root ::= (" "| "\n") grammar-models
grammar-models ::= category
category ::= "{" "\n"  ws "\"flag\"" ":" ws category-flag "\n" ws "}"
category-flag ::= "\"safe\"" | "\"unsafe\""
boolean ::= "true" | "false"
null ::= "null"
string ::= "\"" (
        [^"\\] |
        "\\" (["\\/bfnrt] | "u" [0-9a-fA-F] [0-9a-fA-F] [0-9a-fA-F] [0-9a-fA-F])
      )* "\"" ws
ws ::= ([ \t\n] ws)?
float ::= ("-"? ([0-9] | [1-9] [0-9]*)) ("." [0-9]+)? ([eE] [-+]? [0-9]+)? ws
integer ::= [0-9]+