Joel Galenson | 2370d12 | 2020-10-12 16:02:26 -0700 | [diff] [blame] | 1 | //! A hash set where the elements are held by weak pointers and compared by value. |
| 2 | |
David LeGare | 77e4bb9 | 2022-03-02 16:21:23 +0000 | [diff] [blame] | 3 | use crate::compat::*; |
Joel Galenson | 2370d12 | 2020-10-12 16:02:26 -0700 | [diff] [blame] | 4 | |
| 5 | use super::traits::*; |
| 6 | use super::weak_key_hash_map as base; |
| 7 | |
| 8 | pub use super::WeakHashSet; |
| 9 | |
| 10 | impl <T: WeakKey> WeakHashSet<T, RandomState> { |
| 11 | /// Creates an empty `WeakHashSet`. |
David LeGare | 77e4bb9 | 2022-03-02 16:21:23 +0000 | [diff] [blame] | 12 | /// |
| 13 | /// *O*(1) time |
Joel Galenson | 2370d12 | 2020-10-12 16:02:26 -0700 | [diff] [blame] | 14 | pub fn new() -> Self { |
| 15 | WeakHashSet(base::WeakKeyHashMap::new()) |
| 16 | } |
| 17 | |
| 18 | /// Creates an empty `WeakHashSet` with the given capacity. |
David LeGare | 77e4bb9 | 2022-03-02 16:21:23 +0000 | [diff] [blame] | 19 | /// |
| 20 | /// *O*(*n*) time |
Joel Galenson | 2370d12 | 2020-10-12 16:02:26 -0700 | [diff] [blame] | 21 | pub fn with_capacity(capacity: usize) -> Self { |
| 22 | WeakHashSet(base::WeakKeyHashMap::with_capacity(capacity)) |
| 23 | } |
| 24 | } |
| 25 | |
| 26 | impl <T: WeakKey, S: BuildHasher> WeakHashSet<T, S> { |
| 27 | /// Creates an empty `WeakHashSet` with the given capacity and hasher. |
David LeGare | 77e4bb9 | 2022-03-02 16:21:23 +0000 | [diff] [blame] | 28 | /// |
| 29 | /// *O*(*n*) time |
Joel Galenson | 2370d12 | 2020-10-12 16:02:26 -0700 | [diff] [blame] | 30 | pub fn with_hasher(hash_builder: S) -> Self { |
| 31 | WeakHashSet(base::WeakKeyHashMap::with_hasher(hash_builder)) |
| 32 | } |
| 33 | |
| 34 | /// Creates an empty `WeakHashSet` with the given capacity and hasher. |
David LeGare | 77e4bb9 | 2022-03-02 16:21:23 +0000 | [diff] [blame] | 35 | /// |
| 36 | /// *O*(*n*) time |
Joel Galenson | 2370d12 | 2020-10-12 16:02:26 -0700 | [diff] [blame] | 37 | pub fn with_capacity_and_hasher(capacity: usize, hash_builder: S) -> Self { |
| 38 | WeakHashSet(base::WeakKeyHashMap::with_capacity_and_hasher(capacity, hash_builder)) |
| 39 | } |
| 40 | |
| 41 | /// Returns a reference to the map's `BuildHasher`. |
David LeGare | 77e4bb9 | 2022-03-02 16:21:23 +0000 | [diff] [blame] | 42 | /// |
| 43 | /// *O*(1) time |
Joel Galenson | 2370d12 | 2020-10-12 16:02:26 -0700 | [diff] [blame] | 44 | pub fn hasher(&self) -> &S { |
| 45 | self.0.hasher() |
| 46 | } |
| 47 | |
| 48 | /// Returns the number of elements the map can hold without reallocating. |
David LeGare | 77e4bb9 | 2022-03-02 16:21:23 +0000 | [diff] [blame] | 49 | /// |
| 50 | /// *O*(1) time |
