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+// This is pretty much entirely stolen from TreeSet, since BTreeMap has an identical interface
+// to TreeMap
+
+use crate::vec::Vec;
+use core::borrow::Borrow;
+use core::cmp::Ordering::{self, Equal, Greater, Less};
+use core::cmp::{max, min};
+use core::fmt::{self, Debug};
+use core::hash::{Hash, Hasher};
+use core::iter::{FromIterator, FusedIterator, Peekable};
+use core::mem::ManuallyDrop;
+use core::ops::{BitAnd, BitOr, BitXor, RangeBounds, Sub};
+
+use super::map::{BTreeMap, Keys};
+use super::merge_iter::MergeIterInner;
+use super::set_val::SetValZST;
+use super::Recover;
+
+use crate::alloc::{Allocator, Global};
+
+// FIXME(conventions): implement bounded iterators
+
+/// An ordered 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, but will be encapsulated to the
+/// `BTreeSet` that observed the logic error and not result in undefined behavior. This could
+/// include panics, incorrect results, aborts, memory leaks, and non-termination.
+///
+/// Iterators returned by [`BTreeSet::iter`] produce their items in order, and take worst-case
+/// logarithmic and amortized constant time per item returned.
+///
+/// [`Ord`]: core::cmp::Ord
+/// [`Cell`]: core::cell::Cell
+/// [`RefCell`]: core::cell::RefCell
+///
+/// # 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}");
+/// }
+/// ```
+///
+/// A `BTreeSet` with a known list of items can be initialized from an array:
+///
+/// ```
+/// use std::collections::BTreeSet;
+///
+/// let set = BTreeSet::from([1, 2, 3]);
+/// ```
+#[stable(feature = "rust1", since = "1.0.0")]
+#[cfg_attr(not(test), rustc_diagnostic_item = "BTreeSet")]
+pub struct BTreeSet<
+ T,
+ #[unstable(feature = "allocator_api", issue = "32838")] A: Allocator + Clone = Global,
+> {
+ map: BTreeMap<T, SetValZST, A>,
+}
+
+#[stable(feature = "rust1", since = "1.0.0")]
+impl<T: Hash, A: Allocator + Clone> Hash for BTreeSet<T, A> {
+ fn hash<H: Hasher>(&self, state: &mut H) {
+ self.map.hash(state)
+ }
+}
+
+#[stable(feature = "rust1", since = "1.0.0")]
+impl<T: PartialEq, A: Allocator + Clone> PartialEq for BTreeSet<T, A> {
+ fn eq(&self, other: &BTreeSet<T, A>) -> bool {
+ self.map.eq(&other.map)
+ }
+}
+
+#[stable(feature = "rust1", since = "1.0.0")]
+impl<T: Eq, A: Allocator + Clone> Eq for BTreeSet<T, A> {}
+
+#[stable(feature = "rust1", since = "1.0.0")]
+impl<T: PartialOrd, A: Allocator + Clone> PartialOrd for BTreeSet<T, A> {
+ fn partial_cmp(&self, other: &BTreeSet<T, A>) -> Option<Ordering> {
+ self.map.partial_cmp(&other.map)
+ }
+}
+
+#[stable(feature = "rust1", since = "1.0.0")]
+impl<T: Ord, A: Allocator + Clone> Ord for BTreeSet<T, A> {
+ fn cmp(&self, other: &BTreeSet<T, A>) -> Ordering {
+ self.map.cmp(&other.map)
+ }
+}
+
+#[stable(feature = "rust1", since = "1.0.0")]
+impl<T: Clone, A: Allocator + Clone> Clone for BTreeSet<T, A> {
+ fn clone(&self) -> Self {
+ BTreeSet { map: self.map.clone() }
+ }
+
+ fn clone_from(&mut self, other: &Self) {
+ self.map.clone_from(&other.map);
+ }
+}
+
+/// An iterator over the items of a `BTreeSet`.
+///
+/// This `struct` is created by the [`iter`] method on [`BTreeSet`].
+/// See its documentation for more.
+///
+/// [`iter`]: BTreeSet::iter
+#[must_use = "iterators are lazy and do nothing unless consumed"]
+#[stable(feature = "rust1", since = "1.0.0")]
+pub struct Iter<'a, T: 'a> {
+ iter: Keys<'a, T, SetValZST>,
+}
+
+#[stable(feature = "collection_debug", since = "1.17.0")]
+impl<T: fmt::Debug> fmt::Debug for Iter<'_, T> {
+ fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+ f.debug_tuple("Iter").field(&self.iter.clone()).finish()
+ }
+}
+
+/// An owning iterator over the items of a `BTreeSet`.
+///
+/// This `struct` is created by the [`into_iter`] method on [`BTreeSet`]
+/// (provided by the [`IntoIterator`] trait). See its documentation for more.
+///
+/// [`into_iter`]: BTreeSet#method.into_iter
+/// [`IntoIterator`]: core::iter::IntoIterator
+#[stable(feature = "rust1", since = "1.0.0")]
+#[derive(Debug)]
+pub struct IntoIter<
+ T,
+ #[unstable(feature = "allocator_api", issue = "32838")] A: Allocator + Clone = Global,
+> {
+ iter: super::map::IntoIter<T, SetValZST, A>,
+}
+
+/// An iterator over a sub-range of items in a `BTreeSet`.
+///
+/// This `struct` is created by the [`range`] method on [`BTreeSet`].
+/// See its documentation for more.
+///
+/// [`range`]: BTreeSet::range
+#[must_use = "iterators are lazy and do nothing unless consumed"]
+#[derive(Debug)]
+#[stable(feature = "btree_range", since = "1.17.0")]
+pub struct Range<'a, T: 'a> {
+ iter: super::map::Range<'a, T, SetValZST>,
+}
+
+/// A lazy iterator producing elements in the difference of `BTreeSet`s.
+///
+/// This `struct` is created by the [`difference`] method on [`BTreeSet`].
+/// See its documentation for more.
