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1 | use std::fmt; | |
2 | use std::hash::Hash; | |
3 | ||
4 | use super::map::SsoHashMap; | |
5 | ||
6 | /// Small-storage-optimized implementation of a set. | |
7 | /// | |
8 | /// Stores elements in a small array up to a certain length | |
9 | /// and switches to `HashSet` when that length is exceeded. | |
10 | // | |
11 | // FIXME: Implements subset of HashSet API. | |
12 | // | |
13 | // Missing HashSet API: | |
14 | // all hasher-related | |
15 | // try_reserve | |
16 | // shrink_to (unstable) | |
17 | // drain_filter (unstable) | |
18 | // replace | |
19 | // get_or_insert/get_or_insert_owned/get_or_insert_with (unstable) | |
20 | // difference/symmetric_difference/intersection/union | |
21 | // is_disjoint/is_subset/is_superset | |
22 | // PartialEq/Eq (requires SsoHashMap implementation) | |
23 | // BitOr/BitAnd/BitXor/Sub | |
24 | #[derive(Clone)] | |
25 | pub struct SsoHashSet<T> { | |
26 | map: SsoHashMap<T, ()>, | |
27 | } | |
28 | ||
29 | /// Adapter function used to return | |
30 | /// result if SsoHashMap functions into | |
31 | /// result SsoHashSet should return. | |
32 | #[inline(always)] | |
33 | fn entry_to_key<K, V>((k, _v): (K, V)) -> K { | |
34 | k | |
35 | } | |
36 | ||
37 | impl<T> SsoHashSet<T> { | |
38 | /// Creates an empty `SsoHashSet`. | |
39 | #[inline] | |
40 | pub fn new() -> Self { | |
41 | Self { map: SsoHashMap::new() } | |
42 | } | |
43 | ||
44 | /// Creates an empty `SsoHashSet` with the specified capacity. | |
45 | #[inline] | |
46 | pub fn with_capacity(cap: usize) -> Self { | |
47 | Self { map: SsoHashMap::with_capacity(cap) } | |
48 | } | |
49 | ||
50 | /// Clears the set, removing all values. | |
51 | #[inline] | |
52 | pub fn clear(&mut self) { | |
53 | self.map.clear() | |
54 | } | |
55 | ||
56 | /// Returns the number of elements the set can hold without reallocating. | |
57 | #[inline] | |
58 | pub fn capacity(&self) -> usize { | |
59 | self.map.capacity() | |
60 | } | |
61 | ||
62 | /// Returns the number of elements in the set. | |
63 | #[inline] | |
64 | pub fn len(&self) -> usize { | |
65 | self.map.len() | |
66 | } | |
67 | ||
68 | /// Returns `true` if the set contains no elements. | |
69 | #[inline] | |
70 | pub fn is_empty(&self) -> bool { | |
71 | self.map.is_empty() | |
72 | } | |
73 | ||
74 | /// An iterator visiting all elements in arbitrary order. | |
75 | /// The iterator element type is `&'a T`. | |
76 | #[inline] | |
77 | pub fn iter(&self) -> impl Iterator<Item = &T> { | |
78 | self.into_iter() | |
79 | } | |
80 | ||
81 | /// Clears the set, returning all elements in an iterator. | |
82 | #[inline] | |
83 | pub fn drain(&mut self) -> impl Iterator<Item = T> + '_ { | |
84 | self.map.drain().map(entry_to_key) | |
85 | } | |
86 | } | |
87 | ||
88 | impl<T: Eq + Hash> SsoHashSet<T> { | |
89 | /// Reserves capacity for at least `additional` more elements to be inserted | |
90 | /// in the `SsoHashSet`. The collection may reserve more space to avoid | |
91 | /// frequent reallocations. | |
92 | #[inline] | |
93 | pub fn reserve(&mut self, additional: usize) { | |
94 | self.map.reserve(additional) | |
95 | } | |
96 | ||
97 | /// Shrinks the capacity of the set as much as possible. It will drop | |
98 | /// down as much as possible while maintaining the internal rules | |
99 | /// and possibly leaving some space in accordance with the resize policy. | |
100 | #[inline] | |
101 | pub fn shrink_to_fit(&mut self) { | |
102 | self.map.shrink_to_fit() | |
103 | } | |
104 | ||
105 | /// Retains only the elements specified by the predicate. | |
106 | #[inline] | |
107 | pub fn retain<F>(&mut self, mut f: F) | |
108 | where | |
109 | F: FnMut(&T) -> bool, | |
110 | { | |
111 | self.map.retain(|k, _v| f(k)) | |
112 | } | |
113 | ||
114 | /// Removes and returns the value in the set, if any, that is equal to the given one. | |
