cranelift_entity/
set.rs

1//! Densely numbered entity references as set keys.
2
3use crate::keys::Keys;
4use crate::EntityRef;
5use core::fmt;
6use core::marker::PhantomData;
7use cranelift_bitset::CompoundBitSet;
8
9/// A set of `K` for densely indexed entity references.
10///
11/// The `EntitySet` data structure uses the dense index space to implement a set with a bitvector.
12/// Like `SecondaryMap`, an `EntitySet` is used to associate secondary information with entities.
13#[derive(Clone, PartialEq, Eq)]
14#[cfg_attr(
15    feature = "enable-serde",
16    derive(serde_derive::Serialize, serde_derive::Deserialize)
17)]
18pub struct EntitySet<K>
19where
20    K: EntityRef,
21{
22    bitset: CompoundBitSet,
23    unused: PhantomData<K>,
24}
25
26impl<K: fmt::Debug> fmt::Debug for EntitySet<K>
27where
28    K: EntityRef,
29{
30    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
31        f.debug_set().entries(self.keys()).finish()
32    }
33}
34
35impl<K: EntityRef> Default for EntitySet<K> {
36    fn default() -> Self {
37        Self {
38            bitset: CompoundBitSet::default(),
39            unused: PhantomData,
40        }
41    }
42}
43
44impl<K: EntityRef> Extend<K> for EntitySet<K> {
45    fn extend<T: IntoIterator<Item = K>>(&mut self, iter: T) {
46        for k in iter {
47            self.insert(k);
48        }
49    }
50}
51
52/// Shared `EntitySet` implementation for all value types.
53impl<K> EntitySet<K>
54where
55    K: EntityRef,
56{
57    /// Create a new empty set.
58    pub fn new() -> Self {
59        Self::default()
60    }
61
62    /// Creates a new empty set with the specified capacity.
63    pub fn with_capacity(capacity: usize) -> Self {
64        Self {
65            bitset: CompoundBitSet::with_capacity(capacity),
66            unused: PhantomData,
67        }
68    }
69
70    /// Ensure that the set has enough capacity to hold `capacity` total
71    /// elements.
72    pub fn ensure_capacity(&mut self, capacity: usize) {
73        self.bitset.ensure_capacity(capacity);
74    }
75
76    /// Get the element at `k` if it exists.
77    pub fn contains(&self, k: K) -> bool {
78        let index = k.index();
79        self.bitset.contains(index)
80    }
81
82    /// Is this set completely empty?
83    pub fn is_empty(&self) -> bool {
84        self.bitset.is_empty()
85    }
86
87    /// Remove all entries from this set.
88    pub fn clear(&mut self) {
89        self.bitset.clear()
90    }
91
92    /// Iterate over all the keys up to the maximum in this set.
93    ///
94    /// This will yield intermediate keys on the way up to the max key, even if
95    /// they are not contained within the set.
96    ///
97    /// ```
98    /// use cranelift_entity::{entity_impl, EntityRef, EntitySet};
99    ///
100    /// #[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
101    /// struct Entity(u32);
102    /// entity_impl!(Entity);
103    ///
104    /// let mut set = EntitySet::new();
105    /// set.insert(Entity::new(2));
106    ///
107    /// let mut keys = set.keys();
108    /// assert_eq!(keys.next(), Some(Entity::new(0)));
109    /// assert_eq!(keys.next(), Some(Entity::new(1)));
110    /// assert_eq!(keys.next(), Some(Entity::new(2)));
111    /// assert!(keys.next().is_none());
112    /// ```
113    pub fn keys(&self) -> Keys<K> {
114        Keys::with_len(self.bitset.max().map_or(0, |x| x + 1))
115    }
116
117    /// Iterate over the elements of this set.
118    ///
119    /// ```
120    /// use cranelift_entity::{entity_impl, EntityRef, EntitySet};
121    ///
122    /// #[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
123    /// struct Entity(u32);
124    /// entity_impl!(Entity);
125    ///
126    /// let mut set = EntitySet::new();
127    /// set.insert(Entity::new(2));
128    /// set.insert(Entity::new(3));
129    ///
130    /// let mut iter = set.iter();
131    /// assert_eq!(iter.next(), Some(Entity::new(2)));
132    /// assert_eq!(iter.next(), Some(Entity::new(3)));
133    /// assert!(iter.next().is_none());
134    /// ```
135    pub fn iter(&self) -> SetIter<K> {
136        SetIter {
137            inner: self.bitset.iter(),
138            _phantom: PhantomData,
139        }
140    }
141
142    /// Insert the element at `k`.
