is defined, and applies the partial function to it.

Finds the first element of the collection for which the given partial function is defined, and applies the partial function to it.

Note: may not terminate for infinite-sized collections.

Note: might return different results for different runs, unless the underlying collection type is ordered.

Value parameters:
pf

the partial function

Returns:

an option value containing pf applied to the first value for which it is defined, or None if none exists.

Example:

Seq("a", 1, 5L).collectFirst({ case x: Int => x*10 }) = Some(10)

Inherited from:
IterableOnceOps
Source:
IterableOnce.scala

Iterates over combinations.

Iterates over combinations. A _combination_ of length n is a subsequence of the original sequence, with the elements taken in order. Thus, "xy" and "yy" are both length-2 combinations of "xyy", but "yx" is not. If there is more than one way to generate the same subsequence, only one will be returned.

For example, "xyyy" has three different ways to generate "xy" depending on whether the first, second, or third "y" is selected. However, since all are identical, only one will be chosen. Which of the three will be taken is an implementation detail that is not defined.

Note: Even when applied to a view or a lazy collection it will always force the elements.

Returns:

An Iterator which traverses the possible n-element combinations of this sequence.

Example:

"abbbc".combinations(2) = Iterator(ab, ac, bb, bc)

Inherited from:
SeqOps
Source:
Seq.scala

Composes another partial function k with this partial function so that this partial function gets applied to results of k.

Composes another partial function k with this partial function so that this partial function gets applied to results of k.

Note that calling isDefinedAt on the resulting partial function may apply the first partial function and execute its side effect. For efficiency, it is recommended to call applyOrElse instead of isDefinedAt or apply.

Type parameters:
R

the parameter type of the transformation function.

Value parameters:
k

the transformation function

Returns:

a partial function with the domain of other partial function narrowed by this partial function, which maps arguments x to this(k(x)).

Inherited from:
PartialFunction
Source:
PartialFunction.scala
def compose[A](g: A => Int): A => A

Composes two instances of Function1 in a new Function1, with this function applied last.

Composes two instances of Function1 in a new Function1, with this function applied last.

Type parameters:
A

the type to which function g can be applied

Value parameters:
g

a function A => T1

Returns:

a new function f such that f(x) == apply(g(x))

Inherited from:
Function1
Source:
Function1.scala
final override def concat[B >: A](suffix: IterableOnce[B]): Queue[B]
Definition Classes
Inherited from:
SeqOps
Source:
Seq.scala
override def contains[A1 >: A](elem: A1): Boolean
Definition Classes
Inherited from:
LinearSeqOps
Source:
LinearSeq.scala
def containsSlice[B >: A](that: Seq[B]): Boolean

Tests whether this sequence contains a given sequence as a slice.

Tests whether this sequence contains a given sequence as a slice.

Note: may not terminate for infinite-sized collections.

Value parameters:
that

the sequence to test

Returns:

true if this sequence contains a slice with the same elements as that, otherwise false.

Inherited from:
SeqOps
Source:
Seq.scala
def copyToArray[B >: A](xs: Array[B], start: Int, len: Int): Int

Copy elements to an array, returning the number of elements written.

Copy elements to an array, returning the number of elements written.

Fills the given array xs starting at index start with at most len elements of this collection.

Copying will stop once either all the elements of this collection have been copied, or the end of the array is reached, or len elements have been copied.

Type parameters:
B

the type of the elements of the array.

Value parameters:
len

the maximal number of elements to copy.

start

the starting index of xs.

xs

the array to fill.

Returns:

the number of elements written to the array

Note:

Reuse: After calling this method, one should discard the iterator it was called on. Using it is undefined and subject to change.

Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
@deprecatedOverriding("This should always forward to the 3-arg version of this method", since = "2.13.4")
def copyToArray[B >: A](xs: Array[B], start: Int): Int

Copy elements to an array, returning the number of elements written.

Copy elements to an array, returning the number of elements written.

Fills the given array xs starting at index start with values of this collection.

Copying will stop once either all the elements of this collection have been copied, or the end of the array is reached.

Type parameters:
B

the type of the elements of the array.

Value parameters:
start

the starting index of xs.

xs

the array to fill.

Returns:

the number of elements written to the array

Note:

Reuse: After calling this method, one should discard the iterator it was called on. Using it is undefined and subject to change.

Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
@deprecatedOverriding("This should always forward to the 3-arg version of this method", since = "2.13.4")
def copyToArray[B >: A](xs: Array[B]): Int

Copy elements to an array, returning the number of elements written.

Copy elements to an array, returning the number of elements written.

Fills the given array xs starting at index start with values of this collection.

Copying will stop once either all the elements of this collection have been copied, or the end of the array is reached.

Type parameters:
B

the type of the elements of the array.

Value parameters:
xs

the array to fill.

Returns:

the number of elements written to the array

Note:

Reuse: After calling this method, one should discard the iterator it was called on. Using it is undefined and subject to change.

Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
def corresponds[B](that: IterableOnce[B])(p: (A, B) => Boolean): Boolean

Tests whether every element of this collection's iterator relates to the corresponding element of another collection by satisfying a test predicate.

Tests whether every element of this collection's iterator relates to the corresponding element of another collection by satisfying a test predicate.

Note: will not terminate for infinite-sized collections.

Type parameters:
B

the type of the elements of that

Value parameters:
p

the test predicate, which relates elements from both collections

that

the other collection

Returns:

true if both collections have the same length and p(x, y) is true for all corresponding elements x of this iterator and y of that, otherwise false

Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
def corresponds[B](that: Seq[B])(p: (A, B) => Boolean): Boolean

Tests whether every element of this sequence relates to the corresponding element of another sequence by satisfying a test predicate.

Tests whether every element of this sequence relates to the corresponding element of another sequence by satisfying a test predicate.

Type parameters:
B

the type of the elements of that

Value parameters:
p

the test predicate, which relates elements from both sequences

that

the other sequence

Returns:

true if both sequences have the same length and p(x, y) is true for all corresponding elements x of this sequence and y of that, otherwise false.

Inherited from:
SeqOps
Source:
Seq.scala
def count(p: A => Boolean): Int

Counts the number of elements in the collection which satisfy a predicate.

Counts the number of elements in the collection which satisfy a predicate.

Note: will not terminate for infinite-sized collections.

Value parameters:
p

the predicate used to test elements.

Returns:

the number of elements satisfying the predicate p.

Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
override def diff[B >: A](that: Seq[B]): Queue[A]
Definition Classes
Inherited from:
StrictOptimizedSeqOps
Source:
StrictOptimizedSeqOps.scala
def distinct: Queue[A]

Selects all the elements of this sequence ignoring the duplicates.

Selects all the elements of this sequence ignoring the duplicates.

Returns:

a new sequence consisting of all the elements of this sequence without duplicates.

Inherited from:
SeqOps
Source:
Seq.scala
override def distinctBy[B](f: A => B): Queue[A]
Definition Classes
Inherited from:
StrictOptimizedSeqOps
Source:
StrictOptimizedSeqOps.scala
override def drop(n: Int): Queue[A]
Definition Classes
Inherited from:
StrictOptimizedLinearSeqOps
Source:
LinearSeq.scala
override def dropRight(n: Int): Queue[A]

The rest of the collection without its n last elements.

