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 pointer. |
| 2 | |
| 3 | use std::collections::hash_map::RandomState; |
| 4 | use std::fmt::{self, Debug}; |
| 5 | use std::hash::BuildHasher; |
| 6 | use std::iter::FromIterator; |
| 7 | use std::ops::Deref; |
| 8 | |
| 9 | use super::traits::*; |
| 10 | use super::ptr_weak_key_hash_map as base; |
| 11 | use super::by_ptr::ByPtr; |
| 12 | |
| 13 | pub use super::PtrWeakHashSet; |
| 14 | |
| 15 | impl <T: WeakElement> PtrWeakHashSet<T, RandomState> |
| 16 | where T::Strong: Deref |
| 17 | { |
| 18 | /// Creates an empty `PtrWeakHashSet`. |
| 19 | pub fn new() -> Self { |
| 20 | PtrWeakHashSet(base::PtrWeakKeyHashMap::new()) |
| 21 | } |
| 22 | |
| 23 | /// Creates an empty `PtrWeakHashSet` with the given capacity. |
| 24 | pub fn with_capacity(capacity: usize) -> Self { |
| 25 | PtrWeakHashSet(base::PtrWeakKeyHashMap::with_capacity(capacity)) |
| 26 | } |
| 27 | } |
| 28 | |
| 29 | impl <T: WeakElement, S: BuildHasher> PtrWeakHashSet<T, S> |
| 30 | where T::Strong: Deref |
| 31 | { |
| 32 | /// Creates an empty `PtrWeakHashSet` with the given capacity and hasher. |
| 33 | pub fn with_hasher(hash_builder: S) -> Self { |
| 34 | PtrWeakHashSet(base::PtrWeakKeyHashMap::with_hasher(hash_builder)) |
| 35 | } |
| 36 | |
| 37 | /// Creates an empty `PtrWeakHashSet` with the given capacity and hasher. |
| 38 | pub fn with_capacity_and_hasher(capacity: usize, hash_builder: S) -> Self { |
| 39 | PtrWeakHashSet(base::PtrWeakKeyHashMap::with_capacity_and_hasher(capacity, hash_builder)) |
| 40 | } |
| 41 | |
| 42 | /// Returns a reference to the map's `BuildHasher`. |
| 43 | pub fn hasher(&self) -> &S { |
| 44 | self.0.hasher() |
| 45 | } |
| 46 | |
| 47 | /// Returns the number of elements the map can hold without reallocating. |
| 48 | pub fn capacity(&self) -> usize { |
| 49 | self.0.capacity() |
| 50 | } |
| 51 | |
| 52 | /// Removes all mappings whose keys have expired. |
| 53 | pub fn remove_expired(&mut self) { |
| 54 | self.0.remove_expired() |
| 55 | } |
| 56 | |
| 57 | /// Reserves room for additional elements. |
| 58 | pub fn reserve(&mut self, additional_capacity: usize) { |
| 59 | self.0.reserve(additional_capacity) |
| 60 | } |
| 61 | |
| 62 | /// Shrinks the capacity to the minimum allowed to hold the current number of elements. |
| 63 | pub fn shrink_to_fit(&mut self) { |
| 64 | self.0.shrink_to_fit() |
| 65 | } |
| 66 | |
| 67 | /// Returns an over-approximation of the number of elements. |
| 68 | pub fn len(&self) -> usize { |
| 69 | self.0.len() |
| 70 | } |
| 71 | |
| 72 | /// Is the set known to be empty? |
| 73 | /// |
| 74 | /// This could answer `false` for an empty set whose elements have |
| 75 | /// expired but have yet to be collected. |
| 76 | pub fn is_empty(&self) -> bool { |
| 77 | self.len() == 0 |
| 78 | } |
| 79 | |
| 80 | |
