Comment syntax?

[pmetzger]

I find myself wanting to comment my re2c grammar, but it isn't clear if there's any sort of text inside the re2c C comment block itself that won't be treated as though it is valid re2c code.

How can I do this cleanly? Is there some undocumented method?

[skvadrik]

Sure, both single-line comments // and multiliine comments /* ... */ should work.

[skvadrik]

Also, if you want to comment the whole /*!re2c ... */ block, the best way is just to put an extra space between /* and !re2c.

[pmetzger]

You can't put a /* ... / inside a / ... */ comment unfortunately, they don't nest.
But you're saying I should be able to put a // anywhere inside the comment block anywhere and that will not be a problem?

[pmetzger]

(And could that be documented?)

[skvadrik]

Well, inside of a re2c block you can have another multiline comment, but it will probably break your syntax highlighter. Single-line comments won't break syntax highlighter. Do you have an example of code that doesn't work?

As for documentation, I already added a reminder in #140.

[pmetzger]

Is the reason a multi-line comment will work that re2c preprocesses the c-like comments in the first place? Because C itself does not allow nested comments.

[skvadrik]

Yes. re2c parses C/C++ code, finds multiline comments of the form /*!re2c ... */ (and a couple of variations) and parses the code inside of these comments.

This is the exact place in the re2c source code that handles nested multiline comments: https://github.com/skvadrik/re2c/blob/devel/re2c/src/ast/lex.re#L207, and this one handles single-line comments https://github.com/skvadrik/re2c/blob/devel/re2c/src/ast/lex.re#L204.

[pmetzger]

Cool! Thank you so much!