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+// Copyright 2014 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+use std::borrow::Borrow;
+use std::fmt;
+use std::hash::{BuildHasher, Hash};
+use std::iter::{Chain, FromIterator};
+use std::ops::{BitAnd, BitOr, BitXor, Sub};
+
+use super::hash_map::{self, HashMap, Keys, RandomState};
+use super::Recover;
+
+use crate::FailedAllocationError;
+
+// Future Optimization (FIXME!)
+// =============================
+//
+// Iteration over zero sized values is a noop. There is no need
+// for `bucket.val` in the case of HashSet. I suppose we would need HKT
+// to get rid of it properly.
+
+/// A hash set implemented as a `HashMap` where the value is `()`.
+///
+/// As with the [`HashMap`] type, a `HashSet` requires that the elements
+/// implement the [`Eq`] and [`Hash`] traits. This can frequently be achieved by
+/// using `#[derive(PartialEq, Eq, Hash)]`. If you implement these yourself,
+/// it is important that the following property holds:
+///
+/// ```text
+/// k1 == k2 -> hash(k1) == hash(k2)
+/// ```
+///
+/// In other words, if two keys are equal, their hashes must be equal.
+///
+///
+/// It is a logic error for an item to be modified in such a way that the
+/// item's hash, as determined by the [`Hash`] trait, or its equality, as
+/// determined by the [`Eq`] 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::HashSet;
+/// // Type inference lets us omit an explicit type signature (which
+/// // would be `HashSet<&str>` in this example).
+/// let mut books = HashSet::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);
+/// }
+/// ```
+///
+/// The easiest way to use `HashSet` with a custom type is to derive
+/// [`Eq`] and [`Hash`]. We must also derive [`PartialEq`], this will in the
+/// future be implied by [`Eq`].
+///
+/// ```
+/// use std::collections::HashSet;
+/// #[derive(Hash, Eq, PartialEq, Debug)]
+/// struct Viking<'a> {
+/// name: &'a str,
+/// power: usize,
+/// }
+///
+/// let mut vikings = HashSet::new();
+///
+/// vikings.insert(Viking { name: "Einar", power: 9 });
+/// vikings.insert(Viking { name: "Einar", power: 9 });
+/// vikings.insert(Viking { name: "Olaf", power: 4 });
+/// vikings.insert(Viking { name: "Harald", power: 8 });
+///
+/// // Use derived implementation to print the vikings.
+/// for x in &vikings {
+/// println!("{:?}", x);
+/// }
+/// ```
+///
+/// A `HashSet` with fixed list of elements can be initialized from an array:
+///
+/// ```
+/// use std::collections::HashSet;
+///
+/// fn main() {
+/// let viking_names: HashSet<&str> =
+/// [ "Einar", "Olaf", "Harald" ].iter().cloned().collect();
+/// // use the values stored in the set
+/// }
+/// ```
+///
+/// [`Cell`]: ../../std/cell/struct.Cell.html
+/// [`Eq`]: ../../std/cmp/trait.Eq.html
+/// [`Hash`]: ../../std/hash/trait.Hash.html
+/// [`HashMap`]: struct.HashMap.html
+/// [`PartialEq`]: ../../std/cmp/trait.PartialEq.html
+/// [`RefCell`]: ../../std/cell/struct.RefCell.html
+#[derive(Clone)]
+pub struct HashSet<T, S = RandomState> {
+ map: HashMap<T, (), S>,
+}
+
+impl<T, S> HashSet<T, S>
+where
+ T: Eq + Hash,
+ S: BuildHasher,
+{
+ /// Creates a new empty hash set which will use the given hasher to hash
+ /// keys.
+ ///
+ /// The hash set is also created with the default initial capacity.
+ ///
+ /// Warning: `hasher` is normally randomly generated, and
+ /// is designed to allow `HashSet`s to be resistant to attacks that
+ /// cause many collisions and very poor performance. Setting it
+ /// manually using this function can expose a DoS attack vector.
+ ///
+ /// # Examples
+ ///
+ /// ```
+ /// use std::collections::HashSet;
+ /// use std::collections::hash_map::RandomState;
+ ///
+ /// let s = RandomState::new();
+ /// let mut set = HashSet::with_hasher(s);
+ /// set.insert(2);
+ /// ```
+ #[inline]
+ pub fn with_hasher(hasher: S) -> HashSet<T, S> {
+ HashSet {
+ map: HashMap::with_hasher(hasher),
+ }
+ }
+
+ /// Creates an empty `HashSet` with with the specified capacity, using
+ /// `hasher` to hash the keys.
+ ///
+ /// The hash set will be able to hold at least `capacity` elements without
+ /// reallocating. If `capacity` is 0, the hash set will not allocate.
+ ///
+ /// Warning: `hasher` is normally randomly generated, and
+ /// is designed to allow `HashSet`s to be resistant to attacks that
+ /// cause many collisions and very poor performance. Setting it
+ /// manually using this function can expose a DoS attack vector.
+ ///
+ /// # Examples
+ ///
+ /// ```
+ /// use std::collections::HashSet;
+ /// use std::collections::hash_map::RandomState;
+ ///
+ /// let s = RandomState::new();
+ /// let mut set = HashSet::with_capacity_and_hasher(10, s);
+ /// set.insert(1);
+ /// ```
+ #[inline]
+ pub fn with_capacity_and_hasher(capacity: usize, hasher: S) -> HashSet<T, S> {
+ HashSet {
+ map: HashMap::with_capacity_and_hasher(capacity, hasher),
+ }
+ }
+
+ /// Returns a reference to the set's [`BuildHasher`].
+ ///
+ /// [`BuildHasher`]: ../../std/hash/trait.BuildHasher.html
+ ///
+ /// # Examples
+ ///
+ /// ```
+ /// use std::collections::HashSet;
+ /// use std::collections::hash_map::RandomState;
+ ///
+ /// let hasher = RandomState::new();
+ /// let set: HashSet<i32> = HashSet::with_hasher(hasher);
+ /// let hasher: &RandomState = set.hasher();
+ /// ```
+ pub fn hasher(&self) -> &S {
+ self.map.hasher()
+ }
+
+ /// Returns the number of elements the set can hold without reallocating.
