Struct std::collections::btree_set::BTreeSet
1.0.0 · source · pub struct BTreeSet<T, A = Global>{ /* private fields */ }
Expand description
An ordered set based on a B-Tree.
See BTreeMap
’s documentation for a detailed discussion of this collection’s performance
benefits and drawbacks.
It is a logic error for an item to be modified in such a way that the item’s ordering relative
to any other item, as determined by the Ord
trait, changes while it is in the set. This is
normally only possible through Cell
, RefCell
, global state, I/O, or unsafe code.
The behavior resulting from such a logic error is not specified, but will be encapsulated to the
BTreeSet
that observed the logic error and not result in undefined behavior. This could
include panics, incorrect results, aborts, memory leaks, and non-termination.
Iterators returned by BTreeSet::iter
produce their items in order, and take worst-case
logarithmic and amortized constant time per item returned.
§Examples
use std::collections::BTreeSet;
// Type inference lets us omit an explicit type signature (which
// would be `BTreeSet<&str>` in this example).
let mut books = BTreeSet::new();
// Add some books.
books.insert("A Dance With Dragons");
books.insert("To Kill a Mockingbird");
books.insert("The Odyssey");
books.insert("The Great Gatsby");
// Check for a specific one.
if !books.contains("The Winds of Winter") {
println!("We have {} books, but The Winds of Winter ain't one.",
books.len());
}
// Remove a book.
books.remove("The Odyssey");
// Iterate over everything.
for book in &books {
println!("{book}");
}
RunA BTreeSet
with a known list of items can be initialized from an array:
use std::collections::BTreeSet;
let set = BTreeSet::from([1, 2, 3]);
RunImplementations§
source§impl<T, A> BTreeSet<T, A>
impl<T, A> BTreeSet<T, A>
sourcepub const fn new_in(alloc: A) -> BTreeSet<T, A>
🔬This is a nightly-only experimental API. (btreemap_alloc
#32838)
pub const fn new_in(alloc: A) -> BTreeSet<T, A>
btreemap_alloc
#32838)1.17.0 · sourcepub fn range<K, R>(&self, range: R) -> Range<'_, T> ⓘ
pub fn range<K, R>(&self, range: R) -> Range<'_, T> ⓘ
Constructs a double-ended iterator over a sub-range of elements in the set.
The simplest way is to use the range syntax min..max
, thus range(min..max)
will
yield elements from min (inclusive) to max (exclusive).
The range may also be entered as (Bound<T>, Bound<T>)
, so for example
range((Excluded(4), Included(10)))
will yield a left-exclusive, right-inclusive
range from 4 to 10.
§Panics
Panics if range start > end
.
Panics if range start == end
and both bounds are Excluded
.
§Examples
use std::collections::BTreeSet;
use std::ops::Bound::Included;
let mut set = BTreeSet::new();
set.insert(3);
set.insert(5);
set.insert(8);
for &elem in set.range((Included(&4), Included(&8))) {
println!("{elem}");
}
assert_eq!(Some(&5), set.range(4..).next());
Runsourcepub fn difference<'a>(
&'a self,
other: &'a BTreeSet<T, A>
) -> Difference<'a, T, A> ⓘwhere
T: Ord,
pub fn difference<'a>(
&'a self,
other: &'a BTreeSet<T, A>
) -> Difference<'a, T, A> ⓘwhere
T: Ord,
Visits the elements representing the difference,
i.e., the elements that are in self
but not in other
,
in ascending order.
§Examples
use std::collections::BTreeSet;
let mut a = BTreeSet::new();
a.insert(1);
a.insert(2);
let mut b = BTreeSet::new();
b.insert(2);
b.insert(3);
let diff: Vec<_> = a.difference(&b).cloned().collect();
assert_eq!(diff, [1]);
Runsourcepub fn symmetric_difference<'a>(
&'a self,
other: &'a BTreeSet<T, A>
) -> SymmetricDifference<'a, T> ⓘwhere
T: Ord,
pub fn symmetric_difference<'a>(
&'a self,
other: &'a BTreeSet<T, A>
) -> SymmetricDifference<'a, T> ⓘwhere
T: Ord,
Visits the elements representing the symmetric difference,
i.e., the elements that are in self
or in other
but not in both,
in ascending order.