+///
+/// [`difference`]: BTreeSet::difference
+#[must_use = "this returns the difference as an iterator, \
+ without modifying either input set"]
+#[stable(feature = "rust1", since = "1.0.0")]
+pub struct Difference<
+ 'a,
+ T: 'a,
+ #[unstable(feature = "allocator_api", issue = "32838")] A: Allocator + Clone = Global,
+> {
+ inner: DifferenceInner<'a, T, A>,
+}
+enum DifferenceInner<'a, T: 'a, A: Allocator + Clone> {
+ Stitch {
+ // iterate all of `self` and some of `other`, spotting matches along the way
+ self_iter: Iter<'a, T>,
+ other_iter: Peekable<Iter<'a, T>>,
+ },
+ Search {
+ // iterate `self`, look up in `other`
+ self_iter: Iter<'a, T>,
+ other_set: &'a BTreeSet<T, A>,
+ },
+ Iterate(Iter<'a, T>), // simply produce all elements in `self`
+}
+
+// Explicit Debug impl necessary because of issue #26925
+impl<T: Debug, A: Allocator + Clone> Debug for DifferenceInner<'_, T, A> {
+ fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+ match self {
+ DifferenceInner::Stitch { self_iter, other_iter } => f
+ .debug_struct("Stitch")
+ .field("self_iter", self_iter)
+ .field("other_iter", other_iter)
+ .finish(),
+ DifferenceInner::Search { self_iter, other_set } => f
+ .debug_struct("Search")
+ .field("self_iter", self_iter)
+ .field("other_iter", other_set)
+ .finish(),
+ DifferenceInner::Iterate(x) => f.debug_tuple("Iterate").field(x).finish(),
+ }
+ }
+}
+
+#[stable(feature = "collection_debug", since = "1.17.0")]
+impl<T: fmt::Debug, A: Allocator + Clone> fmt::Debug for Difference<'_, T, A> {
+ fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+ f.debug_tuple("Difference").field(&self.inner).finish()
+ }
+}
+
+/// A lazy iterator producing elements in the symmetric difference of `BTreeSet`s.
+///
+/// This `struct` is created by the [`symmetric_difference`] method on
+/// [`BTreeSet`]. See its documentation for more.
+///
+/// [`symmetric_difference`]: BTreeSet::symmetric_difference
+#[must_use = "this returns the difference as an iterator, \
+ without modifying either input set"]
+#[stable(feature = "rust1", since = "1.0.0")]
+pub struct SymmetricDifference<'a, T: 'a>(MergeIterInner<Iter<'a, T>>);
+
+#[stable(feature = "collection_debug", since = "1.17.0")]
+impl<T: fmt::Debug> fmt::Debug for SymmetricDifference<'_, T> {
+ fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+ f.debug_tuple("SymmetricDifference").field(&self.0).finish()
+ }
+}
+
+/// A lazy iterator producing elements in the intersection of `BTreeSet`s.
+///
+/// This `struct` is created by the [`intersection`] method on [`BTreeSet`].
+/// See its documentation for more.
+///
+/// [`intersection`]: BTreeSet::intersection
+#[must_use = "this returns the intersection as an iterator, \
+ without modifying either input set"]
+#[stable(feature = "rust1", since = "1.0.0")]
+pub struct Intersection<
+ 'a,
+ T: 'a,
+ #[unstable(feature = "allocator_api", issue = "32838")] A: Allocator + Clone = Global,
+> {
+ inner: IntersectionInner<'a, T, A>,
+}
+enum IntersectionInner<'a, T: 'a, A: Allocator + Clone> {
+ Stitch {
+ // iterate similarly sized sets jointly, spotting matches along the way
+ a: Iter<'a, T>,
+ b: Iter<'a, T>,
+ },
+ Search {
+ // iterate a small set, look up in the large set
+ small_iter: Iter<'a, T>,
+ large_set: &'a BTreeSet<T, A>,
+ },
+ Answer(Option<&'a T>), // return a specific element or emptiness
+}
+
+// Explicit Debug impl necessary because of issue #26925
+impl<T: Debug, A: Allocator + Clone> Debug for IntersectionInner<'_, T, A> {
+ fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+ match self {
+ IntersectionInner::Stitch { a, b } => {
+ f.debug_struct("Stitch").field("a", a).field("b", b).finish()
+ }
+ IntersectionInner::Search { small_iter, large_set } => f
+ .debug_struct("Search")
+ .field("small_iter", small_iter)
+ .field("large_set", large_set)
+ .finish(),
+ IntersectionInner::Answer(x) => f.debug_tuple("Answer").field(x).finish(),
+ }
+ }
+}
+
+#[stable(feature = "collection_debug", since = "1.17.0")]
+impl<T: Debug, A: Allocator + Clone> Debug for Intersection<'_, T, A> {
+ fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+ f.debug_tuple("Intersection").field(&self.inner).finish()
+ }
+}
+
+/// A lazy iterator producing elements in the union of `BTreeSet`s.
+///
+/// This `struct` is created by the [`union`] method on [`BTreeSet`].
+/// See its documentation for more.
+///
+/// [`union`]: BTreeSet::union
+#[must_use = "this returns the union as an iterator, \
+ without modifying either input set"]
+#[stable(feature = "rust1", since = "1.0.0")]
+pub struct Union<'a, T: 'a>(MergeIterInner<Iter<'a, T>>);
+
+#[stable(feature = "collection_debug", since = "1.17.0")]
+impl<T: fmt::Debug> fmt::Debug for Union<'_, T> {
+ fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+ f.debug_tuple("Union").field(&self.0).finish()
+ }
+}
+
+// This constant is used by functions that compare two sets.
+// It estimates the relative size at which searching performs better
+// than iterating, based on the benchmarks in
+// https://github.com/ssomers/rust_bench_btreeset_intersection.
+// It's used to divide rather than multiply sizes, to rule out overflow,
+// and it's a power of two to make that division cheap.
+const ITER_PERFORMANCE_TIPPING_SIZE_DIFF: usize = 16;
+
+impl<T> BTreeSet<T> {
+ /// Makes a new, empty `BTreeSet`.
+ ///
+ /// Does not allocate anything on its own.
+ ///
+ /// # Examples
+ ///
+ /// ```
+ /// # #![allow(unused_mut)]
+ /// use std::collections::BTreeSet;
+ ///
+ /// let mut set: BTreeSet<i32> = BTreeSet::new();
+ /// ```
+ #[stable(feature = "rust1", since = "1.0.0")]
+ #[rustc_const_unstable(feature = "const_btree_new", issue = "71835")]
+ #[must_use]
+ pub const fn new() -> BTreeSet<T> {
+ BTreeSet { map: BTreeMap::new() }
+ }
+}
+
+impl<T, A: Allocator + Clone> BTreeSet<T, A> {
+ /// Makes a new `BTreeSet` with a reasonable choice of B.
+ ///
+ /// # Examples
+ ///
+ /// ```
+ /// # #![allow(unused_mut)]
+ /// # #![feature(allocator_api)]
+ /// # #![feature(btreemap_alloc)]
+ /// use std::collections::BTreeSet;
+ /// use std::alloc::Global;
+ ///
+ /// let mut set: BTreeSet<i32> = BTreeSet::new_in(Global);
+ /// ```
+ #[unstable(feature = "btreemap_alloc", issue = "32838")]
+ pub fn new_in(alloc: A) -> BTreeSet<T, A> {
+ BTreeSet { map: BTreeMap::new_in(alloc) }
+ }
+
+ /// 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.