+ ///
+ /// # Examples
+ ///
+ /// ```
+ /// use std::collections::HashSet;
+ /// let set: HashSet<i32> = HashSet::with_capacity(100);
+ /// assert!(set.capacity() >= 100);
+ /// ```
+ #[inline]
+ pub fn capacity(&self) -> usize {
+ self.map.capacity()
+ }
+
+ /// Reserves capacity for at least `additional` more elements to be inserted
+ /// in the `HashSet`. The collection may reserve more space to avoid
+ /// frequent reallocations.
+ ///
+ /// # Panics
+ ///
+ /// Panics if the new allocation size overflows `usize`.
+ ///
+ /// # Examples
+ ///
+ /// ```
+ /// use std::collections::HashSet;
+ /// let mut set: HashSet<i32> = HashSet::new();
+ /// set.reserve(10);
+ /// assert!(set.capacity() >= 10);
+ /// ```
+ pub fn reserve(&mut self, additional: usize) {
+ self.map.reserve(additional)
+ }
+
+ /// Shrinks the capacity of the set as much as possible. It will drop
+ /// down as much as possible while maintaining the internal rules
+ /// and possibly leaving some space in accordance with the resize policy.
+ ///
+ /// # Examples
+ ///
+ /// ```
+ /// use std::collections::HashSet;
+ ///
+ /// let mut set = HashSet::with_capacity(100);
+ /// set.insert(1);
+ /// set.insert(2);
+ /// assert!(set.capacity() >= 100);
+ /// set.shrink_to_fit();
+ /// assert!(set.capacity() >= 2);
+ /// ```
+ pub fn shrink_to_fit(&mut self) {
+ self.map.shrink_to_fit()
+ }
+
+ /// An iterator visiting all elements in arbitrary order.
+ /// The iterator element type is `&'a T`.
+ ///
+ /// # Examples
+ ///
+ /// ```
+ /// use std::collections::HashSet;
+ /// let mut set = HashSet::new();
+ /// set.insert("a");
+ /// set.insert("b");
+ ///
+ /// // Will print in an arbitrary order.
+ /// for x in set.iter() {
+ /// println!("{}", x);
+ /// }
+ /// ```
+ pub fn iter(&self) -> Iter<T> {
+ Iter {
+ iter: self.map.keys(),
+ }
+ }
+
+ /// Visits the values representing the difference,
+ /// i.e. the values that are in `self` but not in `other`.
+ ///
+ /// # Examples
+ ///
+ /// ```
+ /// use std::collections::HashSet;
+ /// let a: HashSet<_> = [1, 2, 3].iter().cloned().collect();
+ /// let b: HashSet<_> = [4, 2, 3, 4].iter().cloned().collect();
+ ///
+ /// // Can be seen as `a - b`.
+ /// for x in a.difference(&b) {
+ /// println!("{}", x); // Print 1
+ /// }
+ ///
+ /// let diff: HashSet<_> = a.difference(&b).collect();
+ /// assert_eq!(diff, [1].iter().collect());
+ ///
+ /// // Note that difference is not symmetric,
+ /// // and `b - a` means something else:
+ /// let diff: HashSet<_> = b.difference(&a).collect();
+ /// assert_eq!(diff, [4].iter().collect());
+ /// ```
+ pub fn difference<'a>(&'a self, other: &'a HashSet<T, S>) -> Difference<'a, T, S> {
+ Difference {
+ iter: self.iter(),
+ other,
+ }
+ }
+
+ /// Visits the values representing the symmetric difference,
+ /// i.e. the values that are in `self` or in `other` but not in both.
+ ///
+ /// # Examples
+ ///
+ /// ```
+ /// use std::collections::HashSet;
+ /// let a: HashSet<_> = [1, 2, 3].iter().cloned().collect();
+ /// let b: HashSet<_> = [4, 2, 3, 4].iter().cloned().collect();
+ ///
+ /// // Print 1, 4 in arbitrary order.
+ /// for x in a.symmetric_difference(&b) {
+ /// println!("{}", x);
+ /// }
+ ///
+ /// let diff1: HashSet<_> = a.symmetric_difference(&b).collect();
+ /// let diff2: HashSet<_> = b.symmetric_difference(&a).collect();
+ ///
+ /// assert_eq!(diff1, diff2);
+ /// assert_eq!(diff1, [1, 4].iter().collect());
+ /// ```
+ pub fn symmetric_difference<'a>(
+ &'a self,
+ other: &'a HashSet<T, S>,
+ ) -> SymmetricDifference<'a, T, S> {
+ SymmetricDifference {
+ iter: self.difference(other).chain(other.difference(self)),
+ }
+ }
+
+ /// Visits the values representing the intersection,
+ /// i.e. the values that are both in `self` and `other`.
+ ///
+ /// # Examples
+ ///
+ /// ```
+ /// use std::collections::HashSet;
+ /// let a: HashSet<_> = [1, 2, 3].iter().cloned().collect();
+ /// let b: HashSet<_> = [4, 2, 3, 4].iter().cloned().collect();
+ ///
+ /// // Print 2, 3 in arbitrary order.
+ /// for x in a.intersection(&b) {
+ /// println!("{}", x);
+ /// }
+ ///
+ /// let intersection: HashSet<_> = a.intersection(&b).collect();
+ /// assert_eq!(intersection, [2, 3].iter().collect());
+ /// ```
+ pub fn intersection<'a>(&'a self, other: &'a HashSet<T, S>) -> Intersection<'a, T, S> {
+ Intersection {
+ iter: self.iter(),
+ other,
+ }
+ }
+
+ /// Visits the values representing the union,
+ /// i.e. all the values in `self` or `other`, without duplicates.
+ ///
+ /// # Examples
+ ///
+ /// ```
+ /// use std::collections::HashSet;
+ /// let a: HashSet<_> = [1, 2, 3].iter().cloned().collect();
+ /// let b: HashSet<_> = [4, 2, 3, 4].iter().cloned().collect();
+ ///
+ /// // Print 1, 2, 3, 4 in arbitrary order.
