This module defines the lex action to lex nested comments. As is well-known this cannot be done by regular expressions (which, incidently, is probably the reason why C-comments don't nest).
When scanning nested comments we simply keep track of the nesting level, counting up for open comments and down for close comments.
Manually lexing a block comment. Assumes an open comment has been lexed.
In the end the comment is discarded and
lexToken is called to lex a real