# Struct collections::btree_set::BTreeSet [−] [src]

    pub struct BTreeSet<T> {
        // some 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.

## Methods

### `impl<T: Ord> BTreeSet<T>`

#### `fn new() -> BTreeSet<T>`

Makes a new BTreeSet with a reasonable choice of B.

# Examples

extern crate collections; 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();

### `impl<T> BTreeSet<T>`

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

Gets an iterator over the BTreeSet's contents.

# Examples

extern crate collections; 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: Ord> BTreeSet<T>`

#### `fn range<'a, Min: ?Sized + Ord, Max: ?Sized + Ord>(&'a self, min: Bound<&Min>, max: Bound<&Max>) -> Range<'a, T> where T: Borrow<Min> + Borrow<Max>`

Unstable (`btree_range` #27787)

: matches collection reform specification, waiting for dust to settle

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)] extern crate collections; 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: Ord> BTreeSet<T>`

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

Visits the values representing the difference, in ascending order.

# Examples

extern crate collections; 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>(&'a self, other: &'a BTreeSet<T>) -> SymmetricDifference<'a, T>`

Visits the values representing the symmetric difference, in ascending order.

# Examples

extern crate collections; 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>(&'a self, other: &'a BTreeSet<T>) -> Intersection<'a, T>`

Visits the values representing the intersection, in ascending order.

# Examples

extern crate collections; 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>(&'a self, other: &'a BTreeSet<T>) -> Union<'a, T>`

Visits the values representing the union, in ascending order.

# Examples

extern crate collections; 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

extern crate collections; 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

extern crate collections; 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

extern crate collections; 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: ?Sized>(&self, value: &Q) -> bool where T: Borrow<Q>, Q: Ord`

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

extern crate collections; 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: ?Sized>(&self, value: &Q) -> Option<&T> where T: Borrow<Q>, Q: Ord`

Unstable (`set_recovery` #28050)

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

extern crate collections; 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

extern crate collections; 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

extern crate collections; 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

extern crate collections; 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>`

Unstable (`set_recovery` #28050)

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

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

extern crate collections; 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: ?Sized>(&mut self, value: &Q) -> Option<T> where T: Borrow<Q>, Q: Ord`

Unstable (`set_recovery` #28050)

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.

## Trait Implementations

### `impl<T: Ord> FromIterator<T> for BTreeSet<T>`

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

### `impl<T> IntoIterator for BTreeSet<T>`

#### `type Item = T`

#### `type IntoIter = IntoIter<T>`

#### `fn into_iter(self) -> IntoIter<T>`

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

#### `type Item = &'a T`

#### `type IntoIter = Iter<'a, T>`

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

### `impl<T: Ord> Extend<T> for BTreeSet<T>`

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

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

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

### `impl<T: Ord> Default for BTreeSet<T>`

#### `fn default() -> BTreeSet<T>`

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

#### `type Output = BTreeSet<T>`

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

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

#### `type Output = BTreeSet<T>`

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

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

#### `type Output = BTreeSet<T>`

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

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

#### `type Output = BTreeSet<T>`

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

### `impl<T: Debug> Debug for BTreeSet<T>`

#### `fn fmt(&self, f: &mut Formatter) -> Result`

### Derived Implementations

### `impl<T: PartialOrd> PartialOrd for BTreeSet<T>`

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

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

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

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

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

### `impl<T: Ord> Ord for BTreeSet<T>`

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

### `impl<T: Eq> Eq for BTreeSet<T>`

### `impl<T: PartialEq> PartialEq for BTreeSet<T>`

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

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

### `impl<T: Hash> Hash for BTreeSet<T>`

#### `fn hash<__H: Hasher>(&self, __arg_0: &mut __H)`

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

### `impl<T: Clone> Clone for BTreeSet<T>`

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

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

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