Struct std::collections::BTreeSet

pub struct BTreeSet<T> { /* fields omitted */ }

A 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.

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);
}

Methods

impl<T> BTreeSet<T> where T: Ord

fn new() -> BTreeSet<T>

Makes a new BTreeSet with a reasonable choice of B.

Examples

use std::collections::BTreeSet;

let mut set: BTreeSet<i32> = BTreeSet::new();

impl<T> BTreeSet<T>

fn iter(&self) -> Iter<T>

Gets an iterator that visits the values in the BTreeSet in ascending order.

Examples

use std::collections::BTreeSet;

let set: BTreeSet<usize> = [1, 2, 3].iter().cloned().collect();
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);

Values returned by the iterator are returned in ascending order:

use std::collections::BTreeSet;

let set: BTreeSet<usize> = [3, 1, 2].iter().cloned().collect();
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);

impl<T> BTreeSet<T> where T: Ord

fn range<K, R>(&self, range: R) -> Range<T> where K: Ord + ?Sized, R: RangeArgument<K>, T: Borrow<K>

🔬 This is a nightly-only experimental API.   (btree_range)

matches collection reform specification, waiting for dust to settle

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.

Examples

#![feature(btree_range, collections_bound)]

use std::collections::BTreeSet;
use std::collections::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());

impl<T> BTreeSet<T> where T: Ord

fn difference(&'a self, other: &'a BTreeSet<T>) -> Difference<'a, T>

Visits the values representing the difference, 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]);

fn symmetric_difference(&'a self,
                        other: &'a BTreeSet<T>)
                        -> SymmetricDifference<'a, T>

Visits the values representing the symmetric difference, 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]);

fn intersection(&'a self, other: &'a BTreeSet<T>) -> Intersection<'a, T>

Visits the values representing the intersection, 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]);

fn union(&'a self, other: &'a BTreeSet<T>) -> Union<'a, T>

Visits the values representing the union, 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]);

fn len(&self) -> usize

Returns the number of elements in the set.

Examples

use std::collections::BTreeSet;

let mut v = BTreeSet::new();
assert_eq!(v.len(), 0);
v.insert(1);
assert_eq!(v.len(), 1);

fn is_empty(&self) -> bool

Returns true if the set contains no elements.

Examples

use std::collections::BTreeSet;

let mut v = BTreeSet::new();
assert!(v.is_empty());
v.insert(1);
assert!(!v.is_empty());

fn clear(&mut self)

Clears the set, removing all values.

Examples

use std::collections::BTreeSet;

let mut v = BTreeSet::new();
v.insert(1);
v.clear();
assert!(v.is_empty());

fn contains<Q>(&self, value: &Q) -> bool where Q: Ord + ?Sized, T: Borrow<Q>

Returns true if the set contains a value.

The value may be any borrowed form of the set's value type, but the ordering on the borrowed form must match the ordering on the value type.

Examples

use std::collections::BTreeSet;

let set: BTreeSet<_> = [1, 2, 3].iter().cloned().collect();
assert_eq!(set.contains(&1), true);
assert_eq!(set.contains(&4), false);

fn get<Q>(&self, value: &Q) -> Option<&T> where Q: Ord + ?Sized, T: Borrow<Q>

Returns a reference to the value in the set, if any, that is equal to the given value.

The value may be any borrowed form of the set's value type, but the ordering on the borrowed form must match the ordering on the value type.

fn is_disjoint(&self, other: &BTreeSet<T>) -> bool

Returns true if the set has no elements in common with other. This is equivalent to checking for an empty intersection.

Examples

use std::collections::BTreeSet;

let a: BTreeSet<_> = [1, 2, 3].iter().cloned().collect();
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);

fn is_subset(&self, other: &BTreeSet<T>) -> bool

Returns true if the set is a subset of another.

Examples

use std::collections::BTreeSet;

let sup: BTreeSet<_> = [1, 2, 3].iter().cloned().collect();
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);

fn is_superset(&self, other: &BTreeSet<T>) -> bool

Returns true if the set is a superset of another.