143    ///
144    /// Returns `true` if `k` was not present in the set, i.e. this is a
145    /// newly-added element. Returns `false` otherwise.
146    pub fn insert(&mut self, k: K) -> bool {
147        let index = k.index();
148        self.bitset.insert(index)
149    }
150
151    /// Removes and returns the entity from the set if it exists.
152    pub fn pop(&mut self) -> Option<K> {
153        let index = self.bitset.pop()?;
154        Some(K::new(index))
155    }
156}
157
158/// An iterator over the elements in an `EntitySet`.
159pub struct SetIter<'a, K> {
160    inner: cranelift_bitset::compound::Iter<'a>,
161    _phantom: PhantomData<K>,
162}
163
164impl<K> Iterator for SetIter<'_, K>
165where
166    K: EntityRef,
167{
168    type Item = K;
169
170    #[inline]
171    fn next(&mut self) -> Option<Self::Item> {
172        let k = self.inner.next()?;
173        Some(K::new(k))
174    }
175}
176
177#[cfg(test)]
178mod tests {
179    use super::*;
180    use alloc::vec::Vec;
181    use core::u32;
182
183    // `EntityRef` impl for testing.
184    #[derive(Clone, Copy, Debug, PartialEq, Eq, PartialOrd, Ord)]
185    struct E(u32);
186
187    impl EntityRef for E {
188        fn new(i: usize) -> Self {
189            E(i as u32)
190        }
191        fn index(self) -> usize {
192            self.0 as usize
193        }
194    }
195
196    #[test]
197    fn basic() {
198        let r0 = E(0);
199        let r1 = E(1);
200        let r2 = E(2);
201        let mut m = EntitySet::new();
202
203        let v: Vec<E> = m.keys().collect();
204        assert_eq!(v, []);
205        assert!(m.is_empty());
206
207        m.insert(r2);
208        m.insert(r1);
209
210        assert!(!m.contains(r0));
211        assert!(m.contains(r1));
212        assert!(m.contains(r2));
213        assert!(!m.contains(E(3)));
214        assert!(!m.is_empty());
215
216        let v: Vec<E> = m.keys().collect();
217        assert_eq!(v, [r0, r1, r2]);
218
219        assert!(!m.contains(E(3)));
220        assert!(!m.contains(E(4)));
221        assert!(!m.contains(E(8)));
222        assert!(!m.contains(E(15)));
223        assert!(!m.contains(E(19)));
224
225        m.insert(E(8));
226        m.insert(E(15));
227        assert!(!m.contains(E(3)));
228        assert!(!m.contains(E(4)));
229        assert!(m.contains(E(8)));
230        assert!(!m.contains(E(9)));
231        assert!(!m.contains(E(14)));
232        assert!(m.contains(E(15)));
233        assert!(!m.contains(E(16)));
234        assert!(!m.contains(E(19)));
235        assert!(!m.contains(E(20)));
236        assert!(!m.contains(E(u32::MAX)));
237
238        m.clear();
239        assert!(m.is_empty());
240    }
241
242    #[test]
243    fn pop_ordered() {
244        let r0 = E(0);
245        let r1 = E(1);
246        let r2 = E(2);
247        let mut m = EntitySet::new();
248        m.insert(r0);
249        m.insert(r1);
250        m.insert(r2);
251
252        assert_eq!(r2, m.pop().unwrap());
253        assert_eq!(r1, m.pop().unwrap());
254        assert_eq!(r0, m.pop().unwrap());
255        assert!(m.pop().is_none());
256        assert!(m.pop().is_none());
257    }
258
259    #[test]
260    fn pop_unordered() {
261        let mut blocks = [
262            E(0),
263            E(1),
264            E(6),
265            E(7),
266            E(5),
267            E(9),
268            E(10),
269            E(2),
270            E(3),
271            E(11),
272            E(12),
273        ];
274
275        let mut m = EntitySet::new();
276        for &block in &blocks {
277            m.insert(block);
278        }
279        assert_eq!(m.bitset.max(), Some(12));
280        blocks.sort();
281
282        for &block in blocks.iter().rev() {
283            assert_eq!(block, m.pop().unwrap());
284        }
285
286        assert!(m.is_empty());
287    }
288}
cranelift_entity/set.rs

cranelift_entity/
set.rs
