Joel Galenson | 2370d12 | 2020-10-12 16:02:26 -0700 | [diff] [blame] | 1 | //! A hash map where the keys and values are both held by weak pointers, and keys are compared by |
| 2 | //! pointer. |
| 3 | |
| 4 | use std::collections::hash_map::RandomState; |
| 5 | use std::fmt::{self, Debug}; |
| 6 | use std::hash::BuildHasher; |
| 7 | use std::iter::FromIterator; |
| 8 | use std::ops::Deref; |
| 9 | |
| 10 | use super::by_ptr::*; |
| 11 | use super::traits::*; |
| 12 | use super::weak_weak_hash_map as base; |
| 13 | |
| 14 | pub use super::PtrWeakWeakHashMap; |
| 15 | pub use super::weak_weak_hash_map::{Entry, Iter, Keys, Values, Drain, IntoIter}; |
| 16 | |
| 17 | impl <K: WeakElement, V: WeakElement> PtrWeakWeakHashMap<K, V, RandomState> |
| 18 | where K::Strong: Deref |
| 19 | { |
| 20 | /// Creates an empty `PtrWeakWeakHashMap`. |
| 21 | pub fn new() -> Self { |
| 22 | PtrWeakWeakHashMap(base::WeakWeakHashMap::new()) |
| 23 | } |
| 24 | |
| 25 | /// Creates an empty `PtrWeakWeakHashMap` with the given capacity. |
| 26 | pub fn with_capacity(capacity: usize) -> Self { |
| 27 | PtrWeakWeakHashMap(base::WeakWeakHashMap::with_capacity(capacity)) |
| 28 | } |
| 29 | } |
| 30 | |
| 31 | impl <K: WeakElement, V: WeakElement, S: BuildHasher> PtrWeakWeakHashMap<K, V, S> |
| 32 | where K::Strong: Deref |
| 33 | { |
| 34 | /// Creates an empty `PtrWeakWeakHashMap` with the given capacity and hasher. |
| 35 | pub fn with_hasher(hash_builder: S) -> Self { |
| 36 | PtrWeakWeakHashMap(base::WeakWeakHashMap::with_hasher(hash_builder)) |
| 37 | } |
| 38 | |
| 39 | /// Creates an empty `PtrWeakWeakHashMap` with the given capacity and hasher. |
| 40 | pub fn with_capacity_and_hasher(capacity: usize, hash_builder: S) -> Self { |
| 41 | PtrWeakWeakHashMap(base::WeakWeakHashMap::with_capacity_and_hasher(capacity, hash_builder)) |
| 42 | } |
| 43 | |
| 44 | /// Returns a reference to the map's `BuildHasher`. |
| 45 | pub fn hasher(&self) -> &S { |
| 46 | self.0.hasher() |
| 47 | } |
| 48 | |
| 49 | /// Returns the number of elements the map can hold without reallocating. |
| 50 | pub fn capacity(&self) -> usize { |
| 51 | self.0.capacity() |
| 52 | } |
| 53 | |
| 54 | /// Removes all mappings whose keys have expired. |
| 55 | pub fn remove_expired(&mut self) { |
| 56 | self.0.remove_expired() |
| 57 | } |
| 58 | |
| 59 | /// Reserves room for additional elements. |
| 60 | pub fn reserve(&mut self, additional_capacity: usize) { |
| 61 | self.0.reserve(additional_capacity) |
| 62 | } |
| 63 | |
| 64 | /// Shrinks the capacity to the minimum allowed to hold the current number of elements. |
| 65 | pub fn shrink_to_fit(&mut self) { |
| 66 | self.0.shrink_to_fit() |
| 67 | } |
| 68 | |
| 69 | /// Returns an over-approximation of the number of elements. |
| 70 | pub fn len(&self) -> usize { |
| 71 | self.0.len() |
| 72 | } |
| 73 | |
| 74 | /// Is the map empty? |
| 75 | /// |
| 76 | /// Note that this may return false even if all keys in the map have |
| 77 | /// expired, if they haven't been collected yet. |
| 78 | pub fn is_empty(&self) -> bool { |
| 79 | self.0.is_empty() |
| 80 | } |
| 81 | |
| 82 | /// The proportion of buckets that are used. |
| 83 | /// |
| 84 | /// This is an over-approximation because of expired keys. |
| 85 | pub fn load_factor(&self) -> f32 { |
| 86 | self.0.load_factor() |
| 87 | } |
| 88 | |
| 89 | /// Gets the requested entry. |
| 90 | pub fn entry(&mut self, key: K::Strong) -> Entry<ByPtr<K>, V> { |
| 91 | self.0.entry(key) |
| 92 | } |
| 93 | |
| 94 | /// Removes all associations from the map. |
| 95 | pub fn clear(&mut self) { |
| 96 | self.0.clear() |
| 97 | } |
| 98 | |
