70 lines
1.2 KiB
Go
70 lines
1.2 KiB
Go
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package random
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import (
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"math/rand"
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"time"
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"unsafe"
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)
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type Mode int // 随机数模式
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const (
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Letter Mode = iota
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Number
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LetterNumber
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LetterHex
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)
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const (
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letters = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
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numbers = "0123456789"
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lettersHex = "0123456789abcdef"
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letterIdBit = 6
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letterIdxMask = 1<<letterIdBit - 1
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letterIdxMax = 63 / letterIdBit
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)
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func StrRandom(n int64) string {
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return Random(n, Letter)
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}
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func NumRandom(n int64) string {
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return Random(n, Number)
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}
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func Random(n int64, mode ...Mode) string {
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var baseStr string
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mode = append(mode, LetterNumber)
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switch mode[0] {
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case LetterHex:
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baseStr = lettersHex
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case Letter:
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baseStr = letters
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case Number:
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baseStr = numbers
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case LetterNumber:
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fallthrough
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default:
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baseStr = letters + numbers
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}
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return random(n, baseStr)
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}
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func random(n int64, baseStr string) string {
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var src = rand.NewSource(time.Now().UnixNano())
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b := make([]byte, n)
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for i, cache, remain := n-1, src.Int63(), letterIdxMax; i >= 0; {
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if remain == 0 {
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cache, remain = src.Int63(), letterIdxMax
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}
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if idx := int(cache & letterIdxMask); idx < len(baseStr) {
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b[i] = baseStr[idx]
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i--
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}
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cache >>= letterIdBit
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remain--
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}
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return *(*string)(unsafe.Pointer(&b))
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}
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