§Examples
use std::collections::BTreeSet;
let mut a = BTreeSet::new();
a.insert(1);
a.insert(2);
let mut b = BTreeSet::new();
b.insert(2);
b.insert(3);
let sym_diff: Vec<_> = a.symmetric_difference(&b).cloned().collect();
assert_eq!(sym_diff, [1, 3]);
Runsourcepub fn intersection<'a>(
&'a self,
other: &'a BTreeSet<T, A>
) -> Intersection<'a, T, A> ⓘwhere
T: Ord,
pub fn intersection<'a>(
&'a self,
other: &'a BTreeSet<T, A>
) -> Intersection<'a, T, A> ⓘwhere
T: Ord,
Visits the elements representing the intersection,
i.e., the elements that are both in self
and other
,
in ascending order.
§Examples
use std::collections::BTreeSet;
let mut a = BTreeSet::new();
a.insert(1);
a.insert(2);
let mut b = BTreeSet::new();
b.insert(2);
b.insert(3);
let intersection: Vec<_> = a.intersection(&b).cloned().collect();
assert_eq!(intersection, [2]);
Runsourcepub fn union<'a>(&'a self, other: &'a BTreeSet<T, A>) -> Union<'a, T> ⓘwhere
T: Ord,
pub fn union<'a>(&'a self, other: &'a BTreeSet<T, A>) -> Union<'a, T> ⓘwhere
T: Ord,
Visits the elements representing the union,
i.e., all the elements in self
or other
, without duplicates,
in ascending order.
§Examples
use std::collections::BTreeSet;
let mut a = BTreeSet::new();
a.insert(1);
let mut b = BTreeSet::new();
b.insert(2);
let union: Vec<_> = a.union(&b).cloned().collect();
assert_eq!(union, [1, 2]);
Runsourcepub fn contains<Q>(&self, value: &Q) -> bool
pub fn contains<Q>(&self, value: &Q) -> bool
Returns true
if the set contains an element equal to the value.
The value may be any borrowed form of the set’s element type, but the ordering on the borrowed form must match the ordering on the element type.
§Examples
use std::collections::BTreeSet;
let set = BTreeSet::from([1, 2, 3]);
assert_eq!(set.contains(&1), true);
assert_eq!(set.contains(&4), false);
Run1.9.0 · sourcepub fn get<Q>(&self, value: &Q) -> Option<&T>
pub fn get<Q>(&self, value: &Q) -> Option<&T>
Returns a reference to the element in the set, if any, that is equal to the value.
The value may be any borrowed form of the set’s element type, but the ordering on the borrowed form must match the ordering on the element type.
§Examples
use std::collections::BTreeSet;
let set = BTreeSet::from([1, 2, 3]);
assert_eq!(set.get(&2), Some(&2));
assert_eq!(set.get(&4), None);
Runsourcepub fn is_disjoint(&self, other: &BTreeSet<T, A>) -> boolwhere
T: Ord,
pub fn is_disjoint(&self, other: &BTreeSet<T, A>) -> boolwhere
T: Ord,
Returns true
if self
has no elements in common with other
.
This is equivalent to checking for an empty intersection.
§Examples
use std::collections::BTreeSet;
let a = BTreeSet::from([1, 2, 3]);
let mut b = BTreeSet::new();
assert_eq!(a.is_disjoint(&b), true);
b.insert(4);
assert_eq!(a.is_disjoint(&b), true);
b.insert(1);
assert_eq!(a.is_disjoint(&b), false);
Runsourcepub fn is_subset(&self, other: &BTreeSet<T, A>) -> boolwhere
T: Ord,
pub fn is_subset(&self, other: &BTreeSet<T, A>) -> boolwhere
T: Ord,
Returns true
if the set is a subset of another,
i.e., other
contains at least all the elements in self
.
§Examples
use std::collections::BTreeSet;
let sup = BTreeSet::from([1, 2, 3]);
let mut set = BTreeSet::new();
assert_eq!(set.is_subset(&sup), true);
set.insert(2);
assert_eq!(set.is_subset(&sup), true);
set.insert(4);
assert_eq!(set.is_subset(&sup), false);
Runsourcepub fn is_superset(&self, other: &BTreeSet<T, A>) -> boolwhere
T: Ord,
pub fn is_superset(&self, other: &BTreeSet<T, A>) -> boolwhere
T: Ord,
Returns true
if the set is a superset of another,
i.e., self
contains at least all the elements in other
.
