Generate Combinations

Generate Combinations

<?php

function array_outer($f, array $array1) {
    $res = array();
    $arrays = $array1;
    foreach ($arrays as $a) {
        if (empty($a))
            return $res;
    }

    $num_arrays = count($arrays);
    $pos = array_fill(0, $num_arrays, 0);
    while (true) {
        $cur = array();
        for ($i = 0; $i < $num_arrays; $i++) {
            $cur[] = $arrays[$i][$pos[$i]];
        }
        $res[] = call_user_func_array($f, $cur);
        for ($i = $num_arrays-1; $i >= 0; $i--) {
            if ($pos[$i] < count($arrays[$i]) - 1) {
                $pos[$i]++;
                break;
            } else {
                if ($i == 0)
                    break 2;
                $pos[$i] = 0;
            }
        }
    }
    return $res;
}

$f = function () { return func_get_args(); };
$res = array_outer($f, array( array("small", "medium", "big"),
    array("blue", "red", "green", "pink"),
    array("sunny", "cloudy", "snowy"),
    array("sweet", "acid", "bitter", "edible")));
echo '<pre>'; var_dump($res); echo '</pre>';
?>