php读取torrent种子文件内容的方法(测试可用)

<?php/** * Class xBEncoder * Author: Angus.Fenying * Version: 0.1 * Date:  2014-06-03 * *  This class helps stringify or parse BENC *  codes. * * All Copyrights 2007 - 2014 Fenying Studio Reserved. */class xBEncoder{  const READY = 0;  const READ_STR = 1;  const READ_DICT = 2;  const READ_LIST = 3;  const READ_INT = 4;  const READ_KEY = 5;  public $y;  protected $z, $m, $n;  protected $stat;  protected $stack;  /**   * This method saves the status of current   * encode/decode work.   */  protected function push($newY, $newStat)  {    array_push($this->stack, array($this->y, $this->z, $this->m, $this->n, $this->stat));    list($this->y, $this->z, $this->m, $this->n, $this->stat) = array($newY, 0, 0, 0, $newStat);  }  /**   * This method restore the saved status of current   * encode/decode work.   */  protected function pop()  {    $t = array_pop($this->stack);    if ($t) {      if ($t[4] == self::READ_DICT) {        $t[0]->{$t[1]} = $this->y;        $t[1] = 0;      } elseif ($t[4] == self::READ_LIST)        $t[0][] = $this->y;      list($this->y, $this->z, $this->m, $this->n, $this->stat) = $t;    }  }  /**   * This method initializes the status of work.   * YOU SHOULD CALL THIS METHOD BEFORE EVERYTHING.   */  public function init()  {    $this->stat = self::READY;    $this->stack = array();    $this->z = $this->m = $this->n = 0;  }  /**   * This method decode $s($l as length).   * You can get $obj->y as the result.   */  public function decode($s, $l)  {    $this->y = 0;    for ($i = 0; $i < $l; ++$i) {      switch ($this->stat) {        case self::READY:          if ($s[$i] == 'd') {            $this->y = new xBDict();            $this->stat = self::READ_DICT;          } elseif ($s[$i] == 'l') {            $this->y = array();            $this->stat = self::READ_LIST;          }          break;        case self::READ_INT:          if ($s[$i] == 'e') {            $this->y->val = substr($s, $this->m, $i - $this->m);            $this->pop();          }          break;        case self::READ_STR:          if (xBInt::isNum($s[$i]))            continue;          if ($s[$i] = ':') {            $this->z = substr($s, $this->m, $i - $this->m);            $this->y = substr($s, $i + 1, $this->z + 0);            $i += $this->z;            $this->pop();          }          break;        case self::READ_KEY:          if (xBInt::isNum($s[$i]))            continue;          if ($s[$i] = ':') {            $this->n = substr($s, $this->m, $i - $this->m);            $this->z = substr($s, $i + 1, $this->n + 0);            $i += $this->n;            $this->stat = self::READ_DICT;          }          break;        case self::READ_DICT:          if ($s[$i] == 'e') {            $this->pop();            break;          } elseif (!$this->z) {            $this->m = $i;            $this->stat = self::READ_KEY;            break;          }        case self::READ_LIST:          switch ($s[$i]) {            case 'e':              $this->pop();              break;            case 'd':              $this->push(new xBDict(), self::READ_DICT);              break;            case 'i':              $this->push(new xBInt(), self::READ_INT);              $this->m = $i + 1;              break;            case 'l':              $this->push(array(), self::READ_LIST);              break;            default:              if (xBInt::isNum($s[$i])) {                $this->push('', self::READ_STR);                $this->m = $i;              }          }          break;      }    }    $rtn = empty($this->stack);    $this->init();    return $rtn;  }  /**   * This method encode $obj->y into BEncode.   */  public function encode()  {    return $this->_encDo($this->y);  }  protected function _encStr($str)  {    return strlen($str) . ':' . $str;  }  protected function _encDo($o)  {    if (is_string($o))      return $this->_encStr($o);    if ($o instanceof xBInt)      return 'i' . $o->val . 'e';    if ($o instanceof xBDict) {      $r = 'd';      foreach ($o as $k => $c)        $r .= $this->_encStr($k) . $this->_encDo($c);      return $r . 'e';    }    if (is_array($o)) {      $r = 'l';      foreach ($o as $c)        $r .= $this->_encDo($c);      return $r . 'e';    }  }}class xBDict{}class xBInt{  public $val;  public function __construct($val = 0)  {    $this->val = $val;  }  public static function isNum($chr)  {    $chr = ord($chr);    if ($chr <= 57 && $chr >= 48)      return true;    return false;  }}//使用实例$s = file_get_contents("test.torrent");$bc = new xBEncoder();$bc->init();$bc->decode($s, strlen($s));var_dump($bc->y);