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

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

1.0.0

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 over the BTreeSet's contents.

# Examples

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

Unstable (`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, 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)]

    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> 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 T: Borrow<Q>, Q: Ord + ?Sized`

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 T: Borrow<Q>, Q: Ord + ?Sized` 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

    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 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

    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 T: Borrow<Q>, Q: Ord + ?Sized`

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 T: Borrow<Q>, Q: Ord + ?Sized` 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>)`

Unstable (`btree_append`)

: recently added as part of collections reform 2

Moves all elements from `other` into `Self`, leaving `other` empty.

# Examples

    #![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));

## Trait Implementations

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

#### `fn from_iter<I>(iter: I) -> BTreeSet<T> where I: 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

    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`

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

#### `fn into_iter(self) -> Iter<'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<'a, T> Extend<&'a T> for BTreeSet<T> where T: Copy + 'a + Ord` 1.2.0

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

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

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

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

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

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

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

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

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

#### `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>`

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

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

### Derived Implementations

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

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

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

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

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

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

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

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

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

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

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

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

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