Joel Galenson | 2370d12 | 2020-10-12 16:02:26 -0700 | [diff] [blame] | 51 | pub fn capacity(&self) -> usize { |
| 52 | self.0.capacity() |
| 53 | } |
| 54 | |
| 55 | /// Removes all mappings whose keys have expired. |
David LeGare | 77e4bb9 | 2022-03-02 16:21:23 +0000 | [diff] [blame] | 56 | /// |
| 57 | /// *O*(*n*) time |
Joel Galenson | 2370d12 | 2020-10-12 16:02:26 -0700 | [diff] [blame] | 58 | pub fn remove_expired(&mut self) { |
| 59 | self.0.remove_expired() |
| 60 | } |
| 61 | |
| 62 | /// Reserves room for additional elements. |
David LeGare | 77e4bb9 | 2022-03-02 16:21:23 +0000 | [diff] [blame] | 63 | /// |
| 64 | /// *O*(*n*) time |
Joel Galenson | 2370d12 | 2020-10-12 16:02:26 -0700 | [diff] [blame] | 65 | pub fn reserve(&mut self, additional_capacity: usize) { |
| 66 | self.0.reserve(additional_capacity) |
| 67 | } |
| 68 | |
| 69 | /// Shrinks the capacity to the minimum allowed to hold the current number of elements. |
David LeGare | 77e4bb9 | 2022-03-02 16:21:23 +0000 | [diff] [blame] | 70 | /// |
| 71 | /// *O*(*n*) time |
Joel Galenson | 2370d12 | 2020-10-12 16:02:26 -0700 | [diff] [blame] | 72 | pub fn shrink_to_fit(&mut self) { |
| 73 | self.0.shrink_to_fit() |
| 74 | } |
| 75 | |
| 76 | /// Returns an over-approximation of the number of elements. |
David LeGare | 77e4bb9 | 2022-03-02 16:21:23 +0000 | [diff] [blame] | 77 | /// |
| 78 | /// *O*(1) time |
Joel Galenson | 2370d12 | 2020-10-12 16:02:26 -0700 | [diff] [blame] | 79 | pub fn len(&self) -> usize { |
| 80 | self.0.len() |
| 81 | } |
| 82 | |
| 83 | /// Is the set empty? |
| 84 | /// |
| 85 | /// Note that this may return false even if all keys in the set have |
| 86 | /// expired, if they haven't been collected yet. |
David LeGare | 77e4bb9 | 2022-03-02 16:21:23 +0000 | [diff] [blame] | 87 | /// |
| 88 | /// *O*(1) time |
Joel Galenson | 2370d12 | 2020-10-12 16:02:26 -0700 | [diff] [blame] | 89 | pub fn is_empty(&self) -> bool { |
| 90 | self.0.is_empty() |
| 91 | } |
| 92 | |
| 93 | /// The proportion of buckets that are used. |
| 94 | /// |
| 95 | /// This is an over-approximation because of expired elements. |
David LeGare | 77e4bb9 | 2022-03-02 16:21:23 +0000 | [diff] [blame] | 96 | /// |
| 97 | /// *O*(1) time |
Joel Galenson | 2370d12 | 2020-10-12 16:02:26 -0700 | [diff] [blame] | 98 | pub fn load_factor(&self) -> f32 { |
| 99 | self.0.load_factor() |
| 100 | } |
| 101 | |
| 102 | /// Removes all associations from the map. |
David LeGare | 77e4bb9 | 2022-03-02 16:21:23 +0000 | [diff] [blame] | 103 | /// |
| 104 | /// *O*(*n*) time |
Joel Galenson | 2370d12 | 2020-10-12 16:02:26 -0700 | [diff] [blame] | 105 | pub fn clear(&mut self) { |
| 106 | self.0.clear() |
| 107 | } |
| 108 | |
| 109 | // Non-ptr WeakHashSet should probably have `get` method. |