Examples

use std::collections::BTreeSet;

let sub: BTreeSet<_> = [1, 2].iter().cloned().collect();
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);

fn insert(&mut self, value: T) -> bool

Adds a value to the set.

If the set did not have this value present, true is returned.

If the set did have this value present, 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);

fn replace(&mut self, value: T) -> Option<T>

Adds a value to the set, replacing the existing value, if any, that is equal to the given one. Returns the replaced value.

fn remove<Q>(&mut self, value: &Q) -> bool where Q: Ord + ?Sized, T: Borrow<Q>

Removes a value from the set. Returns true if the value was present in the set.

The value may be any borrowed form of the set's value type, but the ordering on the borrowed form must match the ordering on the value 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);

fn take<Q>(&mut self, value: &Q) -> Option<T> where Q: Ord + ?Sized, T: Borrow<Q>

Removes and returns the value in the set, if any, that is equal to the given one.

The value may be any borrowed form of the set's value type, but the ordering on the borrowed form must match the ordering on the value type.

fn append(&mut self, other: &mut BTreeSet<T>)

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));

fn split_off<Q>(&mut self, key: &Q) -> BTreeSet<T> where Q: Ord + ?Sized, T: Borrow<Q>

Splits the collection into two at the given key. Returns everything after the given key, including the key.

Examples

Basic usage:

use std::collections::BTreeMap;

let mut a = BTreeMap::new();
a.insert(1, "a");
a.insert(2, "b");
a.insert(3, "c");
a.insert(17, "d");
a.insert(41, "e");

let b = a.split_off(&3);

assert_eq!(a.len(), 2);
assert_eq!(b.len(), 3);

assert_eq!(a[&1], "a");
assert_eq!(a[&2], "b");

assert_eq!(b[&3], "c");
assert_eq!(b[&17], "d");
assert_eq!(b[&41], "e");

Trait Implementations

impl<T> Default for BTreeSet<T> where T: Ord

fn default() -> BTreeSet<T>

Makes an empty BTreeSet<T> with a reasonable choice of B.

impl<T> Hash for BTreeSet<T> where T: Hash

fn hash<__HT>(&self, __arg_0: &mut __HT) where __HT: Hasher

Feeds this value into the state given, updating the hasher as necessary.

fn hash_slice<H>(data: &[Self], state: &mut H) where H: Hasher

Feeds a slice of this type into the state provided.

impl<T> PartialEq<BTreeSet<T>> for BTreeSet<T> where T: PartialEq<T>

fn eq(&self, __arg_0: &BTreeSet<T>) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, __arg_0: &BTreeSet<T>) -> bool

This method tests for !=.

impl<T> PartialOrd<BTreeSet<T>> for BTreeSet<T> where T: PartialOrd<T>

fn partial_cmp(&self, __arg_0: &BTreeSet<T>) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

fn lt(&self, __arg_0: &BTreeSet<T>) -> bool

This method tests less than (for self and other) and is used by the < operator.

fn le(&self, __arg_0: &BTreeSet<T>) -> bool

This method tests less than or equal to (for self and other) and is used by the <= operator.

fn gt(&self, __arg_0: &BTreeSet<T>) -> bool

This method tests greater than (for self and other) and is used by the > operator.

fn ge(&self, __arg_0: &BTreeSet<T>) -> bool

This method tests greater than or equal to (for self and other) and is used by the >= operator.

impl<'a, 'b, T> Sub<&'b BTreeSet<T>> for &'a BTreeSet<T> where T: Ord + Clone

type Output = BTreeSet<T>

The resulting type after applying the - operator

fn sub(self, rhs: &BTreeSet<T>) -> BTreeSet<T>

Returns the difference of self and rhs as a new BTreeSet<T>.

Examples

use std::collections::BTreeSet;

let a: BTreeSet<_> = vec![1, 2, 3].into_iter().collect();
let b: BTreeSet<_> = vec![3, 4, 5].into_iter().collect();

let result = &a - &b;
let result_vec: Vec<_> = result.into_iter().collect();
assert_eq!(result_vec, [1, 2]);

impl<T> Clone for BTreeSet<T> where T: Clone

fn clone(&self) -> BTreeSet<T>

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<'a, 'b, T> BitXor<&'b BTreeSet<T>> for &'a BTreeSet<T> where T: Ord + Clone

type Output = BTreeSet<T>

The resulting type after applying the ^ operator

fn bitxor(self, rhs: &BTreeSet<T>) -> BTreeSet<T>

Returns the symmetric difference of self and rhs as a new BTreeSet<T>.