+ ///
+ /// # Panics
+ ///
+ /// Panics if range `start > end`.
+ /// Panics if range `start == end` and both bounds are `Excluded`.
+ ///
+ /// # 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());
+ /// ```
+ #[stable(feature = "btree_range", since = "1.17.0")]
+ pub fn range<K: ?Sized, R>(&self, range: R) -> Range<'_, T>
+ where
+ K: Ord,
+ T: Borrow<K> + Ord,
+ R: RangeBounds<K>,
+ {
+ Range { iter: self.map.range(range) }
+ }
+
+ /// Visits the elements representing the difference,
+ /// i.e., the elements 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]);
+ /// ```
+ #[stable(feature = "rust1", since = "1.0.0")]
+ pub fn difference<'a>(&'a self, other: &'a BTreeSet<T, A>) -> Difference<'a, T, A>
+ where
+ T: Ord,
+ {
+ let (self_min, self_max) =
+ if let (Some(self_min), Some(self_max)) = (self.first(), self.last()) {
+ (self_min, self_max)
+ } else {
+ return Difference { inner: DifferenceInner::Iterate(self.iter()) };
+ };
+ let (other_min, other_max) =
+ if let (Some(other_min), Some(other_max)) = (other.first(), other.last()) {
+ (other_min, other_max)
+ } else {
+ return Difference { inner: DifferenceInner::Iterate(self.iter()) };
+ };
+ Difference {
+ inner: match (self_min.cmp(other_max), self_max.cmp(other_min)) {
+ (Greater, _) | (_, Less) => DifferenceInner::Iterate(self.iter()),
+ (Equal, _) => {
+ let mut self_iter = self.iter();
+ self_iter.next();
+ DifferenceInner::Iterate(self_iter)
+ }
+ (_, Equal) => {
+ let mut self_iter = self.iter();
+ self_iter.next_back();
+ DifferenceInner::Iterate(self_iter)
+ }
+ _ if self.len() <= other.len() / ITER_PERFORMANCE_TIPPING_SIZE_DIFF => {
+ DifferenceInner::Search { self_iter: self.iter(), other_set: other }
+ }
+ _ => DifferenceInner::Stitch {
+ self_iter: self.iter(),
+ other_iter: other.iter().peekable(),
+ },
+ },
+ }
+ }
+
+ /// Visits the elements representing the symmetric difference,
+ /// i.e., the elements 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]);
+ /// ```
+ #[stable(feature = "rust1", since = "1.0.0")]
+ pub fn symmetric_difference<'a>(
+ &'a self,
+ other: &'a BTreeSet<T, A>,
+ ) -> SymmetricDifference<'a, T>
+ where
+ T: Ord,
+ {
+ SymmetricDifference(MergeIterInner::new(self.iter(), other.iter()))
+ }
+
+ /// Visits the elements representing the intersection,
+ /// i.e., the elements 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]);
+ /// ```
+ #[stable(feature = "rust1", since = "1.0.0")]
+ pub fn intersection<'a>(&'a self, other: &'a BTreeSet<T, A>) -> Intersection<'a, T, A>
+ where
+ T: Ord,
+ {
+ let (self_min, self_max) =
+ if let (Some(self_min), Some(self_max)) = (self.first(), self.last()) {
+ (self_min, self_max)
+ } else {
+ return Intersection { inner: IntersectionInner::Answer(None) };
+ };
+ let (other_min, other_max) =
+ if let (Some(other_min), Some(other_max)) = (other.first(), other.last()) {
+ (other_min, other_max)
+ } else {
+ return Intersection { inner: IntersectionInner::Answer(None) };
+ };
+ Intersection {
+ inner: match (self_min.cmp(other_max), self_max.cmp(other_min)) {
+ (Greater, _) | (_, Less) => IntersectionInner::Answer(None),
+ (Equal, _) => IntersectionInner::Answer(Some(self_min)),
+ (_, Equal) => IntersectionInner::Answer(Some(self_max)),
+ _ if self.len() <= other.len() / ITER_PERFORMANCE_TIPPING_SIZE_DIFF => {
+ IntersectionInner::Search { small_iter: self.iter(), large_set: other }
+ }
+ _ if other.len() <= self.len() / ITER_PERFORMANCE_TIPPING_SIZE_DIFF => {
+ IntersectionInner::Search { small_iter: other.iter(), large_set: self }
+ }
+ _ => IntersectionInner::Stitch { a: self.iter(), b: other.iter() },
+ },
+ }
+ }
+
+ /// Visits the elements representing the union,
+ /// i.e., all the elements 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]);
+ /// ```
+ #[stable(feature = "rust1", since = "1.0.0")]
+ pub fn union<'a>(&'a self, other: &'a BTreeSet<T, A>) -> Union<'a, T>
+ where
+ T: Ord,
+ {
+ Union(MergeIterInner::new(self.iter(), other.iter()))
+ }
+
+ /// Clears the set, removing all elements.
+ ///
+ /// # Examples
+ ///
+ /// ```
+ /// use std::collections::BTreeSet;
+ ///
+ /// let mut v = BTreeSet::new();
+ /// v.insert(1);
+ /// v.clear();
+ /// assert!(v.is_empty());
+ /// ```
+ #[stable(feature = "rust1", since = "1.0.0")]
+ pub fn clear(&mut self)
+ where
+ A: Clone,
+ {
+ self.map.clear()
+ }
+
+ /// Returns `true` if the set contains an element equal to the value.
+ ///
+ /// The value may be any borrowed form of the set's element type,
+ /// but the ordering on the borrowed form *must* match the
+ /// ordering on the element type.
+ ///
+ /// # Examples
+ ///
+ /// ```
+ /// use std::collections::BTreeSet;
+ ///
+ /// let set = BTreeSet::from([1, 2, 3]);
+ /// assert_eq!(set.contains(&1), true);
+ /// assert_eq!(set.contains(&4), false);
+ /// ```
+ #[stable(feature = "rust1", since = "1.0.0")]
+ pub fn contains<Q: ?Sized>(&self, value: &Q) -> bool
+ where
+ T: Borrow<Q> + Ord,
+ Q: Ord,
+ {
+ self.map.contains_key(value)
+ }
+
+ /// Returns a reference to the element in the set, if any, that is equal to
+ /// the value.
+ ///
+ /// The value may be any borrowed form of the set's element type,
+ /// but the ordering on the borrowed form *must* match the
+ /// ordering on the element type.