| 110 | |
| 111 | /// Returns true if the map contains the specified key. |
David LeGare | 77e4bb9 | 2022-03-02 16:21:23 +0000 | [diff] [blame] | 112 | /// |
| 113 | /// expected *O*(1) time; worst-case *O*(*p*) time |
Joel Galenson | 2370d12 | 2020-10-12 16:02:26 -0700 | [diff] [blame] | 114 | pub fn contains<Q>(&self, key: &Q) -> bool |
| 115 | where Q: ?Sized + Eq + Hash, |
| 116 | T::Key: Borrow<Q> |
| 117 | { |
| 118 | self.0.contains_key(key) |
| 119 | } |
| 120 | |
| 121 | /// Gets a strong reference to the given key, if found. |
| 122 | /// |
| 123 | /// # Examples |
| 124 | /// |
| 125 | /// ``` |
| 126 | /// use weak_table::WeakHashSet; |
| 127 | /// use std::rc::{Rc, Weak}; |
| 128 | /// use std::ops::Deref; |
| 129 | /// |
| 130 | /// let mut set: WeakHashSet<Weak<String>> = WeakHashSet::new(); |
| 131 | /// |
| 132 | /// let a = Rc::new("a".to_owned()); |
| 133 | /// set.insert(a.clone()); |
| 134 | /// |
| 135 | /// let also_a = set.get("a").unwrap(); |
| 136 | /// |
| 137 | /// assert!(Rc::ptr_eq( &a, &also_a )); |
| 138 | /// ``` |
David LeGare | 77e4bb9 | 2022-03-02 16:21:23 +0000 | [diff] [blame] | 139 | /// |
| 140 | /// expected *O*(1) time; worst-case *O*(*p*) time |
Joel Galenson | 2370d12 | 2020-10-12 16:02:26 -0700 | [diff] [blame] | 141 | pub fn get<Q>(&self, key: &Q) -> Option<T::Strong> |
| 142 | where Q: ?Sized + Eq + Hash, |
| 143 | T::Key: Borrow<Q> |
| 144 | { |
| 145 | self.0.get_key(key) |
| 146 | } |
| 147 | |
| 148 | /// Unconditionally inserts the value, returning the old value if already present. Does not |
| 149 | /// replace the key. |
David LeGare | 77e4bb9 | 2022-03-02 16:21:23 +0000 | [diff] [blame] | 150 | /// |
| 151 | /// expected *O*(1) time; worst-case *O*(*p*) time |
Joel Galenson | 2370d12 | 2020-10-12 16:02:26 -0700 | [diff] [blame] | 152 | pub fn insert(&mut self, key: T::Strong) -> bool { |
| 153 | self.0.insert(key, ()).is_some() |
| 154 | } |
| 155 | |
| 156 | /// Removes the entry with the given key, if it exists, and returns the value. |
David LeGare | 77e4bb9 | 2022-03-02 16:21:23 +0000 | [diff] [blame] | 157 | /// |
| 158 | /// expected *O*(1) time; worst-case *O*(*p*) time |
Joel Galenson | 2370d12 | 2020-10-12 16:02:26 -0700 | [diff] [blame] | 159 | pub fn remove<Q>(&mut self, key: &Q) -> bool |
| 160 | where Q: ?Sized + Eq + Hash, |
| 161 | T::Key: Borrow<Q> |
| 162 | { |
| 163 | self.0.remove(key).is_some() |
| 164 | } |
| 165 | |
| 166 | /// Removes all mappings not satisfying the given predicate. |
| 167 | /// |
| 168 | /// Also removes any expired mappings. |
David LeGare | 77e4bb9 | 2022-03-02 16:21:23 +0000 | [diff] [blame] | 169 | /// |
| 170 | /// *O*(*n*) time |
