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v/vlib/rand/rand.v

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// Copyright (c) 2019-2022 Alexander Medvednikov. All rights reserved.
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// Use of this source code is governed by an MIT license
// that can be found in the LICENSE file.
[has_globals]
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module rand
import math.bits
import rand.config
import rand.constants
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import rand.wyrand
import time
// PRNG is a common interface for all PRNGs that can be used seamlessly with the rand
// modules's API. It defines all the methods that a PRNG (in the vlib or custom made) must
// implement in order to ensure that _all_ functions can be used with the generator.
pub interface PRNG {
mut:
seed(seed_data []u32)
byte() byte
u16() u16
u32() u32
u64() u64
block_size() int
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free()
}
// bytes returns a buffer of `bytes_needed` random bytes
[inline]
pub fn (mut rng PRNG) bytes(bytes_needed int) ?[]byte {
if bytes_needed < 0 {
return error('can not read < 0 random bytes')
}
mut buffer := []byte{len: bytes_needed}
read_internal(mut rng, mut buffer)
return buffer
}
// read fills in `buf` with a maximum of `buf.len` random bytes
pub fn (mut rng PRNG) read(mut buf []byte) {
read_internal(mut rng, mut buf)
}
// u32n returns a uniformly distributed pseudorandom 32-bit signed positive `u32` in range `[0, max)`.
[inline]
pub fn (mut rng PRNG) u32n(max u32) ?u32 {
if max == 0 {
return error('max must be positive integer')
}
// Owing to the pigeon-hole principle, we can't simply do
// val := rng.u32() % max.
// It'll wreck the properties of the distribution unless
// max evenly divides 2^32. So we divide evenly to
// the closest power of two. Then we loop until we find
// an int in the required range
bit_len := bits.len_32(max)
if bit_len == 32 {
for {
value := rng.u32()
if value < max {
return value
}
}
} else {
mask := (u32(1) << (bit_len + 1)) - 1
for {
value := rng.u32() & mask
if value < max {
return value
}
}
}
return u32(0)
}
// u64n returns a uniformly distributed pseudorandom 64-bit signed positive `u64` in range `[0, max)`.
[inline]
pub fn (mut rng PRNG) u64n(max u64) ?u64 {
if max == 0 {
return error('max must be positive integer')
}
bit_len := bits.len_64(max)
if bit_len == 64 {
for {
value := rng.u64()
if value < max {
return value
}
}
} else {
mask := (u64(1) << (bit_len + 1)) - 1
for {
value := rng.u64() & mask
if value < max {
return value
}
}
}
return u64(0)
}
// u32_in_range returns a uniformly distributed pseudorandom 32-bit unsigned `u32` in range `[min, max)`.
[inline]
pub fn (mut rng PRNG) u32_in_range(min u32, max u32) ?u32 {
if max <= min {
return error('max must be greater than min')
}
return min + rng.u32n(max - min) ?
}
// u64_in_range returns a uniformly distributed pseudorandom 64-bit unsigned `u64` in range `[min, max)`.
[inline]
pub fn (mut rng PRNG) u64_in_range(min u64, max u64) ?u64 {
if max <= min {
return error('max must be greater than min')
}
return min + rng.u64n(max - min) ?
}
// i8 returns a (possibly negative) pseudorandom 8-bit `i8`.
[inline]
pub fn (mut rng PRNG) i8() i8 {
return i8(rng.byte())
}
// i16 returns a (possibly negative) pseudorandom 16-bit `i16`.
[inline]
pub fn (mut rng PRNG) i16() i16 {
return i16(rng.u16())
}
// int returns a (possibly negative) pseudorandom 32-bit `int`.
[inline]
pub fn (mut rng PRNG) int() int {
return int(rng.u32())
}
// i64 returns a (possibly negative) pseudorandom 64-bit `i64`.