| 81 | /// The proportion of buckets that are used. |
| 82 | /// |
| 83 | /// This is an over-approximation because of expired elements. |
| 84 | pub fn load_factor(&self) -> f32 { |
| 85 | self.0.load_factor() |
| 86 | } |
| 87 | |
| 88 | /// Removes all associations from the map. |
| 89 | pub fn clear(&mut self) { |
| 90 | self.0.clear() |
| 91 | } |
| 92 | |
| 93 | /// Returns true if the map contains the specified key. |
| 94 | pub fn contains(&self, key: &T::Strong) -> bool { |
| 95 | self.0.contains_key(key) |
| 96 | } |
| 97 | |
| 98 | /// Unconditionally inserts the value, returning the old value if already present. Does not |
| 99 | /// replace the key. |
| 100 | pub fn insert(&mut self, key: T::Strong) -> bool { |
| 101 | self.0.insert(key, ()).is_some() |
| 102 | } |
| 103 | |
| 104 | /// Removes the entry with the given key, if it exists, and returns the value. |
| 105 | pub fn remove(&mut self, key: &T::Strong) -> bool { |
| 106 | self.0.remove(key).is_some() |
| 107 | } |
| 108 | |
| 109 | /// Removes all mappings not satisfying the given predicate. |
| 110 | /// |
| 111 | /// Also removes any expired mappings. |
| 112 | pub fn retain<F>(&mut self, mut f: F) |
| 113 | where F: FnMut(T::Strong) -> bool |
| 114 | { |
| 115 | self.0.retain(|k, _| f(k)) |
| 116 | } |
| 117 | |
| 118 | /// Is self a subset of other? |
| 119 | pub fn is_subset<S1>(&self, other: &PtrWeakHashSet<T, S1>) -> bool |
| 120 | where S1: BuildHasher |
| 121 | { |
| 122 | self.0.domain_is_subset(&other.0) |
| 123 | } |
| 124 | } |
| 125 | |
| 126 | /// An iterator over the elements of a set. |
| 127 | pub struct Iter<'a, T: 'a>(base::Keys<'a, ByPtr<T>, ()>); |
| 128 | |
| 129 | impl<'a, T: WeakElement> Iterator for Iter<'a, T> { |
| 130 | type Item = T::Strong; |
| 131 | |
| 132 | fn next(&mut self) -> Option<Self::Item> { |
| 133 | self.0.next() |
| 134 | } |
| 135 | |
| 136 | fn size_hint(&self) -> (usize, Option<usize>) { |
| 137 | self.0.size_hint() |
| 138 | } |
| 139 | } |
| 140 | |
| 141 | /// An iterator over the elements of a set. |
| 142 | pub struct IntoIter<T>(base::IntoIter<ByPtr<T>, ()>); |
| 143 | |
| 144 | impl<T: WeakElement> Iterator for IntoIter<T> { |
| 145 | type Item = T::Strong; |
| 146 | |
| 147 | fn next(&mut self) -> Option<Self::Item> { |
| 148 | self.0.next().map(|pair| pair.0) |
| 149 | } |
| 150 | |
| 151 | fn size_hint(&self) -> (usize, Option<usize>) { |
| 152 | self.0.size_hint() |
| 153 | } |
| 154 | } |
| 155 | |
| 156 | /// A draining iterator over the elements of a set. |
| 157 | pub struct Drain<'a, T: 'a>(base::Drain<'a, ByPtr<T>, ()>); |
| 158 | |
| 159 | impl<'a, T: WeakElement> Iterator for Drain<'a, T> { |
| 160 | type Item = T::Strong; |
| 161 | |
| 162 | fn next(&mut self) -> Option<Self::Item> { |
| 163 | self.0.next().map(|pair| pair.0) |
| 164 | } |
| 165 | |
| 166 | fn size_hint(&self) -> (usize, Option<usize>) { |
