normalization.go

package unify4g

// normalize_rune takes a rune as input and returns its normalized string representation.
//
// The function handles a wide variety of special characters and diacritics, replacing them with their
// more common ASCII equivalents. The specific transformations are defined in a switch statement that
// maps each rune to its normalized string value. This includes:
//
//   - Ligatures (e.g., 'Æ' to "AE", 'Œ' to "OE")
//   - Special characters (e.g., 'ß' to "ss")
//   - Accented characters (e.g., 'é' to "e", 'ç' to "c")
//   - Various other characters with diacritics are converted to their closest ASCII equivalent.
//
// If the input rune does not match any of the defined cases, the function returns the rune as a string,
// preserving its original representation.
//
// Parameters:
//   - `r`: A rune representing a Unicode character that may need normalization.
//
// Returns:
//   - A string that represents the normalized form of the input rune. This string is typically ASCII,
//     making it easier to handle in contexts where only basic characters are expected.
//
// Example:
//
//	normalized := normalize_rune('É')
//	fmt.Println(normalized) // Output: "E"
//
// Notes:
//   - This function is particularly useful for text processing, sanitization, or when preparing data
//     for systems that require ASCII-compatible strings.
//
// Replacements are taken from
//   - https://github.com/sindresorhus/slugify/blob/master/replacements.js
//   - https://github.com/cocur/slugify/tree/master/Resources/rules
func normalize_rune(r rune) string {
	switch r {
	case 'Ə':
		return "E"
	case 'Æ':
		return "AE"
	case 'ß':
		return "ss"
	case 'æ':
		return "ae"
	case 'Ø':
		return "OE"
	case 'ø':
		return "oe"
	case 'Å':
		return "a"
	case 'å':
		return "a"
	case 'É':
		return "E"
	case 'é':
		return "e"
	case 'Č':
		return "C"
	case 'Ć':
		return "C"
	case 'Ž':
		return "Z"
	case 'Š':
		return "S"
	case 'Đ':
		return "D"
	case 'č':
		return "c"
	case 'ć':
		return "c"
	case 'ž':
		return "z"
	case 'š':
		return "s"
	case 'đ':
		return "d"
	case 'Ď':
		return "D"
	case 'Ě':
		return "E"
	case 'Ň':
		return "N"
	case 'Ř':
		return "R"
	case 'Ť':
		return "T"
	case 'Ů':
		return "U"
	case 'ď':
		return "d"
	case 'ě':
		return "e"
	case 'ň':
		return "n"
	case 'ř':
		return "r"
	case 'ť':
		return "t"
	case 'ů':
		return "u"
	case 'ǽ':
		return "ae"
	case 'À':
		return "A"
	case 'Á':
		return "A"
	case 'Â':
		return "A"
	case 'Ã':
		return "A"
	case 'Ǻ':
		return "A"
	case 'Ă':
		return "A"
	case 'Ǎ':
		return "A"
	case 'Ǽ':
		return "AE"
	case 'à':
		return "a"
	case 'á':
		return "a"
	case 'â':
		return "a"
	case 'ã':
		return "a"
	case 'ǻ':
		return "a"
	case 'ă':
		return "a"
	case 'ǎ':
		return "a"
	case 'ª':
		return "a"
	case '@':
		return "at"
	case 'Ĉ':
		return "C"
	case 'Ċ':
		return "C"
	case 'Ç':
		return "C"
	case 'ç':
		return "c"
	case 'ĉ':
		return "c"
	case 'ċ':
		return "c"
	case '©':
		return "c"
	case 'Ð':
		return "Dj"
	case 'ð':
		return "dj"
	case 'È':
		return "E"