The rest of the collection without its n last elements. For linear, immutable collections this should avoid making a copy.

Note: Even when applied to a view or a lazy collection it will always force the elements.

Definition Classes
Inherited from:
StrictOptimizedIterableOps
Source:
StrictOptimizedIterableOps.scala
override def dropWhile(p: A => Boolean): Queue[A]
Definition Classes
Inherited from:
StrictOptimizedLinearSeqOps
Source:
LinearSeq.scala

Returns an extractor object with a unapplySeq method, which extracts each element of a sequence data.

Returns an extractor object with a unapplySeq method, which extracts each element of a sequence data.

Example:

val firstChar: String => Option[Char] = _.headOption
Seq("foo", "bar", "baz") match {
case firstChar.unlift.elementWise(c0, c1, c2) =>
println(s"\$c0, \$c1, \$c2") // Output: f, b, b
}
Inherited from:
PartialFunction
Source:
PartialFunction.scala
override def empty: Queue[A]
Definition Classes
Inherited from:
IterableFactoryDefaults
Source:
Iterable.scala
def endsWith[B >: A](that: Iterable[B]): Boolean

Tests whether this sequence ends with the given sequence.

Tests whether this sequence ends with the given sequence.

Note: will not terminate for infinite-sized collections.

Value parameters:
that

the sequence to test

Returns:

true if this sequence has that as a suffix, false otherwise.

Inherited from:
SeqOps
Source:
Seq.scala
override def equals(o: Any): Boolean
Definition Classes
Seq -> Equals -> Any
Inherited from:
Seq
Source:
Seq.scala
override def filter(pred: A => Boolean): Queue[A]
Definition Classes
Inherited from:
StrictOptimizedIterableOps
Source:
StrictOptimizedIterableOps.scala
override def filterNot(pred: A => Boolean): Queue[A]
Definition Classes
Inherited from:
StrictOptimizedIterableOps
Source:
StrictOptimizedIterableOps.scala
override def find(p: A => Boolean): Option[A]
Definition Classes
Inherited from:
LinearSeqOps
Source:
LinearSeq.scala
override def findLast(p: A => Boolean): Option[A]
Definition Classes
Inherited from:
LinearSeqOps
Source:
LinearSeq.scala
override def flatMap[B](f: A => IterableOnce[B]): Queue[B]
Definition Classes
Inherited from:
StrictOptimizedIterableOps
Source:
StrictOptimizedIterableOps.scala
override def flatten[B](implicit toIterableOnce: A => IterableOnce[B]): Queue[B]
Definition Classes
Inherited from:
StrictOptimizedIterableOps
Source:
StrictOptimizedIterableOps.scala
def fold[A1 >: A](z: A1)(op: (A1, A1) => A1): A1

Folds the elements of this collection using the specified associative binary operator.

Folds the elements of this collection using the specified associative binary operator. The default implementation in IterableOnce is equivalent to foldLeft but may be overridden for more efficient traversal orders.

The order in which operations are performed on elements is unspecified and may be nondeterministic.

Note: will not terminate for infinite-sized collections.

Type parameters:
A1

a type parameter for the binary operator, a supertype of A.

Value parameters:
op

a binary operator that must be associative.

z

a neutral element for the fold operation; may be added to the result an arbitrary number of times, and must not change the result (e.g., Nil for list concatenation, 0 for addition, or 1 for multiplication).

Returns:

the result of applying the fold operator op between all the elements and z, or z if this collection is empty.

Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
override def foldLeft[B](z: B)(op: (B, A) => B): B
Definition Classes
Inherited from:
LinearSeqOps
Source:
LinearSeq.scala
def foldRight[B](z: B)(op: (A, B) => B): B

Applies a binary operator to all elements of this collection and a start value, going right to left.

Applies a binary operator to all elements of this collection and a start value, going right to left.

Note: will not terminate for infinite-sized collections.

Note: might return different results for different runs, unless the underlying collection type is ordered or the operator is associative and commutative.

Type parameters:
B

the result type of the binary operator.

Value parameters:
op

the binary operator.

z

the start value.

Returns:

the result of inserting op between consecutive elements of this collection, going right to left with the start value z on the right: op(x1, op(x2, ... op(xn, z)...)) where x1, ..., xn are the elements of this collection. Returns z if this collection is empty.

Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
override def foreach[U](f: A => U): Unit
Definition Classes
Inherited from:
LinearSeqOps
Source:
LinearSeq.scala
protected def fromSpecific(coll: IterableOnce[A]): Queue[A]
def groupBy[K](f: A => K): Map[K, Queue[A]]

Partitions this iterable collection into a map of iterable collections according to some discriminator function.

Partitions this iterable collection into a map of iterable collections according to some discriminator function.

Note: Even when applied to a view or a lazy collection it will always force the elements.

Type parameters:
K

the type of keys returned by the discriminator function.

Value parameters:
f

the discriminator function.

Returns:

A map from keys to iterable collections such that the following invariant holds:

(xs groupBy f)(k) = xs filter (x => f(x) == k)

That is, every key k is bound to a iterable collection of those elements x for which f(x) equals k.

Inherited from:
IterableOps
Source:
Iterable.scala
def groupMap[K, B](key: A => K)(f: A => B): Map[K, Queue[B]]

Partitions this iterable collection into a map of iterable collections according to a discriminator function key.

Partitions this iterable collection into a map of iterable collections according to a discriminator function key. Each element in a group is transformed into a value of type B using the value function.

It is equivalent to groupBy(key).mapValues(_.map(f)), but more efficient.

case class User(name: String, age: Int)

def namesByAge(users: Seq[User]): Map[Int, Seq[String]] =
users.groupMap(_.age)(_.name)

Note: Even when applied to a view or a lazy collection it will always force the elements.

Type parameters:
B

the type of values returned by the transformation function

K

the type of keys returned by the discriminator function

Value parameters:
f

the element transformation function

key

the discriminator function

Inherited from:
IterableOps
Source:
Iterable.scala
def groupMapReduce[K, B](key: A => K)(f: A => B)(reduce: (B, B) => B): Map[K, B]

Partitions this iterable collection into a map according to a discriminator function key.

Partitions this iterable collection into a map according to a discriminator function key. All the values that have the same discriminator are then transformed by the f function and then reduced into a single value with the reduce function.

It is equivalent to groupBy(key).mapValues(_.map(f).reduce(reduce)), but more efficient.

def occurrences[A](as: Seq[A]): Map[A, Int] =
as.groupMapReduce(identity)(_ => 1)(_ + _)

Note: Even when applied to a view or a lazy collection it will always force the elements.

Inherited from:
IterableOps
Source:
Iterable.scala
def grouped(size: Int): Iterator[Queue[A]]

Partitions elements in fixed size iterable collections.

Partitions elements in fixed size iterable collections.

Value parameters:
size

the number of elements per group

Returns:

An iterator producing iterable collections of size size, except the last will be less than size size if the elements don't divide evenly.

Inherited from:
IterableOps
Source:
Iterable.scala
override def hashCode(): Int
Definition Classes
Seq -> Any
Inherited from:
Seq
Source:
Seq.scala
Definition Classes
Inherited from:
LinearSeqOps
Source:
LinearSeq.scala
@deprecatedOverriding("Override indexOf(elem, from) instead - indexOf(elem) calls indexOf(elem, 0)", "2.13.0")
def indexOf[B >: A](elem: B): Int

Finds index of first occurrence of some value in this sequence.

