Question

Possible Duplicate:
Simulate php array language construct or parse with regexp?

suppose I have the string

$str = "array(1,3,4),array(array(4,5,6)),'this is a comma , inside a string',array('asdf' => 'lalal')";

and I try to explode this into an array by comma so that the desired end result is

$explode[0] =  array(1,3,4);
$explode[1] = array(array(4,5,6));
$explode[2] = 'this is a comma , inside a string';
$explode[3] = array('asdf' => 'lalal');

simply calling explode(',',$str) is not going to cut it since there are also commas within those chunks…

is there a way to explode this reliably even if there is commas inside the desired chunks

Answer 1

is there a way to explode this reliably even if there is commas inside the desired chunks?

PHP by default does not provide such a function. However you have a compact subset of PHP inside your string and PHP offers some tools here: A PHP tokenizer and a PHP parser.

Therefore it’s possible for your string specification to create a helper function that validates the input against allowed tokens and then parse it:

$str = "array(1,3,4),array(array(4,5,6)),'this is a comma , inside a string', array('asdf' => 'lalal')";

function explode_string($str)
{
    $result = NULL;
    
    // validate string
    $isValid = FALSE;
    $tokens = token_get_all(sprintf('<?php %s', $str));
    array_shift($tokens);
    $valid = array(305, 315, 358, 360, 371, '(', ')', ',');
    foreach($tokens as $token)
    {
        list($index) = (array) $token;
        if (!in_array($index, $valid))
        {
            $isValid = FALSE;
            break;
        }
    }
    if (!$isValid)
        throw new InvalidArgumentException('Invalid string.');
    
    // parse string
    $return = eval(sprintf('return array(%s);', $str));

    return $return;
}

echo $str, "\n";

$result = explode_string($str);

var_dump($result);

The tokens used are:

T_LNUMBER (305)
T_CONSTANT_ENCAPSED_STRING (315)
T_DOUBLE_ARROW (358)
T_ARRAY (360)
T_WHITESPACE (371)

The token index number can be given a token name by using token_name.

Which gives you (Demo):

Array
(
    [0] => Array
        (
            [0] => 1
            [1] => 3
            [2] => 4
        )

    [1] => Array
        (
            [0] => Array
                (
                    [0] => 4
                    [1] => 5
                    [2] => 6
                )

        )

    [2] => this is a comma , inside a string
    [3] => Array
        (
            [asdf] => lalal
        )

)