| 167 | self.0.size_hint() |
| 168 | } |
| 169 | } |
| 170 | |
| 171 | impl<T: WeakElement, S> PtrWeakHashSet<T, S> |
| 172 | where T::Strong: Deref |
| 173 | { |
| 174 | /// Gets an iterator over the keys and values. |
| 175 | pub fn iter(&self) -> Iter<T> { |
| 176 | Iter(self.0.keys()) |
| 177 | } |
| 178 | |
| 179 | /// Gets a draining iterator, which removes all the values but retains the storage. |
| 180 | pub fn drain(&mut self) -> Drain<T> { |
| 181 | Drain(self.0.drain()) |
| 182 | } |
| 183 | } |
| 184 | |
| 185 | impl<T, S, S1> PartialEq<PtrWeakHashSet<T, S1>> for PtrWeakHashSet<T, S> |
| 186 | where T: WeakElement, |
| 187 | T::Strong: Deref, |
| 188 | S: BuildHasher, |
| 189 | S1: BuildHasher |
| 190 | { |
| 191 | fn eq(&self, other: &PtrWeakHashSet<T, S1>) -> bool { |
| 192 | self.0 == other.0 |
| 193 | } |
| 194 | } |
| 195 | |
| 196 | impl<T: WeakElement, S: BuildHasher> Eq for PtrWeakHashSet<T, S> |
| 197 | where T::Strong: Deref |
| 198 | { } |
| 199 | |
| 200 | impl<T: WeakElement, S: BuildHasher + Default> Default for PtrWeakHashSet<T, S> |
| 201 | where T::Strong: Deref |
| 202 | { |
| 203 | fn default() -> Self { |
| 204 | PtrWeakHashSet(base::PtrWeakKeyHashMap::<T, (), S>::default()) |
| 205 | } |
| 206 | } |
| 207 | |
| 208 | impl<T, S> FromIterator<T::Strong> for PtrWeakHashSet<T, S> |
| 209 | where T: WeakElement, |
| 210 | T::Strong: Deref, |
| 211 | S: BuildHasher + Default |
| 212 | { |
| 213 | fn from_iter<I: IntoIterator<Item=T::Strong>>(iter: I) -> Self { |
| 214 | PtrWeakHashSet(base::PtrWeakKeyHashMap::<T, (), S>::from_iter( |
| 215 | iter.into_iter().map(|k| (k, ())))) |
| 216 | } |
| 217 | } |
| 218 | |
| 219 | impl<T, S> Extend<T::Strong> for PtrWeakHashSet<T, S> |
| 220 | where T: WeakElement, |
| 221 | T::Strong: Deref, |
| 222 | S: BuildHasher |
| 223 | { |
| 224 | fn extend<I: IntoIterator<Item=T::Strong>>(&mut self, iter: I) { |
| 225 | self.0.extend(iter.into_iter().map(|k| (k, ()))) |
| 226 | } |
| 227 | } |
| 228 | |
| 229 | impl<T, S> Debug for PtrWeakHashSet<T, S> |
| 230 | where T: WeakElement, |
| 231 | T::Strong: Debug |
| 232 | { |
| 233 | fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { |
| 234 | self.0.fmt(f) |
| 235 | } |
| 236 | } |
| 237 | |
| 238 | impl<T: WeakElement, S> IntoIterator for PtrWeakHashSet<T, S> { |
| 239 | type Item = T::Strong; |
| 240 | type IntoIter = IntoIter<T>; |
| 241 | |
| 242 | fn into_iter(self) -> Self::IntoIter { |
| 243 | IntoIter(self.0.into_iter()) |
| 244 | } |
| 245 | } |
| 246 | |
| 247 | impl<'a, T: WeakElement, S> IntoIterator for &'a PtrWeakHashSet<T, S> |
| 248 | where T::Strong: Deref |
| 249 | { |
| 250 | type Item = T::Strong; |
| 251 | type IntoIter = Iter<'a, T>; |
| 252 | |
| 253 | fn into_iter(self) -> Self::IntoIter { |
| 254 | Iter(self.0.keys()) |
| 255 | } |
| 256 | } |
| 257 | |