| 99 | /// Returns a reference to the value corresponding to the key. |
| 100 | pub fn get(&self, key: &K::Strong) -> Option<V::Strong> { |
| 101 | self.0.get(&(key.deref() as *const _)) |
| 102 | } |
| 103 | |
| 104 | /// Returns true if the map contains the specified key. |
| 105 | pub fn contains_key(&self, key: &K::Strong) -> bool { |
| 106 | self.0.contains_key(&(key.deref() as *const _)) |
| 107 | } |
| 108 | |
| 109 | /// Unconditionally inserts the value, returning the old value if already present. Does not |
| 110 | /// replace the key. |
| 111 | pub fn insert(&mut self, key: K::Strong, value: V::Strong) -> Option<V::Strong> { |
| 112 | self.0.insert(key, value) |
| 113 | } |
| 114 | |
| 115 | /// Removes the entry with the given key, if it exists, and returns the value. |
| 116 | pub fn remove(&mut self, key: &K::Strong) -> Option<V::Strong> { |
| 117 | self.0.remove(&(key.deref() as *const _)) |
| 118 | } |
| 119 | |
| 120 | /// Removes all mappings not satisfying the given predicate. |
| 121 | /// |
| 122 | /// Also removes any expired mappings. |
| 123 | pub fn retain<F>(&mut self, f: F) |
| 124 | where F: FnMut(K::Strong, V::Strong) -> bool |
| 125 | { |
| 126 | self.0.retain(f) |
| 127 | } |
| 128 | |
| 129 | /// Is this map a submap of the other, using the given value comparison. |
| 130 | /// |
| 131 | /// In particular, all the keys of self must be in other and the values must compare true with |
| 132 | /// value_equal. |
| 133 | pub fn submap_with<F, S1, V1>(&self, other: &PtrWeakWeakHashMap<K, V1, S1>, value_equal: F) -> bool |
| 134 | where F: FnMut(V::Strong, V1::Strong) -> bool, |
| 135 | V1: WeakElement, |
| 136 | S1: BuildHasher |
| 137 | { |
| 138 | self.0.is_submap_with(&other.0, value_equal) |
| 139 | } |
| 140 | |
| 141 | /// Is self a submap of other? |
| 142 | pub fn is_submap<V1, S1>(&self, other: &PtrWeakWeakHashMap<K, V1, S1>) -> bool |
| 143 | where V1: WeakElement, |
| 144 | V::Strong: PartialEq<V1::Strong>, |
| 145 | S1: BuildHasher |
| 146 | { |
| 147 | self.0.is_submap(&other.0) |
| 148 | } |
| 149 | |
| 150 | /// Are the keys of self a subset of the keys of other? |
| 151 | pub fn domain_is_subset<V1, S1>(&self, other: &PtrWeakWeakHashMap<K, V1, S1>) -> bool |
| 152 | where V1: WeakElement, |
| 153 | S1: BuildHasher |
| 154 | { |
| 155 | self.0.domain_is_subset(&other.0) |
| 156 | } |
| 157 | } |
| 158 | |
| 159 | impl<K: WeakElement, V: WeakElement, S> PtrWeakWeakHashMap<K, V, S> |
| 160 | where K::Strong: Deref |
| 161 | { |
| 162 | /// Gets an iterator over the keys and values. |
| 163 | pub fn iter(&self) -> Iter<ByPtr<K>, V> { |
| 164 | self.0.iter() |
| 165 | } |
| 166 | |
| 167 | /// Gets an iterator over the keys. |
| 168 | pub fn keys(&self) -> Keys<ByPtr<K>, V> { |
| 169 | self.0.keys() |
| 170 | } |
| 171 | |
| 172 | /// Gets an iterator over the values. |
| 173 | pub fn values(&self) -> Values<ByPtr<K>, V> { |
| 174 | self.0.values() |
| 175 | } |
| 176 | |
| 177 | /// Gets a draining iterator, which removes all the values but retains the storage. |
| 178 | pub fn drain(&mut self) -> Drain<ByPtr<K>, V> { |
| 179 | self.0.drain() |
| 180 | } |
| 181 | } |
| 182 | |
| 183 | impl<K, V, V1, S, S1> PartialEq<PtrWeakWeakHashMap<K, V1, S1>> |
| 184 | for PtrWeakWeakHashMap<K, V, S> |
| 185 | where K: WeakElement, |
| 186 | K::Strong: Deref, |
| 187 | V: WeakElement, |
| 188 | V1: WeakElement, |
| 189 | V::Strong: PartialEq<V1::Strong>, |
| 190 | S: BuildHasher, |
| 191 | S1: BuildHasher |
| 192 | { |
| 193 | fn eq(&self, other: &PtrWeakWeakHashMap<K, V1, S1>) -> bool { |
| 194 | self.0 == other.0 |
| 195 | } |
| 196 | } |
| 197 | |
| 198 | impl<K: WeakElement, V: WeakElement, S: BuildHasher> Eq for PtrWeakWeakHashMap<K, V, S> |
