# Queue<E> class

A Queue is a collection that can be manipulated at both ends. One can iterate over the elements of a queue through forEach or with an Iterator.

It is generally not allowed to modify the queue (add or remove entries) while an operation on the queue is being performed, for example during a call to forEach. Modifying the queue while it is being iterated will most likely break the iteration. This goes both for using the iterator directly, or for iterating an `Iterable` returned by a method like map or where.

Implementers
  - DoubleLinkedQueue
  - ListQueue

## Constructors

Queue()
  Creates a queue.
  factory
Queue.from(Iterable elements)
  Creates a queue containing all `elements`. [...]
  factory
Queue.of(Iterable<E> elements)
  Creates a queue from `elements`. [...]
  factory

## Properties

first → E
  Returns the first element. [...]
  read-only, inherited
hashCode → int
  The hash code for this object. [...]
  read-only, inherited
isEmpty → bool
  Returns `true` if there are no elements in this collection. [...]
  read-only, inherited
isNotEmpty → bool
  Returns true if there is at least one element in this collection. [...]
  read-only, inherited
iterator → Iterator<E>
  Returns a new `Iterator` that allows iterating the elements of this `Iterable`. [...]
  read-only, inherited
last → E
  Returns the last element. [...]
  read-only, inherited
length → int
  Returns the number of elements in the iterable. [...]
  read-only, inherited
runtimeType → Type
  A representation of the runtime type of the object.
  read-only, inherited
single → E
  Checks that this iterable has only one element, and returns that element. [...]
  read-only, inherited

## Methods

add(E value) → void
  Adds `value` at the end of the queue.
addAll(Iterable<E> iterable) → void
  Adds all elements of `iterable` at the end of the queue. The length of the queue is extended by the length of `iterable`.
addFirst(E value) → void
  Adds `value` at the beginning of the queue.
addLast(E value) → void
  Adds `value` at the end of the queue.
cast<R>() → Queue<R>
  Provides a view of this queue as a queue of `R` instances, if necessary. [...]
  override
clear() → void
  Removes all elements in the queue. The size of the queue becomes zero.
remove(Object value) → bool
  Remove a single instance of `value` from the queue. [...]
removeFirst() → E
  Removes and returns the first element of this queue. [...]
removeLast() → E
  Removes and returns the last element of the queue. [...]
removeWhere(bool test(E element)) → void
  Removes all elements matched by `test` from the queue. [...]
retainWhere(bool test(E element)) → void
  Removes all elements not matched by `test` from the queue. [...]
any(bool test(E element)) → bool
  Checks whether any element of this iterable satisfies `test`. [...]
  inherited
contains(Object element) → bool
  Returns true if the collection contains an element equal to `element`. [...]
  inherited
elementAt(int index) → E
  Returns the `index`th element. [...]
  inherited
every(bool test(E element)) → bool
  Checks whether every element of this iterable satisfies `test`. [...]
  inherited
expand<T>(Iterable<T> f(E element)) → Iterable<T>
  Expands each element of this Iterable into zero or more elements. [...]
  inherited
firstWhere(bool test(E element), { E orElse() }) → E
  Returns the first element that satisfies the given predicate `test`. [...]
  inherited
fold<T>(T initialValue, T combine(T previousValue, E element)) → T
  Reduces a collection to a single value by iteratively combining each element of the collection with an existing value [...]
  inherited
followedBy(Iterable<E> other) → Iterable<E>
  Returns the lazy concatentation of this iterable and `other`. [...]
  inherited
forEach(void f(E element)) → void
  Applies the function `f` to each element of this collection in iteration order.
  inherited
join([String separator = "" ]) → String
  Converts each element to a String and concatenates the strings. [...]
  inherited
lastWhere(bool test(E element), { E orElse() }) → E
  Returns the last element that satisfies the given predicate `test`. [...]
  inherited
map<T>(T f(E e)) → Iterable<T>
  Returns a new lazy Iterable with elements that are created by calling `f` on each element of this `Iterable` in iteration order. [...]
  inherited
noSuchMethod(Invocation invocation) → dynamic
  Invoked when a non-existent method or property is accessed. [...]
  inherited
reduce(E combine(E value, E element)) → E
  Reduces a collection to a single value by iteratively combining elements of the collection using the provided function. [...]
  inherited
singleWhere(bool test(E element), { E orElse() }) → E
  Returns the single element that satisfies `test`. [...]
  inherited
skip(int count) → Iterable<E>
  Returns an Iterable that provides all but the first `count` elements. [...]
  inherited
skipWhile(bool test(E value)) → Iterable<E>
  Returns an `Iterable` that skips leading elements while `test` is satisfied. [...]
  inherited
take(int count) → Iterable<E>
  Returns a lazy iterable of the `count` first elements of this iterable. [...]
  inherited
takeWhile(bool test(E value)) → Iterable<E>
  Returns a lazy iterable of the leading elements satisfying `test`. [...]
  inherited
toList({bool growable: true }) → List<E>
  Creates a List containing the elements of this Iterable. [...]
  inherited
toSet() → Set<E>
  Creates a Set containing the same elements as this iterable. [...]
  inherited
toString() → String
  Returns a string representation of this object.
  inherited
where(bool test(E element)) → Iterable<E>
  Returns a new lazy Iterable with all elements that satisfy the predicate `test`. [...]
  inherited
whereType<T>() → Iterable<T>
  Returns a new lazy Iterable with all elements that have type `T`. [...]
  inherited

## Operators

operator ==(dynamic other) → bool
  The equality operator. [...]
  inherited

## Static Methods

castFrom<S, T>(Queue<S> source) → Queue<T>
  Adapts `source` to be a `Queue<T>`. [...]
  override