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