forked from RustPython/RustPython
-
Notifications
You must be signed in to change notification settings - Fork 0
Expand file tree
/
Copy pathrandom.rs
More file actions
155 lines (141 loc) · 4.65 KB
/
random.rs
File metadata and controls
155 lines (141 loc) · 4.65 KB
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
//! Random module.
pub(crate) use _random::make_module;
#[pymodule]
mod _random {
use crate::common::lock::PyMutex;
use crate::vm::{
builtins::{PyInt, PyTypeRef},
function::OptionalOption,
types::Constructor,
PyObjectRef, PyPayload, PyResult, VirtualMachine,
};
use num_bigint::{BigInt, Sign};
use num_traits::{Signed, Zero};
use rand::{rngs::StdRng, RngCore, SeedableRng};
#[derive(Debug)]
enum PyRng {
Std(Box<StdRng>),
MT(Box<mt19937::MT19937>),
}
impl Default for PyRng {
fn default() -> Self {
PyRng::Std(Box::new(StdRng::from_entropy()))
}
}
impl RngCore for PyRng {
fn next_u32(&mut self) -> u32 {
match self {
Self::Std(s) => s.next_u32(),
Self::MT(m) => m.next_u32(),
}
}
fn next_u64(&mut self) -> u64 {
match self {
Self::Std(s) => s.next_u64(),
Self::MT(m) => m.next_u64(),
}
}
fn fill_bytes(&mut self, dest: &mut [u8]) {
match self {
Self::Std(s) => s.fill_bytes(dest),
Self::MT(m) => m.fill_bytes(dest),
}
}
fn try_fill_bytes(&mut self, dest: &mut [u8]) -> Result<(), rand::Error> {
match self {
Self::Std(s) => s.try_fill_bytes(dest),
Self::MT(m) => m.try_fill_bytes(dest),
}
}
}
#[pyattr]
#[pyclass(name = "Random")]
#[derive(Debug, PyPayload)]
struct PyRandom {
rng: PyMutex<PyRng>,
}
impl Constructor for PyRandom {
type Args = OptionalOption<PyObjectRef>;
fn py_new(
cls: PyTypeRef,
// TODO: use x as the seed.
_x: Self::Args,
vm: &VirtualMachine,
) -> PyResult {
PyRandom {
rng: PyMutex::default(),
}
.into_ref_with_type(vm, cls)
.map(Into::into)
}
}
#[pyclass(flags(BASETYPE), with(Constructor))]
impl PyRandom {
#[pymethod]
fn random(&self) -> f64 {
let mut rng = self.rng.lock();
mt19937::gen_res53(&mut *rng)
}
#[pymethod]
fn seed(&self, n: OptionalOption<PyObjectRef>, vm: &VirtualMachine) -> PyResult<()> {
let new_rng = n
.flatten()
.map(|n| {
// Fallback to using hash if object isn't Int-like.
let (_, mut key) = match n.downcast::<PyInt>() {
Ok(n) => n.as_bigint().abs(),
Err(obj) => BigInt::from(obj.hash(vm)?).abs(),
}
.to_u32_digits();
if cfg!(target_endian = "big") {
key.reverse();
}
let key = if key.is_empty() { &[0] } else { key.as_slice() };
Ok(PyRng::MT(Box::new(mt19937::MT19937::new_with_slice_seed(
key,
))))
})
.transpose()?
.unwrap_or_default();
*self.rng.lock() = new_rng;
Ok(())
}
#[pymethod]
fn getrandbits(&self, k: isize, vm: &VirtualMachine) -> PyResult<BigInt> {
match k {
k if k < 0 => {
Err(vm.new_value_error("number of bits must be non-negative".to_owned()))
}
0 => Ok(BigInt::zero()),
_ => {
let mut rng = self.rng.lock();
let mut k = k;
let mut gen_u32 = |k| {
let r = rng.next_u32();
if k < 32 {
r >> (32 - k)
} else {
r
}
};
let words = (k - 1) / 32 + 1;
let wordarray = (0..words)
.map(|_| {
let word = gen_u32(k);
k = k.wrapping_sub(32);
word
})
.collect::<Vec<_>>();
let uint = num_bigint::BigUint::new(wordarray);
// very unlikely but might as well check
let sign = if uint.is_zero() {
Sign::NoSign
} else {
Sign::Plus
};
Ok(BigInt::from_biguint(sign, uint))
}
}
}
}
}