+ /// for x in a.union(&b) {
+ /// println!("{}", x);
+ /// }
+ ///
+ /// let union: HashSet<_> = a.union(&b).collect();
+ /// assert_eq!(union, [1, 2, 3, 4].iter().collect());
+ /// ```
+ pub fn union<'a>(&'a self, other: &'a HashSet<T, S>) -> Union<'a, T, S> {
+ Union {
+ iter: self.iter().chain(other.difference(self)),
+ }
+ }
+
+ /// Returns the number of elements in the set.
+ ///
+ /// # Examples
+ ///
+ /// ```
+ /// use std::collections::HashSet;
+ ///
+ /// let mut v = HashSet::new();
+ /// assert_eq!(v.len(), 0);
+ /// v.insert(1);
+ /// assert_eq!(v.len(), 1);
+ /// ```
+ pub fn len(&self) -> usize {
+ self.map.len()
+ }
+
+ /// Returns true if the set contains no elements.
+ ///
+ /// # Examples
+ ///
+ /// ```
+ /// use std::collections::HashSet;
+ ///
+ /// let mut v = HashSet::new();
+ /// assert!(v.is_empty());
+ /// v.insert(1);
+ /// assert!(!v.is_empty());
+ /// ```
+ pub fn is_empty(&self) -> bool {
+ self.map.is_empty()
+ }
+
+ /// Clears the set, returning all elements in an iterator.
+ ///
+ /// # Examples
+ ///
+ /// ```
+ /// use std::collections::HashSet;
+ ///
+ /// let mut set: HashSet<_> = [1, 2, 3].iter().cloned().collect();
+ /// assert!(!set.is_empty());
+ ///
+ /// // print 1, 2, 3 in an arbitrary order
+ /// for i in set.drain() {
+ /// println!("{}", i);
+ /// }
+ ///
+ /// assert!(set.is_empty());
+ /// ```
+ #[inline]
+ pub fn drain(&mut self) -> Drain<T> {
+ Drain {
+ iter: self.map.drain(),
+ }
+ }
+
+ /// Clears the set, removing all values.
+ ///
+ /// # Examples
+ ///
+ /// ```
+ /// use std::collections::HashSet;
+ ///
+ /// let mut v = HashSet::new();
+ /// v.insert(1);
+ /// v.clear();
+ /// assert!(v.is_empty());
+ /// ```
+ pub fn clear(&mut self)
+ where
+ T: 'static,
+ {
+ self.map.clear()
+ }
+
+ /// Returns `true` if the set contains a value.
+ ///
+ /// The value may be any borrowed form of the set's value type, but
+ /// [`Hash`] and [`Eq`] on the borrowed form *must* match those for
+ /// the value type.
+ ///
+ /// # Examples
+ ///
+ /// ```
+ /// use std::collections::HashSet;
+ ///
+ /// let set: HashSet<_> = [1, 2, 3].iter().cloned().collect();
+ /// assert_eq!(set.contains(&1), true);
+ /// assert_eq!(set.contains(&4), false);
+ /// ```
+ ///
+ /// [`Eq`]: ../../std/cmp/trait.Eq.html
+ /// [`Hash`]: ../../std/hash/trait.Hash.html
+ pub fn contains<Q: ?Sized>(&self, value: &Q) -> bool
+ where
+ T: Borrow<Q>,
+ Q: Hash + Eq,
+ {
+ self.map.contains_key(value)
+ }
+
+ /// 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
+ /// [`Hash`] and [`Eq`] on the borrowed form *must* match those for
+ /// the value type.
+ ///
+ /// [`Eq`]: ../../std/cmp/trait.Eq.html
+ /// [`Hash`]: ../../std/hash/trait.Hash.html
+ pub fn get<Q: ?Sized>(&self, value: &Q) -> Option<&T>
+ where
+ T: Borrow<Q>,
+ Q: Hash + Eq,
+ {
+ 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::HashSet;
+ ///
+ /// let a: HashSet<_> = [1, 2, 3].iter().cloned().collect();
+ /// let mut b = HashSet::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);
+ /// ```
+ pub fn is_disjoint(&self, other: &HashSet<T, S>) -> bool {
+ self.iter().all(|v| !other.contains(v))
+ }
+
+ /// 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::HashSet;
+ ///
+ /// let sup: HashSet<_> = [1, 2, 3].iter().cloned().collect();
+ /// let mut set = HashSet::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);
+ /// ```
+ pub fn is_subset(&self, other: &HashSet<T, S>) -> bool {
+ self.iter().all(|v| other.contains(v))
+ }
+
+ /// 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::HashSet;
+ ///
+ /// let sub: HashSet<_> = [1, 2].iter().cloned().collect();
+ /// let mut set = HashSet::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);
+ /// ```
+ #[inline]
+ pub fn is_superset(&self, other: &HashSet<T, S>) -> bool {
+ other.is_subset(self)
+ }
+
+ /// 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.
+ ///
+ /// # Examples
+ ///
+ /// ```
+ /// use std::collections::HashSet;
+ ///
+ /// let mut set = HashSet::new();
+ ///
+ /// assert_eq!(set.insert(2), true);
+ /// assert_eq!(set.insert(2), false);
+ /// assert_eq!(set.len(), 1);
+ /// ```
+ pub fn insert(&mut self, value: T) -> bool {
+ self.map.insert(value, ()).is_none()
+ }
+
+ /// Fallible version of `insert`.
+ #[inline]
+ pub fn try_insert(&mut self, value: T) -> Result<bool, FailedAllocationError> {
+ Ok(self.map.try_insert(value, ())?.is_none())
+ }
+
+ /// Adds a value to the set, replacing the existing value, if any, that is equal to the given
+ /// one. Returns the replaced value.
+ pub fn replace(&mut self, value: T) -> Option<T> {
+ Recover::replace(&mut self.map, value)
+ }
+
+ /// 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
+ /// [`Hash`] and [`Eq`] on the borrowed form *must* match those for
+ /// the value type.
+ ///
+ /// # Examples
+ ///
+ /// ```
+ /// use std::collections::HashSet;
+ ///
+ /// let mut set = HashSet::new();
+ ///
+ /// set.insert(2);
+ /// assert_eq!(set.remove(&2), true);
+ /// assert_eq!(set.remove(&2), false);
+ /// ```
+ ///
+ /// [`Eq`]: ../../std/cmp/trait.Eq.html
+ /// [`Hash`]: ../../std/hash/trait.Hash.html
+ pub fn remove<Q: ?Sized>(&mut self, value: &Q) -> bool
+ where
+ T: Borrow<Q>,
+ Q: Hash + Eq,
+ {
+ self.map.remove(value).is_some()
+ }
+
+ /// 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
+ /// [`Hash`] and [`Eq`] on the borrowed form *must* match those for
+ /// the value type.
