Drupal hierarchical taxonomy terms find/create from an array

custom_module.module.php

<?php

/**
 * Helper function to retrieve tid of nested term, by tracing or creating terms.
 *
 * @param array $term_names
 *   The term names used to create the hierarchy from the parent to the child.
 *
 * @param string $vocabulary
 *   The machine name of the vocabulary the terms should be found/built within.
 *
 * @return
 *   The tid of the last term in the array.
 */
function taxonomy_find_create_nested_terms($term_names, $vocabulary) {
  $terms_string = implode('|', $term_names);
  $vocab_and_terms = hash('md5', $vocabulary . "_" . $terms_string);
  if ($cache = cache_get('taxonomy_find_create_' . $vocab_and_terms)) {
    $current_tid = $cache->data;
    return $current_tid;
  }
  else {
    $vocabularies = taxonomy_vocabulary_get_names();
    $vid = $vocabularies[$vocabulary]->vid;
    $current_tid = '0';
    $create_term = FALSE; // We start with the assumption we will find terms
    foreach ($term_names as $term_name) {
      // If $create_term == True, we want to skip searching the DB
      if (!$create_term) {
        $record = taxonomy_find_term_by_name_and_parent($current_tid, $term_name, $vid);
        if ($record) { // Term exists
          $current_tid = $record['tid'];
        }
        else {
          $create_term = TRUE;  // Terms will need created from here on out
        }
      }
      // This needs to be a separate conditional to catch $create_term when flipped
      if ($create_term) {
        // Term needs to be created
        $term = new stdClass();
        $term->name = $term_name;
        $term->vid = $vid;
        $term->parent = $current_tid;
        taxonomy_term_save($term);
        $current_tid = $term->tid;
      }
    }
    cache_set('taxonomy_find_create_' . $vocab_and_terms, $current_tid);
    return $current_tid;
  }
}

/**
 * Helper function to find a term by name in vid when it has a specific parent
 *
 * @param string $parent_tid
 *   The parent tid by which to filter terms
 *
 * @param string $term_name
 *   The term name for which to search
 *
 * @param string $vid
 *   The vocabulary id for which to filter terms
 *
 * @return
 *   The first record returned by the query.
 */
function taxonomy_find_term_by_name_and_parent($parent_tid, $term_name, $vid) {
  $query = db_select('taxonomy_term_data', 'd');
  $query->join('taxonomy_term_hierarchy', 'h', 'h.tid = d.tid');
  $result = $query
    ->fields('d', array('tid', 'name', 'weight'))
    ->fields('h', array('parent'))
    ->orderBy('weight', 'ASC')
    ->condition('d.vid', $vid)
    ->condition('h.parent', $parent_tid)
    ->condition('d.name', $term_name)
    ->execute();
  $record = $result->fetchAssoc();
  return $record;
}