ch2-09.l

%{
int comments, code, whiteSpace;
%}

%s COMMENT

%%
^[ \t]*"/*"  { BEGIN COMMENT; /* enter comment eating state */ }
^[ \t]*"/*".*"*/"[ \t]*\n {
     comments++; /* self-contained comment */
     }

<COMMENT>"*/"[ \t]*\n  { BEGIN 0;  comments++;}
<COMMENT>"*/"    { BEGIN 0; }
<COMMENT>\n  { comments++; }
<COMMENT>.\n  { comments++; }

^[ \t]*\n  { whiteSpace++; }

.+"/*".*"*/".*\n  { code++; }
.*"/*".*"*/".+\n  { code++; }
.+"/*".*\n    { code++; BEGIN COMMENT; }
.\n      { code++; }

.      ; /* ignore everything else */
%%
int main()
{
  yylex();
  printf("code: %d, comments %d, white space %d\n",
    code, comments, whiteSpace);
  return 0;
}

int yywrap()
{
  return 1;
}