1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
|
//! Densely numbered entity references as set keys.
use crate::keys::Keys;
use crate::EntityRef;
use core::marker::PhantomData;
use std::vec::Vec;
/// A set of `K` for densely indexed entity references.
///
/// The `EntitySet` data structure uses the dense index space to implement a set with a bitvector.
/// Like `SecondaryMap`, an `EntitySet` is used to associate secondary information with entities.
#[derive(Debug, Clone)]
pub struct EntitySet<K>
where
K: EntityRef,
{
elems: Vec<u8>,
len: usize,
unused: PhantomData<K>,
}
/// Shared `EntitySet` implementation for all value types.
impl<K> EntitySet<K>
where
K: EntityRef,
{
/// Create a new empty set.
pub fn new() -> Self {
Self {
elems: Vec::new(),
len: 0,
unused: PhantomData,
}
}
/// Get the element at `k` if it exists.
pub fn contains(&self, k: K) -> bool {
let index = k.index();
if index < self.len {
(self.elems[index / 8] & (1 << (index % 8))) != 0
} else {
false
}
}
/// Is this set completely empty?
pub fn is_empty(&self) -> bool {
// Note that this implementation will become incorrect should it ever become possible
// to remove elements from an `EntitySet`.
self.len == 0
}
/// Returns the cardinality of the set. More precisely, it returns the number of calls to
/// `insert` with different key values, that have happened since the the set was most recently
/// `clear`ed or created with `new`.
pub fn cardinality(&self) -> usize {
let mut n: usize = 0;
for byte_ix in 0..self.len / 8 {
n += self.elems[byte_ix].count_ones() as usize;
}
for bit_ix in (self.len / 8) * 8..self.len {
if (self.elems[bit_ix / 8] & (1 << (bit_ix % 8))) != 0 {
n += 1;
}
}
n
}
/// Remove all entries from this set.
pub fn clear(&mut self) {
self.len = 0;
self.elems.clear()
}
/// Iterate over all the keys in this set.
pub fn keys(&self) -> Keys<K> {
Keys::with_len(self.len)
}
/// Resize the set to have `n` entries by adding default entries as needed.
pub fn resize(&mut self, n: usize) {
self.elems.resize((n + 7) / 8, 0);
self.len = n
}
/// Insert the element at `k`.
pub fn insert(&mut self, k: K) -> bool {
let index = k.index();
if index >= self.len {
self.resize(index + 1)
}
let result = !self.contains(k);
self.elems[index / 8] |= 1 << (index % 8);
result
}
}
#[cfg(test)]
mod tests {
use super::*;
use core::u32;
// `EntityRef` impl for testing.
#[derive(Clone, Copy, Debug, PartialEq, Eq)]
struct E(u32);
impl EntityRef for E {
fn new(i: usize) -> Self {
E(i as u32)
}
fn index(self) -> usize {
self.0 as usize
}
}
#[test]
fn basic() {
let r0 = E(0);
let r1 = E(1);
let r2 = E(2);
let mut m = EntitySet::new();
let v: Vec<E> = m.keys().collect();
assert_eq!(v, []);
assert!(m.is_empty());
m.insert(r2);
m.insert(r1);
assert!(!m.contains(r0));
assert!(m.contains(r1));
assert!(m.contains(r2));
assert!(!m.contains(E(3)));
assert!(!m.is_empty());
let v: Vec<E> = m.keys().collect();
assert_eq!(v, [r0, r1, r2]);
m.resize(20);
assert!(!m.contains(E(3)));
assert!(!m.contains(E(4)));
assert!(!m.contains(E(8)));
assert!(!m.contains(E(15)));
assert!(!m.contains(E(19)));
m.insert(E(8));
m.insert(E(15));
assert!(!m.contains(E(3)));
assert!(!m.contains(E(4)));
assert!(m.contains(E(8)));
assert!(!m.contains(E(9)));
assert!(!m.contains(E(14)));
assert!(m.contains(E(15)));
assert!(!m.contains(E(16)));
assert!(!m.contains(E(19)));
assert!(!m.contains(E(20)));
assert!(!m.contains(E(u32::MAX)));
m.clear();
assert!(m.is_empty());
}
}
|
