Convert var_dump of array back to array variable

Question

I have never really thought about this until today, but after searching the web I didn't really find anything. Maybe I wasn't wording it right in the search.

Given an array (of multiple dimensions or not):

$data = array('this' => array('is' => 'the'), 'challenge' => array('for' => array('you')));

When var_dumped:

array(2) { ["this"]=> array(1) { ["is"]=> string(3) "the" } ["challenge"]=> array(1) { ["for"]=> array(1) { [0]=> string(3) "you" } } }

The challenge is this: What is the best optimized method for recompiling the array to a useable array for PHP? Like an undump_var() function. Whether the data is all on one line as output in a browser or whether it contains the line breaks as output to terminal.

Is it just a matter of regex? Or is there some other way? I am looking for creativity.

UPDATE: Note. I am familiar with serialize and unserialize folks. I am not looking for alternative solutions. This is a code challenge to see if it can be done in an optimized and creative way. So serialize and var_export are not solutions here. Nor are they the best answers.

Answer 1

If you want to encode/decode an array like this, you should either use var_export(), which generates output in PHP's array for, for instance:

array(
  1 => 'foo',
  2 => 'bar'
)

could be the result of it. You would have to use eval() to get the array back, though, and that is a potentially dangerous way (especially since eval() really executes PHP code, so a simple code injection could make hackers able to gain control over your PHP script).

Some even better solutions are serialize(), which creates a serialized version of any array or object; and json_encode(), which encodes any array or object with the JSON format (which is more preferred for data exchange between different languages).

Answer 2

var_export or serialize is what you're looking for. var_export will render a PHP parsable array syntax, and serialize will render a non-human readable but reversible "array to string" conversion...

Edit Alright, for the challenge:

Basically, I convert the output into a serialized string (and then unserialize it). I don't claim this to be perfect, but it appears to work on some pretty complex structures that I've tried...

function unvar_dump($str) {
    if (strpos($str, "\n") === false) {
        //Add new lines:
        $regex = array(
            '#(\\[.*?\\]=>)#',
            '#(string\\(|int\\(|float\\(|array\\(|NULL|object\\(|})#',
        );
        $str = preg_replace($regex, "\n\\1", $str);
        $str = trim($str);
    }
    $regex = array(
        '#^\\040*NULL\\040*$#m',
        '#^\\s*array\\((.*?)\\)\\s*{\\s*$#m',
        '#^\\s*string\\((.*?)\\)\\s*(.*?)$#m',
        '#^\\s*int\\((.*?)\\)\\s*$#m',
        '#^\\s*bool\\(true\\)\\s*$#m',
        '#^\\s*bool\\(false\\)\\s*$#m',
        '#^\\s*float\\((.*?)\\)\\s*$#m',
        '#^\\s*\[(\\d+)\\]\\s*=>\\s*$#m',
        '#\\s*?\\r?\\n\\s*#m',
    );
    $replace = array(
        'N',
        'a:\\1:{',
        's:\\1:\\2',
        'i:\\1',
        'b:1',
        'b:0',
        'd:\\1',
        'i:\\1',
        ';'
    );
    $serialized = preg_replace($regex, $replace, $str);
    $func = create_function(
        '$match', 
        'return "s:".strlen($match[1]).":\\"".$match[1]."\\"";'
    );
    $serialized = preg_replace_callback(
        '#\\s*\\["(.*?)"\\]\\s*=>#', 
        $func,
        $serialized
    );
    $func = create_function(
        '$match', 
        'return "O:".strlen($match[1]).":\\"".$match[1]."\\":".$match[2].":{";'
    );
    $serialized = preg_replace_callback(
        '#object\\((.*?)\\).*?\\((\\d+)\\)\\s*{\\s*;#', 
        $func, 
        $serialized
    );
    $serialized = preg_replace(
        array('#};#', '#{;#'), 
        array('}', '{'), 
        $serialized
    );

    return unserialize($serialized);
}

I tested it on a complex structure such as:

array(4) {
  ["foo"]=>
  string(8) "Foo"bar""
  [0]=>
  int(4)
  [5]=>
  float(43.2)
  ["af"]=>
  array(3) {
    [0]=>
    string(3) "123"
    [1]=>
    object(stdClass)#2 (2) {
      ["bar"]=>
      string(4) "bart"
      ["foo"]=>
      array(1) {
        [0]=>
        string(2) "re"
      }
    }
    [2]=>
    NULL
  }
}

Answer 3

I think you are looking for the serialize function:

serialize — Generates a storable representation of a value

It allows you to save the contents of array in readable format and later you can read the array back with unserialize function.

Using these functions, you can store/retrieve the arrays even in text/flat files as well as database.