§Examples
use std::collections::BTreeSet;
let sub = BTreeSet::from([1, 2]);
let mut set = BTreeSet::new();
assert_eq!(set.is_superset(&sub), false);
set.insert(0);
set.insert(1);
assert_eq!(set.is_superset(&sub), false);
set.insert(2);
assert_eq!(set.is_superset(&sub), true);
Run1.66.0 · sourcepub fn first(&self) -> Option<&T>where
T: Ord,
pub fn first(&self) -> Option<&T>where
T: Ord,
Returns a reference to the first element in the set, if any. This element is always the minimum of all elements in the set.
§Examples
Basic usage:
use std::collections::BTreeSet;
let mut set = BTreeSet::new();
assert_eq!(set.first(), None);
set.insert(1);
assert_eq!(set.first(), Some(&1));
set.insert(2);
assert_eq!(set.first(), Some(&1));
Run1.66.0 · sourcepub fn last(&self) -> Option<&T>where
T: Ord,
pub fn last(&self) -> Option<&T>where
T: Ord,
Returns a reference to the last element in the set, if any. This element is always the maximum of all elements in the set.
§Examples
Basic usage:
use std::collections::BTreeSet;
let mut set = BTreeSet::new();
assert_eq!(set.last(), None);
set.insert(1);
assert_eq!(set.last(), Some(&1));
set.insert(2);
assert_eq!(set.last(), Some(&2));
Runsourcepub fn insert(&mut self, value: T) -> boolwhere
T: Ord,
pub fn insert(&mut self, value: T) -> boolwhere
T: Ord,
Adds a value to the set.
Returns whether the value was newly inserted. That is:
- If the set did not previously contain an equal value,
true
is returned. - If the set already contained an equal value,
false
is returned, and the entry is not updated.
See the module-level documentation for more.
§Examples
use std::collections::BTreeSet;
let mut set = BTreeSet::new();
assert_eq!(set.insert(2), true);
assert_eq!(set.insert(2), false);
assert_eq!(set.len(), 1);
Run1.9.0 · sourcepub fn replace(&mut self, value: T) -> Option<T>where
T: Ord,
pub fn replace(&mut self, value: T) -> Option<T>where
T: Ord,
Adds a value to the set, replacing the existing element, if any, that is equal to the value. Returns the replaced element.
§Examples
use std::collections::BTreeSet;
let mut set = BTreeSet::new();
set.insert(Vec::<i32>::new());
assert_eq!(set.get(&[][..]).unwrap().capacity(), 0);
set.replace(Vec::with_capacity(10));
assert_eq!(set.get(&[][..]).unwrap().capacity(), 10);
Runsourcepub fn remove<Q>(&mut self, value: &Q) -> bool
pub fn remove<Q>(&mut self, value: &Q) -> bool
If the set contains an element equal to the value, removes it from the set and drops it. Returns whether such an element was present.
The value may be any borrowed form of the set’s element type, but the ordering on the borrowed form must match the ordering on the element type.
§Examples
use std::collections::BTreeSet;
let mut set = BTreeSet::new();
set.insert(2);
assert_eq!(set.remove(&2), true);
assert_eq!(set.remove(&2), false);
Run1.9.0 · sourcepub fn take<Q>(&mut self, value: &Q) -> Option<T>
pub fn take<Q>(&mut self, value: &Q) -> Option<T>
Removes and returns the element in the set, if any, that is equal to the value.
The value may be any borrowed form of the set’s element type, but the ordering on the borrowed form must match the ordering on the element type.
§Examples
use std::collections::BTreeSet;
let mut set = BTreeSet::from([1, 2, 3]);
assert_eq!(set.take(&2), Some(2));
assert_eq!(set.take(&2), None);
Run1.53.0 · sourcepub fn retain<F>(&mut self, f: F)
pub fn retain<F>(&mut self, f: F)
Retains only the elements specified by the predicate.
In other words, remove all elements e
for which f(&e)
returns false
.
The elements are visited in ascending order.
§Examples
use std::collections::BTreeSet;
let mut set = BTreeSet::from([1, 2, 3, 4, 5, 6]);
// Keep only the even numbers.
set.retain(|&k| k % 2 == 0);
assert!(set.iter().eq([2, 4, 6].iter()));
Run1.11.0 · sourcepub fn append(&mut self, other: &mut BTreeSet<T, A>)
pub fn append(&mut self, other: &mut BTreeSet<T, A>)
Moves all elements from other
into self
, leaving other
empty.
