private PsiBuilder.Marker parseClass(PsiBuilder builder) {
    final PsiBuilder.Marker marker = builder.mark();
    builder.advanceLexer();

    if (builder.getTokenType() == RegExpTT.CARET) {
      builder.advanceLexer();
    }
    parseClassIntersection(builder);

    checkMatches(builder, RegExpTT.CLASS_END, RegExpBundle.message("parse.error.unclosed.character.class"));
    marker.done(RegExpElementTypes.CLASS);
    return marker;
  }
private PsiBuilder.Marker parseClass(PsiBuilder builder)