Finds index of first occurrence of some value in this sequence.

Type parameters:
B

the type of the element elem.

Value parameters:
elem

the element value to search for.

Returns:

the index >= 0 of the first element of this sequence that is equal (as determined by ==) to elem, or -1, if none exists.

Inherited from:
SeqOps
Source:
Seq.scala
def indexOf[B >: A](elem: B, from: Int): Int

Finds index of first occurrence of some value in this sequence after or at some start index.

Finds index of first occurrence of some value in this sequence after or at some start index.

Type parameters:
B

the type of the element elem.

Value parameters:
elem

the element value to search for.

from

the start index

Returns:

the index >= from of the first element of this sequence that is equal (as determined by ==) to elem, or -1, if none exists.

Inherited from:
SeqOps
Source:
Seq.scala
@deprecatedOverriding("Override indexOfSlice(that, from) instead - indexOfSlice(that) calls indexOfSlice(that, 0)", "2.13.0")
def indexOfSlice[B >: A](that: Seq[B]): Int

Finds first index where this sequence contains a given sequence as a slice.

Finds first index where this sequence contains a given sequence as a slice.

Note: may not terminate for infinite-sized collections.

Value parameters:
that

the sequence to test

Returns:

the first index >= 0 such that the elements of this sequence starting at this index match the elements of sequence that, or -1 of no such subsequence exists.

Inherited from:
SeqOps
Source:
Seq.scala
def indexOfSlice[B >: A](that: Seq[B], from: Int): Int

Finds first index after or at a start index where this sequence contains a given sequence as a slice.

Finds first index after or at a start index where this sequence contains a given sequence as a slice.

Note: may not terminate for infinite-sized collections.

Value parameters:
from

the start index

that

the sequence to test

Returns:

the first index >= from such that the elements of this sequence starting at this index match the elements of sequence that, or -1 of no such subsequence exists.

Inherited from:
SeqOps
Source:
Seq.scala
@deprecatedOverriding("Override indexWhere(p, from) instead - indexWhere(p) calls indexWhere(p, 0)", "2.13.0")
def indexWhere(p: A => Boolean): Int

Finds index of the first element satisfying some predicate.

Finds index of the first element satisfying some predicate.

Note: may not terminate for infinite-sized collections.

Value parameters:
p

the predicate used to test elements.

Returns:

the index >= 0 of the first element of this sequence that satisfies the predicate p, or -1, if none exists.

Inherited from:
SeqOps
Source:
Seq.scala
override def indexWhere(p: A => Boolean, from: Int): Int
Definition Classes
Inherited from:
LinearSeqOps
Source:
LinearSeq.scala

Produces the range of all indices of this sequence.

Produces the range of all indices of this sequence.

Note: Even when applied to a view or a lazy collection it will always force the elements.

Returns:

a Range value from 0 to one less than the length of this sequence.

Inherited from:
SeqOps
Source:
Seq.scala
def init: Queue[A]

The initial part of the collection without its last element.

The initial part of the collection without its last element.

Note: Even when applied to a view or a lazy collection it will always force the elements.

Inherited from:
IterableOps
Source:
Iterable.scala

Iterates over the inits of this iterable collection.

Iterates over the inits of this iterable collection. The first value will be this iterable collection and the final one will be an empty iterable collection, with the intervening values the results of successive applications of init.

Note: Even when applied to a view or a lazy collection it will always force the elements.

Returns:

an iterator over all the inits of this iterable collection

Example:

List(1,2,3).inits = Iterator(List(1,2,3), List(1,2), List(1), Nil)

Inherited from:
IterableOps
Source:
Iterable.scala
override def intersect[B >: A](that: Seq[B]): Queue[A]
Definition Classes
Inherited from:
StrictOptimizedSeqOps
Source:
StrictOptimizedSeqOps.scala
override def isDefinedAt(x: Int): Boolean
Definition Classes
Inherited from:
LinearSeqOps
Source:
LinearSeq.scala
override def isTraversableAgain
Definition Classes
Inherited from:
IterableOps
Source:
Iterable.scala
Returns:

The number of elements in this collection, if it can be cheaply computed, -1 otherwise. Cheaply usually means: Not requiring a collection traversal.

Inherited from:
IterableOnce
Source:
IterableOnce.scala
def lastIndexOf[B >: A](elem: B, end: Int): Int

Finds index of last occurrence of some value in this sequence before or at a given end index.

Finds index of last occurrence of some value in this sequence before or at a given end index.

Note: will not terminate for infinite-sized collections.

Type parameters:
B

the type of the element elem.

Value parameters:
elem

the element value to search for.

end

the end index.

Returns:

the index <= end of the last element of this sequence that is equal (as determined by ==) to elem, or -1, if none exists.

Inherited from:
SeqOps
Source:
Seq.scala
@deprecatedOverriding("Override lastIndexOfSlice(that, end) instead - lastIndexOfSlice(that) calls lastIndexOfSlice(that, Int.MaxValue)", "2.13.0")
def lastIndexOfSlice[B >: A](that: Seq[B]): Int

Finds last index where this sequence contains a given sequence as a slice.

Finds last index where this sequence contains a given sequence as a slice.

Note: will not terminate for infinite-sized collections.

Value parameters:
that

the sequence to test

Returns:

the last index such that the elements of this sequence starting at this index match the elements of sequence that, or -1 of no such subsequence exists.

Inherited from:
SeqOps
Source:
Seq.scala
def lastIndexOfSlice[B >: A](that: Seq[B], end: Int): Int

Finds last index before or at a given end index where this sequence contains a given sequence as a slice.

Finds last index before or at a given end index where this sequence contains a given sequence as a slice.

Note: will not terminate for infinite-sized collections.

Value parameters:
end

the end index

that

the sequence to test

Returns:

the last index <= end such that the elements of this sequence starting at this index match the elements of sequence that, or -1 of no such subsequence exists.

Inherited from:
SeqOps
Source:
Seq.scala
@deprecatedOverriding("Override lastIndexWhere(p, end) instead - lastIndexWhere(p) calls lastIndexWhere(p, Int.MaxValue)", "2.13.0")
def lastIndexWhere(p: A => Boolean): Int

Finds index of last element satisfying some predicate.

Finds index of last element satisfying some predicate.

Note: will not terminate for infinite-sized collections.

Value parameters:
p

the predicate used to test elements.

Returns:

the index of the last element of this sequence that satisfies the predicate p, or -1, if none exists.

Inherited from:
SeqOps
Source:
Seq.scala
override def lastIndexWhere(p: A => Boolean, end: Int): Int
Definition Classes
Inherited from:
LinearSeqOps
Source:
LinearSeq.scala

Optionally selects the last element.

Optionally selects the last element.

Note: might return different results for different runs, unless the underlying collection type is ordered.

Returns:

the last element of this iterable collection\$ if it is nonempty, None if it is empty.

Inherited from:
IterableOps
Source:
Iterable.scala
def lazyZip[B](that: Iterable[B]): LazyZip2[A, B, Queue[A]]

Analogous to zip except that the elements in each collection are not consumed until a strict operation is invoked on the returned LazyZip2 decorator.