§Examples
use std::collections::BTreeSet;
let mut a = BTreeSet::new();
a.insert(1);
a.insert(2);
a.insert(3);
let mut b = BTreeSet::new();
b.insert(3);
b.insert(4);
b.insert(5);
a.append(&mut b);
assert_eq!(a.len(), 5);
assert_eq!(b.len(), 0);
assert!(a.contains(&1));
assert!(a.contains(&2));
assert!(a.contains(&3));
assert!(a.contains(&4));
assert!(a.contains(&5));
Run1.11.0 · sourcepub fn split_off<Q>(&mut self, value: &Q) -> BTreeSet<T, A>
pub fn split_off<Q>(&mut self, value: &Q) -> BTreeSet<T, A>
Splits the collection into two at the value. Returns a new collection with all elements greater than or equal to the value.
§Examples
Basic usage:
use std::collections::BTreeSet;
let mut a = BTreeSet::new();
a.insert(1);
a.insert(2);
a.insert(3);
a.insert(17);
a.insert(41);
let b = a.split_off(&3);
assert_eq!(a.len(), 2);
assert_eq!(b.len(), 3);
assert!(a.contains(&1));
assert!(a.contains(&2));
assert!(b.contains(&3));
assert!(b.contains(&17));
assert!(b.contains(&41));
Runsourcepub fn extract_if<'a, F>(&'a mut self, pred: F) -> ExtractIf<'a, T, F, A> ⓘ
🔬This is a nightly-only experimental API. (btree_extract_if
#70530)
pub fn extract_if<'a, F>(&'a mut self, pred: F) -> ExtractIf<'a, T, F, A> ⓘ
btree_extract_if
#70530)Creates an iterator that visits all elements in ascending order and uses a closure to determine if an element should be removed.
If the closure returns true
, the element is removed from the set and
yielded. If the closure returns false
, or panics, the element remains
in the set and will not be yielded.
If the returned ExtractIf
is not exhausted, e.g. because it is dropped without iterating
or the iteration short-circuits, then the remaining elements will be retained.
Use retain
with a negated predicate if you do not need the returned iterator.
§Examples
Splitting a set into even and odd values, reusing the original set:
#![feature(btree_extract_if)]
use std::collections::BTreeSet;
let mut set: BTreeSet<i32> = (0..8).collect();
let evens: BTreeSet<_> = set.extract_if(|v| v % 2 == 0).collect();
let odds = set;
assert_eq!(evens.into_iter().collect::<Vec<_>>(), vec![0, 2, 4, 6]);
assert_eq!(odds.into_iter().collect::<Vec<_>>(), vec![1, 3, 5, 7]);
Runsourcepub fn iter(&self) -> Iter<'_, T> ⓘ
pub fn iter(&self) -> Iter<'_, T> ⓘ
Gets an iterator that visits the elements in the BTreeSet
in ascending
order.
§Examples
use std::collections::BTreeSet;
let set = BTreeSet::from([3, 1, 2]);
let mut set_iter = set.iter();
assert_eq!(set_iter.next(), Some(&1));
assert_eq!(set_iter.next(), Some(&2));
assert_eq!(set_iter.next(), Some(&3));
assert_eq!(set_iter.next(), None);
RunTrait Implementations§
source§impl<T, A> BitAnd<&BTreeSet<T, A>> for &BTreeSet<T, A>
impl<T, A> BitAnd<&BTreeSet<T, A>> for &BTreeSet<T, A>
source§impl<T, A> BitOr<&BTreeSet<T, A>> for &BTreeSet<T, A>
impl<T, A> BitOr<&BTreeSet<T, A>> for &BTreeSet<T, A>
source§impl<T, A> BitXor<&BTreeSet<T, A>> for &BTreeSet<T, A>
impl<T, A> BitXor<&BTreeSet<T, A>> for &BTreeSet<T, A>
1.2.0 · source§impl<'a, T, A> Extend<&'a T> for BTreeSet<T, A>
impl<'a, T, A> Extend<&'a T> for BTreeSet<T, A>
source§impl<T, A> Extend<T> for BTreeSet<T, A>
impl<T, A> Extend<T> for BTreeSet<T, A>
source§fn extend<Iter>(&mut self, iter: Iter)where
Iter: IntoIterator<Item = T>,
fn extend<Iter>(&mut self, iter: Iter)where
Iter: IntoIterator<Item = T>,
source§fn extend_one(&mut self, elem: T)
fn extend_one(&mut self, elem: T)
extend_one
#72631)