	case 'Ê':
		return "E"
	case 'Ë':
		return "E"
	case 'Ĕ':
		return "E"
	case 'Ė':
		return "E"
	case 'è':
		return "e"
	case 'ê':
		return "e"
	case 'ë':
		return "e"
	case 'ĕ':
		return "e"
	case 'ė':
		return "e"
	case 'ƒ':
		return "f"
	case 'Ĝ':
		return "G"
	case 'Ġ':
		return "G"
	case 'ĝ':
		return "g"
	case 'ġ':
		return "g"
	case 'Ĥ':
		return "H"
	case 'Ħ':
		return "H"
	case 'ĥ':
		return "h"
	case 'ħ':
		return "h"
	case 'Ì':
		return "I"
	case 'Í':
		return "I"
	case 'Î':
		return "I"
	case 'Ï':
		return "I"
	case 'Ĩ':
		return "I"
	case 'Ĭ':
		return "I"
	case 'Ǐ':
		return "I"
	case 'Į':
		return "I"
	case 'IJ':
		return "IJ"
	case 'ì':
		return "i"
	case 'í':
		return "i"
	case 'î':
		return "i"
	case 'ï':
		return "i"
	case 'ĩ':
		return "i"
	case 'ĭ':
		return "i"
	case 'ǐ':
		return "i"
	case 'į':
		return "i"
	case 'ij':
		return "ij"
	case 'Ĵ':
		return "J"
	case 'ĵ':
		return "j"
	case 'Ĺ':
		return "L"
	case 'Ľ':
		return "L"
	case 'Ŀ':
		return "L"
	case 'ĺ':
		return "l"
	case 'ľ':
		return "l"
	case 'ŀ':
		return "l"
	case 'Ñ':
		return "N"
	case 'ñ':
		return "n"
	case 'ʼn':
		return "n"
	case 'Ò':
		return "O"
	case 'Ó':
		return "O"
	case 'Ô':
		return "O"
	case 'Õ':
		return "O"
	case 'Ō':
		return "O"
	case 'Ŏ':
		return "O"
	case 'Ǒ':
		return "O"
	case 'Ő':
		return "O"
	case 'Ơ':
		return "O"
	case 'Ǿ':
		return "O"
	case 'Œ':
		return "OE"
	case 'ò':
		return "o"
	case 'ó':
		return "o"
	case 'ô':
		return "o"
	case 'õ':
		return "o"
	case 'ō':
		return "o"
	case 'ŏ':
		return "o"
	case 'ǒ':
		return "o"
	case 'ő':
		return "o"
	case 'ơ':
		return "o"
	case 'ǿ':
		return "o"
	case 'º':
		return "o"
	case 'œ':
		return "oe"
	case 'Ŕ':
		return "R"
	case 'Ŗ':
		return "R"
	case 'ŕ':
		return "r"
	case 'ŗ':
		return "r"
	case 'Ŝ':
		return "S"
	case 'Ș':
		return "S"
	case 'ŝ':
		return "s"
	case 'ș':
		return "s"
	case 'ſ':
		return "s"
	case 'Ţ':
		return "T"
	case 'Ț':
		return "T"
	case 'Ŧ':
		return "T"
	case 'Þ':
		return "TH"
	case 'ţ':
		return "t"
	case 'ț':
		return "t"
	case 'ŧ':
		return "t"
	case 'þ':
		return "th"
	case 'Ù':
		return "U"
	case 'Ú':
		return "U"
	case 'Û':
		return "U"
	case 'Ü':
		return "U"
	case 'Ũ':
		return "U"
	case 'Ŭ':
		return "U"
	case 'Ű':
		return "U"
	case 'Ų':
		return "U"
	case 'Ư':
		return "U"
	case 'Ǔ':
		return "U"
	case 'Ǖ':
		return "U"
	case 'Ǘ':
		return "U"
	case 'Ǚ':
		return "U"
	case 'Ǜ':
		return "U"
	case 'ù':
		return "u"
	case 'ú':
		return "u"
	case 'û':
		return "u"
	case 'ü':
		return "u"
	case 'ũ':
		return "u"
	case 'ŭ':
		return "u"
	case 'ű':
		return "u"
	case 'ų':
		return "u"
	case 'ư':
		return "u"
	case 'ǔ':
		return "u"
	case 'ǖ':
		return "u"
	case 'ǘ':
		return "u"
	case 'ǚ':
		return "u"
	case 'ǜ':
		return "u"
	case 'Ŵ':
		return "W"
	case 'ŵ':
		return "w"
	case 'Ý':
		return "Y"
	case 'Ÿ':
		return "Y"
	case 'Ŷ':
		return "Y"
	case 'ý':
		return "y"
	case 'ÿ':
		return "y"
	case 'ŷ':
		return "y"
	case 'Ä':
		return "A"
	case 'Ö':
		return "O"
	case 'ä':
		return "a"
	case 'ö':
		return "o"
