313 lines
9.1 KiB
V
313 lines
9.1 KiB
V
// Copyright (c) 2019-2021 Alexander Medvednikov. All rights reserved.
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// Use of this source code is governed by an MIT license
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// that can be found in the LICENSE file.
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module rand
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import rand.seed
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import rand.wyrand
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import time
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// PRNGConfigStruct is a configuration struct for creating a new instance of the default RNG.
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// Note that the RNGs may have a different number of u32s required for seeding. The default
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// generator WyRand used 64 bits, ie. 2 u32s so that is the default. In case your desired generator
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// uses a different number of u32s, use the `seed.time_seed_array()` method with the correct
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// number of u32s.
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pub struct PRNGConfigStruct {
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seed []u32 = seed.time_seed_array(2)
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}
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// PRNG is a common interface for all PRNGs that can be used seamlessly with the rand
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// modules's API. It defines all the methods that a PRNG (in the vlib or custom made) must
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// implement in order to ensure that _all_ functions can be used with the generator.
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pub interface PRNG {
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seed(seed_data []u32)
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u32() u32
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u64() u64
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u32n(max u32) u32
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u64n(max u64) u64
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u32_in_range(min u32, max u32) u32
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u64_in_range(min u64, max u64) u64
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int() int
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i64() i64
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int31() int
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int63() i64
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intn(max int) int
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i64n(max i64) i64
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int_in_range(min int, max int) int
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i64_in_range(min i64, max i64) i64
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f32() f32
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f64() f64
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f32n(max f32) f32
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f64n(max f64) f64
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f32_in_range(min f32, max f32) f32
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f64_in_range(min f64, max f64) f64
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}
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__global ( default_rng &PRNG )
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// init initializes the default RNG.
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fn init() {
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default_rng = new_default({})
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}
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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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pub fn new_default(config PRNGConfigStruct) &PRNG {
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mut rng := &wyrand.WyRandRNG{}
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rng.seed(config.seed)
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return rng
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}
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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.
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pub fn get_current_rng() &PRNG {
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return default_rng
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}
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// set_rng changes the default RNG from wyrand.WyRandRNG (or whatever the last RNG was) to the one
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// provided by the user. Note that this new RNG must be seeded manually with a constant seed or the
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// `seed.time_seed_array()` method. Also, it is recommended to store the old RNG in a variable and
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// should be restored if work with the custom RNG is complete. It is not necessary to restore if the
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// program terminates soon afterwards.
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pub fn set_rng(rng &PRNG) {
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default_rng = unsafe { rng }
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}
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// seed sets the given array of `u32` values as the seed for the `default_rng`. The default_rng is
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// an instance of WyRandRNG which takes 2 u32 values. When using a custom RNG, make sure to use
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// the correct number of u32s.
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pub fn seed(seed []u32) {
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default_rng.seed(seed)
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}
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// u32 returns a uniformly distributed `u32` in range `[0, 2³²)`.
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pub fn u32() u32 {
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return default_rng.u32()
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}
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// u64 returns a uniformly distributed `u64` in range `[0, 2⁶⁴)`.
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pub fn u64() u64 {
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return default_rng.u64()
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}
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// u32n returns a uniformly distributed pseudorandom 32-bit signed positive `u32` in range `[0, max)`.
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pub fn u32n(max u32) u32 {
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return default_rng.u32n(max)
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}
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// u64n returns a uniformly distributed pseudorandom 64-bit signed positive `u64` in range `[0, max)`.
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pub fn u64n(max u64) u64 {
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return default_rng.u64n(max)
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}
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// u32_in_range returns a uniformly distributed pseudorandom 32-bit unsigned `u32` in range `[min, max)`.
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pub fn u32_in_range(min u32, max u32) u32 {
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return default_rng.u32_in_range(min, max)
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}
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// u64_in_range returns a uniformly distributed pseudorandom 64-bit unsigned `u64` in range `[min, max)`.
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pub fn u64_in_range(min u64, max u64) u64 {
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return default_rng.u64_in_range(min, max)
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}
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// int returns a uniformly distributed pseudorandom 32-bit signed (possibly negative) `int`.
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pub fn int() int {
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return default_rng.int()
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}
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// intn returns a uniformly distributed pseudorandom 32-bit signed positive `int` in range `[0, max)`.
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pub fn intn(max int) int {
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return default_rng.intn(max)
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}
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// byte returns a uniformly distributed pseudorandom 8-bit unsigned positive `byte`.
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pub fn byte() byte {
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return byte(default_rng.u32() & 0xff)
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}
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// int_in_range returns a uniformly distributed pseudorandom 32-bit signed int in range `[min, max)`.
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// Both `min` and `max` can be negative, but we must have `min < max`.
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pub fn int_in_range(min int, max int) int {
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return default_rng.int_in_range(min, max)
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}
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// int31 returns a uniformly distributed pseudorandom 31-bit signed positive `int`.
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pub fn int31() int {
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return default_rng.int31()
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}
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// i64 returns a uniformly distributed pseudorandom 64-bit signed (possibly negative) `i64`.
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pub fn i64() i64 {
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return default_rng.i64()
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}
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// i64n returns a uniformly distributed pseudorandom 64-bit signed positive `i64` in range `[0, max)`.
