Cool; interesting to see how it's done elsewhere. In go:-

http://code.google.com/p/go/source/browse/src/cmd/gc/go.y

  /*
   * Go language grammar.
   *
   * The Go semicolon rules are:
   *
   *  1. all statements and declarations are terminated by semicolons.
   *  2. semicolons can be omitted before a closing ) or }.
   *  3. semicolons are inserted by the lexer before a newline
   *      following a specific list of tokens.
   *
   * Rules #1 and #2 are accomplished by writing the lists as
   * semicolon-separated lists with an optional trailing semicolon.
   * Rule #3 is implemented in yylex.
   */

But obviously this is very language-specific and given the case discussed above likely not to work in quite the same way.