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// Copyright 2020 The Gogs Authors. All rights reserved.
// Use of this source code is governed by a MIT-style
// license that can be found in the LICENSE file.
package strutil
import (
"crypto/rand"
"math/big"
"unicode"
)
// ToUpperFirst returns s with only the first Unicode letter mapped to its upper case.
func ToUpperFirst(s string) string {
for i, v := range s {
return string(unicode.ToUpper(v)) + s[i+1:]
}
return ""
}
// RandomChars returns a generated string in given number of random characters.
func RandomChars(n int) (string, error) {
const alphanum = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"
randomInt := func(max *big.Int) (int, error) {
r, err := rand.Int(rand.Reader, max)
if err != nil {
return 0, err
}
return int(r.Int64()), nil
}
buffer := make([]byte, n)
max := big.NewInt(int64(len(alphanum)))
for i := 0; i < n; i++ {
index, err := randomInt(max)
if err != nil {
return "", err
}
buffer[i] = alphanum[index]
}
return string(buffer), nil
}
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