php 解码 javascript 的escape函数加密的字符串

//php解码javascript escape过的内容
function js_unescape($str)
{
$ret = '';
$len = strlen($str);
for ($i = 0; $i < $len; $i++)
{
if ($str[$i] == '%' && $str[$i+1] == 'u')
{
$val = hexdec(substr($str, $i+2, 4));
if ($val < 0x7f) $ret .= chr($val);
else if($val < 0x800) $ret .= chr(0xc0 |($val>>6)).chr(0x80 |($val&0x3f));
else $ret .= chr(0xe0 |($val>>12)).chr(0x80 |(($val>>6)&0x3f)).chr(0x80 |($val&0x3f));
$i += 5;
}
else if ($str[$i] == '%')
{
$ret .= urldecode(substr($str, $i, 3));
$i += 2;
}
else $ret .= $str[$i];
}
return $ret;
}

//两个函数都可以用
function phpUnescape($escstr)
{
preg_match_all("/%u[0-9A-Za-z]{4}|%.{2}|[0-9a-zA-Z.+-_]+/", $escstr, $matches);
$ar = &$matches[0];
$c = "";
foreach($ar as $val)
{
if (substr($val, 0, 1) != "%")
{
$c .= $val;
} elseif (substr($val, 1, 1) != "u")
{
$x = hexdec(substr($val, 1, 2));
$c .= chr($x);
}
else
{
$val = intval(substr($val, 2), 16);
if ($val < 0x7F) // 0000-007F
{
$c .= chr($val);
} elseif ($val < 0x800) // 0080-0800
{
$c .= chr(0xC0 | ($val / 64));
$c .= chr(0x80 | ($val % 64));
}
else // 0800-FFFF
{
$c .= chr(0xE0 | (($val / 64) / 64));
$c .= chr(0x80 | (($val / 64) % 64));
$c .= chr(0x80 | ($val % 64));
}
}
}
return $c;
}