description

# SplayTreeSet<E> class final

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
  - Iterable<E>
  - SetMixin<E>
Available extensions
  - EnumByName
  - FutureIterable
  - IterableExtensions
  - IterableToJSIterable
  - NullableIterableExtensions

## Constructors

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

## Properties

first → E
  The first element.
  no setteroverride
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 setterinherited
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 setteroverride
isNotEmpty → bool
  Whether this collection has at least one element.
  no setteroverride
iterator → Iterator<E>
  A new `Iterator` that allows iterating the elements of this `Iterable`.
  no setteroverride
last → E
  The last element.
  no setteroverride
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
  The number of elements in this Iterable.
  no setteroverride
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 setterinherited
single → E
  Checks that this iterable has only one element, and returns that element.
  no setteroverride
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 element) → bool
  Adds `value` to the set.
  override
addAll(Iterable<E> elements) → void
  Adds all `elements` to this set.
  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>() → Set<R>
  A view of this iterable as an iterable of `R` instances.
  override
clear() → void
  Removes all elements from the set.
  override
contains(Object? element) → bool
  Whether the collection contains an element equal to `element`.
  override
containsAll(Iterable<Object?> other) → bool
  Whether this set contains all the elements of `other`.
  inherited
difference(Set<Object?> other) → Set<E>
  Creates a new set with the elements of this that are not in `other`.
  override
elementAt(int index) → E
  Returns the `index`th 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 f(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
  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 element)) → void
  Invokes `action` on each element of this iterable in iteration order.
  inherited
intersection(Set<Object?> other) → Set<E>
  Creates a new set which is the intersection between this set and `other`.
  override
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
lookup(Object? object) → E?
  If an object equal to `object` is in the set, return it.
  override
map<T>(T f(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? object) → bool
  Removes `value` from the set.
  override
removeAll(Iterable<Object?> elements) → void
  Removes each element of `elements` from this set.
  override
removeWhere(bool test(E element)) → void
  Removes all elements of this set that satisfy `test`.
  inherited
retainAll(Iterable<Object?> elements) → void
  Removes all elements of this set that are not elements in `elements`.
  override
retainWhere(bool test(E element)) → void
  Removes all elements of this set that fail to satisfy `test`.
  inherited
singleWhere(bool test(E element), {E orElse()?}) → E
  The single element that satisfies `test`.
  inherited
skip(int n) → 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 n) → 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.
  inherited
toSet() → Set<E>
  Creates a Set containing the same elements as this iterable.
  override
toString() → String
  A string representation of this object.
  override
union(Set<E> other) → Set<E>
  Creates a new set which contains all the elements of this set and `other`.
  override
where(bool f(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