Drupal : Global class for long text elements

gistfile1.php

<?php

/**
 * Implements template_preprocess_field().
 */
function EXAMPLE_preprocess_field(&$vars) {
  /*
   * theme_hook_suggestion:
   *  $variables['theme_hook_suggestions'] = array(
        'field__' . $element['#field_type'],
        'field__' . $element['#field_name'],
        'field__' . $element['#bundle'],
        'field__' . $element['#field_name'] . '__' . $element['#bundle'],
  );
   * ex: field__field_faq_question
   * ex: field__field_faq_question__field_faq (here, bundle = field_collection field
   * ex: field__field_faq_answer
   */

  $element = $vars['element'];

  // Global class for long text elements
  $field_type_text = array(
    'text',
    'text_long',
    'text_with_summary',
    'paragraphs' // Not always
  );
  if (in_array($element['#field_type'], $field_type_text)) {
    $vars['classes_array'][] = 'text-field';
  }

}