Analogous to zip except that the elements in each collection are not consumed until a strict operation is invoked on the returned LazyZip2 decorator.

Calls to lazyZip can be chained to support higher arities (up to 4) without incurring the expense of constructing and deconstructing intermediary tuples.

val xs = List(1, 2, 3)
val res = (xs lazyZip xs lazyZip xs lazyZip xs).map((a, b, c, d) => a + b + c + d)
// res == List(4, 8, 12)
Type parameters:
B

the type of the second element in each eventual pair

Value parameters:
that

the iterable providing the second element of each eventual pair

Returns:

a decorator LazyZip2 that allows strict operations to be performed on the lazily evaluated pairs or chained calls to lazyZip. Implicit conversion to Iterable[(A, B)] is also supported.

Inherited from:
Iterable
Source:
Iterable.scala
override def lengthCompare(that: Iterable[_]): Int
Definition Classes
Inherited from:
LinearSeqOps
Source:
LinearSeq.scala
override def lengthCompare(len: Int): Int
Definition Classes
Inherited from:
LinearSeqOps
Source:
LinearSeq.scala
final def lengthIs

Returns a value class containing operations for comparing the length of this sequence to a test value.

Returns a value class containing operations for comparing the length of this sequence to a test value.

These operations are implemented in terms of lengthCompare(Int), and allow the following more readable usages:

this.lengthIs < len     // this.lengthCompare(len) < 0
this.lengthIs <= len    // this.lengthCompare(len) <= 0
this.lengthIs == len    // this.lengthCompare(len) == 0
this.lengthIs != len    // this.lengthCompare(len) != 0
this.lengthIs >= len    // this.lengthCompare(len) >= 0
this.lengthIs > len     // this.lengthCompare(len) > 0
Inherited from:
SeqOps
Source:
Seq.scala
def lift: Int => Option[A]

Turns this partial function into a plain function returning an Option result.

Turns this partial function into a plain function returning an Option result.

Returns:

a function that takes an argument x to Some(this(x)) if this is defined for x, and to None otherwise.

Function.unlift

Inherited from:
PartialFunction
Source:
PartialFunction.scala
override def map[B](f: A => B): Queue[B]
Definition Classes
Inherited from:
StrictOptimizedIterableOps
Source:
StrictOptimizedIterableOps.scala
def max[B >: A](implicit ord: Ordering[B]): A

Finds the largest element.

Finds the largest element.

Note: will not terminate for infinite-sized collections.

Type parameters:
B

The type over which the ordering is defined.

Value parameters:
ord

An ordering to be used for comparing elements.

Returns:

the largest element of this collection with respect to the ordering ord.

Throws:
UnsupportedOperationException

if this collection is empty.

Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
def maxBy[B](f: A => B)(implicit cmp: Ordering[B]): A

Finds the first element which yields the largest value measured by function f.

Finds the first element which yields the largest value measured by function f.

Note: will not terminate for infinite-sized collections.

Type parameters:
B

The result type of the function f.

Value parameters:
cmp

An ordering to be used for comparing elements.

f

The measuring function.

Returns:

the first element of this collection with the largest value measured by function f with respect to the ordering cmp.

Throws:
UnsupportedOperationException

if this collection is empty.

Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
def maxByOption[B](f: A => B)(implicit cmp: Ordering[B]): Option[A]

Finds the first element which yields the largest value measured by function f.

Finds the first element which yields the largest value measured by function f.

Note: will not terminate for infinite-sized collections.

Type parameters:
B

The result type of the function f.

Value parameters:
cmp

An ordering to be used for comparing elements.

f

The measuring function.

Returns:

an option value containing the first element of this collection with the largest value measured by function f with respect to the ordering cmp.

Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
def maxOption[B >: A](implicit ord: Ordering[B]): Option[A]

Finds the largest element.

Finds the largest element.

Note: will not terminate for infinite-sized collections.

Type parameters:
B

The type over which the ordering is defined.

Value parameters:
ord

An ordering to be used for comparing elements.

Returns:

an option value containing the largest element of this collection with respect to the ordering ord.

Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
def min[B >: A](implicit ord: Ordering[B]): A

Finds the smallest element.

Finds the smallest element.

Note: will not terminate for infinite-sized collections.

Type parameters:
B

The type over which the ordering is defined.

Value parameters:
ord

An ordering to be used for comparing elements.

Returns:

the smallest element of this collection with respect to the ordering ord.

Throws:
UnsupportedOperationException

if this collection is empty.

Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
def minBy[B](f: A => B)(implicit cmp: Ordering[B]): A

Finds the first element which yields the smallest value measured by function f.

Finds the first element which yields the smallest value measured by function f.

Note: will not terminate for infinite-sized collections.

Type parameters:
B

The result type of the function f.

Value parameters:
cmp

An ordering to be used for comparing elements.

f

The measuring function.

Returns:

the first element of this collection with the smallest value measured by function f with respect to the ordering cmp.

Throws:
UnsupportedOperationException

if this collection is empty.

Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
def minByOption[B](f: A => B)(implicit cmp: Ordering[B]): Option[A]

Finds the first element which yields the smallest value measured by function f.

Finds the first element which yields the smallest value measured by function f.

Note: will not terminate for infinite-sized collections.

Type parameters:
B

The result type of the function f.

Value parameters:
cmp

An ordering to be used for comparing elements.

f

The measuring function.

Returns:

an option value containing the first element of this collection with the smallest value measured by function f with respect to the ordering cmp.

Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
def minOption[B >: A](implicit ord: Ordering[B]): Option[A]

Finds the smallest element.

Finds the smallest element.

Note: will not terminate for infinite-sized collections.

Type parameters:
B

The type over which the ordering is defined.

Value parameters:
ord

An ordering to be used for comparing elements.

Returns:

an option value containing the smallest element of this collection with respect to the ordering ord.

Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
final def mkString

Displays all elements of this collection in a string.

Displays all elements of this collection in a string.

Delegates to addString, which can be overridden.

Returns:

a string representation of this collection. In the resulting string the string representations (w.r.t. the method toString) of all elements of this collection follow each other without any separator string.

Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
final def mkString(sep: String): String

Displays all elements of this collection in a string using a separator string.

Displays all elements of this collection in a string using a separator string.

Delegates to addString, which can be overridden.

Value parameters:
sep

the separator string.

Returns:

a string representation of this collection. In the resulting string the string representations (w.r.t. the method toString) of all elements of this collection are separated by the string sep.

Example:

List(1, 2, 3).mkString("|") = "1|2|3"

Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
final def mkString(start: String, sep: String, end: String): String

Displays all elements of this collection in a string using start, end, and separator strings.

Displays all elements of this collection in a string using start, end, and separator strings.

Delegates to addString, which can be overridden.

Value parameters:
end

the ending string.

sep

the separator string.

start

the starting string.

Returns:

a string representation of this collection. The resulting string begins with the string start and ends with the string end. Inside, the string representations (w.r.t. the method toString) of all elements of this collection are separated by the string sep.

Example:

List(1, 2, 3).mkString("(", "; ", ")") = "(1; 2; 3)"

Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
protected def newSpecificBuilder: Builder[A, Queue[A]]
@deprecatedOverriding("nonEmpty is defined as !isEmpty; override isEmpty instead", "2.13.0")

Tests whether the collection is not empty.

