Add Transliteration

[sudhirj]

Rails' paramterization method also performs transliteration of unicode characters, can do the same in Go using https://github.com/rainycape/unidecode

External libs aren't required, there a normalization feature in the stdlib https://godoc.org/golang.org/x/text/runes#Remove

[sudhirj]

var nonWord = regexp.MustCompile(`\W+`)
var whitespace = regexp.MustCompile(`\s+`)
var doubleDash = regexp.MustCompile(`-+`)

func normalize(u string) string {
	t := transform.Chain(norm.NFD, runes.Remove(runes.In(unicode.Mn)), norm.NFC)
	s, _, _ := transform.String(t, u)
	return s
}

func parameterize(u string) string {
	u = normalize(u)
	u = strings.ToLower(u)
	u = strings.TrimSpace(u)
	// protect dashes from replacement by making them underscores
	u = strings.ReplaceAll(u, "-", "_")
	u = whitespace.ReplaceAllString(u, "_")
	u = nonWord.ReplaceAllString(u, "")
	// restore dashes
	u = strings.ReplaceAll(u, "_", "-")
	// collapse multiple dashes to one
	u = doubleDash.ReplaceAllString(u, "-")
	// get the dashes off the ends
	u = strings.Trim(u, "-")
	return u
}