Struct std::collections::BTreeSet
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pub struct BTreeSet<T> {
// some fields omitted
}1.0.0A 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
fn main() { 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); } }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 difference(&'a self, other: &'a BTreeSet<T>) -> Difference<'a, T>
Visits the values representing the difference, in ascending order.
Examples
fn main() { 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]); }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
fn main() { 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]); }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
fn main() { 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]); }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
fn main() { 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]); }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
fn main() { use std::collections::BTreeSet; let mut v = BTreeSet::new(); assert_eq!(v.len(), 0); v.insert(1); assert_eq!(v.len(), 1); }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
fn main() { use std::collections::BTreeSet; let mut v = BTreeSet::new(); assert!(v.is_empty()); v.insert(1); assert!(!v.is_empty()); }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
fn main() { use std::collections::BTreeSet; let mut v = BTreeSet::new(); v.insert(1); v.clear(); assert!(v.is_empty()); }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
fn main() { 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); }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>1.9.0
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
fn main() { 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); }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
fn main() { 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); }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
fn main() { 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); }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 a value present, true is returned.
If the set did have this key present, false is returned, and the
entry is not updated. See the module-level documentation for more.
Examples
fn main() { 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); }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>1.9.0
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
fn main() { use std::collections::BTreeSet; let mut set = BTreeSet::new(); set.insert(2); assert_eq!(set.remove(&2), true); assert_eq!(set.remove(&2), false); }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>1.9.0
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
#![feature(btree_append)] fn main() { 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)); }#![feature(btree_append)] 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));
impl<T> BTreeSet<T> where T: Ord
fn range<Min, Max>(&'a self, min: Bound<&Min>, max: Bound<&Max>) -> Range<'a, T> where Min: Ord + ?Sized, T: Borrow<Min> + Borrow<Max>, Max: Ord + ?Sized
Constructs a double-ended iterator over a sub-range of elements in the set, starting
at min, and ending at max. If min is Unbounded, then it will be treated as "negative
infinity", and if max is Unbounded, then it will be treated as "positive infinity".
Thus range(Unbounded, Unbounded) will yield the whole collection.
Examples
#![feature(btree_range, collections_bound)] fn main() { use std::collections::BTreeSet; use std::collections::Bound::{Included, Unbounded}; 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(Included(&4), Unbounded).next()); }#![feature(btree_range, collections_bound)] use std::collections::BTreeSet; use std::collections::Bound::{Included, Unbounded}; 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(Included(&4), Unbounded).next());
impl<T> BTreeSet<T>
fn iter(&self) -> Iter<T>
Gets an iterator over the BTreeSet's contents.
Examples
fn main() { use std::collections::BTreeSet; let set: BTreeSet<usize> = [1, 2, 3, 4].iter().cloned().collect(); for x in set.iter() { println!("{}", x); } let v: Vec<_> = set.iter().cloned().collect(); assert_eq!(v, [1, 2, 3, 4]); }use std::collections::BTreeSet; let set: BTreeSet<usize> = [1, 2, 3, 4].iter().cloned().collect(); for x in set.iter() { println!("{}", x); } let v: Vec<_> = set.iter().cloned().collect(); assert_eq!(v, [1, 2, 3, 4]);
impl<T> BTreeSet<T> where T: Ord
fn new() -> BTreeSet<T>
Makes a new BTreeSet with a reasonable choice of B.
Examples
fn main() { #![allow(unused_mut)] use std::collections::BTreeSet; let mut set: BTreeSet<i32> = BTreeSet::new(); }use std::collections::BTreeSet; let mut set: BTreeSet<i32> = BTreeSet::new();
Trait Implementations
impl<T> Debug for BTreeSet<T> where T: Debug
impl<T> Default for BTreeSet<T> where T: Ord
impl<'a, T> Extend<&'a T> for BTreeSet<T> where T: Copy + 'a + Ord1.2.0
fn extend<I>(&mut self, iter: I) where I: IntoIterator<Item=&'a T>
impl<T> Extend<T> for BTreeSet<T> where T: Ord
fn extend<Iter>(&mut self, iter: Iter) where Iter: IntoIterator<Item=T>
impl<T> IntoIterator for BTreeSet<T>
type Item = T
type IntoIter = IntoIter<T>
fn into_iter(self) -> IntoIter<T>
Gets an iterator for moving out the BtreeSet's contents.
Examples
fn main() { 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]); }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]);