+ ///
+ /// [`Eq`]: ../../std/cmp/trait.Eq.html
+ /// [`Hash`]: ../../std/hash/trait.Hash.html
+ pub fn take<Q: ?Sized>(&mut self, value: &Q) -> Option<T>
+ where
+ T: Borrow<Q>,
+ Q: Hash + Eq,
+ {
+ Recover::take(&mut self.map, value)
+ }
+
+ /// Retains only the elements specified by the predicate.
+ ///
+ /// In other words, remove all elements `e` such that `f(&e)` returns `false`.
+ ///
+ /// # Examples
+ ///
+ /// ```
+ /// use std::collections::HashSet;
+ ///
+ /// let xs = [1,2,3,4,5,6];
+ /// let mut set: HashSet<isize> = xs.iter().cloned().collect();
+ /// set.retain(|&k| k % 2 == 0);
+ /// assert_eq!(set.len(), 3);
+ /// ```
+ pub fn retain<F>(&mut self, mut f: F)
+ where
+ F: FnMut(&T) -> bool,
+ {
+ self.map.retain(|k, _| f(k));
+ }
+}
+
+impl<T, S> PartialEq for HashSet<T, S>
+where
+ T: Eq + Hash,
+ S: BuildHasher,
+{
+ fn eq(&self, other: &HashSet<T, S>) -> bool {
+ if self.len() != other.len() {
+ return false;
+ }
+
+ self.iter().all(|key| other.contains(key))
+ }
+}
+
+impl<T, S> Eq for HashSet<T, S>
+where
+ T: Eq + Hash,
+ S: BuildHasher,
+{
+}
+
+impl<T, S> fmt::Debug for HashSet<T, S>
+where
+ T: Eq + Hash + fmt::Debug,
+ S: BuildHasher,
+{
+ fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+ f.debug_set().entries(self.iter()).finish()
+ }
+}
+
+impl<T, S> FromIterator<T> for HashSet<T, S>
+where
+ T: Eq + Hash,
+ S: BuildHasher + Default,
+{
+ fn from_iter<I: IntoIterator<Item = T>>(iter: I) -> HashSet<T, S> {
+ let mut set = HashSet::with_hasher(Default::default());
+ set.extend(iter);
+ set
+ }
+}
+
+impl<T, S> Extend<T> for HashSet<T, S>
+where
+ T: Eq + Hash,
+ S: BuildHasher,
+{
+ fn extend<I: IntoIterator<Item = T>>(&mut self, iter: I) {
+ self.map.extend(iter.into_iter().map(|k| (k, ())));
+ }
+}
+
+impl<'a, T, S> Extend<&'a T> for HashSet<T, S>
+where
+ T: 'a + Eq + Hash + Copy,
+ S: BuildHasher,
+{
+ fn extend<I: IntoIterator<Item = &'a T>>(&mut self, iter: I) {
+ self.extend(iter.into_iter().cloned());
+ }
+}
+
+impl<T, S> Default for HashSet<T, S>
+where
+ T: Eq + Hash,
+ S: BuildHasher + Default,
+{
+ /// Creates an empty `HashSet<T, S>` with the `Default` value for the hasher.
+ fn default() -> HashSet<T, S> {
+ HashSet {
+ map: HashMap::default(),
+ }
+ }
+}
+
+impl<'a, 'b, T, S> BitOr<&'b HashSet<T, S>> for &'a HashSet<T, S>
+where
+ T: Eq + Hash + Clone,
+ S: BuildHasher + Default,
+{
+ type Output = HashSet<T, S>;
+
+ /// Returns the union of `self` and `rhs` as a new `HashSet<T, S>`.
+ ///
+ /// # Examples
+ ///
+ /// ```
+ /// use std::collections::HashSet;
+ ///
+ /// let a: HashSet<_> = vec![1, 2, 3].into_iter().collect();
+ /// let b: HashSet<_> = vec![3, 4, 5].into_iter().collect();
+ ///
+ /// let set = &a | &b;
+ ///
+ /// let mut i = 0;
+ /// let expected = [1, 2, 3, 4, 5];
+ /// for x in &set {
+ /// assert!(expected.contains(x));
+ /// i += 1;
+ /// }
+ /// assert_eq!(i, expected.len());
+ /// ```
+ fn bitor(self, rhs: &HashSet<T, S>) -> HashSet<T, S> {
+ self.union(rhs).cloned().collect()
+ }
+}
+
+impl<'a, 'b, T, S> BitAnd<&'b HashSet<T, S>> for &'a HashSet<T, S>
+where
+ T: Eq + Hash + Clone,
+ S: BuildHasher + Default,
+{
+ type Output = HashSet<T, S>;
+
+ /// Returns the intersection of `self` and `rhs` as a new `HashSet<T, S>`.
+ ///
+ /// # Examples
+ ///
+ /// ```
+ /// use std::collections::HashSet;
+ ///
+ /// let a: HashSet<_> = vec![1, 2, 3].into_iter().collect();
+ /// let b: HashSet<_> = vec![2, 3, 4].into_iter().collect();
+ ///
+ /// let set = &a & &b;
+ ///
+ /// let mut i = 0;
+ /// let expected = [2, 3];
+ /// for x in &set {
+ /// assert!(expected.contains(x));
+ /// i += 1;
+ /// }
+ /// assert_eq!(i, expected.len());
+ /// ```
+ fn bitand(self, rhs: &HashSet<T, S>) -> HashSet<T, S> {
+ self.intersection(rhs).cloned().collect()
+ }
+}
+
+impl<'a, 'b, T, S> BitXor<&'b HashSet<T, S>> for &'a HashSet<T, S>
+where
+ T: Eq + Hash + Clone,
+ S: BuildHasher + Default,
+{
+ type Output = HashSet<T, S>;
+
+ /// Returns the symmetric difference of `self` and `rhs` as a new `HashSet<T, S>`.
