function diff_cleanupSemanticScore_(one, two) {
    if (!one || !two) {
      // Edges are the best.
      return 6;
    }

    // Each port of this function behaves slightly differently due to
    // subtle differences in each language's definition of things like
    // 'whitespace'.  Since this function's purpose is largely cosmetic,
    // the choice has been made to use each language's native features
    // rather than force total conformity.
    var char1 = one.charAt(one.length - 1);
    var char2 = two.charAt(0);
    var nonAlphaNumeric1 = char1.match(diff_match_patch.nonAlphaNumericRegex_);
    var nonAlphaNumeric2 = char2.match(diff_match_patch.nonAlphaNumericRegex_);
    var whitespace1 = nonAlphaNumeric1 &&
        char1.match(diff_match_patch.whitespaceRegex_);
    var whitespace2 = nonAlphaNumeric2 &&
        char2.match(diff_match_patch.whitespaceRegex_);
    var lineBreak1 = whitespace1 &&
        char1.match(diff_match_patch.linebreakRegex_);
    var lineBreak2 = whitespace2 &&
        char2.match(diff_match_patch.linebreakRegex_);
    var blankLine1 = lineBreak1 &&
        one.match(diff_match_patch.blanklineEndRegex_);
    var blankLine2 = lineBreak2 &&
        two.match(diff_match_patch.blanklineStartRegex_);

    if (blankLine1 || blankLine2) {
      // Five points for blank lines.
      return 5;
    } else if (lineBreak1 || lineBreak2) {
      // Four points for line breaks.
      return 4;
    } else if (nonAlphaNumeric1 && !whitespace1 && whitespace2) {
      // Three points for end of sentences.
      return 3;
    } else if (whitespace1 || whitespace2) {
      // Two points for whitespace.
      return 2;
    } else if (nonAlphaNumeric1 || nonAlphaNumeric2) {
      // One point for non-alphanumeric.
      return 1;
    }
    return 0;
  }
Given two strings, compute a score representing whether the internal
boundary falls on logical boundaries.
Scores range from 6 (best) to 0 (worst).
Closure, but does not reference any external variables.
@param {string} one First string.
@param {string} two Second string.
@return {number} The score.
@private