def stmt: Parser[Any] = assignstmt|blockstmt|ifstmt|"break" ~ ";"|"continue" ~ ";"|whilestmt|repeatstmt|forstmt|invokestmt| "return" ~ exp
            def assignstmt: Parser[Any] = ((ident ~ "[" ~ exp ~ "]")| ident ~ rep("." ~ ident))|ident ~ ":=" ~ exp ~ ";"
            def blockstmt: Parser[Any] = "{" ~ rep(constdecl|vardecl)~ rep(stmt) ~ "}"
            def ifstmt: Parser[Any] = "if" ~ exp ~ "then" ~ stmt ~ opt("else" ~ stmt)
            def whilestmt: Parser[Any] = "while" ~ exp ~ "do" ~ stmt
            def repeatstmt: Parser[Any] = "repeat" ~ rep1(stmt) ~ "until" ~ exp  ~ ";"
            def forstmt: Parser[Any] = "for" ~ ident ~ ":=" ~ exp ~ ("to"|"downto") ~ exp ~ "do" ~ stmt
            def invokestmt: Parser[Any] = ident ~ "." ~ ident ~ "(" ~ explist ~ ")" ~ ";"
            // declare
            def classdecl: Parser[Any] = "class" ~ ident ~ opt("extends" ~ ident) ~ "{" ~ rep(constdecl|abstractmethoddecl|vardecl|method) ~ "}"
            def vardecl: Parser[Any] = rep1sep(ident, ",") ~ ":" ~ (arraytypes|types) ~ ";"
            def constdecl: Parser[Any] = "final" ~ arraytypes|types ~ ident ~ "=" ~ exp ~ ";"
            def abstractmethoddecl : Parser[Any] = "abstract" ~ returntype ~ ident ~ "(" ~ parameterlist ~ ")" ~ ";"
            def method:Parser[Any] = methoddecl|constructordecl
            def methoddecl : Parser[Any] = returntype ~ ident ~ "(" ~ parameterlist ~ ")" ~ "{" ~ rep(constdecl| vardecl) ~ rep(stmt) ~ "}"
            def constructordecl : Parser[Any] = ident ~ "(" ~ parameterlist ~ ")" ~ "{"  ~ rep(constdecl|vardecl)~ rep(stmt) ~ "}"

            //exp
            def exp : Parser[Any] = term ~ opt("<"|">"|"<="|">=" ~ term)
            def term : Parser[Any] = term1 ~ opt("=="|"<>" ~ term1)
            def term1: Parser[Any] = term2 ~ rep("&&"|"||" ~ term2)
            def term2: Parser[Any] = term3 ~ rep("+"|"-" ~ term3)
            def term3: Parser[Any] = term4 ~ rep(("*"|"/"|"\\"|"%") ~ term4)
            def term4: Parser[Any] = term5 ~ rep("^" ~ term5)
            def term5: Parser[Any] = opt("!") ~ term6
            def term6: Parser[Any] = opt("-"|"+") ~ term7
            def term7: Parser[Any] = term8 ~ opt("[" ~ exp ~ "]")
            def term8: Parser[Any] = term9 ~ rep("." ~ ident ~ opt("(" ~ explist ~ ")"))
            def term9: Parser[Any] = ("new" ~ ident ~ "(" ~ explist ~ ")")|term10
            def term10: Parser[Any] = ident| lit| "(" ~ exp ~ ")" | "self"
            // list
            def explist : Parser[Any] = repsep(exp, ",")
            def identifierlist : Parser[Any] = rep1sep(ident,",")
            def parameter : Parser[Any] = ident ~ ":" ~ arraytypes|types
            def parameterlist : Parser[Any] = repsep( parameter, ";")

            // type
            def classtype: Parser[Any] = ident
            def primitivetype: Parser[Any] = "integer"|"float"|"bool"|"string"
            def types: Parser[Any] = classtype|primitivetype
            def arraytypes: Parser[Any] = types ~ "[" ~ lit ~ "]"
            def returntype: Parser[Any] = arraytypes|types|"void"
            // literal
            def lit : Parser[Any] = stringlit|boollit|floatlit|intlit
            def stringlit: Parser[Any] = elem("string", _.isInstanceOf[lexical.StringLit2])
            def boollit: Parser[Any] = elem("boolean", _.isInstanceOf[lexical.BooleanLit])
            def floatlit: Parser[Any] = elem("real", _.isInstanceOf[lexical.FloatLit])
            def intlit: Parser[Any] = elem("integer", _.isInstanceOf[lexical.IntLit])