[inline]
pub fn (mut rng PRNG) i64() i64 {
return i64(rng.u64())
}
// int31 returns a positive pseudorandom 31-bit `int`.
[inline]
pub fn (mut rng PRNG) int31() int {
return int(rng.u32() & constants.u31_mask) // Set the 32nd bit to 0.
}
// int63 returns a positive pseudorandom 63-bit `i64`.
[inline]
pub fn (mut rng PRNG) int63() i64 {
return i64(rng.u64() & constants.u63_mask) // Set the 64th bit to 0.
}
// intn returns a pseudorandom `int` in range `[0, max)`.
[inline]
pub fn (mut rng PRNG) intn(max int) ?int {
if max <= 0 {
return error('max has to be positive.')
}
return int(rng.u32n(u32(max)) ?)
}
// i64n returns a pseudorandom int that lies in `[0, max)`.
[inline]
pub fn (mut rng PRNG) i64n(max i64) ?i64 {
if max <= 0 {
return error('max has to be positive.')
}
return i64(rng.u64n(u64(max)) ?)
}
// int_in_range returns a pseudorandom `int` in range `[min, max)`.
[inline]
pub fn (mut rng PRNG) int_in_range(min int, max int) ?int {
if max <= min {
return error('max must be greater than min')
}
// This supports negative ranges like [-10, -5) because the difference is positive
return min + rng.intn(max - min) ?
}
// i64_in_range returns a pseudorandom `i64` in range `[min, max)`.
[inline]
pub fn (mut rng PRNG) i64_in_range(min i64, max i64) ?i64 {
if max <= min {
return error('max must be greater than min')
}
return min + rng.i64n(max - min) ?
}
// f32 returns a pseudorandom `f32` value in range `[0, 1)`.
[inline]
pub fn (mut rng PRNG) f32() f32 {
return f32(rng.u32()) / constants.max_u32_as_f32
}
// f64 returns a pseudorandom `f64` value in range `[0, 1)`.
[inline]
pub fn (mut rng PRNG) f64() f64 {
return f64(rng.u64()) / constants.max_u64_as_f64
}
// f32n returns a pseudorandom `f32` value in range `[0, max]`.
[inline]
pub fn (mut rng PRNG) f32n(max f32) ?f32 {
if max < 0 {
return error('max has to be non-negative.')
}
return rng.f32() * max
}
// f64n returns a pseudorandom `f64` value in range `[0, max]`.
[inline]
pub fn (mut rng PRNG) f64n(max f64) ?f64 {
if max < 0 {
return error('max has to be non-negative.')
}
return rng.f64() * max
}
// f32_in_range returns a pseudorandom `f32` in range `[min, max]`.
[inline]
pub fn (mut rng PRNG) f32_in_range(min f32, max f32) ?f32 {
if max < min {
return error('max must be greater than or equal to min')
}
return min + rng.f32n(max - min) ?
}
// i64_in_range returns a pseudorandom `i64` in range `[min, max]`.
[inline]
pub fn (mut rng PRNG) f64_in_range(min f64, max f64) ?f64 {
if max < min {
return error('max must be greater than or equal to min')
}
return min + rng.f64n(max - min) ?
}
// ulid generates an Unique Lexicographically sortable IDentifier.
// See https://github.com/ulid/spec .
// Note: ULIDs can leak timing information, if you make them public, because
// you can infer the rate at which some resource is being created, like
// users or business transactions.