+ ///
+ /// # Examples
+ ///
+ /// ```
+ /// use std::collections::BTreeSet;
+ ///
+ /// let set = BTreeSet::from([1, 2, 3]);
+ /// assert_eq!(set.get(&2), Some(&2));
+ /// assert_eq!(set.get(&4), None);
+ /// ```
+ #[stable(feature = "set_recovery", since = "1.9.0")]
+ pub fn get<Q: ?Sized>(&self, value: &Q) -> Option<&T>
+ where
+ T: Borrow<Q> + Ord,
+ Q: Ord,
+ {
+ Recover::get(&self.map, value)
+ }
+
+ /// 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::from([1, 2, 3]);
+ /// 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);
+ /// ```
+ #[must_use]
+ #[stable(feature = "rust1", since = "1.0.0")]
+ pub fn is_disjoint(&self, other: &BTreeSet<T, A>) -> bool
+ where
+ T: Ord,
+ {
+ self.intersection(other).next().is_none()
+ }
+
+ /// Returns `true` if the set is a subset of another,
+ /// i.e., `other` contains at least all the elements in `self`.
+ ///
+ /// # Examples
+ ///
+ /// ```
+ /// use std::collections::BTreeSet;
+ ///
+ /// let sup = BTreeSet::from([1, 2, 3]);
+ /// 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);
+ /// ```
+ #[must_use]
+ #[stable(feature = "rust1", since = "1.0.0")]
+ pub fn is_subset(&self, other: &BTreeSet<T, A>) -> bool
+ where
+ T: Ord,
+ {
+ // Same result as self.difference(other).next().is_none()
+ // but the code below is faster (hugely in some cases).
+ if self.len() > other.len() {
+ return false;
+ }
+ let (self_min, self_max) =
+ if let (Some(self_min), Some(self_max)) = (self.first(), self.last()) {
+ (self_min, self_max)
+ } else {
+ return true; // self is empty
+ };
+ let (other_min, other_max) =
+ if let (Some(other_min), Some(other_max)) = (other.first(), other.last()) {
+ (other_min, other_max)
+ } else {
+ return false; // other is empty
+ };
+ let mut self_iter = self.iter();
+ match self_min.cmp(other_min) {
+ Less => return false,
+ Equal => {
+ self_iter.next();
+ }
+ Greater => (),
+ }
+ match self_max.cmp(other_max) {
+ Greater => return false,
+ Equal => {
+ self_iter.next_back();
+ }
+ Less => (),
+ }
+ if self_iter.len() <= other.len() / ITER_PERFORMANCE_TIPPING_SIZE_DIFF {
+ for next in self_iter {
+ if !other.contains(next) {
+ return false;
+ }
+ }
+ } else {
+ let mut other_iter = other.iter();
+ other_iter.next();
+ other_iter.next_back();
+ let mut self_next = self_iter.next();
+ while let Some(self1) = self_next {
+ match other_iter.next().map_or(Less, |other1| self1.cmp(other1)) {
+ Less => return false,
+ Equal => self_next = self_iter.next(),
+ Greater => (),
+ }
+ }
+ }
+ true
+ }
+
+ /// Returns `true` if the set is a superset of another,
+ /// i.e., `self` contains at least all the elements in `other`.
+ ///
+ /// # Examples
+ ///
+ /// ```
+ /// use std::collections::BTreeSet;
+ ///
+ /// let sub = BTreeSet::from([1, 2]);
+ /// 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);
+ /// ```
+ #[must_use]
+ #[stable(feature = "rust1", since = "1.0.0")]
+ pub fn is_superset(&self, other: &BTreeSet<T, A>) -> bool
+ where
+ T: Ord,
+ {
+ other.is_subset(self)
+ }
+
+ /// Returns a reference to the first element in the set, if any.
+ /// This element is always the minimum of all elements 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));
+ /// ```
+ #[must_use]
+ #[unstable(feature = "map_first_last", issue = "62924")]
+ pub fn first(&self) -> Option<&T>
+ where
+ T: Ord,
+ {
+ self.map.first_key_value().map(|(k, _)| k)
+ }
+
+ /// Returns a reference to the last element in the set, if any.
+ /// This element is always the maximum of all elements 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));
+ /// ```
+ #[must_use]
+ #[unstable(feature = "map_first_last", issue = "62924")]
+ pub fn last(&self) -> Option<&T>
+ where
+ T: Ord,
+ {
+ self.map.last_key_value().map(|(k, _)| k)
+ }
+
+ /// Removes the first element from the set and returns it, if any.
+ /// The first element is always the minimum element 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());
+ /// ```
+ #[unstable(feature = "map_first_last", issue = "62924")]
+ pub fn pop_first(&mut self) -> Option<T>
+ where
+ T: Ord,
+ {
+ self.map.pop_first().map(|kv| kv.0)
+ }
+
+ /// Removes the last element from the set and returns it, if any.
+ /// The last element is always the maximum element 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());
+ /// ```
+ #[unstable(feature = "map_first_last", issue = "62924")]
+ pub fn pop_last(&mut self) -> Option<T>
+ where
+ T: Ord,
+ {
+ self.map.pop_last().map(|kv| kv.0)
+ }
+
+ /// Adds a value to the set.
+ ///
+ /// Returns whether the value was newly inserted. That is:
+ ///
+ /// - If the set did not previously contain an equal value, `true` is
+ /// returned.
+ /// - If the set already contained an equal value, `false` is returned, and
+ /// the entry is not updated.
+ ///
+ /// See the [module-level documentation] for more.
+ ///
+ /// [module-level documentation]: index.html#insert-and-complex-keys
+ ///
+ /// # 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);
+ /// ```
+ #[stable(feature = "rust1", since = "1.0.0")]
+ pub fn insert(&mut self, value: T) -> bool
+ where
+ T: Ord,
+ {
+ self.map.insert(value, SetValZST::default()).is_none()
+ }
+
+ /// Adds a value to the set, replacing the existing element, if any, that is
+ /// equal to the value. Returns the replaced element.
+ ///
+ /// # 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);
+ /// ```
+ #[stable(feature = "set_recovery", since = "1.9.0")]
+ pub fn replace(&mut self, value: T) -> Option<T>
+ where
+ T: Ord,
+ {
+ Recover::replace(&mut self.map, value)
+ }
+
+ /// If the set contains an element equal to the value, removes it from the
+ /// set and drops it. Returns whether such an element was present.
+ ///
+ /// The value may be any borrowed form of the set's element type,
+ /// but the ordering on the borrowed form *must* match the
+ /// ordering on the element 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);
+ /// ```
+ #[stable(feature = "rust1", since = "1.0.0")]
+ pub fn remove<Q: ?Sized>(&mut self, value: &Q) -> bool
+ where
+ T: Borrow<Q> + Ord,
+ Q: Ord,
+ {
+ self.map.remove(value).is_some()
+ }
+
+ /// Removes and returns the element in the set, if any, that is equal to
+ /// the value.
