Gatling Gun

gatlinggun.php

<?php
  /**
   * Gatling gun takes an array of valid params and returns every 
   * combination of invalid data caused by blanking out individual params.
   *
   * Example:
   *
   * $validData = array('firstName' => 'Gatling', 'lastName' => 'Gun', 'age' => 12);
   * $ggData = gatlingGun($validData);
   *
   * $ggData = array(
   *     array('firstName' => '',        'lastName' => '',    'age' => ''),
   *     array('firstName' => '',        'lastName' => '',    'age' => 12),
   *     array('firstName' => '',        'lastName' => 'Gun', 'age' => ''),
   *     array('firstName' => '',        'lastName' => 'Gun', 'age' => 12),
   *     array('firstName' => 'Gatling', 'lastName' => '',    'age' => ''),
   *     array('firstName' => 'Gatling', 'lastName' => '',    'age' => 12),
   *     array('firstName' => 'Gatling', 'lastName' => 'Gun', 'age' => '')
   * );
   *
   *
   * @param array $validData
   * @return array
   *
   */
  function gatlingGun($validData) 
  {
      $original = $validData;
      $invalidCombinations = array();

      $max = count($original);
      $keys = array_keys($original);
      $combinations = pow(2, $max) - 1;

      for ($i = 0; $i < $combinations; $i++) {
          $tmp = array();
          $j = count($keys) - 1;
          foreach ($keys as $k => $key) {
              $tmp[$key] = (($i & pow(2,$j)) == 0) ? '' : $original[$key];
              $j--;
          }

          $invalidCombinations[] = $tmp;
      }
      return $invalidCombinations;
  }