REGEXP_FILE
  RegExpPatternImpl: <a[-]?c>
    RegExpBranchImpl: <a[-]?c>
      RegExpCharImpl: <a>
        PsiElement(CHARACTER)('a')
      RegExpClosureImpl: <[-]?>
        RegExpClassImpl: <[-]>
          PsiElement(CLASS_BEGIN)('[')
          RegExpCharImpl: <->
            PsiElement(CHARACTER)('-')
          PsiElement(CLASS_END)(']')
        RegExpQuantifierImpl: <?>
          PsiElement(QUEST)('?')
      RegExpCharImpl: <c>
        PsiElement(CHARACTER)('c')