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v/vlib/rand/rand.js.v

75 lines
1.7 KiB
V

module rand
import time
// init initializes the default RNG.
fn init() {
default_rng = new_default()
}
pub fn string(len int) string {
result := ''
#
#const characters = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789';
#const charactersLength = characters.length;
#for (let i = 0;i < len.val;i++)
#result.str += characters.charAt(Math.random() * charactersLength);
return result
}
const (
ulid_encoding = '0123456789ABCDEFGHJKMNPQRSTVWXYZ'
)
// ulid generates an Unique Lexicographically sortable IDentifier.
// See https://github.com/ulid/spec .
// NB: 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 ulid_at_millisecond(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 ulid_at_millisecond(unix_time_milli u64) string {
mut buf := []byte{cap: 27}
mut t := unix_time_milli
mut i := 9
for i >= 0 {
buf[i] = rand.ulid_encoding[int(t & 0x1f)]
t = t >> 5
i--
}
mut x := default_rng.u64()
i = 10
for i < 19 {
buf[i] = rand.ulid_encoding[int(x & 0x1f)]
x = x >> 5
i++
}
x = default_rng.u64()
for i < 26 {
buf[i] = rand.ulid_encoding[int(x & 0x1f)]
x = x >> 5
i++
}
res := ''
println(buf)
#res.str = buf.arr.arr.map(String.fromCharCode).join('')
return res
}
// read fills in `buf` a maximum of `buf.len` random bytes
pub fn read(mut buf []byte) {
for i in 0 .. buf.len {
buf[i] = byte(default_rng.u32())
}
}