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helpers.go
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/
helpers.go
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package str
import (
"math/rand"
"github.com/totoval/framework/helpers/zone"
)
const letterBytes = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
const numberBytes = "0123456789"
const (
letterIdxBits = 6 // 6 bits to represent a letter index
letterIdxMask = 1<<letterIdxBits - 1 // All 1-bits, as many as letterIdxBits
letterIdxMax = 63 / letterIdxBits // # of letter indices fitting in 63 bits
)
func RandNumberString(length uint) string {
return random(int(length), numberBytes)
}
func RandString(length uint) string {
return random(int(length), letterBytes)
}
func random(n int, bytes string) string {
src := rand.NewSource(zone.Now().UnixNano())
b := make([]byte, n)
for i, cache, remain := n-1, src.Int63(), letterIdxMax; i >= 0; {
if remain == 0 {
cache, remain = src.Int63(), letterIdxMax
}
if idx := int(cache & letterIdxMask); idx < len(bytes) {
b[i] = bytes[idx]
i--
}
cache >>= letterIdxBits
remain--
}
return string(b)
}