#[repr(transparent)]pub struct RandState<'a> { /* private fields */ }
Expand description
The state of a random number generator.
Examples
use rug::rand::RandState;
let mut rand = RandState::new();
let u = rand.bits(32);
println!("32 random bits: {:032b}", u);
Implementations§
source§impl RandState<'_>
impl RandState<'_>
sourcepub fn new() -> RandState<'static>
pub fn new() -> RandState<'static>
Creates a new random generator with a compromise between speed and randomness.
Currently this is equivalent to new_mersenne_twister
.
Examples
use rug::rand::RandState;
let mut rand = RandState::new();
let u = rand.bits(32);
println!("32 random bits: {:032b}", u);
sourcepub fn new_mersenne_twister() -> RandState<'static>
pub fn new_mersenne_twister() -> RandState<'static>
Creates a random generator with a Mersenne Twister algorithm.
This algorithm is fast and has good randomness properties.
Examples
use rug::rand::RandState;
let mut rand = RandState::new_mersenne_twister();
let u = rand.bits(32);
println!("32 random bits: {:032b}", u);
sourcepub fn new_linear_congruential(
a: &Integer,
c: u32,
m: u32
) -> RandState<'static>
pub fn new_linear_congruential( a: &Integer, c: u32, m: u32 ) -> RandState<'static>
Creates a new random generator with a linear congruential algorithm X = (a × X + c) mod 2m.
The low bits of X in this algorithm are not very random, so only the high half of each X is actually used, that is the higher m/2 bits.
Examples
use rug::rand::RandState;
use rug::Integer;
let a = match Integer::from_str_radix("292787ebd3329ad7e7575e2fd", 16) {
Ok(i) => i,
Err(_) => unreachable!(),
};
let c = 1;
let m = 100;
let mut rand = RandState::new_linear_congruential(&a, c, m);
let u = rand.bits(32);
println!("32 random bits: {:032b}", u);
sourcepub fn new_linear_congruential_size(size: u32) -> Option<RandState<'static>>
pub fn new_linear_congruential_size(size: u32) -> Option<RandState<'static>>
Creates a new random generator with a linear congruential algorithm like
the new_linear_congruential
method.
For the linear congruential algorithm X = (a × X +
c) mod 2m, a, c and m are
selected from a table such that at least size bits of each
X will be used, that is m/2 ≥ size. The
table only has values for size ≤ 128; None
will be
returned if the requested size is larger.
Examples
use rug::rand::RandState;
let mut rand = match RandState::new_linear_congruential_size(100) {
Some(r) => r,
None => unreachable!(),
};
let u = rand.bits(32);
println!("32 random bits: {:032b}", u);
sourcepub fn new_custom(custom: &mut dyn RandGen) -> RandState<'_>
pub fn new_custom(custom: &mut dyn RandGen) -> RandState<'_>
Creates a new custom random generator.
If the custom random generator is cloned, the implemented trait method
RandGen::boxed_clone
is called; this leads to panic if
the method returns None
.
Examples
use rug::rand::{RandGen, RandState};
use rug::Integer;
struct Seed;
impl RandGen for Seed {
fn gen(&mut self) -> u32 {
// not really random
0x8CEF_7310
}
}
let mut seed = Seed;
let mut rand = RandState::new_custom(&mut seed);
let mut i = Integer::from(15);
i.random_below_mut(&mut rand);
println!("0 ≤ {} < 15", i);
assert!(i < 15);
sourcepub fn new_custom_boxed(custom: Box<dyn RandGen>) -> RandState<'static>
pub fn new_custom_boxed(custom: Box<dyn RandGen>) -> RandState<'static>
Creates a new custom random generator.
If the custom random generator is cloned, the implemented trait method
RandGen::boxed_clone
is called; this leads to panic if
the method returns None
.
Examples
use rug::rand::{RandGen, RandState};
use rug::Integer;
struct Seed;
impl RandGen for Seed {
fn gen(&mut self) -> u32 {
// not really random
0x8CEF_7310
}
}
let seed = Box::new(Seed);
let mut rand = RandState::new_custom_boxed(seed);
let mut i = Integer::from(15);
i.random_below_mut(&mut rand);
println!("0 ≤ {} < 15", i);
assert!(i < 15);
sourcepub unsafe fn from_raw(raw: randstate_t) -> RandState<'static>
pub unsafe fn from_raw(raw: randstate_t) -> RandState<'static>
Creates a random generator from an initialized GMP random generator.
Safety
- The value must be initialized as a valid
randstate_t
. - The
randstate_t
type can be considered as a kind of pointer, so there can be multiple copies of it. Since this function takes over ownership, no other copies of the passed value should exist. - The object must be thread safe.
