-
-
Save ffffranklin/9e241dc266564b0afa31 to your computer and use it in GitHub Desktop.
An implementation of Ruby's string.succ method in JavaScript
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
/* | |
* An implementation of Ruby's string.succ method. | |
* By Devon Govett | |
* | |
* Returns the successor to str. The successor is calculated by incrementing characters starting | |
* from the rightmost alphanumeric (or the rightmost character if there are no alphanumerics) in the | |
* string. Incrementing a digit always results in another digit, and incrementing a letter results in | |
* another letter of the same case. | |
* | |
* If the increment generates a carry, the character to the left of it is incremented. This | |
* process repeats until there is no carry, adding an additional character if necessary. | |
* | |
* succ("abcd") == "abce" | |
* succ("THX1138") == "THX1139" | |
* succ("<<koala>>") == "<<koalb>>" | |
* succ("1999zzz") == "2000aaa" | |
* succ("ZZZ9999") == "AAAA0000" | |
*/ | |
function succ(input) { | |
var alphabet = 'abcdefghijklmnopqrstuvwxyz', | |
length = alphabet.length, | |
result = input, | |
i = input.length; | |
while(i >= 0) { | |
var last = input.charAt(--i), | |
next = '', | |
carry = false; | |
if (isNaN(last)) { | |
index = alphabet.indexOf(last.toLowerCase()); | |
if (index === -1) { | |
next = last; | |
carry = true; | |
} | |
else { | |
var isUpperCase = last === last.toUpperCase(); | |
next = alphabet.charAt((index + 1) % length); | |
if (isUpperCase) { | |
next = next.toUpperCase(); | |
} | |
carry = index + 1 >= length; | |
if (carry && i === 0) { | |
var added = isUpperCase ? 'A' : 'a'; | |
result = added + next + result.slice(1); | |
break; | |
} | |
} | |
} | |
else { | |
next = +last + 1; | |
if(next > 9) { | |
next = 0; | |
carry = true | |
} | |
if (carry && i === 0) { | |
result = '1' + next + result.slice(1); | |
break; | |
} | |
} | |
result = result.slice(0, i) + next + result.slice(i + 1); | |
if (!carry) { | |
break; | |
} | |
} | |
return result; | |
} | |
/* | |
* Load the succ as a module in CommonJS, AMD, or Native context | |
* By Franklin Clark | |
*/ | |
var root = this; | |
// CommonJS/nodeJS | |
if (typeof module !== 'undefined' && module.exports) { | |
module.exports = succ; | |
// AMD | |
} else if (typeof define === 'function' && define.amd) { | |
define('succ', function () { 'use strict'; return succ; }); | |
// Browser | |
} else { | |
root.succ = succ; | |
} |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment