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