system/core/utf8/substr.php

   1 <?php defined('SYSPATH') OR die('No direct access allowed.');
   2 /**
   3  * utf8::substr
   4  *
   5  * @package    Core
   6  * @author     Kohana Team
   7  * @copyright  (c) 2007 Kohana Team
   8  * @copyright  (c) 2005 Harry Fuecks
   9  * @license    http://www.gnu.org/licenses/old-licenses/lgpl-2.1.txt
  10  */
  11 function _substr($str, $offset, $length = NULL)
  12 {
  13         if (SERVER_UTF8)
  14                 return ($length === NULL) ? mb_substr($str, $offset) : mb_substr($str, $offset, $length);
  15
  16         if (utf8::is_ascii($str))
  17                 return ($length === NULL) ? substr($str, $offset) : substr($str, $offset, $length);
  18
  19         // Normalize params
  20         $str    = (string) $str;
  21         $strlen = utf8::strlen($str);
  22         $offset = (int) ($offset < 0) ? max(0, $strlen + $offset) : $offset; // Normalize to positive offset
  23         $length = ($length === NULL) ? NULL : (int) $length;
  24
  25         // Impossible
  26         if ($length === 0 OR $offset >= $strlen OR ($length < 0 AND $length <= $offset - $strlen))
  27                 return '';
  28
  29         // Whole string
  30         if ($offset == 0 AND ($length === NULL OR $length >= $strlen))
  31                 return $str;
  32
  33         // Build regex
  34         $regex = '^';
  35
  36         // Create an offset expression
  37         if ($offset > 0)
  38         {
  39                 // PCRE repeating quantifiers must be less than 65536, so repeat when necessary
  40                 $x = (int) ($offset / 65535);
  41                 $y = (int) ($offset % 65535);
  42                 $regex .= ($x == 0) ? '' : '(?:.{65535}){'.$x.'}';
  43                 $regex .= ($y == 0) ? '' : '.{'.$y.'}';
  44         }
  45
  46         // Create a length expression
  47         if ($length === NULL)
  48         {
  49                 $regex .= '(.*)'; // No length set, grab it all
  50         }
  51         // Find length from the left (positive length)
  52         elseif ($length > 0)
  53         {
  54                 // Reduce length so that it can't go beyond the end of the string
  55                 $length = min($strlen - $offset, $length);
  56
  57                 $x = (int) ($length / 65535);
  58                 $y = (int) ($length % 65535);
  59                 $regex .= '(';
  60                 $regex .= ($x == 0) ? '' : '(?:.{65535}){'.$x.'}';
  61                 $regex .= '.{'.$y.'})';
  62         }
  63         // Find length from the right (negative length)
  64         else
  65         {
  66                 $x = (int) (-$length / 65535);
  67                 $y = (int) (-$length % 65535);
  68                 $regex .= '(.*)';
  69                 $regex .= ($x == 0) ? '' : '(?:.{65535}){'.$x.'}';
  70                 $regex .= '.{'.$y.'}';
  71         }
  72
  73         preg_match('/'.$regex.'/us', $str, $matches);
  74         return $matches[1];
  75 }