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51 lines
1.2 KiB
Go
51 lines
1.2 KiB
Go
package nrandom
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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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// Random generate a random string based on given string range.
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func Random(letters string, length int) string {
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b := make([]byte, length)
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r := rand.NewSource(time.Now().UnixNano())
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for i, cache, remain := length-1, r.Int63(), letterIdMax; i >= 0; {
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if remain == 0 {
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cache, remain = r.Int63(), letterIdMax
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}
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if idx := int(cache & letterIdMask); idx < len(letters) {
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b[i] = letters[idx]
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i--
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}
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cache >>= letterIdBits
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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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// RandString generate random string of specified length.
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func RandString(length int) string {
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return Random(Letters, length)
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}
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// RandStrUpper generate a random upper case string.
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func RandStrUpper(length int) string {
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return Random(UpperLetters, length)
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}
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// RandStrLower generate a random lower case string.
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func RandStrLower(length int) string {
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return Random(LowerLetters, length)
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}
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// RandNumeralStr generate a random numeral string of specified length.
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func RandNumeralStr(length int) string {
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return Random(Numeral, length)
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}
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// RandNumeralOrLetter generate a random numeral or letter string.
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func RandNumeralOrLetter(length int) string {
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return Random(Numeral+Letters, length)
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}
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