Joel Galenson | 2370d12 | 2020-10-12 16:02:26 -0700 | [diff] [blame] | 171 | pub fn retain<F>(&mut self, mut f: F) |
| 172 | where F: FnMut(T::Strong) -> bool |
| 173 | { |
| 174 | self.0.retain(|k, _| f(k)) |
| 175 | } |
| 176 | |
| 177 | /// Is self a subset of other? |
David LeGare | 77e4bb9 | 2022-03-02 16:21:23 +0000 | [diff] [blame] | 178 | /// |
| 179 | /// expected *O*(*n*) time; worst-case *O*(*nq*) time (where *n* is |
| 180 | /// `self.capacity()` and *q* is the length of the probe sequences |
| 181 | /// in `other`) |
Joel Galenson | 2370d12 | 2020-10-12 16:02:26 -0700 | [diff] [blame] | 182 | pub fn is_subset<S1>(&self, other: &WeakHashSet<T, S1>) -> bool |
| 183 | where S1: BuildHasher |
| 184 | { |
| 185 | self.0.domain_is_subset(&other.0) |
| 186 | } |
| 187 | } |
| 188 | |
| 189 | /// An iterator over the elements of a set. |
| 190 | pub struct Iter<'a, T: 'a>(base::Keys<'a, T, ()>); |
| 191 | |
| 192 | impl<'a, T: WeakElement> Iterator for Iter<'a, T> { |
| 193 | type Item = T::Strong; |
| 194 | |
| 195 | fn next(&mut self) -> Option<Self::Item> { |
| 196 | self.0.next() |
| 197 | } |
| 198 | |
| 199 | fn size_hint(&self) -> (usize, Option<usize>) { |
| 200 | self.0.size_hint() |
| 201 | } |
| 202 | } |
| 203 | |
| 204 | /// An iterator over the elements of a set. |
| 205 | pub struct IntoIter<T>(base::IntoIter<T, ()>); |
| 206 | |
| 207 | impl<T: WeakElement> Iterator for IntoIter<T> { |
| 208 | type Item = T::Strong; |
| 209 | |
| 210 | fn next(&mut self) -> Option<Self::Item> { |
| 211 | self.0.next().map(|pair| pair.0) |
| 212 | } |
| 213 | |
| 214 | fn size_hint(&self) -> (usize, Option<usize>) { |
| 215 | self.0.size_hint() |
| 216 | } |
| 217 | } |
| 218 | |
| 219 | /// A draining iterator over the elements of a set. |
| 220 | pub struct Drain<'a, T: 'a>(base::Drain<'a, T, ()>); |
| 221 | |
| 222 | impl<'a, T: WeakElement> Iterator for Drain<'a, T> { |
| 223 | type Item = T::Strong; |
| 224 | |
| 225 | fn next(&mut self) -> Option<Self::Item> { |
| 226 | self.0.next().map(|pair| pair.0) |
| 227 | } |
| 228 | |
| 229 | fn size_hint(&self) -> (usize, Option<usize>) { |
| 230 | self.0.size_hint() |
| 231 | } |
| 232 | } |
| 233 | |
| 234 | impl<T: WeakKey, S> WeakHashSet<T, S> { |
| 235 | /// Gets an iterator over the keys and values. |
David LeGare | 77e4bb9 | 2022-03-02 16:21:23 +0000 | [diff] [blame] | 236 | /// |
| 237 | /// *O*(1) time |
Joel Galenson | 2370d12 | 2020-10-12 16:02:26 -0700 | [diff] [blame] | 238 | pub fn iter(&self) -> Iter<T> { |
| 239 | Iter(self.0.keys()) |
| 240 | } |
| 241 | |
| 242 | /// Gets a draining iterator, which removes all the values but retains the storage. |
David LeGare | 77e4bb9 | 2022-03-02 16:21:23 +0000 | [diff] [blame] | 243 | /// |
| 244 | /// *O*(1) time (and *O*(*n*) time to dispose of the result) |