| 199 | where K::Strong: Deref, |
| 200 | V::Strong: Eq |
| 201 | { } |
| 202 | |
| 203 | impl<K: WeakElement, V: WeakElement, S: BuildHasher + Default> Default for PtrWeakWeakHashMap<K, V, S> |
| 204 | where K::Strong: Deref |
| 205 | { |
| 206 | fn default() -> Self { |
| 207 | PtrWeakWeakHashMap(base::WeakWeakHashMap::<ByPtr<K>, V, S>::default()) |
| 208 | } |
| 209 | } |
| 210 | |
| 211 | impl<K, V, S> FromIterator<(K::Strong, V::Strong)> for PtrWeakWeakHashMap<K, V, S> |
| 212 | where K: WeakElement, |
| 213 | K::Strong: Deref, |
| 214 | V: WeakElement, |
| 215 | S: BuildHasher + Default |
| 216 | { |
| 217 | fn from_iter<T: IntoIterator<Item=(K::Strong, V::Strong)>>(iter: T) -> Self { |
| 218 | PtrWeakWeakHashMap(base::WeakWeakHashMap::<ByPtr<K>, V, S>::from_iter(iter)) |
| 219 | } |
| 220 | } |
| 221 | |
| 222 | impl<K, V, S> Extend<(K::Strong, V::Strong)> for PtrWeakWeakHashMap<K, V, S> |
| 223 | where K: WeakElement, |
| 224 | K::Strong: Deref, |
| 225 | V: WeakElement, |
| 226 | S: BuildHasher |
| 227 | { |
| 228 | fn extend<T: IntoIterator<Item=(K::Strong, V::Strong)>>(&mut self, iter: T) { |
| 229 | self.0.extend(iter) |
| 230 | } |
| 231 | } |
| 232 | |
| 233 | impl<K, V, S> Debug for PtrWeakWeakHashMap<K, V, S> |
| 234 | where K: WeakElement, |
| 235 | K::Strong: Debug, |
| 236 | V: WeakElement, |
| 237 | V::Strong: Debug |
| 238 | { |
| 239 | fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { |
| 240 | self.0.fmt(f) |
| 241 | } |
| 242 | } |
| 243 | |
| 244 | impl<K: WeakElement, V: WeakElement, S> IntoIterator for PtrWeakWeakHashMap<K, V, S> { |
| 245 | type Item = (K::Strong, V::Strong); |
| 246 | type IntoIter = IntoIter<ByPtr<K>, V>; |
| 247 | |
| 248 | fn into_iter(self) -> Self::IntoIter { |
| 249 | self.0.into_iter() |
| 250 | } |
| 251 | } |
| 252 | |
| 253 | impl<'a, K: WeakElement, V: WeakElement, S> IntoIterator for &'a PtrWeakWeakHashMap<K, V, S> { |
| 254 | type Item = (K::Strong, V::Strong); |
| 255 | type IntoIter = Iter<'a, ByPtr<K>, V>; |
| 256 | |
| 257 | fn into_iter(self) -> Self::IntoIter { |
| 258 | (&self.0).into_iter() |
| 259 | } |
| 260 | } |
| 261 | |
| 262 | #[cfg(test)] |
| 263 | mod test |
| 264 | { |
| 265 | use crate::PtrWeakWeakHashMap; |
| 266 | use crate::weak_weak_hash_map::Entry; |
| 267 | use std::rc::{Rc, Weak}; |
| 268 | |
| 269 | // fn show_me(weakmap: &PtrWeakWeakHashMap<Weak<u32>, Weak<f32>>) { |
| 270 | // for (key, _) in weakmap { |
| 271 | // eprint!(" {:2}", *key); |
| 272 | // } |
| 273 | // eprintln!(); |
| 274 | // } |
| 275 | |
| 276 | // From https://github.com/tov/weak-table-rs/issues/1#issuecomment-461858060 |
| 277 | #[test] |
| 278 | fn insert_and_check() { |
| 279 | let mut rcs: Vec<(Rc<u32>, Rc<f32>)> = Vec::new(); |
| 280 | |
| 281 | for i in 0 .. 200 { |
| 282 | rcs.push((Rc::new(i), Rc::new(i as f32 + 0.1))); |
| 283 | } |
| 284 | |
| 285 | let mut weakmap: PtrWeakWeakHashMap<Weak<u32>, Weak<f32>> = PtrWeakWeakHashMap::new(); |
| 286 | |
| 287 | for (key, value) in rcs.iter().cloned() { |
| 288 | weakmap.insert(key, value); |
| 289 | // show_me(&weakmap); |
| 290 | } |
| 291 | |
| 292 | let mut count = 0; |
| 293 | |
| 294 | for (key, value) in &rcs { |
| 295 | assert!(weakmap.contains_key(key)); |
| 296 | |
| 297 | match weakmap.entry(Rc::clone(key)) { |
| 298 | Entry::Occupied(occ) => { |
| 299 | assert_eq!( occ.get(), value ); |
| 300 | count += 1; |
| 301 | } |
| 302 | Entry::Vacant(_) => { |
| 303 | eprintln!("PointerWeakWeakHashMap: missing: {}", *key); |
| 304 | } |
| 305 | } |
| 306 | } |
| 307 | |
| 308 | assert_eq!( count, rcs.len() ); |
| 309 | } |
| 310 | } |
| 311 | |
| 312 | |