Interface for direction estimators.

abstract class DirectionEstimator {

 /**
  * Estimates the direction of a plain-text string.
  * 
  * @param str The string to check.
  * @return {@code str}'s estimated direction.
  */
 Direction estimateDirection(String str);
 
 /**
  * Estimates the direction of a string.
  *
  * @param str The string to check.
  * @param isHtml Whether {@code str} is HTML / HTML-escaped. {@code false}
  *        means that {@code str} is plain-text.
  * @return {@code str}'s estimated direction.
  */
 Direction estimateStringDirection(String str, [bool isHtml = false]) {
   return estimateDirection(BidiUtils.get().stripHtmlIfNeeded(str, isHtml));
 }

 /**
  * Estimates the direction of a SafeHtml.
  *
  * @param html The string to check.
  * @return {@code html}'s estimated direction.
  */
 Direction estimateSafetmlDirection(SafeHtml html) {
   return estimateDirection(BidiUtils.get().stripHtmlIfNeeded(html.asString(), true));
 }
}