Answer 4

Updated to NOT USE create_function, as it is DEPRECATED as of PHP 7.2.0. Instead it is replaced to use anonymous functions:

    function unvar_dump($str) {
        if (strpos($str, "\n") === false) {
            //Add new lines:
            $regex = array(
                '#(\[.*?\]=>)#',
                '#(string\(|int\(|float\(|array\(|NULL|object\(|})#',
            );
            $str = preg_replace($regex, "\n\1", $str);
            $str = trim($str);
        }
        $regex = array(
            '#^\040*NULL\040*$#m',
            '#^\s*array\((.*?)\)\s*{\s*$#m',
            '#^\s*string\((.*?)\)\s*(.*?)$#m',
            '#^\s*int\((.*?)\)\s*$#m',
            '#^\s*bool\(true\)\s*$#m',
            '#^\s*bool\(false\)\s*$#m',
            '#^\s*float\((.*?)\)\s*$#m',
            '#^\s*\[(\d+)\]\s*=>\s*$#m',
            '#\s*?\r?\n\s*#m',
        );
        $replace = array(
            'N',
            'a:\1:{',
            's:\1:\2',
            'i:\1',
            'b:1',
            'b:0',
            'd:\1',
            'i:\1',
            ';'
        );
        $serialized = preg_replace($regex, $replace, $str);
        $func = function($match) {
            return 's:'.strlen($match[1]).':"'.$match[1].'"';
        };
        $serialized = preg_replace_callback(
            '#\s*\["(.*?)"\]\s*=>#', 
            $func,
            $serialized
        );
        $func = function($match) {
            return 'O:'.strlen($match[1]).':"'.$match[1].'":'.$match[2].':{';
        };
        $serialized = preg_replace_callback(
            '#object\((.*?)\).*?\((\d+)\)\s*{\s*;#', 
            $func, 
            $serialized
        );
        $serialized = preg_replace(
            array('#};#', '#{;#'), 
            array('}', '{'), 
            $serialized
        );

        return unserialize($serialized);
    }

    $test = 'array(10) {
      ["status"]=>
      string(1) "1"
      ["transactionID"]=>
      string(14) "1532xxx"
      ["orderID"]=>
      string(10) "1532xxx"
      ["value"]=>
      string(8) "0.73xxx"
      ["address"]=>
      string(1) "-"
      ["confirmations"]=>
      string(3) "999"
      ["transaction_hash"]=>
      string(64) "internxxx"
      ["notes"]=>
      string(0) ""
      ["txCost"]=>
      string(1) "0"
      ["txTimestamp"]=>
      string(10) "1532078165"
    }';
    var_export(unvar_dump($test));

Answer 5

Use regexp to change array(.) { (.*) } to array($1) and eval the code, this is not so easy as written because You have to deal with matching brackets etc., just a clue on how to find solution ;)

• this will be helpful if You cant change var_dump to var_export, or serialize

Answer 6

There's no other way than manual parsing depending on the type. I didn't add support for objects, but it's very similar to the arrays one; you just need to do some reflection magic to populate not only public properties and to not trigger the constructor.

EDIT: Added support for objects... Reflection magic...

function unserializeDump($str, &$i = 0) {
    $strtok = substr($str, $i);
    switch ($type = strtok($strtok, "(")) { // get type, before first parenthesis
         case "bool":
             return strtok(")") === "true"?(bool) $i += 10:!$i += 11;
         case "int":
             $int = (int)substr($str, $i + 4);
             $i += strlen($int) + 5;
             return $int;
         case "string":
             $i += 11 + ($len = (int)substr($str, $i + 7)) + strlen($len);
             return substr($str, $i - $len - 1, $len);
         case "float":
             return (float)($float = strtok(")")) + !$i += strlen($float) + 7;
         case "NULL":
             return NULL;
         case "array":
             $array = array();
             $len = (int)substr($str, $i + 6);
             $i = strpos($str, "\n", $i) - 1;
             for ($entries = 0; $entries < $len; $entries++) {
                 $i = strpos($str, "\n", $i);
                 $indent = -1 - (int)$i + $i = strpos($str, "[", $i);
                 // get key int/string
                 if ($str[$i + 1] == '"') {
                     // use longest possible sequence to avoid key and dump structure collisions
                     $key = substr($str, $i + 2, - 2 - $i + $i = strpos($str, "\"]=>\n  ", $i));
                 } else {
                     $key = (int)substr($str, $i + 1);
                     $i += strlen($key);
                 }
                 $i += $indent + 5; // jump line
                 $array[$key] = unserializeDump($str, $i);
             }
             $i = strpos($str, "}", $i) + 1;
             return $array;
         case "object":
             $reflection = new ReflectionClass(strtok(")"));
             $object = $reflection->newInstanceWithoutConstructor();
             $len = !strtok("(") + strtok(")");
             $i = strpos($str, "\n", $i) - 1;
             for ($entries = 0; $entries < $len; $entries++) {
                 $i = strpos($str, "\n", $i);
                 $indent = -1 - (int)$i + $i = strpos($str, "[", $i);
                 // use longest possible sequence to avoid key and dump structure collisions
                 $key = substr($str, $i + 2, - 2 - $i + $i = min(strpos($str, "\"]=>\n  ", $i)?:INF, strpos($str, "\":protected]=>\n  ", $i)?:INF, $priv = strpos($str, "\":\"", $i)?:INF));
                 if ($priv == $i) {
                     $ref = new ReflectionClass(substr($str, $i + 3, - 3 - $i + $i = strpos($str, "\":private]=>\n  ", $i)));
                     $i += $indent + 13; // jump line
                 } else {
                     $i += $indent + ($str[$i+1] == ":"?15:5); // jump line
                     $ref = $reflection;
                 }
                 $prop = $ref->getProperty($key);
                 $prop->setAccessible(true);
                 $prop->setValue($object, unserializeDump($str, $i));
             }
             $i = strpos($str, "}", $i) + 1;
             return $object;

    }
    throw new Exception("Type not recognized...: $type");
}

(Here are a lot of "magic" numbers when incrementing string position counter $i, mostly just string lengths of the keywords and some parenthesis etc.)