Tests whether the collection is not empty.

Returns:

true if the collection contains at least one element, false otherwise.

Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
def orElse[A1 <: Int, B1 >: A](that: PartialFunction[A1, B1]): PartialFunction[A1, B1]

Composes this partial function with a fallback partial function which gets applied where this partial function is not defined.

Composes this partial function with a fallback partial function which gets applied where this partial function is not defined.

Type parameters:
A1

the argument type of the fallback function

B1

the result type of the fallback function

Value parameters:
that

the fallback function

Returns:

a partial function which has as domain the union of the domains of this partial function and that. The resulting partial function takes x to this(x) where this is defined, and to that(x) where it is not.

Inherited from:
PartialFunction
Source:
PartialFunction.scala
override def padTo[B >: A](len: Int, elem: B): Queue[B]
Definition Classes
Inherited from:
StrictOptimizedSeqOps
Source:
StrictOptimizedSeqOps.scala
override def partition(p: A => Boolean): (Queue[A], Queue[A])
Definition Classes
Inherited from:
StrictOptimizedIterableOps
Source:
StrictOptimizedIterableOps.scala
override def partitionMap[A1, A2](f: A => Either[A1, A2]): (Queue[A1], Queue[A2])
Definition Classes
Inherited from:
StrictOptimizedIterableOps
Source:
StrictOptimizedIterableOps.scala
override def patch[B >: A](from: Int, other: IterableOnce[B], replaced: Int): Queue[B]
Definition Classes
Inherited from:
StrictOptimizedSeqOps
Source:
StrictOptimizedSeqOps.scala

Iterates over distinct permutations.

Iterates over distinct permutations.

Note: Even when applied to a view or a lazy collection it will always force the elements.

Returns:

An Iterator which traverses the distinct permutations of this sequence.

Example:

"abb".permutations = Iterator(abb, bab, bba)

Inherited from:
SeqOps
Source:
Seq.scala
override def prependedAll[B >: A](prefix: IterableOnce[B]): Queue[B]
Definition Classes
Inherited from:
StrictOptimizedSeqOps
Source:
StrictOptimizedSeqOps.scala
def product[B >: A](implicit num: Numeric[B]): B

Multiplies up the elements of this collection.

Multiplies up the elements of this collection.

Note: will not terminate for infinite-sized collections.

Type parameters:
B

the result type of the * operator.

Value parameters:
num

an implicit parameter defining a set of numeric operations which includes the * operator to be used in forming the product.

Returns:

the product of all elements of this collection with respect to the * operator in num.

Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
def reduce[B >: A](op: (B, B) => B): B

Reduces the elements of this collection using the specified associative binary operator.

Reduces the elements of this collection using the specified associative binary operator.

The order in which operations are performed on elements is unspecified and may be nondeterministic.

Type parameters:
B

A type parameter for the binary operator, a supertype of A.

Value parameters:
op

A binary operator that must be associative.

Returns:

The result of applying reduce operator op between all the elements if the collection is nonempty.

Throws:
UnsupportedOperationException

if this collection is empty.

Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
def reduceLeft[B >: A](op: (B, A) => B): B

Applies a binary operator to all elements of this collection, going left to right.

Applies a binary operator to all elements of this collection, 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 or the operator is associative and commutative.

Type parameters:
B

the result type of the binary operator.

Value parameters:
op

the binary operator.

Returns:

the result of inserting op between consecutive elements of this collection, going left to right: op( op( ... op(x1, x2) ..., xn-1), xn) where x1, ..., xn are the elements of this collection.

Throws:
UnsupportedOperationException

if this collection is empty.

Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
def reduceLeftOption[B >: A](op: (B, A) => B): Option[B]

Optionally applies a binary operator to all elements of this collection, going left to right.

Optionally applies a binary operator to all elements of this collection, 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 or the operator is associative and commutative.

Type parameters:
B

the result type of the binary operator.

Value parameters:
op

the binary operator.

Returns:

an option value containing the result of reduceLeft(op) if this collection is nonempty, None otherwise.

Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
def reduceOption[B >: A](op: (B, B) => B): Option[B]

Reduces the elements of this collection, if any, using the specified associative binary operator.

Reduces the elements of this collection, if any, using the specified associative binary operator.

The order in which operations are performed on elements is unspecified and may be nondeterministic.

Type parameters:
B

A type parameter for the binary operator, a supertype of A.

Value parameters:
op

A binary operator that must be associative.

Returns:

An option value containing result of applying reduce operator op between all the elements if the collection is nonempty, and None otherwise.

Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
def reduceRight[B >: A](op: (A, B) => B): B

Applies a binary operator to all elements of this collection, going right to left.

Applies a binary operator to all elements of this collection, going right to left.

Note: will not terminate for infinite-sized collections.

Note: might return different results for different runs, unless the underlying collection type is ordered or the operator is associative and commutative.

Type parameters:
B

the result type of the binary operator.

Value parameters:
op

the binary operator.

Returns:

the result of inserting op between consecutive elements of this collection, going right to left: op(x1, op(x2, ..., op(xn-1, xn)...)) where x1, ..., xn are the elements of this collection.

Throws:
UnsupportedOperationException

if this collection is empty.

Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
def reduceRightOption[B >: A](op: (A, B) => B): Option[B]

Optionally applies a binary operator to all elements of this collection, going right to left.

Optionally applies a binary operator to all elements of this collection, going right to left.

Note: will not terminate for infinite-sized collections.

Note: might return different results for different runs, unless the underlying collection type is ordered or the operator is associative and commutative.

Type parameters:
B

the result type of the binary operator.

Value parameters:
op

the binary operator.

Returns:

an option value containing the result of reduceRight(op) if this collection is nonempty, None otherwise.

Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
def reverse: Queue[A]

Returns new sequence with elements in reversed order.

Returns new sequence with elements in reversed order.

Note: will not terminate for infinite-sized collections.

Note: Even when applied to a view or a lazy collection it will always force the elements.

Returns:

A new sequence with all elements of this sequence in reversed order.

Inherited from:
SeqOps
Source:
Seq.scala

An iterator yielding elements in reversed order.

An iterator yielding elements in reversed order.

Note: will not terminate for infinite-sized collections.

Note: xs.reverseIterator is the same as xs.reverse.iterator but might be more efficient.

Returns:

an iterator yielding the elements of this sequence in reversed order

Inherited from:
SeqOps
Source:
Seq.scala
protected def reversed: Iterable[A]
Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
def runWith[U](action: A => U): Int => Boolean

Composes this partial function with an action function which gets applied to results of this partial function.

Composes this partial function with an action function which gets applied to results of this partial function. The action function is invoked only for its side effects; its result is ignored.

Note that expression pf.runWith(action)(x) is equivalent to

if(pf isDefinedAt x) { action(pf(x)); true } else false

except that runWith is implemented via applyOrElse and thus potentially more efficient. Using runWith avoids double evaluation of pattern matchers and guards for partial function literals.

Value parameters:
action

the action function

Returns:

a function which maps arguments x to isDefinedAt(x). The resulting function runs action(this(x)) where this is defined.

applyOrElse.

