dart:collection
ListQueue<E> class
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
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- Implemented types
-
- Available Extensions
Constructors
- ListQueue([int? initialCapacity])
- Create an empty queue.
- ListQueue.from(Iterable elements)
factory
- Create a
ListQueue containing all elements. - ListQueue.of(Iterable<E> elements)
factory
- Create a
ListQueue from elements.
Properties
- first → E
read-only
- Returns the first element.
- hashCode → int
read-only, inherited
- The hash code for this object.
- isEmpty → bool
read-only
- Whether this collection has no elements.
- isNotEmpty → bool
read-only, inherited
- Whether this collection has at least one element.
- iterator → Iterator<E>
read-only
- Returns a new
Iterator that allows iterating the elements of this Iterable. - last → E
read-only
- Returns the last element.
- length → int
read-only
- Returns the number of elements in the iterable.
- runtimeType → Type
read-only, inherited
- A representation of the runtime type of the object.
- single → E
read-only
- Checks that this iterable has only one element, and returns that element.
Methods
- add(E value) → void
override
- Adds
value at the end of the queue. - addAll(Iterable<E> elements) → void
override
- 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
override
- Adds
value at the beginning of the queue. - addLast(E value) → void
override
- Adds
value at the end of the queue. - any(bool test(E element)) → bool
inherited
- Checks whether any element of this iterable satisfies
test. - cast<R>() → Queue<R>
override
- Provides a view of this iterable as an iterable of
R instances. - clear() → void
override
- Removes all elements in the queue. The size of the queue becomes zero.
- contains(Object? element) → bool
inherited
- Whether the collection contains an element equal to
element. - elementAt(int index) → E
- Returns the
indexth element. - every(bool test(E element)) → bool
inherited
- Checks whether every element of this iterable satisfies
test. - expand<T>(Iterable<T> toElements(E element)) → Iterable<T>
inherited
- Expands each element of this Iterable into zero or more elements.
- firstWhere(bool test(E element), {E orElse()?}) → E
inherited
- Returns the first element that satisfies the given predicate
test. - fold<T>(T initialValue, T combine(T previousValue, E element)) → T
inherited
- Reduces a collection to a single value by iteratively combining each element of the collection with an existing value
- followedBy(Iterable<E> other) → Iterable<E>
inherited
- Returns the lazy concatenation of this iterable and
other. - forEach(void f(E element)) → void
- Invokes
action on each element of this iterable in iteration order. - join([String separator = ""]) → String
inherited
- Converts each element to a String and concatenates the strings.
- lastWhere(bool test(E element), {E orElse()?}) → E
inherited
- Returns the last element that satisfies the given predicate
test. - map<T>(T toElement(E element)) → Iterable<T>
inherited
- The current elements of this iterable modified by
toElement. - noSuchMethod(Invocation invocation) → dynamic
inherited
- Invoked when a non-existent method or property is accessed.
- reduce(E combine(E value, E element)) → E
inherited
- Reduces a collection to a single value by iteratively combining elements of the collection using the provided function.
- remove(Object? value) → bool
override
- Removes a single instance of
value from the queue. - removeFirst() → E
override
- Removes and returns the first element of this queue.
- removeLast() → E
override
- Removes and returns the last element of the queue.
- removeWhere(bool test(E element)) → void
override
- Remove all elements matched by
test. - retainWhere(bool test(E element)) → void
override
- Remove all elements not matched by
test. - singleWhere(bool test(E element), {E orElse()?}) → E
inherited
- Returns the single element that satisfies
test. - skip(int count) → Iterable<E>
inherited
- Returns an Iterable that provides all but the first
count elements. - skipWhile(bool test(E element)) → Iterable<E>
inherited
- Returns an
Iterable that skips leading elements while test is satisfied. - take(int count) → Iterable<E>
inherited
- Returns a lazy iterable of the
count first elements of this iterable. - takeWhile(bool test(E element)) → Iterable<E>
inherited
- Returns a lazy iterable of the leading elements satisfying
test. - toList({bool growable = true}) → List<E>
- Creates a List containing the elements of this Iterable.
- toSet() → Set<E>
inherited
- Creates a Set containing the same elements as this iterable.
- toString() → String
override
- Returns a string representation of (some of) the elements of
this. - where(bool test(E element)) → Iterable<E>
inherited
- Returns a new lazy Iterable with all elements that satisfy the predicate
test. - whereType<T>() → Iterable<T>
inherited
- Returns a new lazy Iterable with all elements that have type
T.
Operators
- operator ==(Object other) → bool
inherited
- The equality operator.