+ ///
+ /// # Examples
+ ///
+ /// ```
+ /// use std::collections::HashSet;
+ ///
+ /// let a: HashSet<_> = vec![1, 2, 3].into_iter().collect();
+ /// let b: HashSet<_> = vec![3, 4, 5].into_iter().collect();
+ ///
+ /// let set = &a ^ &b;
+ ///
+ /// let mut i = 0;
+ /// let expected = [1, 2, 4, 5];
+ /// for x in &set {
+ /// assert!(expected.contains(x));
+ /// i += 1;
+ /// }
+ /// assert_eq!(i, expected.len());
+ /// ```
+ fn bitxor(self, rhs: &HashSet<T, S>) -> HashSet<T, S> {
+ self.symmetric_difference(rhs).cloned().collect()
+ }
+}
+
+impl<'a, 'b, T, S> Sub<&'b HashSet<T, S>> for &'a HashSet<T, S>
+where
+ T: Eq + Hash + Clone,
+ S: BuildHasher + Default,
+{
+ type Output = HashSet<T, S>;
+
+ /// Returns the difference of `self` and `rhs` as a new `HashSet<T, S>`.
+ ///
+ /// # Examples
+ ///
+ /// ```
+ /// use std::collections::HashSet;
+ ///
+ /// let a: HashSet<_> = vec![1, 2, 3].into_iter().collect();
+ /// let b: HashSet<_> = vec![3, 4, 5].into_iter().collect();
+ ///
+ /// let set = &a - &b;
+ ///
+ /// let mut i = 0;
+ /// let expected = [1, 2];
+ /// for x in &set {
+ /// assert!(expected.contains(x));
+ /// i += 1;
+ /// }
+ /// assert_eq!(i, expected.len());
+ /// ```
+ fn sub(self, rhs: &HashSet<T, S>) -> HashSet<T, S> {
+ self.difference(rhs).cloned().collect()
+ }
+}
+
+/// An iterator over the items of a `HashSet`.
+///
+/// This `struct` is created by the [`iter`] method on [`HashSet`].
+/// See its documentation for more.
+///
+/// [`HashSet`]: struct.HashSet.html
+/// [`iter`]: struct.HashSet.html#method.iter
+pub struct Iter<'a, K: 'a> {
+ iter: Keys<'a, K, ()>,
+}
+
+/// An owning iterator over the items of a `HashSet`.
+///
+/// This `struct` is created by the [`into_iter`] method on [`HashSet`][`HashSet`]
+/// (provided by the `IntoIterator` trait). See its documentation for more.
+///
+/// [`HashSet`]: struct.HashSet.html
+/// [`into_iter`]: struct.HashSet.html#method.into_iter
+pub struct IntoIter<K> {
+ iter: hash_map::IntoIter<K, ()>,
+}
+
+/// A draining iterator over the items of a `HashSet`.
+///
+/// This `struct` is created by the [`drain`] method on [`HashSet`].
+/// See its documentation for more.
+///
+/// [`HashSet`]: struct.HashSet.html
+/// [`drain`]: struct.HashSet.html#method.drain
+pub struct Drain<'a, K: 'static> {
+ iter: hash_map::Drain<'a, K, ()>,
+}
+
+/// A lazy iterator producing elements in the intersection of `HashSet`s.
+///
+/// This `struct` is created by the [`intersection`] method on [`HashSet`].
+/// See its documentation for more.
+///
+/// [`HashSet`]: struct.HashSet.html
+/// [`intersection`]: struct.HashSet.html#method.intersection
+pub struct Intersection<'a, T: 'a, S: 'a> {
+ // iterator of the first set
+ iter: Iter<'a, T>,
+ // the second set
+ other: &'a HashSet<T, S>,
+}
+
+/// A lazy iterator producing elements in the difference of `HashSet`s.
+///
+/// This `struct` is created by the [`difference`] method on [`HashSet`].
+/// See its documentation for more.
+///
+/// [`HashSet`]: struct.HashSet.html
+/// [`difference`]: struct.HashSet.html#method.difference
+pub struct Difference<'a, T: 'a, S: 'a> {
+ // iterator of the first set
+ iter: Iter<'a, T>,
+ // the second set
+ other: &'a HashSet<T, S>,
+}
+
+/// A lazy iterator producing elements in the symmetric difference of `HashSet`s.
+///
+/// This `struct` is created by the [`symmetric_difference`] method on
+/// [`HashSet`]. See its documentation for more.
+///
+/// [`HashSet`]: struct.HashSet.html
+/// [`symmetric_difference`]: struct.HashSet.html#method.symmetric_difference
+pub struct SymmetricDifference<'a, T: 'a, S: 'a> {
+ iter: Chain<Difference<'a, T, S>, Difference<'a, T, S>>,
+}
+
+/// A lazy iterator producing elements in the union of `HashSet`s.
+///
+/// This `struct` is created by the [`union`] method on [`HashSet`].
+/// See its documentation for more.
+///
+/// [`HashSet`]: struct.HashSet.html
+/// [`union`]: struct.HashSet.html#method.union
+pub struct Union<'a, T: 'a, S: 'a> {
+ iter: Chain<Iter<'a, T>, Difference<'a, T, S>>,
+}
+
+impl<'a, T, S> IntoIterator for &'a HashSet<T, S>
+where
+ T: Eq + Hash,
+ S: BuildHasher,
+{
+ type Item = &'a T;
+ type IntoIter = Iter<'a, T>;
+
+ fn into_iter(self) -> Iter<'a, T> {
+ self.iter()
+ }
+}
+
+impl<T, S> IntoIterator for HashSet<T, S>
+where
+ T: Eq + Hash,
+ S: BuildHasher,
+{
+ type Item = T;
+ type IntoIter = IntoIter<T>;
+
+ /// Creates a consuming iterator, that is, one that moves each value out
+ /// of the set in arbitrary order. The set cannot be used after calling
+ /// this.
+ ///
+ /// # Examples
+ ///
+ /// ```
+ /// use std::collections::HashSet;
+ /// let mut set = HashSet::new();
+ /// set.insert("a".to_string());
+ /// set.insert("b".to_string());
+ ///
+ /// // Not possible to collect to a Vec<String> with a regular `.iter()`.