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pub fn i64n(max i64) i64 {
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return default_rng.i64n(max)
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}
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// i64_in_range returns a uniformly distributed pseudorandom 64-bit signed `i64` in range `[min, max)`.
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pub fn i64_in_range(min i64, max i64) i64 {
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return default_rng.i64_in_range(min, max)
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}
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// int63 returns a uniformly distributed pseudorandom 63-bit signed positive `i64`.
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pub fn int63() i64 {
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return default_rng.int63()
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}
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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 {
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return default_rng.f32()
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}
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// f64 returns a uniformly distributed 64-bit floating point in range `[0, 1)`.
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pub fn f64() f64 {
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return default_rng.f64()
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}
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// f32n returns a uniformly distributed 32-bit floating point in range `[0, max)`.
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pub fn f32n(max f32) f32 {
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return default_rng.f32n(max)
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}
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// f64n returns a uniformly distributed 64-bit floating point in range `[0, max)`.
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pub fn f64n(max f64) f64 {
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return default_rng.f64n(max)
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}
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// f32_in_range returns a uniformly distributed 32-bit floating point in range `[min, max)`.
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pub fn f32_in_range(min f32, max f32) f32 {
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return default_rng.f32_in_range(min, max)
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}
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// f64_in_range returns a uniformly distributed 64-bit floating point in range `[min, max)`.
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pub fn f64_in_range(min f64, max f64) f64 {
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return default_rng.f64_in_range(min, max)
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}
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const (
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english_letters = 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ'
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hex_chars = 'abcdef0123456789'
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ascii_chars = '!"#$%&\'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ\\^_`abcdefghijklmnopqrstuvwxyz{|}~'
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)
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// string_from_set returns a string of length `len` containing random characters sampled from the given `charset`
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pub fn string_from_set(charset string, len int) string {
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if len == 0 {
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return ''
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}
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mut buf := unsafe { malloc(len) }
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for i in 0 .. len {
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unsafe {
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buf[i] = charset[intn(charset.len)]
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}
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}
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return unsafe { buf.vstring_with_len(len) }
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}
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// string returns a string of length `len` containing random characters in range `[a-zA-Z]`.
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pub fn string(len int) string {
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return string_from_set(rand.english_letters, len)
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}
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// hex returns a hexadecimal number of length `len` containing random characters in range `[a-f0-9]`.
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pub fn hex(len int) string {
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return string_from_set(rand.hex_chars, len)
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}
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// ascii returns a random string of the printable ASCII characters with length `len`.
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pub fn ascii(len int) string {
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return string_from_set(rand.ascii_chars, len)
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}
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// uuid_v4 generates a random (v4) UUID
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// See https://en.wikipedia.org/wiki/Universally_unique_identifier#Version_4_(random)
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pub fn uuid_v4() string {
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buflen := 36
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mut buf := unsafe { malloc(37) }
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mut i_buf := 0
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mut x := u64(0)
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mut d := byte(0)
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for i_buf < buflen {
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mut c := 0
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x = default_rng.u64()
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// do most of the bit manipulation at once:
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x &= 0x0F0F0F0F0F0F0F0F
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x += 0x3030303030303030
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// write the ASCII codes to the buffer:
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for c < 8 && i_buf < buflen {
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d = byte(x)
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unsafe {
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buf[i_buf] = if d > 0x39 { d + 0x27 } else { d }
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}
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i_buf++
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c++
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x = x >> 8
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}
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}
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// there are still some random bits in x:
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x = x >> 8
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d = byte(x)
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unsafe {
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buf[19] = if d > 0x39 { d + 0x27 } else { d }
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buf[8] = `-`
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buf[13] = `-`
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buf[18] = `-`
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buf[23] = `-`
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buf[14] = `4`
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buf[buflen] = 0
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return buf.vstring_with_len(buflen)
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}
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}
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const (
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ulid_encoding = '0123456789ABCDEFGHJKMNPQRSTVWXYZ'
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)
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// ulid generates an Unique Lexicographically sortable IDentifier.
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// See https://github.com/ulid/spec .
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// NB: ULIDs can leak timing information, if you make them public, because
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// you can infer the rate at which some resource is being created, like
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// users or business transactions.
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// (https://news.ycombinator.com/item?id=14526173)
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pub fn ulid() string {
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return ulid_at_millisecond(time.utc().unix_time_milli())
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}
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// ulid_at_millisecond does the same as `ulid` but takes a custom Unix millisecond timestamp via `unix_time_milli`.
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pub fn ulid_at_millisecond(unix_time_milli u64) string {
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buflen := 26
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mut buf := unsafe { malloc(27) }
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mut t := unix_time_milli
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mut i := 9
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for i >= 0 {
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unsafe {
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buf[i] = rand.ulid_encoding[t & 0x1F]
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}
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t = t >> 5
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i--
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}
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// first rand set
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mut x := default_rng.u64()
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i = 10
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for i < 19 {
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unsafe {
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buf[i] = rand.ulid_encoding[x & 0x1F]
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}
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x = x >> 5
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i++
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}
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// second rand set
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x = default_rng.u64()
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for i < 26 {
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unsafe {
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buf[i] = rand.ulid_encoding[x & 0x1F]
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}
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x = x >> 5
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i++
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}
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unsafe {
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buf[26] = 0
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return buf.vstring_with_len(buflen)
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}
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}
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