Examples

use std::collections::BTreeSet;

let a: BTreeSet<_> = vec![1, 2, 3].into_iter().collect();
let b: BTreeSet<_> = vec![2, 3, 4].into_iter().collect();

let result = &a ^ &b;
let result_vec: Vec<_> = result.into_iter().collect();
assert_eq!(result_vec, [1, 4]);

impl<T> Eq for BTreeSet<T> where T: Eq

impl<T> IntoIterator for BTreeSet<T>

type Item = T

The type of the elements being iterated over.

type IntoIter = IntoIter<T>

Which kind of iterator are we turning this into?

fn into_iter(self) -> IntoIter<T>

Gets an iterator for moving out the BtreeSet's contents.

Examples

use std::collections::BTreeSet;

let set: BTreeSet<usize> = [1, 2, 3, 4].iter().cloned().collect();

let v: Vec<_> = set.into_iter().collect();
assert_eq!(v, [1, 2, 3, 4]);

impl<'a, T> IntoIterator for &'a BTreeSet<T>

type Item = &'a T

The type of the elements being iterated over.

type IntoIter = Iter<'a, T>

Which kind of iterator are we turning this into?

fn into_iter(self) -> Iter<'a, T>

Creates an iterator from a value.

impl<T> Debug for BTreeSet<T> where T: Debug

fn fmt(&self, f: &mut Formatter) -> Result<(), Error>

Formats the value using the given formatter.

impl<T> Ord for BTreeSet<T> where T: Ord

fn cmp(&self, __arg_0: &BTreeSet<T>) -> Ordering

This method returns an Ordering between self and other.

impl<T> FromIterator<T> for BTreeSet<T> where T: Ord

fn from_iter<I>(iter: I) -> BTreeSet<T> where I: IntoIterator<Item=T>

Creates a value from an iterator.

impl<'a, 'b, T> BitAnd<&'b BTreeSet<T>> for &'a BTreeSet<T> where T: Ord + Clone

type Output = BTreeSet<T>

The resulting type after applying the & operator

fn bitand(self, rhs: &BTreeSet<T>) -> BTreeSet<T>

Returns the intersection of self and rhs as a new BTreeSet<T>.

Examples

use std::collections::BTreeSet;

let a: BTreeSet<_> = vec![1, 2, 3].into_iter().collect();
let b: BTreeSet<_> = vec![2, 3, 4].into_iter().collect();

let result = &a & &b;
let result_vec: Vec<_> = result.into_iter().collect();
assert_eq!(result_vec, [2, 3]);

impl<'a, 'b, T> BitOr<&'b BTreeSet<T>> for &'a BTreeSet<T> where T: Ord + Clone

type Output = BTreeSet<T>

The resulting type after applying the | operator

fn bitor(self, rhs: &BTreeSet<T>) -> BTreeSet<T>

Returns the union of self and rhs as a new BTreeSet<T>.

Examples

use std::collections::BTreeSet;

let a: BTreeSet<_> = vec![1, 2, 3].into_iter().collect();
let b: BTreeSet<_> = vec![3, 4, 5].into_iter().collect();

let result = &a | &b;
let result_vec: Vec<_> = result.into_iter().collect();
assert_eq!(result_vec, [1, 2, 3, 4, 5]);

impl<T> Extend<T> for BTreeSet<T> where T: Ord

fn extend<Iter>(&mut self, iter: Iter) where Iter: IntoIterator<Item=T>

Extends a collection with the contents of an iterator.

impl<'a, T> Extend<&'a T> for BTreeSet<T> where T: 'a + Copy + Ord

fn extend<I>(&mut self, iter: I) where I: IntoIterator<Item=&'a T>

Extends a collection with the contents of an iterator.