permute.php

<?php

function pc_next_permutation($p, $size)
{
	// slide down the array looking for where we're smaller than the next guy
	for ($i = $size - 1; $p[$i] >= $p[$i + 1]; --$i);
	
	// if this doesn't occur, we've finished our permutations
	// the array is reversed: (1, 2, 3, 4) => (4, 3, 2, 1)
	if ($i == -1)
	{
	    return false;
	}
	
	// slide down the array looking for a bigger number than what we found before
	for ($j = $size; $p[$j] <= $p[$i]; --$j);
	
	// swap them
	$tmp = $p[$i];
	$p[$i] = $p[$j];
	$p[$j] = $tmp;
	
	// now reverse the elements in between by swapping the ends
	for (++$i, $j = $size; $i < $j; ++$i, --$j)
	{
		$tmp = $p[$i];
		$p[$i] = $p[$j];
		$p[$j] = $tmp;
	}
	
	return $p;
}

$set = array();
foreach ($possible['parameters'] as $p => $info)
{
    $set[] = '(\s+' . $p . '=' . (empty($info['quoted']) ? '' : '"') . (isset($info['match']) ? $info['match'] : '(.+?)') . (empty($info['quoted']) ? '' : '"') . ')' . (empty($info['optional']) ? '' : '?');
}
$size = count($set) - 1;
$keys = range(0, $size);
$message_part = substr($message, $pos1 - 1);

do {
    $match_string = '~^';
    foreach ($keys as $key)
    {
        $match_string .= $set[$key];
    }
    $match_string .= '\]~i';
    $match = preg_match($match_string, $message_part), $matches) != 0;
} while (!$match && ($keys = pc_next_permutation($keys, $size)));