+ /// let v: Vec<String> = set.into_iter().collect();
+ ///
+ /// // Will print in an arbitrary order.
+ /// for x in &v {
+ /// println!("{}", x);
+ /// }
+ /// ```
+ fn into_iter(self) -> IntoIter<T> {
+ IntoIter {
+ iter: self.map.into_iter(),
+ }
+ }
+}
+
+impl<'a, K> Clone for Iter<'a, K> {
+ fn clone(&self) -> Iter<'a, K> {
+ Iter {
+ iter: self.iter.clone(),
+ }
+ }
+}
+impl<'a, K> Iterator for Iter<'a, K> {
+ type Item = &'a K;
+
+ fn next(&mut self) -> Option<&'a K> {
+ self.iter.next()
+ }
+ fn size_hint(&self) -> (usize, Option<usize>) {
+ self.iter.size_hint()
+ }
+}
+impl<'a, K> ExactSizeIterator for Iter<'a, K> {
+ fn len(&self) -> usize {
+ self.iter.len()
+ }
+}
+
+impl<'a, K: fmt::Debug> fmt::Debug for Iter<'a, K> {
+ fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+ f.debug_list().entries(self.clone()).finish()
+ }
+}
+
+impl<K> Iterator for IntoIter<K> {
+ type Item = K;
+
+ fn next(&mut self) -> Option<K> {
+ self.iter.next().map(|(k, _)| k)
+ }
+ fn size_hint(&self) -> (usize, Option<usize>) {
+ self.iter.size_hint()
+ }
+}
+impl<K> ExactSizeIterator for IntoIter<K> {
+ fn len(&self) -> usize {
+ self.iter.len()
+ }
+}
+
+impl<K: fmt::Debug> fmt::Debug for IntoIter<K> {
+ fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+ let entries_iter = self.iter.inner.iter().map(|(k, _)| k);
+ f.debug_list().entries(entries_iter).finish()
+ }
+}
+
+impl<'a, K> Iterator for Drain<'a, K> {
+ type Item = K;
+
+ fn next(&mut self) -> Option<K> {
+ self.iter.next().map(|(k, _)| k)
+ }
+ fn size_hint(&self) -> (usize, Option<usize>) {
+ self.iter.size_hint()
+ }
+}
+impl<'a, K> ExactSizeIterator for Drain<'a, K> {
+ fn len(&self) -> usize {
+ self.iter.len()
+ }
+}
+
+impl<'a, K: fmt::Debug> fmt::Debug for Drain<'a, K> {
+ fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+ let entries_iter = self.iter.inner.iter().map(|(k, _)| k);
+ f.debug_list().entries(entries_iter).finish()
+ }
+}
+
+impl<'a, T, S> Clone for Intersection<'a, T, S> {
+ fn clone(&self) -> Intersection<'a, T, S> {
+ Intersection {
+ iter: self.iter.clone(),
+ ..*self
+ }
+ }
+}
+
+impl<'a, T, S> Iterator for Intersection<'a, T, S>
+where
+ T: Eq + Hash,
+ S: BuildHasher,
+{
+ type Item = &'a T;
+
+ fn next(&mut self) -> Option<&'a T> {
+ loop {
+ let elt = self.iter.next()?;
+ if self.other.contains(elt) {
+ return Some(elt);
+ }
+ }
+ }
+
+ fn size_hint(&self) -> (usize, Option<usize>) {
+ let (_, upper) = self.iter.size_hint();
+ (0, upper)
+ }
+}
+
+impl<'a, T, S> fmt::Debug for Intersection<'a, T, S>
+where
+ T: fmt::Debug + Eq + Hash,
+ S: BuildHasher,
+{
+ fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+ f.debug_list().entries(self.clone()).finish()
+ }
+}
+
+impl<'a, T, S> Clone for Difference<'a, T, S> {
+ fn clone(&self) -> Difference<'a, T, S> {
+ Difference {
+ iter: self.iter.clone(),
+ ..*self
+ }
+ }
+}
+
+impl<'a, T, S> Iterator for Difference<'a, T, S>
+where
+ T: Eq + Hash,
+ S: BuildHasher,
+{
+ type Item = &'a T;
+
+ fn next(&mut self) -> Option<&'a T> {
+ loop {
+ let elt = self.iter.next()?;
+ if !self.other.contains(elt) {
+ return Some(elt);
+ }
+ }
+ }
+
+ fn size_hint(&self) -> (usize, Option<usize>) {
+ let (_, upper) = self.iter.size_hint();
+ (0, upper)
+ }
+}
+
+impl<'a, T, S> fmt::Debug for Difference<'a, T, S>
+where
+ T: fmt::Debug + Eq + Hash,
+ S: BuildHasher,
+{
+ fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+ f.debug_list().entries(self.clone()).finish()
+ }
+}
+
+impl<'a, T, S> Clone for SymmetricDifference<'a, T, S> {
+ fn clone(&self) -> SymmetricDifference<'a, T, S> {
+ SymmetricDifference {
+ iter: self.iter.clone(),
+ }
+ }
+}
+
+impl<'a, T, S> Iterator for SymmetricDifference<'a, T, S>
+where
+ T: Eq + Hash,
+ S: BuildHasher,
+{
+ 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()
+ }
+}
+
+impl<'a, T, S> fmt::Debug for SymmetricDifference<'a, T, S>
+where
+ T: fmt::Debug + Eq + Hash,
+ S: BuildHasher,
+{
+ fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+ f.debug_list().entries(self.clone()).finish()
+ }
+}
+
+impl<'a, T, S> Clone for Union<'a, T, S> {
+ fn clone(&self) -> Union<'a, T, S> {
+ Union {
+ iter: self.iter.clone(),
+ }
+ }
+}
+
+impl<'a, T, S> fmt::Debug for Union<'a, T, S>
+where
+ T: fmt::Debug + Eq + Hash,
+ S: BuildHasher,
+{
+ fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+ f.debug_list().entries(self.clone()).finish()
