52 lines
1.6 KiB
Go
52 lines
1.6 KiB
Go
// Vikunja is a todo-list application to facilitate your life.
|
|
// Copyright 2018-2020 Vikunja and contributors. All rights reserved.
|
|
//
|
|
// This program is free software: you can redistribute it and/or modify
|
|
// it under the terms of the GNU General Public License as published by
|
|
// the Free Software Foundation, either version 3 of the License, or
|
|
// (at your option) any later version.
|
|
//
|
|
// This program is distributed in the hope that it will be useful,
|
|
// but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
// GNU General Public License for more details.
|
|
//
|
|
// You should have received a copy of the GNU General Public License
|
|
// along with this program. If not, see <https://www.gnu.org/licenses/>.
|
|
|
|
package utils
|
|
|
|
import (
|
|
"math/rand"
|
|
"time"
|
|
)
|
|
|
|
func init() {
|
|
rand.Seed(time.Now().UnixNano())
|
|
}
|
|
|
|
const letterBytes = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
|
|
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
|
|
)
|
|
|
|
// MakeRandomString return a random string
|
|
func MakeRandomString(n int) string {
|
|
b := make([]byte, n)
|
|
// A rand.Int63() generates 63 random bits, enough for letterIdxMax letters!
|
|
for i, cache, remain := n-1, rand.Int63(), letterIdxMax; i >= 0; {
|
|
if remain == 0 {
|
|
cache, remain = rand.Int63(), letterIdxMax
|
|
}
|
|
if idx := int(cache & letterIdxMask); idx < len(letterBytes) {
|
|
b[i] = letterBytes[idx]
|
|
i--
|
|
}
|
|
cache >>= letterIdxBits
|
|
remain--
|
|
}
|
|
|
|
return string(b)
|
|
}
|