# Struct std::collections::BTreeSet 1.0.0 [−] [src]

    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);
    }Run

## Methods

### `impl<T> BTreeSet<T> where
T: Ord,`
[src]

#### `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();Run

### `impl<T> BTreeSet<T>`
[src]

#### `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);Run

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);Run

### `impl<T> BTreeSet<T> where
T: Ord,`
[src]

#### `fn range<K, R>(&self, range: R) -> Range<T> where
K: Ord + ?Sized,
R: RangeArgument<K>,
T: Borrow<K>,`
1.17.0

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

    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());Run

### `impl<T> BTreeSet<T> where
T: Ord,`
[src]

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

Visits the values representing the difference, i.e. the values 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]);Run

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

Visits the values representing the symmetric difference, i.e. the values 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]);Run

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

Visits the values representing the intersection, i.e. the values 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]);Run

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

Visits the values representing the union, i.e. all the values 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]);Run

#### `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);Run

#### `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());Run

#### `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());Run

#### `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);Run

#### `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 `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<_> = [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);Run

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

Returns `true` if the set is a subset of another, i.e. `other` contains at least all the values in `self`.

# 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);Run

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

Returns `true` if the set is a superset of another, i.e. `self` contains at least all the values in `other`.

# 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);Run

#### `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);Run

#### `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

    use std::collections::BTreeSet;

    let mut set = BTreeSet::new();

    set.insert(2);
    assert_eq!(set.remove(&2), true);
    assert_eq!(set.remove(&2), false);Run

#### `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>)`
1.11.0

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));Run

#### `fn split_off<Q>(&mut self, key: &Q) -> BTreeSet<T> where
Q: Ord + ?Sized,
T: Borrow<Q>,`
1.11.0

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");Run

## Trait Implementations

### `impl<T> Hash for BTreeSet<T> where
T: Hash,`
[src]

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

Feeds this value into the given [`Hasher`]. Read more

#### `fn hash_slice<H>(data: &[Self], state: &mut H) where
H: Hasher,`
1.3.0

Feeds a slice of this type into the given [`Hasher`]. Read more

### `impl<'a, T> Extend<&'a T> for BTreeSet<T> where
T: 'a + Copy + Ord,`
1.2.0
[src]

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

Extends a collection with the contents of an iterator. Read more

### `impl<T> Extend<T> for BTreeSet<T> where
T: Ord,`
[src]

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

Extends a collection with the contents of an iterator. Read more

### `impl<T> PartialEq<BTreeSet<T>> for BTreeSet<T> where
T: PartialEq<T>,`
[src]

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

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

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

This method tests for `!=`.

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

#### `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]);Run

### `impl<T> Clone for BTreeSet<T> where
T: Clone,`
[src]

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

Returns a copy of the value. Read more

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

Performs copy-assignment from `source`. Read more

### `impl<T> FromIterator<T> for BTreeSet<T> where
T: Ord,`
[src]

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

Creates a value from an iterator. Read more

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

#### `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]);Run

### `impl<T> Debug for BTreeSet<T> where
T: Debug,`
[src]

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

Formats the value using the given formatter.

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

#### `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]);Run

### `impl<T> Default for BTreeSet<T> where
T: Ord,`
[src]

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

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

### `impl<T> Ord for BTreeSet<T> where
T: Ord,`
[src]

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

This method returns an `Ordering` between `self` and `other`. Read more

### `impl<T> IntoIterator for BTreeSet<T>`
[src]

#### `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]);Run

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

#### `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. Read more

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

#### `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]);Run

### `impl<T> PartialOrd<BTreeSet<T>> for BTreeSet<T> where
T: PartialOrd<T>,`
[src]

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

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

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

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

#### `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. Read more

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

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

#### `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. Read more

### `impl<T> Eq for BTreeSet<T> where
T: Eq,`
[src]

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