	case 'Ā':
		return "A"
	case 'Ē':
		return "E"
	case 'Ģ':
		return "G"
	case 'Ī':
		return "I"
	case 'Ķ':
		return "K"
	case 'Ļ':
		return "L"
	case 'Ņ':
		return "N"
	case 'Ū':
		return "U"
	case 'ā':
		return "a"
	case 'ē':
		return "e"
	case 'ģ':
		return "g"
	case 'ī':
		return "i"
	case 'ķ':
		return "k"
	case 'ļ':
		return "l"
	case 'ņ':
		return "n"
	case 'ū':
		return "u"
	case 'Ą':
		return "A"
	case 'Ę':
		return "E"
	case 'ą':
		return "a"
	case 'ę':
		return "e"
	case 'Ł':
		return "L"
	case 'Ń':
		return "N"
	case 'Ś':
		return "S"
	case 'Ź':
		return "Z"
	case 'Ż':
		return "Z"
	case 'ł':
		return "l"
	case 'ń':
		return "n"
	case 'ś':
		return "s"
	case 'ź':
		return "z"
	case 'ż':
		return "z"
	case 'ş':
		return "s"
	case 'Ş':
		return "S"
	case 'Ğ':
		return "G"
	case 'İ':
		return "I"
	case 'ğ':
		return "g"
	case 'ı':
		return "i"
	case 'ạ':
		return "a"
	case 'Ạ':
		return "A"
	case 'ả':
		return "a"
	case 'Ả':
		return "A"
	case 'ấ':
		return "a"
	case 'Ấ':
		return "A"
	case 'ầ':
		return "a"
	case 'Ầ':
		return "A"
	case 'ẩ':
		return "a"
	case 'Ẩ':
		return "A"
	case 'ẫ':
		return "a"
	case 'Ẫ':
		return "A"
	case 'ậ':
		return "a"
	case 'Ậ':
		return "A"
	case 'ắ':
		return "a"
	case 'Ắ':
		return "A"
	case 'ằ':
		return "a"
	case 'Ằ':
		return "A"
	case 'ẳ':
		return "a"
	case 'Ẳ':
		return "A"
	case 'ẵ':
		return "a"
	case 'Ẵ':
		return "A"
	case 'ặ':
		return "a"
	case 'Ặ':
		return "A"
	case 'ẹ':
		return "e"
	case 'Ẹ':
		return "E"
	case 'ẻ':
		return "e"
	case 'Ẻ':
		return "E"
	case 'ẽ':
		return "e"
	case 'Ẽ':
		return "E"
	case 'ế':
		return "e"
	case 'Ế':
		return "E"
	case 'ề':
		return "e"
	case 'Ề':
		return "E"
	case 'ể':
		return "e"
	case 'Ể':
		return "E"
	case 'ễ':
		return "e"
	case 'Ễ':
		return "E"
	case 'ệ':
		return "e"
	case 'Ệ':
		return "E"
	case 'ỉ':
		return "i"
	case 'Ỉ':
		return "I"
	case 'ị':
		return "i"
	case 'Ị':
		return "I"
	case 'ọ':
		return "o"
	case 'Ọ':
		return "O"
	case 'ỏ':
		return "o"
	case 'Ỏ':
		return "O"
	case 'ố':
		return "o"
	case 'Ố':
		return "O"
	case 'ồ':
		return "o"
	case 'Ồ':
		return "O"
	case 'ổ':
		return "o"
	case 'Ổ':
		return "O"
	case 'ỗ':
		return "o"
	case 'Ỗ':
		return "O"
	case 'ộ':
		return "o"
	case 'Ộ':
		return "O"
	case 'ớ':
		return "o"
	case 'Ớ':
		return "O"
	case 'ờ':
		return "o"
	case 'Ờ':
		return "O"
	case 'ở':
		return "o"
	case 'Ở':
		return "O"
	case 'ỡ':
		return "o"
	case 'Ỡ':
		return "O"
	case 'ợ':
		return "o"
	case 'Ợ':
		return "O"
	case 'ụ':
		return "u"
	case 'Ụ':
		return "U"
	case 'ủ':
		return "u"
	case 'Ủ':
		return "U"
	case 'ứ':
		return "u"
	case 'Ứ':
		return "U"
	case 'ừ':
		return "u"
	case 'Ừ':
		return "U"
	case 'ử':
		return "u"
	case 'Ử':
		return "U"
	case 'ữ':
		return "u"
	case 'Ữ':
		return "U"
	case 'ự':
		return "u"
	case 'Ự':
		return "U"
	case 'ỳ':
		return "y"
	case 'Ỳ':
		return "Y"
	case 'ỵ':
		return "y"
	case 'Ỵ':
		return "Y"
	case 'ỷ':
		return "y"
	case 'Ỷ':
		return "Y"
	case 'ỹ':
		return "y"
	case 'Ỹ':
		return "Y"
	}
	return string(r)
}