Break x,y,z and x+y+z into an array. Numeric only.

gistfile1.php

/*
 * Break x,y,z and x+y+z into an array. Numeric only.
 *
 * @param $str
 *   The string to parse.
 *
 * @return $object
 *   An object containing
 *   - operator: Either 'and' or 'or'
 *   - value: An array of numeric values.
 */
function ctools_break_phrase($str) {
  $object = new stdClass();

  if (preg_match('/^([0-9]+[+ ])+[0-9]+$/', $str)) {
    // The '+' character in a query string may be parsed as ' '.
    $object->operator = 'or';
    $object->value = preg_split('/[+ ]/', $str);
  }
  else if (preg_match('/^([0-9]+,)*[0-9]+$/', $str)) {
    $object->operator = 'and';
    $object->value = explode(',', $str);
  }

  // Keep an 'error' value if invalid strings were given.
  if (!empty($str) && (empty($object->value) || !is_array($object->value))) {
    $object->value = array(-1);
    $object->invalid_input = TRUE;
    return $object;
  }

  if (empty($object->value)) {
    $object->value = array();
  }

  // Doubly ensure that all values are numeric only.
  foreach ($object->value as $id => $value) {
    $object->value[$id] = intval($value);
  }

  return $object;
}