return err
			}
		case 'e':
			if string(key) == "exp" {
				if dataType != jsonparser.Number {
					return errors.New("exp: Expected number")
				}
				c.ExpiresAt, err = jsonparser.ParseInt(value)
				return err
			}
		case 'i':
			if string(key) == "iat" {
				if dataType != jsonparser.Number {
					return errors.New("exp: Expected number")
				}
				c.IssuedAt, err = jsonparser.ParseInt(value)

}

// CastFunc represents CAST sql function
type CastFunc struct {
	Expr     *Expression `parser:" \"CAST\" \"(\" @@ "`
	CastType string      `parser:" \"AS\" @(\"BOOL\" | \"INT\" | \"INTEGER\" | \"STRING\" | \"FLOAT\" | \"DECIMAL\" | \"NUMERIC\" | \"TIMESTAMP\") \")\" "`
}

// SubstringFunc represents SUBSTRING sql function
type SubstringFunc struct {
	Expr *PrimaryTerm `parser:" \"SUBSTRING\" \"(\" @@ "`