115 | #[inline] | |
116 | pub fn take(&mut self, value: &T) -> Option<T> { | |
117 | self.map.remove_entry(value).map(entry_to_key) | |
118 | } | |
119 | ||
120 | /// Returns a reference to the value in the set, if any, that is equal to the given value. | |
121 | #[inline] | |
122 | pub fn get(&self, value: &T) -> Option<&T> { | |
123 | self.map.get_key_value(value).map(entry_to_key) | |
124 | } | |
125 | ||
126 | /// Adds a value to the set. | |
127 | /// | |
128 | /// Returns whether the value was newly inserted. That is: | |
129 | /// | |
130 | /// - If the set did not previously contain this value, `true` is returned. | |
131 | /// - If the set already contained this value, `false` is returned. | |
132 | #[inline] | |
133 | pub fn insert(&mut self, elem: T) -> bool { | |
134 | self.map.insert(elem, ()).is_none() | |
135 | } | |
136 | ||
137 | /// Removes a value from the set. Returns whether the value was | |
138 | /// present in the set. | |
139 | #[inline] | |
140 | pub fn remove(&mut self, value: &T) -> bool { | |
141 | self.map.remove(value).is_some() | |
142 | } | |
143 | ||
144 | /// Returns `true` if the set contains a value. | |
145 | #[inline] | |
146 | pub fn contains(&self, value: &T) -> bool { | |
147 | self.map.contains_key(value) | |
148 | } | |
149 | } | |
150 | ||
151 | impl<T: Eq + Hash> FromIterator<T> for SsoHashSet<T> { | |
152 | fn from_iter<I: IntoIterator<Item = T>>(iter: I) -> SsoHashSet<T> { | |
153 | let mut set: SsoHashSet<T> = Default::default(); | |
154 | set.extend(iter); | |
155 | set | |
156 | } | |
157 | } | |
158 | ||
159 | impl<T> Default for SsoHashSet<T> { | |
160 | #[inline] | |
161 | fn default() -> Self { | |
162 | Self::new() | |
163 | } | |
164 | } | |
165 | ||
166 | impl<T: Eq + Hash> Extend<T> for SsoHashSet<T> { | |
167 | fn extend<I>(&mut self, iter: I) | |
168 | where | |
169 | I: IntoIterator<Item = T>, | |
170 | { | |
171 | for val in iter.into_iter() { | |
172 | self.insert(val); | |
173 | } | |
174 | } | |
175 | ||
176 | #[inline] | |
177 | fn extend_one(&mut self, item: T) { | |
178 | self.insert(item); | |
179 | } | |
180 | ||
181 | #[inline] | |
182 | fn extend_reserve(&mut self, additional: usize) { | |
183 | self.map.extend_reserve(additional) | |
184 | } | |
185 | } | |
186 | ||
187 | impl<'a, T> Extend<&'a T> for SsoHashSet<T> | |
188 | where | |
189 | T: 'a + Eq + Hash + Copy, | |
190 | { | |
191 | #[inline] | |
192 | fn extend<I: IntoIterator<Item = &'a T>>(&mut self, iter: I) { | |
193 | self.extend(iter.into_iter().cloned()); | |
194 | } | |
195 | ||
196 | #[inline] | |
197 | fn extend_one(&mut self, &item: &'a T) { | |
198 | self.insert(item); | |
199 | } | |
200 | ||
201 | #[inline] | |
202 | fn extend_reserve(&mut self, additional: usize) { | |
203 | Extend::<T>::extend_reserve(self, additional) | |
204 | } | |
205 | } | |
206 | ||
207 | impl<T> IntoIterator for SsoHashSet<T> { | |
208 | type IntoIter = std::iter::Map<<SsoHashMap<T, ()> as IntoIterator>::IntoIter, fn((T, ())) -> T>; | |
209 | type Item = <Self::IntoIter as Iterator>::Item; | |
210 | ||
211 | #[inline] | |
212 | fn into_iter(self) -> Self::IntoIter { | |
213 | self.map.into_iter().map(entry_to_key) | |
214 | } | |
215 | } | |
216 | ||
217 | impl<'a, T> IntoIterator for &'a SsoHashSet<T> { | |
218 | type IntoIter = std::iter::Map< | |
219 | <&'a SsoHashMap<T, ()> as IntoIterator>::IntoIter, | |
220 | fn((&'a T, &'a ())) -> &'a T, | |
221 | >; | |
222 | type Item = <Self::IntoIter as Iterator>::Item; | |
223 | ||
224 | #[inline] | |
225 | fn into_iter(self) -> Self::IntoIter { | |
226 | self.map.iter().map(entry_to_key) | |
227 | } | |
228 | } | |
229 | ||
230 | impl<T> fmt::Debug for SsoHashSet<T> | |
231 | where | |
232 | T: fmt::Debug, | |
233 | { | |
234 | fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { | |
235 | f.debug_set().entries(self.iter()).finish() | |
236 | } | |
237 | } |