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SplayTreeSet<E> class

A Set of objects that can be ordered relative to each other.

The set is based on a self-balancing binary tree. It allows most operations in amortized logarithmic time.

Elements of the set are compared using the compare function passed in the constructor, both for ordering and for equality. If the set contains only an object a, then set.contains(b) will return true if and only if compare(a, b) == 0, and the value of a == b is not even checked. If the compare function is omitted, the objects are assumed to be Comparable, and are compared using their Comparable.compareTo method. Non-comparable objects (including null) will not work as an element in that case.

Note: Do not modify a set (add or remove elements) while an operation is being performed on that set, for example in functions called during a forEach or containsAll call, or while iterating the set.

Do not modify elements in a way which changes their equality (and thus their hash code) while they are in the set. Some specialized kinds of sets may be more permissive with regards to equality, in which case they should document their different behavior and restrictions.

Example:

final planets = SplayTreeSet<String>((a, b) => a.compareTo(b));

To add data to a set, use add or addAll.

planets.add('Neptune');
planets.addAll({'Venus', 'Mars', 'Earth', 'Jupiter'});
print(planets); // {Earth, Jupiter, Mars, Neptune, Venus}

To check if the set is empty, use isEmpty or isNotEmpty. To find the number of elements in the set, use length.

final isEmpty = planets.isEmpty; // false
final length = planets.length; // 5

To check whether the set contains a specific element, use contains.

final marsExists = planets.contains('Mars'); // true

To get element value using index, use elementAt.

final elementAt = planets.elementAt(1);
print(elementAt); // Jupiter

To make a copy of set, use toSet.

final copySet = planets.toSet(); // a `SplayTreeSet` with the same ordering.
print(copySet); // {Earth, Jupiter, Mars, Neptune, Venus}

To remove an element, use remove.

final removedValue = planets.remove('Mars'); // true
print(planets); // {Earth, Jupiter, Neptune, Venus}

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

planets.removeWhere((element) => element.startsWith('J'));
print(planets); // {Earth, Neptune, Venus}

To removes all elements in this set that do not meet a condition, use retainWhere.

planets.retainWhere((element) => element.contains('Earth'));
print(planets); // {Earth}

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

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

See also:

Set is a base-class for collection of objects.
HashSet the order of the objects in the iterations is not guaranteed.
LinkedHashSet objects stored based on insertion order.

Mixed in types

IterableMixin<E>
SetMixin<E>

Available Extensions

EnumByName

Constructors

SplayTreeSet([int compare(E key1, E key2)?, bool isValidKey(dynamic potentialKey)?]): Create a new SplayTreeSet with the given compare function.
SplayTreeSet.from(Iterable elements, [int compare(E key1, E key2)?, bool isValidKey(dynamic potentialKey)?]) factory: Creates a SplayTreeSet that contains all elements.
SplayTreeSet.of(Iterable<E> elements, [int compare(E key1, E key2)?, bool isValidKey(dynamic potentialKey)?]) factory: Creates a SplayTreeSet from elements.

Properties

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

Methods

add(E element) → bool override: Adds value to the set.
addAll(Iterable<E> elements) → void override: Adds all elements to this set.
any(bool test(E element)) → bool inherited: Checks whether any element of this iterable satisfies test.
cast<R>() → Set<R> override: Provides a view of this iterable as an iterable of R instances.
clear() → void override: Removes all elements from the set.
contains(Object? element) → bool override: Whether the collection contains an element equal to element.
containsAll(Iterable<Object?> other) → bool inherited: Whether this set contains all the elements of other.
difference(Set<Object?> other) → Set<E> override: Creates a new set with the elements of this that are not in other.
elementAt(int index) → E inherited: Returns the indexth element.
every(bool f(E element)) → bool inherited: Checks whether every element of this iterable satisfies test.
expand<T>(Iterable<T> f(E element)) → Iterable<T> inherited: Expands each element of this Iterable into zero or more elements.
firstWhere(bool test(E value), {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 inherited: Invokes action on each element of this iterable in iteration order.
intersection(Set<Object?> other) → Set<E> override: Creates a new set which is the intersection between this set and other.
join([String separator = ""]) → String inherited: Converts each element to a String and concatenates the strings.
lastWhere(bool test(E value), {E orElse()?}) → E inherited: Returns the last element that satisfies the given predicate test.
lookup(Object? object) → E? override: If an object equal to object is in the set, return it.
map<T>(T f(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? object) → bool override: Removes value from the set.
removeAll(Iterable<Object?> elements) → void override: Removes each element of elements from this set.
removeWhere(bool test(E element)) → void inherited: Removes all elements of this set that satisfy test.
retainAll(Iterable<Object?> elements) → void override: Removes all elements of this set that are not elements in elements.
retainWhere(bool test(E element)) → void inherited: Removes all elements of this set that fail to satisfy test.
singleWhere(bool test(E value), {E orElse()?}) → E inherited: Returns the single element that satisfies test.
skip(int n) → Iterable<E> inherited: Returns an Iterable that provides all but the first count elements.
skipWhile(bool test(E value)) → Iterable<E> inherited: Returns an Iterable that skips leading elements while test is satisfied.
take(int n) → Iterable<E> inherited: Returns a lazy iterable of the count first elements of this iterable.
takeWhile(bool test(E value)) → Iterable<E> inherited: Returns a lazy iterable of the leading elements satisfying test.
toList({bool growable = true}) → List<E> inherited: Creates a List containing the elements of this Iterable.
toSet() → Set<E> override: Creates a Set containing the same elements as this iterable.
toString() → String override: A string representation of this object.
union(Set<E> other) → Set<E> override: Creates a new set which contains all the elements of this set and other.
where(bool f(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.

© 2012 the Dart project authors
Licensed under the BSD 3-Clause "New" or "Revised" License.
https://api.dart.dev/stable/2.18.5/dart-collection/SplayTreeSet-class.html