REGEXP_FILE
  RegExpPatternImpl: <[^ab]*>
    RegExpBranchImpl: <[^ab]*>
      RegExpClosureImpl: <[^ab]*>
        RegExpClassImpl: <[^ab]>
          PsiElement(CLASS_BEGIN)('[')
          PsiElement(CARET)('^')
          RegExpCharImpl: <a>
            PsiElement(CHARACTER)('a')
          RegExpCharImpl: <b>
            PsiElement(CHARACTER)('b')
          PsiElement(CLASS_END)(']')
        RegExpQuantifierImpl: <*>
          PsiElement(STAR)('*')