Struct alloc::collections::btree_set::BTreeSet 1.0.0[−][src]
pub struct BTreeSet<T> { /* fields omitted */ }
Expand description
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.
The behavior resulting from such a logic error is not specified (it could include panics,
incorrect results, aborts, memory leaks, or non-termination) but will not be undefined
behavior.
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);
}
RunA BTreeSet
with a known list of items can be initialized from an array:
use std::collections::BTreeSet;
let set = BTreeSet::from([1, 2, 3]);
RunImplementations
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::ops::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());
Runpub fn difference<'a>(&'a self, other: &'a BTreeSet<T>) -> Difference<'a, T>ⓘNotable traits for Difference<'a, T>impl<'a, T: Ord> Iterator for Difference<'a, T> type Item = &'a T;
where
T: Ord,
pub fn difference<'a>(&'a self, other: &'a BTreeSet<T>) -> Difference<'a, T>ⓘNotable traits for Difference<'a, T>impl<'a, T: Ord> Iterator for Difference<'a, T> type Item = &'a T;
where
T: Ord,
impl<'a, T: Ord> Iterator for Difference<'a, T> type Item = &'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]);
Runpub fn symmetric_difference<'a>(
&'a self,
other: &'a BTreeSet<T>
) -> SymmetricDifference<'a, T>ⓘNotable traits for SymmetricDifference<'a, T>impl<'a, T: Ord> Iterator for SymmetricDifference<'a, T> type Item = &'a T;
where
T: Ord,
pub fn symmetric_difference<'a>(
&'a self,
other: &'a BTreeSet<T>
) -> SymmetricDifference<'a, T>ⓘNotable traits for SymmetricDifference<'a, T>impl<'a, T: Ord> Iterator for SymmetricDifference<'a, T> type Item = &'a T;
where
T: Ord,
impl<'a, T: Ord> Iterator for SymmetricDifference<'a, T> type Item = &'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]);
Runpub fn intersection<'a>(&'a self, other: &'a BTreeSet<T>) -> Intersection<'a, T>ⓘNotable traits for Intersection<'a, T>impl<'a, T: Ord> Iterator for Intersection<'a, T> type Item = &'a T;
where
T: Ord,
pub fn intersection<'a>(&'a self, other: &'a BTreeSet<T>) -> Intersection<'a, T>ⓘNotable traits for Intersection<'a, T>impl<'a, T: Ord> Iterator for Intersection<'a, T> type Item = &'a T;
where
T: Ord,
impl<'a, T: Ord> Iterator for Intersection<'a, T> type Item = &'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]);
RunVisits 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]);
RunReturns 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);
RunReturns 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.
Examples
use std::collections::BTreeSet;
let set: BTreeSet<_> = [1, 2, 3].iter().cloned().collect();
assert_eq!(set.get(&2), Some(&2));
assert_eq!(set.get(&4), None);
RunReturns 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);
RunReturns 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);
RunReturns 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);
RunReturns a reference to the first value in the set, if any. This value is always the minimum of all values in the set.
Examples
Basic usage:
#![feature(map_first_last)]
use std::collections::BTreeSet;
let mut set = BTreeSet::new();
assert_eq!(set.first(), None);
set.insert(1);
assert_eq!(set.first(), Some(&1));
set.insert(2);
assert_eq!(set.first(), Some(&1));
RunReturns a reference to the last value in the set, if any. This value is always the maximum of all values in the set.
Examples
Basic usage:
#![feature(map_first_last)]
use std::collections::BTreeSet;
let mut set = BTreeSet::new();
assert_eq!(set.last(), None);
set.insert(1);
assert_eq!(set.last(), Some(&1));
set.insert(2);
assert_eq!(set.last(), Some(&2));
RunRemoves the first value from the set and returns it, if any. The first value is always the minimum value in the set.
Examples
#![feature(map_first_last)]
use std::collections::BTreeSet;
let mut set = BTreeSet::new();
set.insert(1);
while let Some(n) = set.pop_first() {
assert_eq!(n, 1);
}
assert!(set.is_empty());
RunRemoves the last value from the set and returns it, if any. The last value is always the maximum value in the set.
Examples
#![feature(map_first_last)]
use std::collections::BTreeSet;
let mut set = BTreeSet::new();
set.insert(1);
while let Some(n) = set.pop_last() {
assert_eq!(n, 1);
}
assert!(set.is_empty());
RunAdds 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);
RunAdds a value to the set, replacing the existing value, if any, that is equal to the given one. Returns the replaced value.