Inherited from:
PartialFunction
Source:
PartialFunction.scala
override def sameElements[B >: A](that: IterableOnce[B]): Boolean
Definition Classes
Inherited from:
LinearSeqOps
Source:
LinearSeq.scala
def scan[B >: A](z: B)(op: (B, B) => B): Queue[B]

Computes a prefix scan of the elements of the collection.

Computes a prefix scan of the elements of the collection.

Note: The neutral element z may be applied more than once.

Type parameters:
B

element type of the resulting collection

Value parameters:
op

the associative operator for the scan

z

neutral element for the operator op

Returns:

a new iterable collection containing the prefix scan of the elements in this iterable collection

Inherited from:
IterableOps
Source:
Iterable.scala
override def scanLeft[B](z: B)(op: (B, A) => B): Queue[B]
Definition Classes
Inherited from:
StrictOptimizedIterableOps
Source:
StrictOptimizedIterableOps.scala
def scanRight[B](z: B)(op: (A, B) => B): Queue[B]

Produces a collection containing cumulative results of applying the operator going right to left.

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.

Note: Even when applied to a view or a lazy collection it will always force the elements.

Example:

List(1, 2, 3, 4).scanRight(0)(_ + _) == List(10, 9, 7, 4, 0)
Type parameters:
B

the type of the elements in the resulting collection

Value parameters:
op

the binary operator applied to the intermediate result and the element

z

the initial value

Returns:

collection with intermediate results

Inherited from:
IterableOps
Source:
Iterable.scala
def search[B >: A](elem: B, from: Int, to: Int)(implicit ord: Ordering[B]): SearchResult

Search within an interval in this sorted sequence for a specific element.

Search within an interval in this sorted sequence for a specific element. If this sequence is an IndexedSeq, a binary search is used. Otherwise, a linear search is used.

The sequence should be sorted with the same Ordering before calling; otherwise, the results are undefined.

Value parameters:
elem

the element to find.

from

the index where the search starts.

ord

the ordering to be used to compare elements.

to

the index following where the search ends.

Returns:

a Found value containing the index corresponding to the element in the sequence, or the InsertionPoint where the element would be inserted if the element is not in the sequence.

Note:

if to <= from, the search space is empty, and an InsertionPoint at from is returned

Inherited from:
SeqOps
Source:
Seq.scala
def search[B >: A](elem: B)(implicit ord: Ordering[B]): SearchResult

Search this sorted sequence for a specific element.

Search this sorted sequence for a specific element. If the sequence is an IndexedSeq, a binary search is used. Otherwise, a linear search is used.

The sequence should be sorted with the same Ordering before calling; otherwise, the results are undefined.

Value parameters:
elem

the element to find.

ord

the ordering to be used to compare elements.

Returns:

a Found value containing the index corresponding to the element in the sequence, or the InsertionPoint where the element would be inserted if the element is not in the sequence.

Inherited from:
SeqOps
Source:
Seq.scala
override def segmentLength(p: A => Boolean, from: Int): Int
Definition Classes
Inherited from:
LinearSeqOps
Source:
LinearSeq.scala
final def segmentLength(p: A => Boolean): Int

Computes the length of the longest segment that starts from the first element and whose elements all satisfy some predicate.

Computes the length of the longest segment that starts from the first element and whose elements all satisfy some predicate.

Note: may not terminate for infinite-sized collections.

Value parameters:
p

the predicate used to test elements.

Returns:

the length of the longest segment of this sequence that starts from the first element such that every element of the segment satisfies the predicate p.

Inherited from:
SeqOps
Source:
Seq.scala
final override def size: Int
Definition Classes
Inherited from:
SeqOps
Source:
Seq.scala
final override def sizeCompare(that: Iterable[_]): Int
Definition Classes
Inherited from:
SeqOps
Source:
Seq.scala
final override def sizeCompare(otherSize: Int): Int
Definition Classes
Inherited from:
SeqOps
Source:
Seq.scala
final def sizeIs

Returns a value class containing operations for comparing the size of this iterable collection to a test value.

Returns a value class containing operations for comparing the size of this iterable collection to a test value.

These operations are implemented in terms of sizeCompare(Int), and allow the following more readable usages:

this.sizeIs < size     // this.sizeCompare(size) < 0
this.sizeIs <= size    // this.sizeCompare(size) <= 0
this.sizeIs == size    // this.sizeCompare(size) == 0
this.sizeIs != size    // this.sizeCompare(size) != 0
this.sizeIs >= size    // this.sizeCompare(size) >= 0
this.sizeIs > size     // this.sizeCompare(size) > 0
Inherited from:
IterableOps
Source:
Iterable.scala
def slice(from: Int, until: Int): Queue[A]
Inherited from:
IterableOps
Source:
Iterable.scala
def sliding(size: Int, step: Int): Iterator[Queue[A]]

Groups elements in fixed size blocks by passing a "sliding window" over them (as opposed to partitioning them, as is done in grouped.)

Groups elements in fixed size blocks by passing a "sliding window" over them (as opposed to partitioning them, as is done in grouped.)

The returned iterator will be empty when called on an empty collection. The last element the iterator produces may be smaller than the window size when the original collection isn't exhausted by the window before it and its last element isn't skipped by the step before it.

Value parameters:
size

the number of elements per group

step

the distance between the first elements of successive groups

Returns:

An iterator producing iterable collections of size size, except the last element (which may be the only element) will be smaller if there are fewer than size elements remaining to be grouped.

Example:

List(1, 2, 3, 4, 5).sliding(2, 2) = Iterator(List(1, 2), List(3, 4), List(5))

List(1, 2, 3, 4, 5, 6).sliding(2, 3) = Iterator(List(1, 2), List(4, 5))

Inherited from:
IterableOps
Source:
Iterable.scala
def sliding(size: Int): Iterator[Queue[A]]

Groups elements in fixed size blocks by passing a "sliding window" over them (as opposed to partitioning them, as is done in grouped.)

Groups elements in fixed size blocks by passing a "sliding window" over them (as opposed to partitioning them, as is done in grouped.)

An empty collection returns an empty iterator, and a non-empty collection containing fewer elements than the window size returns an iterator that will produce the original collection as its only element.

Value parameters:
size

the number of elements per group

Returns:

An iterator producing iterable collections of size size, except for a non-empty collection with less than size elements, which returns an iterator that produces the source collection itself as its only element.

Example:

List().sliding(2) = empty iterator

List(1).sliding(2) = Iterator(List(1))

List(1, 2).sliding(2) = Iterator(List(1, 2))

List(1, 2, 3).sliding(2) = Iterator(List(1, 2), List(2, 3))

Inherited from:
IterableOps
Source:
Iterable.scala
def sortBy[B](f: A => B)(implicit ord: Ordering[B]): Queue[A]

Sorts this sequence according to the Ordering which results from transforming an implicitly given Ordering with a transformation function.

Sorts this sequence according to the Ordering which results from transforming an implicitly given Ordering with a transformation function.

Note: will not terminate for infinite-sized collections.

Note: Even when applied to a view or a lazy collection it will always force the elements.

The sort is stable. That is, elements that are equal (as determined by ord.compare) appear in the same order in the sorted sequence as in the original.

Type parameters:
B

the target type of the transformation f, and the type where the ordering ord is defined.

Value parameters:
f

the transformation function mapping elements to some other domain B.

ord

the ordering assumed on domain B.