+ }
+}
+
+impl<'a, T, S> Iterator for Union<'a, T, S>
+where
+ T: Eq + Hash,
+ S: BuildHasher,
+{
+ 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()
+ }
+}
+
+#[allow(dead_code)]
+fn assert_covariance() {
+ fn set<'new>(v: HashSet<&'static str>) -> HashSet<&'new str> {
+ v
+ }
+ fn iter<'a, 'new>(v: Iter<'a, &'static str>) -> Iter<'a, &'new str> {
+ v
+ }
+ fn into_iter<'new>(v: IntoIter<&'static str>) -> IntoIter<&'new str> {
+ v
+ }
+ fn difference<'a, 'new>(
+ v: Difference<'a, &'static str, RandomState>,
+ ) -> Difference<'a, &'new str, RandomState> {
+ v
+ }
+ fn symmetric_difference<'a, 'new>(
+ v: SymmetricDifference<'a, &'static str, RandomState>,
+ ) -> SymmetricDifference<'a, &'new str, RandomState> {
+ v
+ }
+ fn intersection<'a, 'new>(
+ v: Intersection<'a, &'static str, RandomState>,
+ ) -> Intersection<'a, &'new str, RandomState> {
+ v
+ }
+ fn union<'a, 'new>(
+ v: Union<'a, &'static str, RandomState>,
+ ) -> Union<'a, &'new str, RandomState> {
+ v
+ }
+ fn drain<'new>(d: Drain<'static, &'static str>) -> Drain<'new, &'new str> {
+ d
+ }
+}
+
+#[cfg(test)]
+mod test_set {
+ use super::hash_map::RandomState;
+ use super::HashSet;
+
+ #[test]
+ fn test_zero_capacities() {
+ type HS = HashSet<i32>;
+
+ let s = HS::new();
+ assert_eq!(s.capacity(), 0);
+
+ let s = HS::default();
+ assert_eq!(s.capacity(), 0);
+
+ let s = HS::with_hasher(RandomState::new());
+ assert_eq!(s.capacity(), 0);
+
+ let s = HS::with_capacity(0);
+ assert_eq!(s.capacity(), 0);
+
+ let s = HS::with_capacity_and_hasher(0, RandomState::new());
+ assert_eq!(s.capacity(), 0);
+
+ let mut s = HS::new();
+ s.insert(1);
+ s.insert(2);
+ s.remove(&1);
+ s.remove(&2);
+ s.shrink_to_fit();
+ assert_eq!(s.capacity(), 0);
+
+ let mut s = HS::new();
+ s.reserve(0);
+ assert_eq!(s.capacity(), 0);
+ }
+
+ #[test]
+ fn test_disjoint() {
+ let mut xs = HashSet::new();
+ let mut ys = HashSet::new();
+ assert!(xs.is_disjoint(&ys));
+ assert!(ys.is_disjoint(&xs));
+ assert!(xs.insert(5));
+ assert!(ys.insert(11));
+ assert!(xs.is_disjoint(&ys));
+ assert!(ys.is_disjoint(&xs));
+ assert!(xs.insert(7));
+ assert!(xs.insert(19));
+ assert!(xs.insert(4));
+ assert!(ys.insert(2));
+ assert!(ys.insert(-11));
+ assert!(xs.is_disjoint(&ys));
+ assert!(ys.is_disjoint(&xs));
+ assert!(ys.insert(7));
+ assert!(!xs.is_disjoint(&ys));
+ assert!(!ys.is_disjoint(&xs));
+ }
+
+ #[test]
+ fn test_subset_and_superset() {
+ let mut a = HashSet::new();
+ assert!(a.insert(0));
+ assert!(a.insert(5));
+ assert!(a.insert(11));
+ assert!(a.insert(7));
+
+ let mut b = HashSet::new();
+ assert!(b.insert(0));
+ assert!(b.insert(7));
+ assert!(b.insert(19));
+ assert!(b.insert(250));
+ assert!(b.insert(11));
+ assert!(b.insert(200));
+
+ assert!(!a.is_subset(&b));
+ assert!(!a.is_superset(&b));
+ assert!(!b.is_subset(&a));
+ assert!(!b.is_superset(&a));
+
+ assert!(b.insert(5));
+
+ assert!(a.is_subset(&b));
+ assert!(!a.is_superset(&b));
+ assert!(!b.is_subset(&a));
+ assert!(b.is_superset(&a));
+ }
+
+ #[test]
+ fn test_iterate() {
+ let mut a = HashSet::new();
+ for i in 0..32 {
+ assert!(a.insert(i));
+ }
+ let mut observed: u32 = 0;
+ for k in &a {
+ observed |= 1 << *k;
+ }
+ assert_eq!(observed, 0xFFFF_FFFF);
+ }
+
+ #[test]
+ fn test_intersection() {
+ let mut a = HashSet::new();
+ let mut b = HashSet::new();
+
+ assert!(a.insert(11));
+ assert!(a.insert(1));
+ assert!(a.insert(3));
+ assert!(a.insert(77));
+ assert!(a.insert(103));
+ assert!(a.insert(5));
+ assert!(a.insert(-5));
+
+ assert!(b.insert(2));
+ assert!(b.insert(11));
+ assert!(b.insert(77));
+ assert!(b.insert(-9));
+ assert!(b.insert(-42));
+ assert!(b.insert(5));
+ assert!(b.insert(3));
+
+ let mut i = 0;
+ let expected = [3, 5, 11, 77];
+ for x in a.intersection(&b) {
+ assert!(expected.contains(x));
+ i += 1
+ }
+ assert_eq!(i, expected.len());
+ }
+
+ #[test]
+ fn test_difference() {
+ let mut a = HashSet::new();
+ let mut b = HashSet::new();
+
+ assert!(a.insert(1));
+ assert!(a.insert(3));
+ assert!(a.insert(5));
+ assert!(a.insert(9));
+ assert!(a.insert(11));
+
+ assert!(b.insert(3));
+ assert!(b.insert(9));
+
+ let mut i = 0;
+ let expected = [1, 5, 11];
+ for x in a.difference(&b) {
+ assert!(expected.contains(x));
+ i += 1
+ }
+ assert_eq!(i, expected.len());
+ }
+
+ #[test]
+ fn test_symmetric_difference() {
