description

# ListQueue<E> class final

List based Queue.

Keeps a cyclic buffer of elements, and grows to a larger buffer when it fills up. This guarantees constant time peek and remove operations, and amortized constant time add operations.

The structure is efficient for any queue or stack usage.

Example:

    final queue = ListQueue<int>();

To add objects to a queue, use add, addAll, addFirst oraddLast.

    queue.add(5);
    queue.addFirst(0);
    queue.addLast(10);
    queue.addAll([1, 2, 3]);
    print(queue); // {0, 5, 10, 1, 2, 3}

To check if the queue is empty, use isEmpty or isNotEmpty. To find the number of queue entries, use length.

    final isEmpty = queue.isEmpty; // false
    final queueSize = queue.length; // 6

To get first or last item from queue, use first or last.

    final first = queue.first; // 0
    final last = queue.last; // 3

To get item value using index, use elementAt.

    final itemAt = queue.elementAt(2); // 10

To convert queue to list, call toList.

    final numbers = queue.toList();
    print(numbers); // [0, 5, 10, 1, 2, 3]

To remove item from queue, call remove, removeFirst or removeLast.

    queue.remove(10);
    queue.removeFirst();
    queue.removeLast();
    print(queue); // {5, 1, 2}

To remove multiple elements at the same time, use removeWhere.

    queue.removeWhere((element) => element == 1);
    print(queue); // {5, 2}

To remove all elements in this queue that do not meet a condition, use retainWhere.

    queue.retainWhere((element) => element < 4);
    print(queue); // {2}

To remove all items and empty the set, use clear.

    queue.clear();
    print(queue.isEmpty); // true
    print(queue); // {}

Inheritance
  - Object
  - Iterable<E>
  - ListQueue
Implemented types
  - Queue<E>
  - Iterable<T>
Available extensions
  - EnumByName
  - FutureIterable
  - IterableExtensions
  - IterableToJSIterable
  - NullableIterableExtensions

## Constructors

ListQueue([int? initialCapacity])
  Create an empty queue.
ListQueue.from(Iterable elements)
  Create a `ListQueue` containing all `elements`.
  factory
ListQueue.of(Iterable<E> elements)
  Create a `ListQueue` from `elements`.
  factory

## Properties

first → E
  The first element.
  no setter
firstOrNull → T?

  Available on Iterable<T>, provided by the IterableExtensions extension

  The first element of this iterator, or `null` if the iterable is empty.
  no setter
hashCode → int
  The hash code for this object.
  no setter inherited
indexed → Iterable<(int, T)>

  Available on Iterable<T>, provided by the IterableExtensions extension

  Pairs of elements of the indices and elements of this iterable.
  no setter
isEmpty → bool
  Whether this collection has no elements.
  no setter
isNotEmpty → bool
  Whether this collection has at least one element.
  no setter inherited
iterator → Iterator<E>
  A new `Iterator` that allows iterating the elements of this `Iterable`.
  no setter
last → E
  The last element.
  no setter
lastOrNull → T?

  Available on Iterable<T>, provided by the IterableExtensions extension

  The last element of this iterable, or `null` if the iterable is empty.
  no setter
length → int
  Returns the number of elements in the iterable.
  no setter
nonNulls → Iterable<T>

  Available on Iterable<T?>, provided by the NullableIterableExtensions extension

  The non-`null` elements of this iterable.
  no setter
runtimeType → Type
  A representation of the runtime type of the object.
  no setter inherited
single → E
  Checks that this iterable has only one element, and returns that element.
  no setter
singleOrNull → T?

  Available on Iterable<T>, provided by the IterableExtensions extension

  The single element of this iterator, or `null`.
  no setter
toJSIterable → JSIterable<T>

  Available on Iterable<T>, provided by the IterableToJSIterable extension

  A JSIterable wrapper that proxies to the Dart iterable API.
  no setter
wait → Future<List<T>>

  Available on Iterable<Future<T>>, provided by the FutureIterable extension

  Waits for futures in parallel.
  no setter

## Methods

add(E value) → void
  Adds `value` at the end of the queue.
  override
addAll(Iterable<E> elements) → void
  Adds all elements of `iterable` at the end of the queue. The length of the queue is extended by the length of `iterable`.
  override
addFirst(E value) → void
  Adds `value` at the beginning of the queue.
  override
addLast(E value) → void
  Adds `value` at the end of the queue.
  override
any(bool test(E element)) → bool
  Checks whether any element of this iterable satisfies `test`.
  inherited
asNameMap() → Map<String, T>

  Available on Iterable<T>, provided by the EnumByName extension

  Creates a map from the names of enum values to the values.
byName(String name) → T

  Available on Iterable<T>, provided by the EnumByName extension

  Finds the enum value in this list with name `name`.
cast<R>() → Queue<R>
  A view of this iterable as an iterable of `R` instances.
  override
clear() → void
  Removes all elements in the queue. The size of the queue becomes zero.
  override
contains(Object? element) → bool
  Whether the collection contains an element equal to `element`.
  inherited
elementAt(int index) → E
  Returns the `index`th element.
elementAtOrNull(int index) → T?

  Available on Iterable<T>, provided by the IterableExtensions extension

  The element at position `index` of this iterable, or `null`.
every(bool test(E element)) → bool
  Checks whether every element of this iterable satisfies `test`.
  inherited
expand<T>(Iterable<T> toElements(E element)) → Iterable<T>
  Expands each element of this Iterable into zero or more elements.
  inherited
firstWhere(bool test(E element), {E orElse()?}) → E
  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>
  Creates the lazy concatenation of this iterable and `other`.
  inherited
forEach(void f(E value)) → void
  Invokes `action` on each element of this iterable in iteration order.
join([String separator = ""]) → String
  Converts each element to a String and concatenates the strings.
  inherited
lastWhere(bool test(E element), {E orElse()?}) → E
  The last element that satisfies the given predicate `test`.
  inherited
map<T>(T toElement(E element)) → Iterable<T>
  The current elements of this iterable modified by `toElement`.
  inherited
noSuchMethod(Invocation invocation) → dynamic
  Invoked when a nonexistent 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
remove(Object? value) → bool
  Removes a single instance of `value` from the queue.
  override
removeFirst() → E
  Removes and returns the first element of this queue.
  override
removeLast() → E
  Removes and returns the last element of the queue.
  override
removeWhere(bool test(E element)) → void
  Remove all elements matched by `test`.
  override
retainWhere(bool test(E element)) → void
  Remove all elements not matched by `test`.
  override
singleWhere(bool test(E element), {E orElse()?}) → E
  The single element that satisfies `test`.
  inherited
skip(int count) → Iterable<E>
  Creates an Iterable that provides all but the first `count` elements.
  inherited
skipWhile(bool test(E element)) → Iterable<E>
  Creates an `Iterable` that skips leading elements while `test` is satisfied.
  inherited
take(int count) → Iterable<E>
  Creates a lazy iterable of the `count` first elements of this iterable.
  inherited
takeWhile(bool test(E element)) → Iterable<E>
  Creates 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.
toSet() → Set<E>
  Creates a Set containing the same elements as this iterable.
  inherited
toString() → String
  Returns a string representation of (some of) the elements of `this`.
  override
where(bool test(E element)) → Iterable<E>
  Creates a new lazy Iterable with all elements that satisfy the predicate `test`.
  inherited
whereType<T>() → Iterable<T>
  Creates a new lazy Iterable with all elements that have type `T`.
  inherited

## Operators

operator ==(Object other) → bool
  The equality operator.
  inherited