// (https://news.ycombinator.com/item?id=14526173)
pub fn (mut rng PRNG) ulid() string {
return internal_ulid_at_millisecond(mut rng, u64(time.utc().unix_time_milli()))
}
// ulid_at_millisecond does the same as `ulid` but takes a custom Unix millisecond timestamp via `unix_time_milli`.
pub fn (mut rng PRNG) ulid_at_millisecond(unix_time_milli u64) string {
return internal_ulid_at_millisecond(mut rng, unix_time_milli)
}
// string_from_set returns a string of length `len` containing random characters sampled from the given `charset`
pub fn (mut rng PRNG) string_from_set(charset string, len int) string {
return internal_string_from_set(mut rng, charset, len)
}
// string returns a string of length `len` containing random characters in range `[a-zA-Z]`.
pub fn (mut rng PRNG) string(len int) string {
return internal_string_from_set(mut rng, rand.english_letters, len)
}
// hex returns a hexadecimal number of length `len` containing random characters in range `[a-f0-9]`.
pub fn (mut rng PRNG) hex(len int) string {
return internal_string_from_set(mut rng, rand.hex_chars, len)
}
// ascii returns a random string of the printable ASCII characters with length `len`.
pub fn (mut rng PRNG) ascii(len int) string {
return internal_string_from_set(mut rng, rand.ascii_chars, len)
}
// Configuration struct for the shuffle functions.
// The start index is inclusive and the end index is exclusive.
// Set the end to 0 to shuffle until the end of the array.
[params]
pub struct ShuffleConfigStruct {
pub:
start int
end int
}
fn (config ShuffleConfigStruct) validate_for<T>(a []T) ? {
if config.start < 0 || config.start >= a.len {
return error("argument 'config.start' must be in range [0, a.len)")
}
if config.end < 0 || config.end > a.len {
return error("argument 'config.end' must be in range [0, a.len]")
}
}
// shuffle randomly permutates the elements in `a`. The range for shuffling is
// optional and the entire array is shuffled by default. Leave the end as 0 to
// shuffle all elements until the end.
[direct_array_access]
pub fn (mut rng PRNG) shuffle<T>(mut a []T, config ShuffleConfigStruct) ? {
config.validate_for(a) ?
new_end := if config.end == 0 { a.len } else { config.end }
for i in config.start .. new_end {
x := rng.int_in_range(i, new_end) or { config.start }
// swap
a_i := a[i]
a[i] = a[x]
a[x] = a_i
}
}
// shuffle_clone returns a random permutation of the elements in `a`.
// The permutation is done on a fresh clone of `a`, so `a` remains unchanged.
pub fn (mut rng PRNG) shuffle_clone<T>(a []T, config ShuffleConfigStruct) ?[]T {
mut res := a.clone()
rng.shuffle(mut res, config) ?
return res
}
// choose samples k elements from the array without replacement.
// This means the indices cannot repeat and it restricts the sample size to be less than or equal to the size of the given array.
// Note that if the array has repeating elements, then the sample may have repeats as well.
pub fn (mut rng PRNG) choose<T>(array []T, k int) ?[]T {
n := array.len
if k > n {
return error('Cannot choose $k elements without replacement from a $n-element array.')
}
mut results := []T{len: k}
mut indices := []int{len: n, init: it}
// TODO: see why exactly it is necessary to enfoce the type here in Checker.infer_fn_generic_types
// (v errors with: `inferred generic type T is ambiguous: got int, expected string`, when <int> is missing)
rng.shuffle<int>(mut indices) ?
for i in 0 .. k {
results[i] = array[indices[i]]
}
return results
}
// sample samples k elements from the array with replacement.
// This means the elements can repeat and the size of the sample may exceed the size of the array.
pub fn (mut rng PRNG) sample<T>(array []T, k int) []T {
mut results := []T{len: k}
for i in 0 .. k {
results[i] = array[rng.intn(array.len) or { 0 }]
}
return results
}
__global default_rng &PRNG
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// new_default returns a new instance of the default RNG. If the seed is not provided, the current time will be used to seed the instance.