+ ///
+ /// The value may be any borrowed form of the set's element type,
+ /// but the ordering on the borrowed form *must* match the
+ /// ordering on the element type.
+ ///
+ /// # Examples
+ ///
+ /// ```
+ /// use std::collections::BTreeSet;
+ ///
+ /// let mut set = BTreeSet::from([1, 2, 3]);
+ /// assert_eq!(set.take(&2), Some(2));
+ /// assert_eq!(set.take(&2), None);
+ /// ```
+ #[stable(feature = "set_recovery", since = "1.9.0")]
+ pub fn take<Q: ?Sized>(&mut self, value: &Q) -> Option<T>
+ where
+ T: Borrow<Q> + Ord,
+ Q: Ord,
+ {
+ Recover::take(&mut self.map, value)
+ }
+
+ /// Retains only the elements specified by the predicate.
+ ///
+ /// In other words, remove all elements `e` for which `f(&e)` returns `false`.
+ /// The elements are visited in ascending order.
+ ///
+ /// # Examples
+ ///
+ /// ```
+ /// use std::collections::BTreeSet;
+ ///
+ /// let mut set = BTreeSet::from([1, 2, 3, 4, 5, 6]);
+ /// // Keep only the even numbers.
+ /// set.retain(|&k| k % 2 == 0);
+ /// assert!(set.iter().eq([2, 4, 6].iter()));
+ /// ```
+ #[stable(feature = "btree_retain", since = "1.53.0")]
+ pub fn retain<F>(&mut self, mut f: F)
+ where
+ T: Ord,
+ F: FnMut(&T) -> bool,
+ {
+ self.drain_filter(|v| !f(v));
+ }
+
+ /// 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));
+ /// ```
+ #[stable(feature = "btree_append", since = "1.11.0")]
+ pub fn append(&mut self, other: &mut Self)
+ where
+ T: Ord,
+ A: Clone,
+ {
+ self.map.append(&mut other.map);
+ }
+
+ /// Splits the collection into two at the value. Returns a new collection
+ /// with all elements greater than or equal to 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));
+ /// ```
+ #[stable(feature = "btree_split_off", since = "1.11.0")]
+ pub fn split_off<Q: ?Sized + Ord>(&mut self, value: &Q) -> Self
+ where
+ T: Borrow<Q> + Ord,
+ A: Clone,
+ {
+ BTreeSet { map: self.map.split_off(value) }
+ }
+
+ /// Creates an iterator that visits all elements in ascending order and
+ /// uses a closure to determine if an element should be removed.
+ ///
+ /// If the closure returns `true`, the element is removed from the set and
+ /// yielded. If the closure returns `false`, or panics, the element 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 elements is still subjected to the closure and removed
+ /// and dropped if it returns `true`.
+ ///
+ /// It is unspecified how many more elements will be subjected to the
+ /// closure if a panic occurs in the closure, or if a panic occurs while
+ /// dropping an element, 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]);
+ /// ```
+ #[unstable(feature = "btree_drain_filter", issue = "70530")]
+ pub fn drain_filter<'a, F>(&'a mut self, pred: F) -> DrainFilter<'a, T, F, A>
+ where
+ T: Ord,
+ F: 'a + FnMut(&T) -> bool,
+ {
+ let (inner, alloc) = self.map.drain_filter_inner();
+ DrainFilter { pred, inner, alloc }
+ }
+
+ /// Gets an iterator that visits the elements in the `BTreeSet` in ascending
+ /// order.
+ ///
+ /// # Examples
+ ///
+ /// ```
+ /// use std::collections::BTreeSet;
+ ///
+ /// let set = BTreeSet::from([1, 2, 3]);
+ /// 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);
+ /// ```
+ ///
+ /// Values returned by the iterator are returned in ascending order:
+ ///
+ /// ```
+ /// use std::collections::BTreeSet;
+ ///
+ /// let set = BTreeSet::from([3, 1, 2]);
+ /// 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);
+ /// ```
+ #[stable(feature = "rust1", since = "1.0.0")]
+ pub fn iter(&self) -> Iter<'_, T> {
+ Iter { iter: self.map.keys() }
+ }
+
+ /// 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);
+ /// ```
+ #[must_use]
+ #[stable(feature = "rust1", since = "1.0.0")]
+ #[rustc_const_unstable(feature = "const_btree_new", issue = "71835")]
+ pub const fn len(&self) -> usize {
+ self.map.len()
+ }
+
+ /// 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());
+ /// ```
+ #[must_use]
+ #[stable(feature = "rust1", since = "1.0.0")]
+ #[rustc_const_unstable(feature = "const_btree_new", issue = "71835")]
+ pub const fn is_empty(&self) -> bool {
+ self.len() == 0
+ }
+}
+
+#[stable(feature = "rust1", since = "1.0.0")]
+impl<T: Ord> FromIterator<T> for BTreeSet<T> {
+ fn from_iter<I: IntoIterator<Item = T>>(iter: I) -> BTreeSet<T> {
+ let mut inputs: Vec<_> = iter.into_iter().collect();
+
+ if inputs.is_empty() {
+ return BTreeSet::new();
+ }
+
+ // use stable sort to preserve the insertion order.
+ inputs.sort();
+ BTreeSet::from_sorted_iter(inputs.into_iter(), Global)
+ }
+}
+
+impl<T: Ord, A: Allocator + Clone> BTreeSet<T, A> {
+ fn from_sorted_iter<I: Iterator<Item = T>>(iter: I, alloc: A) -> BTreeSet<T, A> {
+ let iter = iter.map(|k| (k, SetValZST::default()));
+ let map = BTreeMap::bulk_build_from_sorted_iter(iter, alloc);
+ BTreeSet { map }
+ }
+}
+
+#[stable(feature = "std_collections_from_array", since = "1.56.0")]
+impl<T: Ord, const N: usize> From<[T; N]> for BTreeSet<T> {
+ /// Converts a `[T; N]` into a `BTreeSet<T>`.
+ ///
+ /// ```
+ /// use std::collections::BTreeSet;
+ ///
+ /// let set1 = BTreeSet::from([1, 2, 3, 4]);
+ /// let set2: BTreeSet<_> = [1, 2, 3, 4].into();
+ /// assert_eq!(set1, set2);
+ /// ```
+ fn from(mut arr: [T; N]) -> Self {
+ if N == 0 {
+ return BTreeSet::new();
+ }
+
+ // use stable sort to preserve the insertion order.
