// Vikunja is a todo-list application to facilitate your life. // Copyright 2018 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) }