Queue class - dart:collection library (original) (raw)
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 in 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 anIterable returned by a method like map or where.
Example:
final queue = Queue<int>(); // ListQueue() by default
print(queue.runtimeType); // ListQueue
// Adding items to queue
queue.addAll([1, 2, 3]);
queue.addFirst(0);
queue.addLast(10);
print(queue); // {0, 1, 2, 3, 10}
// Removing items from queue
queue.removeFirst();
queue.removeLast();
print(queue); // {1, 2, 3}
Implemented types
- Iterable<E>
Implementers
Available extensions
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
The first element.
no setterinherited
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
The hash code for this object.
no setterinherited
Available on Iterable<T>, provided by the IterableExtensions extension
Pairs of elements of the indices and elements of this iterable.
no setter
Whether this collection has no elements.
no setterinherited
Whether this collection has at least one element.
no setterinherited
A new Iterator that allows iterating the elements of this Iterable.
no setterinherited
last → E
The last element.
no setterinherited
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
The number of elements in this Iterable.
no setterinherited
Available on Iterable<T?>, provided by the NullableIterableExtensions extension
The non-null elements of this iterable.
no setter
A representation of the runtime type of the object.
no setterinherited
single → E
Checks that this iterable has only one element, and returns that element.
no setterinherited
singleOrNull → T?
Available on Iterable<T>, provided by the IterableExtensions extension
The single element of this iterator, or null.
no setter
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.
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.
any(bool test(E element))→ bool
Checks whether any element of this iterable satisfies test.
inherited
Available on Iterable<T>, provided by the EnumByName extension
Creates a map from the names of enum values to the values.
Available on Iterable<T>, provided by the EnumByName extension
Finds the enum value in this list with name name.
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.
contains(Object? element)→ bool
Whether the collection contains an element equal to element.
inherited
Returns the indexth element.
inherited
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 action(E element))→ void
Invokes action on each element of this iterable 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
The last element that satisfies the given predicate test.
inherited
map<T>(T toElement(E e))→ 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
Removes 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.
singleWhere(bool test(E element), {E orElse()?})→ E
The single element that satisfies test.
inherited
Creates an Iterable that provides all but the first count elements.
inherited
skipWhile(bool test(E value))→ Iterable<E>
Creates an Iterable that skips leading elements while test is satisfied.
inherited
Creates a lazy iterable of the count first elements of this iterable.
inherited
takeWhile(bool test(E value))→ 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.
inherited
Creates a Set containing the same elements as this iterable.
inherited
A string representation of this object.
inherited
where(bool test(E element))→ Iterable<E>
Creates a new lazy Iterable with all elements that satisfy the predicate test.
inherited
Creates a new lazy Iterable with all elements that have type T.
inherited
Operators
operator ==(Object other)→ bool
The equality operator.
inherited
Static Methods
castFrom<S, T>(Queue<S> source)→ Queue<T>
Adapts source to be a Queue<T>.
override