+ arr.sort();
+ let iter = IntoIterator::into_iter(arr).map(|k| (k, SetValZST::default()));
+ let map = BTreeMap::bulk_build_from_sorted_iter(iter, Global);
+ BTreeSet { map }
+ }
+}
+
+#[stable(feature = "rust1", since = "1.0.0")]
+impl<T, A: Allocator + Clone> IntoIterator for BTreeSet<T, A> {
+ type Item = T;
+ type IntoIter = IntoIter<T, A>;
+
+ /// Gets an iterator for moving out the `BTreeSet`'s contents.
+ ///
+ /// # Examples
+ ///
+ /// ```
+ /// use std::collections::BTreeSet;
+ ///
+ /// let set = BTreeSet::from([1, 2, 3, 4]);
+ ///
+ /// let v: Vec<_> = set.into_iter().collect();
+ /// assert_eq!(v, [1, 2, 3, 4]);
+ /// ```
+ fn into_iter(self) -> IntoIter<T, A> {
+ IntoIter { iter: self.map.into_iter() }
+ }
+}
+
+#[stable(feature = "rust1", since = "1.0.0")]
+impl<'a, T, A: Allocator + Clone> IntoIterator for &'a BTreeSet<T, A> {
+ type Item = &'a T;
+ type IntoIter = Iter<'a, T>;
+
+ fn into_iter(self) -> Iter<'a, T> {
+ self.iter()
+ }
+}
+
+/// An iterator produced by calling `drain_filter` on BTreeSet.
+#[unstable(feature = "btree_drain_filter", issue = "70530")]
+pub struct DrainFilter<
+ 'a,
+ T,
+ F,
+ #[unstable(feature = "allocator_api", issue = "32838")] A: Allocator + Clone = Global,
+> where
+ T: 'a,
+ F: 'a + FnMut(&T) -> bool,
+{
+ pred: F,
+ inner: super::map::DrainFilterInner<'a, T, SetValZST>,
+ /// The BTreeMap will outlive this IntoIter so we don't care about drop order for `alloc`.
+ alloc: A,
+}
+
+#[unstable(feature = "btree_drain_filter", issue = "70530")]
+impl<T, F, A: Allocator + Clone> Drop for DrainFilter<'_, T, F, A>
+where
+ F: FnMut(&T) -> bool,
+{
+ fn drop(&mut self) {
+ self.for_each(drop);
+ }
+}
+
+#[unstable(feature = "btree_drain_filter", issue = "70530")]
+impl<T, F, A: Allocator + Clone> fmt::Debug for DrainFilter<'_, T, F, A>
+where
+ T: fmt::Debug,
+ F: FnMut(&T) -> bool,
+{
+ fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+ f.debug_tuple("DrainFilter").field(&self.inner.peek().map(|(k, _)| k)).finish()
+ }
+}
+
+#[unstable(feature = "btree_drain_filter", issue = "70530")]
+impl<'a, T, F, A: Allocator + Clone> Iterator for DrainFilter<'_, T, F, A>
+where
+ F: 'a + FnMut(&T) -> bool,
+{
+ type Item = T;
+
+ fn next(&mut self) -> Option<T> {
+ let pred = &mut self.pred;
+ let mut mapped_pred = |k: &T, _v: &mut SetValZST| pred(k);
+ self.inner.next(&mut mapped_pred, self.alloc.clone()).map(|(k, _)| k)
+ }
+
+ fn size_hint(&self) -> (usize, Option<usize>) {
+ self.inner.size_hint()
+ }
+}
+
+#[unstable(feature = "btree_drain_filter", issue = "70530")]
+impl<T, F, A: Allocator + Clone> FusedIterator for DrainFilter<'_, T, F, A> where
+ F: FnMut(&T) -> bool
+{
+}
+
+#[stable(feature = "rust1", since = "1.0.0")]
+impl<T: Ord, A: Allocator + Clone> Extend<T> for BTreeSet<T, A> {
+ #[inline]
+ fn extend<Iter: IntoIterator<Item = T>>(&mut self, iter: Iter) {
+ iter.into_iter().for_each(move |elem| {
+ self.insert(elem);
+ });
+ }
+
+ #[inline]
+ fn extend_one(&mut self, elem: T) {
+ self.insert(elem);
+ }
+}
+
+#[stable(feature = "extend_ref", since = "1.2.0")]
+impl<'a, T: 'a + Ord + Copy, A: Allocator + Clone> Extend<&'a T> for BTreeSet<T, A> {
+ fn extend<I: IntoIterator<Item = &'a T>>(&mut self, iter: I) {
+ self.extend(iter.into_iter().cloned());
+ }
+
+ #[inline]
+ fn extend_one(&mut self, &elem: &'a T) {
+ self.insert(elem);
+ }
+}
+
+#[stable(feature = "rust1", since = "1.0.0")]
+impl<T> Default for BTreeSet<T> {
+ /// Creates an empty `BTreeSet`.
+ fn default() -> BTreeSet<T> {
+ BTreeSet::new()
+ }
+}
+
+#[stable(feature = "rust1", since = "1.0.0")]
+impl<T: Ord + Clone, A: Allocator + Clone> Sub<&BTreeSet<T, A>> for &BTreeSet<T, A> {
+ type Output = BTreeSet<T, A>;
+
+ /// Returns the difference of `self` and `rhs` as a new `BTreeSet<T>`.
+ ///
+ /// # Examples
+ ///
+ /// ```
+ /// use std::collections::BTreeSet;
+ ///
+ /// let a = BTreeSet::from([1, 2, 3]);
+ /// let b = BTreeSet::from([3, 4, 5]);
+ ///
+ /// let result = &a - &b;
+ /// assert_eq!(result, BTreeSet::from([1, 2]));
+ /// ```
+ fn sub(self, rhs: &BTreeSet<T, A>) -> BTreeSet<T, A> {
+ BTreeSet::from_sorted_iter(
+ self.difference(rhs).cloned(),
+ ManuallyDrop::into_inner(self.map.alloc.clone()),
+ )
+ }
+}
+
+#[stable(feature = "rust1", since = "1.0.0")]
+impl<T: Ord + Clone, A: Allocator + Clone> BitXor<&BTreeSet<T, A>> for &BTreeSet<T, A> {
+ type Output = BTreeSet<T, A>;
+
+ /// Returns the symmetric difference of `self` and `rhs` as a new `BTreeSet<T>`.
+ ///
+ /// # Examples
+ ///
+ /// ```
+ /// use std::collections::BTreeSet;
+ ///
+ /// let a = BTreeSet::from([1, 2, 3]);
+ /// let b = BTreeSet::from([2, 3, 4]);
+ ///
+ /// let result = &a ^ &b;
+ /// assert_eq!(result, BTreeSet::from([1, 4]));
+ /// ```
+ fn bitxor(self, rhs: &BTreeSet<T, A>) -> BTreeSet<T, A> {
+ BTreeSet::from_sorted_iter(
+ self.symmetric_difference(rhs).cloned(),
+ ManuallyDrop::into_inner(self.map.alloc.clone()),
+ )
+ }
+}
+
+#[stable(feature = "rust1", since = "1.0.0")]
+impl<T: Ord + Clone, A: Allocator + Clone> BitAnd<&BTreeSet<T, A>> for &BTreeSet<T, A> {
+ type Output = BTreeSet<T, A>;
+
+ /// Returns the intersection of `self` and `rhs` as a new `BTreeSet<T>`.
