const_random_macro/
span.rs

1use proc_macro::Span;
2use std::option_env;
3
4use once_cell::race::OnceBox;
5use tiny_keccak::{Xof, Hasher, Shake};
6
7
8static SEED: OnceBox<Vec<u8>> = OnceBox::new();
9
10fn get_seed() -> &'static [u8] {
11    &SEED.get_or_init(|| {
12        if let Some(value) = option_env!("CONST_RANDOM_SEED") {
13 	    Box::new(value.as_bytes().to_vec())
14    	} else {
15            let mut value = [0u8; 32];
16            getrandom::getrandom(&mut value).unwrap();
17            Box::new(value.to_vec())
18        }
19    })[..]
20}
21
22pub(crate) fn gen_random<T: Random>() -> T {
23    Random::random()
24}
25
26pub(crate) fn gen_random_bytes(output: &mut [u8]) {
27    hash_stuff().squeeze(output)
28}
29
30pub(crate) trait Random {
31    fn random() -> Self;
32}
33
34fn hash_stuff() -> impl Xof {
35    let span = Span::call_site();
36    let mut hasher = Shake::v256();
37    hasher.update(get_seed());
38    hasher.update(&format!("{:?}", span).as_bytes());
39    hasher
40}
41
42impl Random for u64 {
43    fn random() -> Self {
44        let mut output = [0; 8];
45        hash_stuff().squeeze(&mut output);
46        Self::from_ne_bytes(output)
47    }
48}
49
50impl Random for u128 {
51    fn random() -> Self {
52        let mut output = [0; 16];
53        hash_stuff().squeeze(&mut output);
54        Self::from_ne_bytes(output)
55    }
56}
57
58impl Random for u8 {
59    fn random() -> Self {
60        u64::random() as u8
61    }
62}
63
64impl Random for u16 {
65    fn random() -> Self {
66        u64::random() as u16
67    }
68}
69
70impl Random for u32 {
71    fn random() -> Self {
72        u64::random() as u32
73    }
74}
75
76impl Random for i8 {
77    fn random() -> Self {
78        i64::random() as i8
79    }
80}
81
82impl Random for i16 {
83    fn random() -> Self {
84        i64::random() as i16
85    }
86}
87
88impl Random for i32 {
89    fn random() -> Self {
90        i64::random() as i32
91    }
92}
93
94impl Random for i64 {
95    fn random() -> Self {
96        u64::random() as i64
97    }
98}
99
100impl Random for i128 {
101    fn random() -> Self {
102        u128::random() as i128
103    }
104}
const_random_macro/span.rs

const_random_macro/
span.rs