Returns:

a sequence consisting of the elements of this sequence sorted according to the ordering where x < y if ord.lt(f(x), f(y)).

Example:

val words = "The quick brown fox jumped over the lazy dog".split(' ')
// this works because scala.Ordering will implicitly provide an Ordering[Tuple2[Int, Char]]
res0: Array[String] = Array(The, dog, fox, the, lazy, over, brown, quick, jumped)
Inherited from:
SeqOps
Source:
Seq.scala
def sortWith(lt: (A, A) => Boolean): Queue[A]

Sorts this sequence according to a comparison function.

Sorts this sequence according to a comparison function.

Note: will not terminate for infinite-sized collections.

Note: Even when applied to a view or a lazy collection it will always force the elements.

The sort is stable. That is, elements that are equal (as determined by lt) appear in the same order in the sorted sequence as in the original.

Value parameters:
lt

the comparison function which tests whether its first argument precedes its second argument in the desired ordering.

Returns:

a sequence consisting of the elements of this sequence sorted according to the comparison function lt.

Example:

List("Steve", "Tom", "John", "Bob").sortWith(_.compareTo(_) < 0) =
List("Bob", "John", "Steve", "Tom")
Inherited from:
SeqOps
Source:
Seq.scala
override def sorted[B >: A](implicit ord: Ordering[B]): Queue[A]
Definition Classes
Inherited from:
StrictOptimizedSeqOps
Source:
StrictOptimizedSeqOps.scala
override def span(p: A => Boolean): (Queue[A], Queue[A])
Definition Classes
Inherited from:
StrictOptimizedIterableOps
Source:
StrictOptimizedIterableOps.scala
override def splitAt(n: Int): (Queue[A], Queue[A])
Definition Classes
Inherited from:
IterableOps
Source:
Iterable.scala
def startsWith[B >: A](that: IterableOnce[B], offset: Int): Boolean

Tests whether this sequence contains the given sequence at a given index.

Tests whether this sequence 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.

Value parameters:
offset

the index where the sequence is searched.

that

the sequence to test

Returns:

true if the sequence that is contained in this sequence at index offset, otherwise false.

Inherited from:
SeqOps
Source:
Seq.scala
def stepper[S <: Stepper[_]](implicit shape: StepperShape[A, S]): S

Returns a scala.collection.Stepper for the elements of this collection.

Returns a scala.collection.Stepper for the elements of this collection.

The Stepper enables creating a Java stream to operate on the collection, see scala.jdk.StreamConverters. For collections holding primitive values, the Stepper can be used as an iterator which doesn't box the elements.

The implicit scala.collection.StepperShape parameter defines the resulting Stepper type according to the element type of this collection.

Note that this method is overridden in subclasses and the return type is refined to S with EfficientSplit, for example scala.collection.IndexedSeqOps.stepper. For Steppers marked with scala.collection.Stepper.EfficientSplit, the converters in scala.jdk.StreamConverters allow creating parallel streams, whereas bare Steppers can be converted only to sequential streams.

Inherited from:
IterableOnce
Source:
IterableOnce.scala
def sum[B >: A](implicit num: Numeric[B]): B

Sums up the elements of this collection.

Sums up the elements of this collection.

Note: will not terminate for infinite-sized collections.

Type parameters:
B

the result type of the + operator.

Value parameters:
num

an implicit parameter defining a set of numeric operations which includes the + operator to be used in forming the sum.

Returns:

the sum of all elements of this collection with respect to the + operator in num.

Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
override def tails: Iterator[Queue[A]]
Definition Classes
Inherited from:
LinearSeqOps
Source:
LinearSeq.scala
def take(n: Int): Queue[A]
Inherited from:
IterableOps
Source:
Iterable.scala
override def takeRight(n: Int): Queue[A]

A collection containing the last n elements of this collection.

A collection containing the last n elements of this collection.

Note: Even when applied to a view or a lazy collection it will always force the elements.

Definition Classes
Inherited from:
StrictOptimizedIterableOps
Source:
StrictOptimizedIterableOps.scala
def takeWhile(p: A => Boolean): Queue[A]

Takes longest prefix of elements that satisfy a predicate.

Takes longest prefix of elements that satisfy a predicate.

Note: might return different results for different runs, unless the underlying collection type is ordered.

Value parameters:
p

The predicate used to test elements.

Returns:

the longest prefix of this iterable collection whose elements all satisfy the predicate p.

Inherited from:
IterableOps
Source:
Iterable.scala
override def tapEach[U](f: A => U): Queue[A]
Definition Classes
Inherited from:
StrictOptimizedIterableOps
Source:
StrictOptimizedIterableOps.scala
def to[C1](factory: Factory[A, C1]): C1

Given a collection factory factory, convert this collection to the appropriate representation for the current element type A.

Given a collection factory factory, convert this collection to the appropriate representation for the current element type A. Example uses:

xs.to(List) xs.to(ArrayBuffer) xs.to(BitSet) // for xs: Iterable[Int]

Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
def toArray[B >: A : ClassTag]: Array[B]

Convert collection to array.

Convert collection to array.

Implementation note: DO NOT call Array.from from this method.

Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
final def toBuffer[B >: A]: Buffer[B]
Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
def toList: List[A]
Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
def toMap[K, V](implicit ev: A <:< (K, V)): Map[K, V]
Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
final override def toSeq: Queue[A]
Definition Classes
Inherited from:
Seq
Source:
Seq.scala
def toSet[B >: A]: Set[B]
Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
def transpose[B](implicit asIterable: A => Iterable[B]): Queue[Queue[B]]

Transposes this iterable collection of iterable collections into a iterable collection of iterable collections.

Transposes this iterable collection of iterable collections into a iterable collection of iterable collections.

The resulting collection's type will be guided by the static type of iterable collection. For example:

val xs = List(
Set(1, 2, 3),
Set(4, 5, 6)).transpose
// xs == List(
//         List(1, 4),
//         List(2, 5),
//         List(3, 6))

val ys = Vector(
List(1, 2, 3),
List(4, 5, 6)).transpose
// ys == Vector(
//         Vector(1, 4),
//         Vector(2, 5),
//         Vector(3, 6))

Note: Even when applied to a view or a lazy collection it will always force the elements.

Type parameters:
B

the type of the elements of each iterable collection.

Value parameters:
asIterable

an implicit conversion which asserts that the element type of this iterable collection is an Iterable.

Returns:

a two-dimensional iterable collection of iterable collections which has as nth row the nth column of this iterable collection.

Throws:
IllegalArgumentException

if all collections in this iterable collection are not of the same size.

Inherited from:
IterableOps
Source:
Iterable.scala
def unapply(a: Int): Option[A]

Tries to extract a B from an A in a pattern matching expression.

Tries to extract a B from an A in a pattern matching expression.

