JavaCC：定制词法分析器错误消息

Question

According to the JavaCC documentation , if I want to customize the messages given by errors in the lexer:

To customize error reporting by the lexer, the lexer class must be subclassed and this method [ LexicalError() in TokenMgrError ] redefined in the subclass. To help with creating your error reporting scheme, the following variables are available:

However, I see nothing about how to get the generated code to use that subclass, unlike with the TOKEN_FACTORY option.

On the other hand, looking in the TokenMgrError source, some comments indicate that the source file should be directly edited, rather than subclassed. However, if I do that, the next time I change the .jj file and have Ant regenerate the parser and lexer code, I get this warning:

Warning: TokenMgrError.java: File is obsolete. Please rename or delete this file so that a new one can be generated for you.

So, how am I supposed to be doing this?

Answer 1

You can modify TokenMgrError if you want. There isn't a lot of downside to it.

If you subclass the token manager, then you can subclass TokenMgrError too. You just need to be sure to override all the routines that create TokenMgrError . To get the parser to use your subclass, you just create the parser like this

MyParser parser = new MyParser( new MySubclassTokenManagr(...) ) ;