db_name can't have value "db_name"

[i-rinat]

There is a minor logical issue with the approach. Since strings "db_type", "db_name" and the like come before the line that returns IDENTIFIER, if the value of the identifier will be one of those, lexer will return not a IDENTIFIER, which will cause program to report an error.

Try this as a testcase, for example:

db_type :  mysql
db_name : db_name
db_table_prefix : test_
db_port: 1099

The issue I'm talking about is at the line: db_name : db_name.

[csukuangfj]

You can consider db_name, db_type, ..., as keywords and they cannot be used as identifier values.

In C++, you can use

int a = 0;

But you cannot use

int int = 0;