<?php
 
 /*
  * This file is part of the Symfony package.
  *
  * (c) Fabien Potencier <fabien@symfony.com>
  *
  * For the full copyright and license information, please view the LICENSE
  * file that was distributed with this source code.
  */
 
 namespace Symfony\Component\Translation\Util;
 
 /**
  * ArrayConverter generates tree like structure from a message catalogue.
  * e.g. this
  *   'foo.bar1' => 'test1',
  *   'foo.bar2' => 'test2'
  * converts to follows:
  *   foo:
  *     bar1: test1
  *     bar2: test2.
  *
  * @author Gennady Telegin <gtelegin@gmail.com>
  */
 class ArrayConverter
 {
     /**
      * Converts linear messages array to tree-like array.
      * For example this array('foo.bar' => 'value') will be converted to ['foo' => ['bar' => 'value']].
      *
      * @param array $messages Linear messages array
      *
      * @return array Tree-like messages array
      */
     public static function expandToTree(array $messages)
     {
         $tree = [];
 
         foreach ($messages as $id => $value) {
             $referenceToElement = &self::getElementByPath($tree, explode('.', $id));
 
             $referenceToElement = $value;
 
             unset($referenceToElement);
         }
 
         return $tree;
     }
 
     private static function &getElementByPath(array &$tree, array $parts)
     {
         $elem = &$tree;
         $parentOfElem = null;
 
         foreach ($parts as $i => $part) {
             if (isset($elem[$part]) && \is_string($elem[$part])) {
                 /* Process next case:
                  *    'foo': 'test1',
                  *    'foo.bar': 'test2'
                  *
                  * $tree['foo'] was string before we found array {bar: test2}.
                  *  Treat new element as string too, e.g. add $tree['foo.bar'] = 'test2';
                  */
                 $elem = &$elem[implode('.', \array_slice($parts, $i))];
                 break;
             }
             $parentOfElem = &$elem;
             $elem = &$elem[$part];
         }
 
         if ($elem && \is_array($elem) && $parentOfElem) {
             /* Process next case:
              *    'foo.bar': 'test1'
              *    'foo': 'test2'
              *
              * $tree['foo'] was array = {bar: 'test1'} before we found string constant `foo`.
              * Cancel treating $tree['foo'] as array and cancel back it expansion,
              *  e.g. make it $tree['foo.bar'] = 'test1' again.
              */
             self::cancelExpand($parentOfElem, $part, $elem);
         }
 
         return $elem;
     }
 
     private static function cancelExpand(array &$tree, $prefix, array $node)
     {
         $prefix .= '.';
 
         foreach ($node as $id => $value) {
             if (\is_string($value)) {
                 $tree[$prefix.$id] = $value;
             } else {
                 self::cancelExpand($tree, $prefix.$id, $value);
             }
         }
     }
 }