REGEXP_FILE
  RegExpPatternImpl: <a[b-a]>
    RegExpBranchImpl: <a[b-a]>
      RegExpCharImpl: <a>
        PsiElement(CHARACTER)('a')
      RegExpClassImpl: <[b-a]>
        PsiElement(CLASS_BEGIN)('[')
        RegExpCharRangeImpl: <b-a>
          RegExpCharImpl: <b>
            PsiElement(CHARACTER)('b')
          PsiElement(MINUS)('-')
          RegExpCharImpl: <a>
            PsiElement(CHARACTER)('a')
        PsiElement(CLASS_END)(']')