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
use crate::traits::Capacity;
pub type Cow<'a, T> = crate::generic::Cow<'a, T, Lean>;
pub(crate) mod internal {
#[derive(Clone, Copy, PartialEq, Eq)]
pub struct Lean;
}
use internal::Lean;
const MASK_LO: usize = u32::MAX as usize;
const MASK_HI: usize = !MASK_LO;
impl Lean {
#[inline]
pub const fn mask_len(len: usize) -> usize {
len & MASK_LO
}
}
impl Capacity for Lean {
type Field = Lean;
type NonZero = Lean;
#[inline]
fn len(fat: usize) -> usize {
fat & MASK_LO
}
#[inline]
fn empty(len: usize) -> (usize, Lean) {
(len & MASK_LO, Lean)
}
#[inline]
fn store(len: usize, capacity: usize) -> (usize, Lean) {
if capacity & MASK_HI != 0 {
panic!("beef::lean::Cow: Capacity out of bounds");
}
let fat = ((capacity & MASK_LO) << 32) | (len & MASK_LO);
(fat, Lean)
}
#[inline]
fn unpack(fat: usize, _: Lean) -> (usize, usize) {
(fat & MASK_LO, (fat & MASK_HI) >> 32)
}
#[inline]
fn maybe(fat: usize, _: Lean) -> Option<Lean> {
if fat & MASK_HI != 0 {
Some(Lean)
} else {
None
}
}
}