Joel Galenson | 2370d12 | 2020-10-12 16:02:26 -0700 | [diff] [blame] | 245 | pub fn drain(&mut self) -> Drain<T> { |
| 246 | Drain(self.0.drain()) |
| 247 | } |
| 248 | } |
| 249 | |
| 250 | impl<T, S, S1> PartialEq<WeakHashSet<T, S1>> for WeakHashSet<T, S> |
| 251 | where T: WeakKey, |
| 252 | S: BuildHasher, |
| 253 | S1: BuildHasher |
| 254 | { |
| 255 | fn eq(&self, other: &WeakHashSet<T, S1>) -> bool { |
| 256 | self.0 == other.0 |
| 257 | } |
| 258 | } |
| 259 | |
| 260 | impl<T: WeakKey, S: BuildHasher> Eq for WeakHashSet<T, S> |
| 261 | where T::Key: Eq |
| 262 | { } |
| 263 | |
| 264 | impl<T: WeakKey, S: BuildHasher + Default> Default for WeakHashSet<T, S> { |
| 265 | fn default() -> Self { |
| 266 | WeakHashSet(base::WeakKeyHashMap::<T, (), S>::default()) |
| 267 | } |
| 268 | } |
| 269 | |
| 270 | impl<T, S> FromIterator<T::Strong> for WeakHashSet<T, S> |
| 271 | where T: WeakKey, |
| 272 | S: BuildHasher + Default |
| 273 | { |
| 274 | fn from_iter<I: IntoIterator<Item=T::Strong>>(iter: I) -> Self { |
| 275 | WeakHashSet(base::WeakKeyHashMap::<T, (), S>::from_iter( |
| 276 | iter.into_iter().map(|k| (k, ())))) |
| 277 | } |
| 278 | } |
| 279 | |
| 280 | impl<T: WeakKey, S: BuildHasher> Extend<T::Strong> for WeakHashSet<T, S> { |
| 281 | fn extend<I: IntoIterator<Item=T::Strong>>(&mut self, iter: I) { |
| 282 | self.0.extend(iter.into_iter().map(|k| (k, ()))) |
| 283 | } |
| 284 | } |
| 285 | |
| 286 | impl<T: WeakKey, S> Debug for WeakHashSet<T, S> |
| 287 | where T::Strong: Debug |
| 288 | { |
| 289 | fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { |
| 290 | self.0.fmt(f) |
| 291 | } |
| 292 | } |
| 293 | |
| 294 | impl<T: WeakKey, S> IntoIterator for WeakHashSet<T, S> { |
| 295 | type Item = T::Strong; |
| 296 | type IntoIter = IntoIter<T>; |
| 297 | |
David LeGare | 77e4bb9 | 2022-03-02 16:21:23 +0000 | [diff] [blame] | 298 | /// Creates an owning iterator from `self`. |
| 299 | /// |
| 300 | /// *O*(1) time (and *O*(*n*) time to dispose of the result) |
Joel Galenson | 2370d12 | 2020-10-12 16:02:26 -0700 | [diff] [blame] | 301 | fn into_iter(self) -> Self::IntoIter { |
| 302 | IntoIter(self.0.into_iter()) |
| 303 | } |
| 304 | } |
| 305 | |
| 306 | impl<'a, T: WeakKey, S> IntoIterator for &'a WeakHashSet<T, S> { |
| 307 | type Item = T::Strong; |
| 308 | type IntoIter = Iter<'a, T>; |
| 309 | |
David LeGare | 77e4bb9 | 2022-03-02 16:21:23 +0000 | [diff] [blame] | 310 | /// Creates a borrowing iterator from `self`. |
| 311 | /// |
| 312 | /// *O*(1) time |
Joel Galenson | 2370d12 | 2020-10-12 16:02:26 -0700 | [diff] [blame] | 313 | fn into_iter(self) -> Self::IntoIter { |
| 314 | Iter(self.0.keys()) |
| 315 | } |
| 316 | } |