<?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);
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