Examples
use std::collections::BTreeSet;
let mut set = BTreeSet::new();
set.insert(Vec::<i32>::new());
assert_eq!(set.get(&[][..]).unwrap().capacity(), 0);
set.replace(Vec::with_capacity(10));
assert_eq!(set.get(&[][..]).unwrap().capacity(), 10);
RunRemoves a value from the set. Returns whether 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);
RunRemoves 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.
Examples
use std::collections::BTreeSet;
let mut set: BTreeSet<_> = [1, 2, 3].iter().cloned().collect();
assert_eq!(set.take(&2), Some(2));
assert_eq!(set.take(&2), None);
RunRetains only the elements specified by the predicate.
In other words, remove all elements e
such that f(&e)
returns false
.
The elements are visited in ascending order.
Examples
use std::collections::BTreeSet;
let xs = [1, 2, 3, 4, 5, 6];
let mut set: BTreeSet<i32> = xs.iter().cloned().collect();
// Keep only the even numbers.
set.retain(|&k| k % 2 == 0);
assert!(set.iter().eq([2, 4, 6].iter()));
RunMoves 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));
RunSplits the collection into two at the given value. Returns everything after the given value, including the value.
Examples
Basic usage:
use std::collections::BTreeSet;
let mut a = BTreeSet::new();
a.insert(1);
a.insert(2);
a.insert(3);
a.insert(17);
a.insert(41);
let b = a.split_off(&3);
assert_eq!(a.len(), 2);
assert_eq!(b.len(), 3);
assert!(a.contains(&1));
assert!(a.contains(&2));
assert!(b.contains(&3));
assert!(b.contains(&17));
assert!(b.contains(&41));
Runpub fn drain_filter<'a, F>(&'a mut self, pred: F) -> DrainFilter<'a, T, F>ⓘNotable traits for DrainFilter<'_, T, F>impl<'a, T, F> Iterator for DrainFilter<'_, T, F> where
F: 'a + FnMut(&T) -> bool, type Item = T;
where
T: Ord,
F: 'a + FnMut(&T) -> bool,
pub fn drain_filter<'a, F>(&'a mut self, pred: F) -> DrainFilter<'a, T, F>ⓘNotable traits for DrainFilter<'_, T, F>impl<'a, T, F> Iterator for DrainFilter<'_, T, F> where
F: 'a + FnMut(&T) -> bool, type Item = T;
where
T: Ord,
F: 'a + FnMut(&T) -> bool,
impl<'a, T, F> Iterator for DrainFilter<'_, T, F> where
F: 'a + FnMut(&T) -> bool, type Item = T;
Creates an iterator that visits all values in ascending order and uses a closure to determine if a value should be removed.
If the closure returns true
, the value is removed from the set and yielded. If
the closure returns false
, or panics, the value remains in the set and will
not be yielded.
If the iterator is only partially consumed or not consumed at all, each of the
remaining values is still subjected to the closure and removed and dropped if it
returns true
.
It is unspecified how many more values will be subjected to the closure if a
panic occurs in the closure, or if a panic occurs while dropping a value, or if
the DrainFilter
itself is leaked.
Examples
Splitting a set into even and odd values, reusing the original set:
#![feature(btree_drain_filter)]
use std::collections::BTreeSet;
let mut set: BTreeSet<i32> = (0..8).collect();
let evens: BTreeSet<_> = set.drain_filter(|v| v % 2 == 0).collect();
let odds = set;
assert_eq!(evens.into_iter().collect::<Vec<_>>(), vec![0, 2, 4, 6]);
assert_eq!(odds.into_iter().collect::<Vec<_>>(), vec![1, 3, 5, 7]);
RunGets 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);
RunValues 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);
RunTrait Implementations
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]);
RunReturns 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]);
RunReturns 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]);
RunCreates a value from an iterator. Read more
type Item = T
type Item = T
The type of the elements being iterated over.
This method returns an ordering between self
and other
values if one exists. Read more
This method tests less than (for self
and other
) and is used by the <
operator. Read more
This method tests less than or equal to (for self
and other
) and is used by the <=
operator. Read more
This method tests greater than (for self
and other
) and is used by the >
operator. Read more
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