Inherited from:
PartialFunction
Source:
PartialFunction.scala
override def unzip[A1, A2](implicit asPair: A => (A1, A2)): (Queue[A1], Queue[A2])
Definition Classes
Inherited from:
StrictOptimizedIterableOps
Source:
StrictOptimizedIterableOps.scala
override def unzip3[A1, A2, A3](implicit asTriple: A => (A1, A2, A3)): (Queue[A1], Queue[A2], Queue[A3])
Definition Classes
Inherited from:
StrictOptimizedIterableOps
Source:
StrictOptimizedIterableOps.scala
override def updated[B >: A](index: Int, elem: B): Queue[B]
Definition Classes
Inherited from:
StrictOptimizedSeqOps
Source:
StrictOptimizedSeqOps.scala
override def view: SeqView[A]
Definition Classes
Inherited from:
SeqOps
Source:
Seq.scala

Creates a non-strict filter of this iterable collection.

Creates a non-strict filter of this iterable collection.

Note: the difference between c filter p and c withFilter p is that the former creates a new collection, whereas the latter only restricts the domain of subsequent map, flatMap, foreach, and withFilter operations.

Note: might return different results for different runs, unless the underlying collection type is ordered.

Value parameters:
p

the predicate used to test elements.

Returns:

an object of class WithFilter, which supports map, flatMap, foreach, and withFilter operations. All these operations apply to those elements of this iterable collection which satisfy the predicate p.

Inherited from:
IterableOps
Source:
Iterable.scala
override def zip[B](that: IterableOnce[B]): Queue[(A, B)]
Definition Classes
Inherited from:
StrictOptimizedIterableOps
Source:
StrictOptimizedIterableOps.scala
def zipAll[A1 >: A, B](that: Iterable[B], thisElem: A1, thatElem: B): Queue[(A1, B)]

Returns a iterable collection formed from this iterable collection and another iterable collection by combining corresponding elements in pairs.

Returns a iterable collection formed from this iterable collection and another iterable collection 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.

Value parameters:
that

the iterable providing the second half of each result pair

thatElem

the element to be used to fill up the result if that is shorter than this iterable collection.

thisElem

the element to be used to fill up the result if this iterable collection is shorter than that.

Returns:

a new collection of type That containing pairs consisting of corresponding elements of this iterable collection and that. The length of the returned collection is the maximum of the lengths of this iterable collection and that. If this iterable collection is shorter than that, thisElem values are used to pad the result. If that is shorter than this iterable collection, thatElem values are used to pad the result.

Inherited from:
IterableOps
Source:
Iterable.scala
override def zipWithIndex: Queue[(A, Int)]
Definition Classes
Inherited from:
StrictOptimizedIterableOps
Source:
StrictOptimizedIterableOps.scala

### Deprecated and Inherited methods

@deprecated("Use foldLeft instead of /:", "2.13.0") @inline
final def /:[B](z: B)(op: (B, A) => B): B
Deprecated
Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
@deprecated("Use foldRight instead of :\\", "2.13.0") @inline
final def :\[B](z: B)(op: (A, B) => B): B
Deprecated
Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
@deprecated("`aggregate` is not relevant for sequential collections. Use `foldLeft(z)(seqop)` instead.", "2.13.0")
def aggregate[B](z: => B)(seqop: (B, A) => B, combop: (B, B) => B): B
Deprecated
Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
Deprecated
Inherited from:
IterableOps
Source:
Iterable.scala
@deprecated("Use `dest ++= coll` instead", "2.13.0") @inline
final def copyToBuffer[B >: A](dest: Buffer[B]): Unit
Deprecated
Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
@deprecated("Check .knownSize instead of .hasDefiniteSize for more actionable information (see scaladoc for details)", "2.13.0")

Tests whether this collection is known to have a finite size.

Tests whether this collection is known to have a finite size. All strict collections are known to have finite size. For a non-strict collection such as Stream, the predicate returns true if all elements have been computed. It returns false if the stream is not yet evaluated to the end. Non-empty Iterators usually return false even if they were created from a collection with a known finite size.

Note: many collection methods will not work on collections of infinite sizes. The typical failure mode is an infinite loop. These methods always attempt a traversal without checking first that hasDefiniteSize returns true. However, checking hasDefiniteSize can provide an assurance that size is well-defined and non-termination is not a concern.

Returns:

true if this collection is known to have finite size, false otherwise.

method knownSize for a more useful alternative

Deprecated

This method is deprecated in 2.13 because it does not provide any actionable information. As noted above, even the collection library itself does not use it. When there is no guarantee that a collection is finite, it is generally best to attempt a computation anyway and document that it will not terminate for infinite collections rather than backing out because this would prevent performing the computation on collections that are in fact finite even though hasDefiniteSize returns false.

Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
@deprecated("Use segmentLength instead of prefixLength", "2.13.0") @inline
final def prefixLength(p: A => Boolean): Int

Returns the length of the longest prefix whose elements all satisfy some predicate.

Returns the length of the longest prefix whose elements all satisfy some predicate.

Note: may not terminate for infinite-sized collections.

Value parameters:
p

the predicate used to test elements.

Returns:

the length of the longest prefix of this sequence such that every element of the segment satisfies the predicate p.

Deprecated
Inherited from:
SeqOps
Source:
Seq.scala
@deprecated("Use coll instead of repr in a collection implementation, use the collection value itself from the outside", "2.13.0")
final def repr: Queue[A]
Deprecated
Inherited from:
IterableOps
Source:
Iterable.scala
@deprecated("Use .reverseIterator.map(f).to(...) instead of .reverseMap(f)", "2.13.0")
def reverseMap[B](f: A => B): Queue[B]
Deprecated
Inherited from:
SeqOps
Source:
Seq.scala
@deprecated("Iterable.seq always returns the iterable itself", "2.13.0")
def seq: Queue[A]
Deprecated
Inherited from:
Iterable
Source:
Iterable.scala
@deprecated("toIterable is internal and will be made protected; its name is similar to `toList` or `toSeq`, but it doesn\'t copy non-immutable collections", "2.13.7")
final def toIterable: Queue[A]
Deprecated
Inherited from:
Iterable
Source:
Iterable.scala
@deprecated("Use .iterator instead of .toIterator", "2.13.0") @inline
final def toIterator: Iterator[A]
Deprecated
Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
@deprecated("Use .to(LazyList) instead of .toStream", "2.13.0") @inline
final def toStream: Stream[A]
Deprecated
Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
@deprecated("toTraversable is internal and will be made protected; its name is similar to `toList` or `toSeq`, but it doesn\'t copy non-immutable collections", "2.13.0")
final def toTraversable: Iterable[A]

Converts this iterable collection to an unspecified Iterable.

Converts this iterable collection to an unspecified Iterable. Will return the same collection if this instance is already Iterable.

Returns:

An Iterable containing all elements of this iterable collection.

Deprecated
Inherited from:
IterableOps
Source:
Iterable.scala
final def union[B >: A](that: Seq[B]): Queue[B]

Produces a new sequence which contains all elements of this sequence and also all elements of a given sequence.

Produces a new sequence which contains all elements of this sequence and also all elements of a given sequence. xs union ys is equivalent to xs ++ ys.

Type parameters:
B

the element type of the returned sequence.

Value parameters:
that

Returns:

a new collection which contains all elements of this sequence followed by all elements of that.

Deprecated
Inherited from:
SeqOps
Source:
Seq.scala
@deprecated("Use .view.slice(from, until) instead of .view(from, until)", "2.13.0")
def view(from: Int, until: Int): View[A]

A view over a slice of the elements of this collection.

A view over a slice of the elements of this collection.

Deprecated
Inherited from:
IterableOps
Source:
Iterable.scala