php自定义用preg解析一个字符串

Question

My methods parse strings and do stuff with the information contained in the string. a simple example would be

$string=
"
    user:name,password={$_POST['name']}, {$_POST['password']}(md5); 
    names:name=name;
";
$class->$method($string);

The above would do two insert statements. The first will insert in a table named user the users name and the password encypted in md5.
the second would insert a name in the names table. I'm having setting it up so that characters can be escaped. ie if the users name was p;ez. The string would have p\;ez.
My current method is as follows

    #get position of ;
    $offsetSemi=stripos($s, ";");
    #check if its escaped
    if ($s[$offsetSemi-1]!='\\')
    {
        //not escaped
    }

the problem with the above method is that it will only check the first instance of ;. the other solution i tried was exploding the string on ;. however this would not work because it exploded on all instances including ones that were escaped. the other thing i tried was an explode with the regular expression below

/[^\\\];/

the prolem with this is that it exploded on the charecter before ; on all the instances that were not escaped. is there a way i can explode a string on all instances of ; that are not preceded by a backslash?

Answer 1

Instead of exploding you can parse the string:

$arr = array();
$tmp = "";

for ($i = 0; $i < strlen($s); $i++) {
   switch ($s[$i]) {
      case "\\":
         if ($i < strlen($s) - 1) $tmp .= $s[$i++] . $s[$i++];
      break;
      case ";":
         $arr[] = $tmp;
         $tmp = "";
      break;
      default:
         $tmp .= $s[$i];
   }
}

if (strlen(trim($tmp)) > 0) { // last section
    $arr[] = $tmp;
}