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[manualfree]
pub fn new_default(config config.PRNGConfigStruct) &PRNG {
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mut rng := &wyrand.WyRandRNG{}
rng.seed(config.seed_)
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unsafe { config.seed_.free() }
return &PRNG(rng)
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}
// get_current_rng returns the PRNG instance currently in use. If it is not changed, it will be an instance of wyrand.WyRandRNG.
pub fn get_current_rng() &PRNG {
return default_rng
}
// set_rng changes the default RNG from wyrand.WyRandRNG (or whatever the last RNG was) to the one
// provided by the user. Note that this new RNG must be seeded manually with a constant seed or the
// `seed.time_seed_array()` method. Also, it is recommended to store the old RNG in a variable and
// should be restored if work with the custom RNG is complete. It is not necessary to restore if the
// program terminates soon afterwards.
pub fn set_rng(rng &PRNG) {
default_rng = unsafe { rng }
}
// seed sets the given array of `u32` values as the seed for the `default_rng`. The default_rng is
// an instance of WyRandRNG which takes 2 u32 values. When using a custom RNG, make sure to use
// the correct number of u32s.
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pub fn seed(seed []u32) {
default_rng.seed(seed)
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}
// u32 returns a uniformly distributed `u32` in range `[0, 2³²)`.
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pub fn u32() u32 {
return default_rng.u32()
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}
// u64 returns a uniformly distributed `u64` in range `[0, 2⁶⁴)`.
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pub fn u64() u64 {
return default_rng.u64()
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}
// u32n returns a uniformly distributed pseudorandom 32-bit signed positive `u32` in range `[0, max)`.
pub fn u32n(max u32) ?u32 {
return default_rng.u32n(max)
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}
// u64n returns a uniformly distributed pseudorandom 64-bit signed positive `u64` in range `[0, max)`.
pub fn u64n(max u64) ?u64 {
return default_rng.u64n(max)
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}
// u32_in_range returns a uniformly distributed pseudorandom 32-bit unsigned `u32` in range `[min, max)`.
pub fn u32_in_range(min u32, max u32) ?u32 {
return default_rng.u32_in_range(min, max)
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}
// u64_in_range returns a uniformly distributed pseudorandom 64-bit unsigned `u64` in range `[min, max)`.
pub fn u64_in_range(min u64, max u64) ?u64 {
return default_rng.u64_in_range(min, max)
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}
// i16 returns a uniformly distributed pseudorandom 16-bit signed (possibly negative) `i16`.
pub fn i16() i16 {
return default_rng.i16()
}
// int returns a uniformly distributed pseudorandom 32-bit signed (possibly negative) `int`.
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pub fn int() int {
return default_rng.int()
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}
// intn returns a uniformly distributed pseudorandom 32-bit signed positive `int` in range `[0, max)`.
pub fn intn(max int) ?int {
return default_rng.intn(max)
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}
// byte returns a uniformly distributed pseudorandom 8-bit unsigned positive `byte`.
pub fn byte() byte {
return default_rng.byte()
}
// int_in_range returns a uniformly distributed pseudorandom 32-bit signed int in range `[min, max)`.
// Both `min` and `max` can be negative, but we must have `min < max`.
pub fn int_in_range(min int, max int) ?int {
return default_rng.int_in_range(min, max)
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}
// int31 returns a uniformly distributed pseudorandom 31-bit signed positive `int`.
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pub fn int31() int {
return default_rng.int31()
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}
// i64 returns a uniformly distributed pseudorandom 64-bit signed (possibly negative) `i64`.
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pub fn i64() i64 {
return default_rng.i64()
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}
// i64n returns a uniformly distributed pseudorandom 64-bit signed positive `i64` in range `[0, max)`.
pub fn i64n(max i64) ?i64 {
return default_rng.i64n(max)
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}
// i64_in_range returns a uniformly distributed pseudorandom 64-bit signed `i64` in range `[min, max)`.
pub fn i64_in_range(min i64, max i64) ?i64 {
return default_rng.i64_in_range(min, max)
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}
// int63 returns a uniformly distributed pseudorandom 63-bit signed positive `i64`.
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pub fn int63() i64 {
return default_rng.int63()
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}
// f32 returns a uniformly distributed 32-bit floating point in range `[0, 1)`.
