hanayo/vendor/github.com/felipeweb/gopher-utils/string.go

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2019-02-23 13:29:15 +00:00
package gopher_utils
import (
"bytes"
"unicode"
"unicode/utf8"
)
// IsLetter returns true if the 'l' is an English letter.
func IsLetter(l uint8) bool {
n := (l | 0x20) - 'a'
if n >= 0 && n < 26 {
return true
}
return false
}
// Reverse s string, support unicode
func Reverse(s string) string {
n := len(s)
runes := make([]rune, n)
for _, rune := range s {
n--
runes[n] = rune
}
return string(runes[n:])
}
// ToSnakeCase can convert all upper case characters in a string to
// underscore 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(str string) string {
if len(str) == 0 {
return ""
}
buf := &bytes.Buffer{}
var prev, r0, r1 rune
var size int
r0 = '_'
for len(str) > 0 {
prev = r0
r0, size = utf8.DecodeRuneInString(str)
str = str[size:]
switch {
case r0 == utf8.RuneError:
buf.WriteByte(byte(str[0]))
case unicode.IsUpper(r0):
if prev != '_' {
buf.WriteRune('_')
}
buf.WriteRune(unicode.ToLower(r0))
if len(str) == 0 {
break
}
r0, size = utf8.DecodeRuneInString(str)
str = str[size:]
if !unicode.IsUpper(r0) {
buf.WriteRune(r0)
break
}
// find next non-upper-case character and insert `_` properly.
// it's designed to convert `HTTPServer` to `http_server`.
// if there are more than 2 adjacent upper case characters in a word,
// treat them as an abbreviation plus a normal word.
for len(str) > 0 {
r1 = r0
r0, size = utf8.DecodeRuneInString(str)
str = str[size:]
if r0 == utf8.RuneError {
buf.WriteRune(unicode.ToLower(r1))
buf.WriteByte(byte(str[0]))
break
}
if !unicode.IsUpper(r0) {
if r0 == '_' || r0 == ' ' || r0 == '-' {
r0 = '_'
buf.WriteRune(unicode.ToLower(r1))
} else {
buf.WriteRune('_')
buf.WriteRune(unicode.ToLower(r1))
buf.WriteRune(r0)
}
break
}
buf.WriteRune(unicode.ToLower(r1))
}
if len(str) == 0 || r0 == '_' {
buf.WriteRune(unicode.ToLower(r0))
break
}
default:
if r0 == ' ' || r0 == '-' {
r0 = '_'
}
buf.WriteRune(r0)
}
}
return buf.String()
}