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// Copyright 2022 The Gitea Authors. All rights reserved.
// SPDX-License-Identifier: MIT
package util
import "unsafe"
func isSnakeCaseUpper(c byte) bool {
return 'A' <= c && c <= 'Z'
}
func isSnakeCaseLowerOrNumber(c byte) bool {
return 'a' <= c && c <= 'z' || '0' <= c && c <= '9'
}
// ToSnakeCase convert the input string to snake_case format.
//
// Some samples.
//
// "FirstName" => "first_name"
// "HTTPServer" => "http_server"
// "NoHTTPS" => "no_https"
// "GO_PATH" => "go_path"
// "GO PATH" => "go_path" // space is converted to underscore.
// "GO-PATH" => "go_path" // hyphen is converted to underscore.
func ToSnakeCase(input string) string {
if len(input) == 0 {
return ""
}
var res []byte
if len(input) == 1 {
c := input[0]
if isSnakeCaseUpper(c) {
res = []byte{c + 'a' - 'A'}
} else if isSnakeCaseLowerOrNumber(c) {
res = []byte{c}
} else {
res = []byte{'_'}
}
} else {
res = make([]byte, 0, len(input)*4/3)
pos := 0
needSep := false
for pos < len(input) {
c := input[pos]
if c >= 0x80 {
res = append(res, c)
pos++
continue
}
isUpper := isSnakeCaseUpper(c)
if isUpper || isSnakeCaseLowerOrNumber(c) {
end := pos + 1
if isUpper {
// skip the following upper letters
for end < len(input) && isSnakeCaseUpper(input[end]) {
end++
}
if end-pos > 1 && end < len(input) && isSnakeCaseLowerOrNumber(input[end]) {
end--
}
}
// skip the following lower or number letters
for end < len(input) && (isSnakeCaseLowerOrNumber(input[end]) || input[end] >= 0x80) {
end++
}
if needSep {
res = append(res, '_')
}
res = append(res, input[pos:end]...)
pos = end
needSep = true
} else {
res = append(res, '_')
pos++
needSep = false
}
}
for i := 0; i < len(res); i++ {
if isSnakeCaseUpper(res[i]) {
res[i] += 'a' - 'A'
}
}
}
return UnsafeBytesToString(res)
}
// UnsafeBytesToString uses Go's unsafe package to convert a byte slice to a string.
func UnsafeBytesToString(b []byte) string {
return unsafe.String(unsafe.SliceData(b), len(b))
}
// UnsafeStringToBytes uses Go's unsafe package to convert a string to a byte slice.
func UnsafeStringToBytes(s string) []byte {
return unsafe.Slice(unsafe.StringData(s), len(s))
}
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