Make all available options from a demanded list

script.php

<?php

$sections = [
  'bread' => [
    'multichoice' => false,
    'options' => ['normal','wrap']
  ],
  'salad' => [
    'multichoice' => true,
    'options' => ['lettuce','tomatoes', 'corn']
  ],
  'sauce' => [
    'multichoice' => true,
    'options' => ['mostard','ketchup']
  ],
  'protein' => [
    'multichoice' => false,
    'options' => ['hamburger','tuna', 'smoked salmon']
  ],
];

/**
 * Evaluate if it is NOT a multi dimensional array
 *
 * @param array $list
 *
 * @return bool
 */
function isFlat(array $list)
{
  foreach($list as $element)
  {
    if(is_array($element))
    {
      return false;
    }
  }
  return true;
}

/**
 * Flat multi dimensional arrays into Bi dimensional (max)
 *
 * @param array $list
 *
 * @return array
 */
function flatToBiDimensionalArray(array $list)
{
  if(isFlat($list))
  {
    return $list;
  }

  $final = [];
  foreach($list as $element)
  {
    if(isFlat($element))
    {
      $final[] = $element;
    }
    else
    {
      $final = array_merge($final, flatToBiDimensionalArray($element));
    }
  }

  return $final;
}

/**
 * Make each element of the array into an array of itself
 *
 * @param array $list
 *
 * @return array
 */
function eachElementToArray(array $list)
{
  $final = [];
  foreach($list as $element)
  {
    $final[] = [$element];
  }

  return $final;
}

/**
 * Generate all combinations possible without order mattering
 *
 * @param array $list
 *
 * @return array
 */
function generateAllCombinations(array $list)
{
  if(count($list) === 1)
  {
    return $list;
  }

  $first = array_pop($list);
  $combinations = flatToBiDimensionalArray(generateAllCombinations($list));

  $final = [];
  $final[] = [$first];
  foreach ($combinations as $combination)
  {
    $final[] = is_array($combination)
      ? array_merge([$first], $combination)
      : [$first, $combination];
  }

  if(isFlat($combinations))
  {
    $final[] = $combinations;
  }
  else
  {
    $final = array_merge($final, $combinations);
  }


  return $final;
}


/**
 * Is similar to generateAllCombinations() but doesn't attempt to flat the arrays
 *
 * @param array $sections
 *
 * @return array
 */
function mixTogether(array $sections)
{
  if(count($sections) === 1)
  {
    $key = key($sections);
    $final = [];
    foreach(array_pop($sections) as $type)
    {
      $final[] = [$key => $type];
    }
    return $final;
  }

  $sandwiches = [];
  end($sections);
  $key = key($sections);
  $section = array_pop($sections);
  $combinations = mixTogether($sections);
  foreach($section as $type)
  {
    foreach($combinations as $combination)
    {
      $combination[$key] = $type;
      $sandwiches[] = $combination;
    }
  }

  return $sandwiches;
}

/*
 *
 * Script
 *
 */

$iterations = 100000;
$i = 0;
$start = microtime(true);
while($i++ < $iterations)
{
// generate all combinations for each section
  $sectionCombinations = [];
  foreach ($sections as $id => $section)
  {
    $sectionCombinations[$id] = $section['multichoice']
      ? generateAllCombinations($section['options'])
      : eachElementToArray($section['options']);
  }

  $sandwichList = mixTogether($sectionCombinations);
}
$end = microtime(true);

print_r($sandwichList);

$totalCombinations = count($sandwichList); 
echo "\n\nTotal time for {$iterations} iterations with {$totalCombinations} combinations: " . ($end - $start) . " seconds\n";

This was made for the stackoverflow question:

http://stackoverflow.com/questions/33044401/generate-all-possible-combinations