+ let mut a = HashSet::new();
+ let mut b = HashSet::new();
+
+ assert!(a.insert(1));
+ assert!(a.insert(3));
+ assert!(a.insert(5));
+ assert!(a.insert(9));
+ assert!(a.insert(11));
+
+ assert!(b.insert(-2));
+ assert!(b.insert(3));
+ assert!(b.insert(9));
+ assert!(b.insert(14));
+ assert!(b.insert(22));
+
+ let mut i = 0;
+ let expected = [-2, 1, 5, 11, 14, 22];
+ for x in a.symmetric_difference(&b) {
+ assert!(expected.contains(x));
+ i += 1
+ }
+ assert_eq!(i, expected.len());
+ }
+
+ #[test]
+ fn test_union() {
+ let mut a = HashSet::new();
+ let mut b = HashSet::new();
+
+ assert!(a.insert(1));
+ assert!(a.insert(3));
+ assert!(a.insert(5));
+ assert!(a.insert(9));
+ assert!(a.insert(11));
+ assert!(a.insert(16));
+ assert!(a.insert(19));
+ assert!(a.insert(24));
+
+ assert!(b.insert(-2));
+ assert!(b.insert(1));
+ assert!(b.insert(5));
+ assert!(b.insert(9));
+ assert!(b.insert(13));
+ assert!(b.insert(19));
+
+ let mut i = 0;
+ let expected = [-2, 1, 3, 5, 9, 11, 13, 16, 19, 24];
+ for x in a.union(&b) {
+ assert!(expected.contains(x));
+ i += 1
+ }
+ assert_eq!(i, expected.len());
+ }
+
+ #[test]
+ fn test_from_iter() {
+ let xs = [1, 2, 3, 4, 5, 6, 7, 8, 9];
+
+ let set: HashSet<_> = xs.iter().cloned().collect();
+
+ for x in &xs {
+ assert!(set.contains(x));
+ }
+ }
+
+ #[test]
+ fn test_move_iter() {
+ let hs = {
+ let mut hs = HashSet::new();
+
+ hs.insert('a');
+ hs.insert('b');
+
+ hs
+ };
+
+ let v = hs.into_iter().collect::<Vec<char>>();
+ assert!(v == ['a', 'b'] || v == ['b', 'a']);
+ }
+
+ #[test]
+ fn test_eq() {
+ // These constants once happened to expose a bug in insert().
+ // I'm keeping them around to prevent a regression.
+ let mut s1 = HashSet::new();
+
+ s1.insert(1);
+ s1.insert(2);
+ s1.insert(3);
+
+ let mut s2 = HashSet::new();
+
+ s2.insert(1);
+ s2.insert(2);
+
+ assert_ne!(s1, s2);
+
+ s2.insert(3);
+
+ assert_eq!(s1, s2);
+ }
+
+ #[test]
+ fn test_show() {
+ let mut set = HashSet::new();
+ let empty = HashSet::<i32>::new();
+
+ set.insert(1);
+ set.insert(2);
+
+ let set_str = format!("{:?}", set);
+
+ assert!(set_str == "{1, 2}" || set_str == "{2, 1}");
+ assert_eq!(format!("{:?}", empty), "{}");
+ }
+
+ #[test]
+ fn test_trivial_drain() {
+ let mut s = HashSet::<i32>::new();
+ for _ in s.drain() {}
+ assert!(s.is_empty());
+ drop(s);
+
+ let mut s = HashSet::<i32>::new();
+ drop(s.drain());
+ assert!(s.is_empty());
+ }
+
+ #[test]
+ fn test_drain() {
+ let mut s: HashSet<_> = (1..100).collect();
+
+ // try this a bunch of times to make sure we don't screw up internal state.
+ for _ in 0..20 {
+ assert_eq!(s.len(), 99);
+
+ {
+ let mut last_i = 0;
+ let mut d = s.drain();
+ for (i, x) in d.by_ref().take(50).enumerate() {
+ last_i = i;
+ assert_ne!(x, 0);
+ }
+ assert_eq!(last_i, 49);
+ }
+
+ for _ in &s {
+ panic!("s should be empty!");
+ }
+
+ // reset to try again.
+ s.extend(1..100);
+ }
+ }
+
+ #[test]
+ fn test_replace() {
+ use hash;
+
+ #[derive(Debug)]
+ struct Foo(&'static str, i32);
+
+ impl PartialEq for Foo {
+ fn eq(&self, other: &Self) -> bool {
+ self.0 == other.0
+ }
+ }
+
+ impl Eq for Foo {}
+
+ impl hash::Hash for Foo {
+ fn hash<H: hash::Hasher>(&self, h: &mut H) {
+ self.0.hash(h);
+ }
+ }
+
+ let mut s = HashSet::new();
+ assert_eq!(s.replace(Foo("a", 1)), None);
+ assert_eq!(s.len(), 1);
+ assert_eq!(s.replace(Foo("a", 2)), Some(Foo("a", 1)));
+ assert_eq!(s.len(), 1);
+
+ let mut it = s.iter();
+ assert_eq!(it.next(), Some(&Foo("a", 2)));
+ assert_eq!(it.next(), None);
+ }
+
+ #[test]
+ fn test_extend_ref() {
+ let mut a = HashSet::new();
+ a.insert(1);
+
+ a.extend(&[2, 3, 4]);
+
+ assert_eq!(a.len(), 4);
+ assert!(a.contains(&1));
+ assert!(a.contains(&2));
+ assert!(a.contains(&3));
+ assert!(a.contains(&4));
+
+ let mut b = HashSet::new();
+ b.insert(5);
+ b.insert(6);
+
+ a.extend(&b);
+
+ assert_eq!(a.len(), 6);
+ assert!(a.contains(&1));
+ assert!(a.contains(&2));
+ assert!(a.contains(&3));
+ assert!(a.contains(&4));
+ assert!(a.contains(&5));
+ assert!(a.contains(&6));
+ }
+
+ #[test]
+ fn test_retain() {
+ let xs = [1, 2, 3, 4, 5, 6];
+ let mut set: HashSet<isize> = xs.iter().cloned().collect();
+ set.retain(|&k| k % 2 == 0);
+ assert_eq!(set.len(), 3);
+ assert!(set.contains(&2));
+ assert!(set.contains(&4));
+ assert!(set.contains(&6));
+ }
+}
generated by cgit v1.2.3 (git 2.39.1) at 2025-02-13 19:56:57 +0000