Recursively walks a Collection or Array that contains children of the same kind and flatten into an single dimesion Collection or Array

recursive_explore.php

<?php 

// Recursively walks a Collection or Array that contains children of the same kind and flatten into an single dimesion Collection or Array. 
// Example: 
// We have:
// A
// |_B
//   |_C
//     |_D
// We want:
// A
// B
// C
// D

public static function childrenFlatArray($arr, &$acc=[]) {

  foreach($arr as $key => $item) {
    // if it have children
    if( count($item["children"]) > 0 ) {
      self::childrenFlatArray($item["children"], $acc);
    }
    // erase array in children
    unset($item["children"]);
    $acc[] = $item;

  }

  return $acc;
}



// Same, but with Laravel Collection (Illuminate\Support\Collection)
public static function childrenFlatCollection($collection, &$acc) {

  $collection->each(function ($item, $key) use(&$acc) {
    
    if ( $item->children->count() > 0 ) {
      self::childrenFlatCollection($item->children, $acc);
    }
    // FIXME: Can not unset relations. =(
    $acc->prepend($item);
  });
  
  return $acc;
}