URLHash php

URLHash.php

<?php

// Port of http://code.google.com/p/loolu/source/browse/trunk/common/lib/url/hash.py to PHP
/**
 * LooLu is Copyright (c) 2009 Shannon Johnson, http://loo.lu/
 */

class URLHash {
		
		private $codeset  = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";
		private $base = 62; 
		
		public function __construct($codeset = null) {	
			if ($codeset) {
				$this->codeset = $codeset;
				$this->base = strlen($codeset);
			}
		}
		
		public function encode($id) {
			$hash = "";
			while ($id > 0) {
				$hash = $this->codeset[$id % $this->base] . $hash;
				$id = floor($id / $this->base);
			}
			
			return $hash;
		}
		
		public function decode($value) {
			$id = 0;
			
			$chars = array_reverse(preg_split('//', $value, -1, PREG_SPLIT_NO_EMPTY));
			foreach ($chars as $index => $char) {
				$n = strpos($this->codeset, $char);
				if ($n == -1) {
					return 0;
				}
				$id += $n * pow($this->base, $index);
			}
			
			return $id;
		}
		
}