authcache_enum.comb.inc in Authenticated User Page Caching (Authcache) 7.2

Private helper functions for the Authcache Enum module.

File

modules/authcache_enum/authcache_enum.comb.inc

<?php

/**
 * @file
 * Private helper functions for the Authcache Enum module.
 */

/**
 * Given a set of elements, return all possible subsets with a size of k.
 *
 * If the input looks like this:
 *   $set = array('a', 'b', 'c', 'd')
 *   $k = 2
 *
 * The result will be:
 *   $result = array(
 *     array('a', 'b'),
 *     array('a', 'c'),
 *     array('a', 'd'),
 *     array('b', 'c'),
 *     array('b', 'd'),
 *     array('c', 'd'),
 *   );
 */
function _authcache_enum_comb_k(array $set, $k) {
  if ($k >= count($set)) {
    return array(
      $set,
    );
  }
  elseif ($k <= 1) {
    return array_chunk($set, 1);
  }
  $result = array();
  while ($k <= count($set)) {
    $head = array_shift($set);
    $tails = _authcache_enum_comb_k($set, $k - 1);
    foreach ($tails as $tail) {
      array_unshift($tail, $head);
      array_push($result, $tail);
    }
  }
  return $result;
}

/**
 * Given a set of elements, return all possible subsets.
 */
function _authcache_enum_comb(array $set) {
  $result = array();
  for ($k = 1; $k <= count($set); $k++) {
    $result = array_merge($result, _authcache_enum_comb_k($set, $k));
  }
  return $result;
}

/**
 * Generate a cartesian product of the given associative array of arrays.
 *
 * If the input looks like this:
 *   $sets = array(
 *     'x' => array(1, 2, 3),
 *     'y' => array('a', 'b'),
 *   );
 *
 * The result consists of an array with 6 elements:
 *   $result = array(
 *     array('x' => 1, 'y' => 'a'),
 *     array('x' => 2, 'y' => 'a'),
 *     array('x' => 3, 'y' => 'a'),
 *     array('x' => 1, 'y' => 'b'),
 *     array('x' => 2, 'y' => 'b'),
 *     array('x' => 3, 'y' => 'b'),
 *   );
 */
function _authcache_enum_cartesian(array $sets) {
  $n = 1;
  $div = array();
  $mod = array();
  foreach ($sets as $set_id => $elements) {
    $c = count($elements);
    $div[$set_id] = $n;
    $mod[$set_id] = $c;
    $n *= $c;
  }
  $result = array();
  for ($i = 0; $i < $n; $i++) {
    foreach ($sets as $set_id => $elements) {
      $j = (int) ($i / $div[$set_id]) % $mod[$set_id];
      $result[$i][$set_id] = $elements[$j];
    }
  }
  return $result;
}

Functions

Name	Description
_authcache_enum_cartesian	Generate a cartesian product of the given associative array of arrays.
_authcache_enum_comb	Given a set of elements, return all possible subsets.
_authcache_enum_comb_k	Given a set of elements, return all possible subsets with a size of k.