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pub fn f32() f32 {
return default_rng.f32()
}
// f64 returns a uniformly distributed 64-bit floating point in range `[0, 1)`.
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pub fn f64() f64 {
return default_rng.f64()
}
// f32n returns a uniformly distributed 32-bit floating point in range `[0, max)`.
pub fn f32n(max f32) ?f32 {
return default_rng.f32n(max)
}
// f64n returns a uniformly distributed 64-bit floating point in range `[0, max)`.
pub fn f64n(max f64) ?f64 {
return default_rng.f64n(max)
}
// f32_in_range returns a uniformly distributed 32-bit floating point in range `[min, max)`.
pub fn f32_in_range(min f32, max f32) ?f32 {
return default_rng.f32_in_range(min, max)
}
// f64_in_range returns a uniformly distributed 64-bit floating point in range `[min, max)`.
pub fn f64_in_range(min f64, max f64) ?f64 {
return default_rng.f64_in_range(min, max)
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}
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// bytes returns a buffer of `bytes_needed` random bytes
pub fn bytes(bytes_needed int) ?[]byte {
return default_rng.bytes(bytes_needed)
}
// read fills in `buf` a maximum of `buf.len` random bytes
pub fn read(mut buf []byte) {
read_internal(mut default_rng, mut buf)
}
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const (
english_letters = 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ'
hex_chars = 'abcdef0123456789'
ascii_chars = '!"#$%&\'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ\\^_`abcdefghijklmnopqrstuvwxyz{|}~'
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)
// ulid generates an Unique Lexicographically sortable IDentifier.
// See https://github.com/ulid/spec .
// Note: ULIDs can leak timing information, if you make them public, because
// you can infer the rate at which some resource is being created, like
// users or business transactions.
// (https://news.ycombinator.com/item?id=14526173)
pub fn ulid() string {
return default_rng.ulid()
}
// ulid_at_millisecond does the same as `ulid` but takes a custom Unix millisecond timestamp via `unix_time_milli`.
pub fn ulid_at_millisecond(unix_time_milli u64) string {
return default_rng.ulid_at_millisecond(unix_time_milli)
}
// string_from_set returns a string of length `len` containing random characters sampled from the given `charset`
pub fn string_from_set(charset string, len int) string {
return default_rng.string_from_set(charset, len)
}
// string returns a string of length `len` containing random characters in range `[a-zA-Z]`.
pub fn string(len int) string {
return string_from_set(rand.english_letters, len)
}
// hex returns a hexadecimal number of length `len` containing random characters in range `[a-f0-9]`.
pub fn hex(len int) string {
return string_from_set(rand.hex_chars, len)
}
// ascii returns a random string of the printable ASCII characters with length `len`.
pub fn ascii(len int) string {
return string_from_set(rand.ascii_chars, len)
}
// shuffle randomly permutates the elements in `a`. The range for shuffling is
// optional and the entire array is shuffled by default. Leave the end as 0 to
// shuffle all elements until the end.
pub fn shuffle<T>(mut a []T, config ShuffleConfigStruct) ? {
default_rng.shuffle(mut a, config) ?
}
// shuffle_clone returns a random permutation of the elements in `a`.
// The permutation is done on a fresh clone of `a`, so `a` remains unchanged.
pub fn shuffle_clone<T>(a []T, config ShuffleConfigStruct) ?[]T {
return default_rng.shuffle_clone(a, config)
}
// choose samples k elements from the array without replacement.
// This means the indices cannot repeat and it restricts the sample size to be less than or equal to the size of the given array.
// Note that if the array has repeating elements, then the sample may have repeats as well.
pub fn choose<T>(array []T, k int) ?[]T {
return default_rng.choose(array, k)
}
// sample samples k elements from the array with replacement.
// This means the elements can repeat and the size of the sample may exceed the size of the array.
pub fn sample<T>(array []T, k int) []T {
return default_rng.sample(array, k)
}