+ ///
+ /// # Examples
+ ///
+ /// ```
+ /// use std::collections::BTreeSet;
+ ///
+ /// let a = BTreeSet::from([1, 2, 3]);
+ /// let b = BTreeSet::from([2, 3, 4]);
+ ///
+ /// let result = &a & &b;
+ /// assert_eq!(result, BTreeSet::from([2, 3]));
+ /// ```
+ fn bitand(self, rhs: &BTreeSet<T, A>) -> BTreeSet<T, A> {
+ BTreeSet::from_sorted_iter(
+ self.intersection(rhs).cloned(),
+ ManuallyDrop::into_inner(self.map.alloc.clone()),
+ )
+ }
+}
+
+#[stable(feature = "rust1", since = "1.0.0")]
+impl<T: Ord + Clone, A: Allocator + Clone> BitOr<&BTreeSet<T, A>> for &BTreeSet<T, A> {
+ type Output = BTreeSet<T, A>;
+
+ /// Returns the union of `self` and `rhs` as a new `BTreeSet<T>`.
+ ///
+ /// # Examples
+ ///
+ /// ```
+ /// use std::collections::BTreeSet;
+ ///
+ /// let a = BTreeSet::from([1, 2, 3]);
+ /// let b = BTreeSet::from([3, 4, 5]);
+ ///
+ /// let result = &a | &b;
+ /// assert_eq!(result, BTreeSet::from([1, 2, 3, 4, 5]));
+ /// ```
+ fn bitor(self, rhs: &BTreeSet<T, A>) -> BTreeSet<T, A> {
+ BTreeSet::from_sorted_iter(
+ self.union(rhs).cloned(),
+ ManuallyDrop::into_inner(self.map.alloc.clone()),
+ )
+ }
+}
+
+#[stable(feature = "rust1", since = "1.0.0")]
+impl<T: Debug, A: Allocator + Clone> Debug for BTreeSet<T, A> {
+ fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+ f.debug_set().entries(self.iter()).finish()
+ }
+}
+
+#[stable(feature = "rust1", since = "1.0.0")]
+impl<T> Clone for Iter<'_, T> {
+ fn clone(&self) -> Self {
+ Iter { iter: self.iter.clone() }
+ }
+}
+#[stable(feature = "rust1", since = "1.0.0")]
+impl<'a, T> Iterator for Iter<'a, T> {
+ type Item = &'a T;
+
+ fn next(&mut self) -> Option<&'a T> {
+ self.iter.next()
+ }
+
+ fn size_hint(&self) -> (usize, Option<usize>) {
+ self.iter.size_hint()
+ }
+
+ fn last(mut self) -> Option<&'a T> {
+ self.next_back()
+ }
+
+ fn min(mut self) -> Option<&'a T> {
+ self.next()
+ }
+
+ fn max(mut self) -> Option<&'a T> {
+ self.next_back()
+ }
+}
+#[stable(feature = "rust1", since = "1.0.0")]
+impl<'a, T> DoubleEndedIterator for Iter<'a, T> {
+ fn next_back(&mut self) -> Option<&'a T> {
+ self.iter.next_back()
+ }
+}
+#[stable(feature = "rust1", since = "1.0.0")]
+impl<T> ExactSizeIterator for Iter<'_, T> {
+ fn len(&self) -> usize {
+ self.iter.len()
+ }
+}
+
+#[stable(feature = "fused", since = "1.26.0")]
+impl<T> FusedIterator for Iter<'_, T> {}
+
+#[stable(feature = "rust1", since = "1.0.0")]
+impl<T, A: Allocator + Clone> Iterator for IntoIter<T, A> {
+ type Item = T;
+
+ fn next(&mut self) -> Option<T> {
+ self.iter.next().map(|(k, _)| k)
+ }
+
+ fn size_hint(&self) -> (usize, Option<usize>) {
+ self.iter.size_hint()
+ }
+}
+#[stable(feature = "rust1", since = "1.0.0")]
+impl<T, A: Allocator + Clone> DoubleEndedIterator for IntoIter<T, A> {
+ fn next_back(&mut self) -> Option<T> {
+ self.iter.next_back().map(|(k, _)| k)
+ }
+}
+#[stable(feature = "rust1", since = "1.0.0")]
+impl<T, A: Allocator + Clone> ExactSizeIterator for IntoIter<T, A> {
+ fn len(&self) -> usize {
+ self.iter.len()
+ }
+}
+
+#[stable(feature = "fused", since = "1.26.0")]
+impl<T, A: Allocator + Clone> FusedIterator for IntoIter<T, A> {}
+
+#[stable(feature = "btree_range", since = "1.17.0")]
+impl<T> Clone for Range<'_, T> {
+ fn clone(&self) -> Self {
+ Range { iter: self.iter.clone() }
+ }
+}
+
+#[stable(feature = "btree_range", since = "1.17.0")]
+impl<'a, T> Iterator for Range<'a, T> {
+ type Item = &'a T;
+
+ fn next(&mut self) -> Option<&'a T> {
+ self.iter.next().map(|(k, _)| k)
+ }
+
+ fn last(mut self) -> Option<&'a T> {
+ self.next_back()
+ }
+
+ fn min(mut self) -> Option<&'a T> {
+ self.next()
+ }
+
+ fn max(mut self) -> Option<&'a T> {
+ self.next_back()
+ }
+}
+
+#[stable(feature = "btree_range", since = "1.17.0")]
+impl<'a, T> DoubleEndedIterator for Range<'a, T> {
+ fn next_back(&mut self) -> Option<&'a T> {
+ self.iter.next_back().map(|(k, _)| k)
+ }
+}
+
+#[stable(feature = "fused", since = "1.26.0")]
+impl<T> FusedIterator for Range<'_, T> {}
+
+#[stable(feature = "rust1", since = "1.0.0")]
+impl<T, A: Allocator + Clone> Clone for Difference<'_, T, A> {
+ fn clone(&self) -> Self {
+ Difference {
+ inner: match &self.inner {
+ DifferenceInner::Stitch { self_iter, other_iter } => DifferenceInner::Stitch {
+ self_iter: self_iter.clone(),
+ other_iter: other_iter.clone(),
+ },
+ DifferenceInner::Search { self_iter, other_set } => {
+ DifferenceInner::Search { self_iter: self_iter.clone(), other_set }
+ }
+ DifferenceInner::Iterate(iter) => DifferenceInner::Iterate(iter.clone()),
+ },
+ }
+ }
+}
+#[stable(feature = "rust1", since = "1.0.0")]
+impl<'a, T: Ord, A: Allocator + Clone> Iterator for Difference<'a, T, A> {
+ type Item = &'a T;
+
+ fn next(&mut self) -> Option<&'a T> {