Examples
use core::mem::MaybeUninit;
use gmp_mpfr_sys::gmp;
use rug::rand::RandState;
let mut rand = unsafe {
let mut raw = MaybeUninit::uninit();
gmp::randinit_default(raw.as_mut_ptr());
let raw = raw.assume_init();
// raw is initialized and unique
RandState::from_raw(raw)
};
let u = rand.bits(32);
println!("32 random bits: {:032b}", u);
// since rand is a RandState now, deallocation is automatic
sourcepub fn into_raw(self) -> randstate_t
pub fn into_raw(self) -> randstate_t
Converts a random generator into a GMP random generator.
The returned object should be freed to avoid memory leaks.
Panics
This method panics if the RandState
object was created using
new_custom
, as the borrow into the custom generator would be
terminated once self
is consumed. This would lead to undefined
behavior if the returned object is used. This method does work with
objects created using new_custom_boxed
.
Examples
use gmp_mpfr_sys::gmp;
use rug::rand::RandState;
let rand = RandState::new();
let mut raw = rand.into_raw();
unsafe {
let u = gmp::urandomb_ui(&mut raw, 32) as u32;
println!("32 random bits: {:032b}", u);
// free object to prevent memory leak
gmp::randclear(&mut raw);
}
sourcepub fn as_raw(&self) -> *const randstate_t
pub fn as_raw(&self) -> *const randstate_t
Returns a pointer to the inner GMP random generator.
The returned pointer will be valid for as long as self
is valid.
Examples
use rug::rand::RandState;
let mut rand = RandState::new();
let raw_ptr = rand.as_raw();
// There is not much you can do with an immutable randstate_t pointer.
println!("pointer: {:p}", raw_ptr);
let u = rand.bits(32);
println!("32 random bits: {:032b}", u);
sourcepub fn as_raw_mut(&mut self) -> *mut randstate_t
pub fn as_raw_mut(&mut self) -> *mut randstate_t
Returns an unsafe mutable pointer to the inner GMP random generator.
The returned pointer will be valid for as long as self
is valid.
Examples
use gmp_mpfr_sys::gmp;
use rug::rand::RandState;
let mut rand = RandState::new();
let raw_ptr = rand.as_raw_mut();
unsafe {
let u1 = gmp::urandomb_ui(raw_ptr, 32) as u32;
println!("32 random bits: {:032b}", u1);
}
let u2 = rand.bits(32);
println!("another 32 random bits: {:032b}", u2);
sourcepub fn into_custom_boxed(self) -> Result<Box<dyn RandGen>, Self>
pub fn into_custom_boxed(self) -> Result<Box<dyn RandGen>, Self>
Converts a random generator into Box<dyn RandGen>
if
possible.
If the conversion is not possible, Err(self)
is
returned.
This conversion is always possible when the random generator was created
with new_custom_boxed
. It is also possible if the generator was
cloned, directly or indirectly, from another generator that was created
with new_custom
or new_custom_boxed
.
Examples
use rug::rand::{RandGen, RandState};
struct Seed;
impl RandGen for Seed {
fn gen(&mut self) -> u32 {
// not really random
0x8CEF_7310
}
}
let seed = Box::new(Seed);
let rand = RandState::new_custom_boxed(seed);
let mut back_to_seed = rand.into_custom_boxed().unwrap();
assert_eq!(back_to_seed.gen(), 0x8CEF_7310);
sourcepub fn seed(&mut self, seed: &Integer)
pub fn seed(&mut self, seed: &Integer)
Seeds the random generator.
Examples
use rug::rand::RandState;
use rug::Integer;
let seed = Integer::from(123456);
let mut rand = RandState::new();
rand.seed(&seed);
let u1a = rand.bits(32);
let u1b = rand.bits(32);
// reseed with the same seed
rand.seed(&seed);
let u2a = rand.bits(32);
let u2b = rand.bits(32);
assert_eq!(u1a, u2a);
assert_eq!(u1b, u2b);
sourcepub fn below(&mut self, bound: u32) -> u32
pub fn below(&mut self, bound: u32) -> u32
Generates a random number below the given boundary value.
This function can never return the maximum 32-bit value; in order to
generate a 32-bit random value that covers the whole range, use the
bits
method with bits
set to 32.
Panics
Panics if the boundary value is zero.
Examples
use rug::rand::RandState;
let mut rand = RandState::new();
let u = rand.below(10000);
assert!(u < 10000);
println!("0 ≤ {} < 10000", u);