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
163
164
165
166
167
168
169
170
171
use std::any::TypeId;
use std::cell::UnsafeCell;
use std::collections::HashSet;
use std::marker::PhantomData;
use std::sync::Mutex;
lazy_static! {
static ref SINGLETON_CHECK: Mutex<HashSet<TypeId>> = Mutex::new(HashSet::new());
}
pub struct TCellOwner<Q: 'static> {
typ: PhantomData<Q>,
}
impl<Q: 'static> Drop for TCellOwner<Q> {
fn drop(&mut self) {
SINGLETON_CHECK.lock().unwrap().remove(&TypeId::of::<Q>());
}
}
impl<Q: 'static> TCellOwner<Q> {
pub fn new() -> Self {
assert!(
SINGLETON_CHECK.lock().unwrap().insert(TypeId::of::<Q>()),
"Illegal to create two TCellOwner instances with the same marker type parameter"
);
Self { typ: PhantomData }
}
pub fn cell<T>(&self, value: T) -> TCell<Q, T> {
TCell::<Q, T>::new(value)
}
#[inline]
pub fn ro<'a, T>(&'a self, tc: &'a TCell<Q, T>) -> &'a T {
unsafe { &*tc.value.get() }
}
#[inline]
pub fn rw<'a, T>(&'a mut self, tc: &'a TCell<Q, T>) -> &'a mut T {
unsafe { &mut *tc.value.get() }
}
#[inline]
pub fn rw2<'a, T, U>(
&'a mut self,
tc1: &'a TCell<Q, T>,
tc2: &'a TCell<Q, U>,
) -> (&'a mut T, &'a mut U) {
assert!(
tc1 as *const _ as usize != tc2 as *const _ as usize,
"Illegal to borrow same TCell twice with rw2()"
);
unsafe { (&mut *tc1.value.get(), &mut *tc2.value.get()) }
}
#[inline]
pub fn rw3<'a, T, U, V>(
&'a mut self,
tc1: &'a TCell<Q, T>,
tc2: &'a TCell<Q, U>,
tc3: &'a TCell<Q, V>,
) -> (&'a mut T, &'a mut U, &'a mut V) {
assert!(
(tc1 as *const _ as usize != tc2 as *const _ as usize)
&& (tc2 as *const _ as usize != tc3 as *const _ as usize)
&& (tc3 as *const _ as usize != tc1 as *const _ as usize),
"Illegal to borrow same TCell twice with rw3()"
);
unsafe {
(
&mut *tc1.value.get(),
&mut *tc2.value.get(),
&mut *tc3.value.get(),
)
}
}
}
pub struct TCell<Q, T> {
owner: PhantomData<Q>,
value: UnsafeCell<T>,
}
impl<Q, T> TCell<Q, T> {
#[inline]
pub const fn new(value: T) -> TCell<Q, T> {
TCell {
owner: PhantomData,
value: UnsafeCell::new(value),
}
}
}
#[cfg(test)]
mod tests {
use super::{TCell, TCellOwner};
#[test]
#[should_panic]
fn tcell_singleton_1() {
struct Marker;
let _owner1 = TCellOwner::<Marker>::new();
let _owner2 = TCellOwner::<Marker>::new();
}
#[test]
fn tcell_singleton_2() {
struct Marker;
let owner1 = TCellOwner::<Marker>::new();
drop(owner1);
let _owner2 = TCellOwner::<Marker>::new();
}
#[test]
fn tcell_singleton_3() {
struct Marker1;
struct Marker2;
let _owner1 = TCellOwner::<Marker1>::new();
let _owner2 = TCellOwner::<Marker2>::new();
}
#[test]
fn tcell() {
struct Marker;
type ACellOwner = TCellOwner<Marker>;
type ACell<T> = TCell<Marker, T>;
let mut owner = ACellOwner::new();
let c1 = ACell::new(100u32);
let c2 = owner.cell(200u32);
(*owner.rw(&c1)) += 1;
(*owner.rw(&c2)) += 2;
let c1ref = owner.ro(&c1);
let c2ref = owner.ro(&c2);
let total = *c1ref + *c2ref;
assert_eq!(total, 303);
}
}