+ match &mut self.inner {
+ DifferenceInner::Stitch { self_iter, other_iter } => {
+ let mut self_next = self_iter.next()?;
+ loop {
+ match other_iter.peek().map_or(Less, |other_next| self_next.cmp(other_next)) {
+ Less => return Some(self_next),
+ Equal => {
+ self_next = self_iter.next()?;
+ other_iter.next();
+ }
+ Greater => {
+ other_iter.next();
+ }
+ }
+ }
+ }
+ DifferenceInner::Search { self_iter, other_set } => loop {
+ let self_next = self_iter.next()?;
+ if !other_set.contains(&self_next) {
+ return Some(self_next);
+ }
+ },
+ DifferenceInner::Iterate(iter) => iter.next(),
+ }
+ }
+
+ fn size_hint(&self) -> (usize, Option<usize>) {
+ let (self_len, other_len) = match &self.inner {
+ DifferenceInner::Stitch { self_iter, other_iter } => {
+ (self_iter.len(), other_iter.len())
+ }
+ DifferenceInner::Search { self_iter, other_set } => (self_iter.len(), other_set.len()),
+ DifferenceInner::Iterate(iter) => (iter.len(), 0),
+ };
+ (self_len.saturating_sub(other_len), Some(self_len))
+ }
+
+ fn min(mut self) -> Option<&'a T> {
+ self.next()
+ }
+}
+
+#[stable(feature = "fused", since = "1.26.0")]
+impl<T: Ord, A: Allocator + Clone> FusedIterator for Difference<'_, T, A> {}
+
+#[stable(feature = "rust1", since = "1.0.0")]
+impl<T> Clone for SymmetricDifference<'_, T> {
+ fn clone(&self) -> Self {
+ SymmetricDifference(self.0.clone())
+ }
+}
+#[stable(feature = "rust1", since = "1.0.0")]
+impl<'a, T: Ord> Iterator for SymmetricDifference<'a, T> {
+ type Item = &'a T;
+
+ fn next(&mut self) -> Option<&'a T> {
+ loop {
+ let (a_next, b_next) = self.0.nexts(Self::Item::cmp);
+ if a_next.and(b_next).is_none() {
+ return a_next.or(b_next);
+ }
+ }
+ }
+
+ fn size_hint(&self) -> (usize, Option<usize>) {
+ let (a_len, b_len) = self.0.lens();
+ // No checked_add, because even if a and b refer to the same set,
+ // and T is a zero-sized type, the storage overhead of sets limits
+ // the number of elements to less than half the range of usize.
+ (0, Some(a_len + b_len))
+ }
+
+ fn min(mut self) -> Option<&'a T> {
+ self.next()
+ }
+}
+
+#[stable(feature = "fused", since = "1.26.0")]
+impl<T: Ord> FusedIterator for SymmetricDifference<'_, T> {}
+
+#[stable(feature = "rust1", since = "1.0.0")]
+impl<T, A: Allocator + Clone> Clone for Intersection<'_, T, A> {
+ fn clone(&self) -> Self {
+ Intersection {
+ inner: match &self.inner {
+ IntersectionInner::Stitch { a, b } => {
+ IntersectionInner::Stitch { a: a.clone(), b: b.clone() }
+ }
+ IntersectionInner::Search { small_iter, large_set } => {
+ IntersectionInner::Search { small_iter: small_iter.clone(), large_set }
+ }
+ IntersectionInner::Answer(answer) => IntersectionInner::Answer(*answer),
+ },
+ }
+ }
+}
+#[stable(feature = "rust1", since = "1.0.0")]
+impl<'a, T: Ord, A: Allocator + Clone> Iterator for Intersection<'a, T, A> {
+ type Item = &'a T;
+
+ fn next(&mut self) -> Option<&'a T> {
+ match &mut self.inner {
+ IntersectionInner::Stitch { a, b } => {
+ let mut a_next = a.next()?;
+ let mut b_next = b.next()?;
+ loop {
+ match a_next.cmp(b_next) {
+ Less => a_next = a.next()?,
+ Greater => b_next = b.next()?,
+ Equal => return Some(a_next),
+ }
+ }
+ }
+ IntersectionInner::Search { small_iter, large_set } => loop {
+ let small_next = small_iter.next()?;
+ if large_set.contains(&small_next) {
+ return Some(small_next);
+ }
+ },
+ IntersectionInner::Answer(answer) => answer.take(),
+ }
+ }
+
+ fn size_hint(&self) -> (usize, Option<usize>) {
+ match &self.inner {
+ IntersectionInner::Stitch { a, b } => (0, Some(min(a.len(), b.len()))),
+ IntersectionInner::Search { small_iter, .. } => (0, Some(small_iter.len())),
+ IntersectionInner::Answer(None) => (0, Some(0)),
+ IntersectionInner::Answer(Some(_)) => (1, Some(1)),
+ }
+ }
+
+ fn min(mut self) -> Option<&'a T> {
+ self.next()
+ }
+}
+
+#[stable(feature = "fused", since = "1.26.0")]
+impl<T: Ord, A: Allocator + Clone> FusedIterator for Intersection<'_, T, A> {}
+
+#[stable(feature = "rust1", since = "1.0.0")]
+impl<T> Clone for Union<'_, T> {
+ fn clone(&self) -> Self {
+ Union(self.0.clone())
+ }
+}
+#[stable(feature = "rust1", since = "1.0.0")]
+impl<'a, T: Ord> Iterator for Union<'a, T> {
+ type Item = &'a T;
+
+ fn next(&mut self) -> Option<&'a T> {
+ let (a_next, b_next) = self.0.nexts(Self::Item::cmp);
+ a_next.or(b_next)
+ }
+
+ fn size_hint(&self) -> (usize, Option<usize>) {
+ let (a_len, b_len) = self.0.lens();
+ // No checked_add - see SymmetricDifference::size_hint.
+ (max(a_len, b_len), Some(a_len + b_len))
+ }
+
+ fn min(mut self) -> Option<&'a T> {
+ self.next()
+ }
+}
+
+#[stable(feature = "fused", since = "1.26.0")]
+impl<T: Ord> FusedIterator for Union<'_, T> {}
+
+#[cfg(test)]
+mod tests;
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