Add translation support to custom alphabet

README.md

@@ -94,6 +94,9 @@ a.sort(function(a, b){
 It is possible to configure a custom alphabet
 to achieve a desired order.
 
+At the end of alphabet after "\b" can be a translation table
+when some letters needs to be equal.
+
 ```javascript
 // Estonian alphabet
 String.alphabet = "ABDEFGHIJKLMNOPRSŠZŽTUVÕÄÖÜXYabdefghijklmnoprsšzžtuvõäöüxy"
@@ -104,6 +107,11 @@ String.alphabet = "ABDEFGHIJKLMNOPRSŠZŽTUVÕÄÖÜXYabdefghijklmnoprsšzžtuv
 String.alphabet = "АБВГДЕЁЖЗИЙКЛМНОПРСТУФХЦЧШЩЪЫЬЭЮЯабвгдеёжзийклмнопрстуфхцчшщъыьэюя"
 ["Ё", "А", "Б"].sort(String.naturalCompare)
 // ["А", "Б", "Ё"]
+
+// Spanish alphabet
+String.alphabet = "ABCDEFGHIJKLMNÑOPQRSTUVWXYZabcdefghijklmnñopqrstuvwxyz\bÁAÉEÍIÓOÚUÜUáaéeíióoúuüu"
+["á3", "a2", "á1", "piñata", "pinza"].sort(String.naturalCompare)
+// ["á1", "a2", "á3", "pinza", "piñata"]
 ```
 
 

index.js

@@ -16,14 +16,20 @@ String.naturalCompare = function(a, b) {
 	, posA = 0
 	, posB = 0
 	, alphabet = String.alphabet
+	, tr = alphabet && alphabet.split("\b")[1]
 
 	function getCode(str, pos, code) {
 		if (code) {
 			for (i = pos; code = getCode(str, i), code < 76 && code > 65;) ++i;
 			return +str.slice(pos - 1, i)
 		}
-		code = alphabet && alphabet.indexOf(str.charAt(pos))
-		return code > -1 ? code + 76 : ((code = str.charCodeAt(pos) || 0), code < 45 || code > 127) ? code
+
+		str = tr && str && (code = tr.indexOf(str) + 1) % 2 ?
+			tr.charAt(code) :
+			str.charAt(pos)
+
+		code = alphabet && alphabet.indexOf(str)
+		return code > -1 ? code + 76 : ((code = str.charCodeAt() || 0), code < 45 || code > 127) ? code
 			: code < 46 ? 65               // -
 			: code < 48 ? code - 1
 			: code < 58 ? code + 18        // 0-9