39 lines
899 B
Go
39 lines
899 B
Go
package tool
|
||
|
||
import (
|
||
"crypto/sha256"
|
||
"encoding/binary"
|
||
"errors"
|
||
"math/rand"
|
||
)
|
||
|
||
func FixedUniqueString(s string, length int, alphabet string) (string, error) {
|
||
if alphabet == "" {
|
||
alphabet = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
|
||
}
|
||
if length <= 0 {
|
||
return "", errors.New("length must be > 0")
|
||
}
|
||
if length > len(alphabet) {
|
||
return "", errors.New("length greater than available unique characters")
|
||
}
|
||
|
||
// Generate deterministic seed from SHA256
|
||
hash := sha256.Sum256([]byte(s))
|
||
seed := int64(binary.LittleEndian.Uint64(hash[:8])) // 前 8 字节
|
||
|
||
r := rand.New(rand.NewSource(seed))
|
||
|
||
// Copy alphabet to mutable array
|
||
data := []rune(alphabet)
|
||
|
||
// Deterministic shuffle (Fisher–Yates)
|
||
for i := len(data) - 1; i > 0; i-- {
|
||
j := r.Intn(i + 1)
|
||
data[i], data[j] = data[j], data[i]
|
||
}
|
||
|
||
// Take first N characters
|
||
return string(data[:length]), nil
|
||
}
|