%{
#define NEWLINE 1
#define KEY_BEGIN 2
#define ID 3
%}

%%
\n              { return NEWLINE; }
begin           { return KEY_BEGIN; }
[a-z][a-z0-9_]* { return ID; }
.		{ }
%%
main() {
  int tok;
  while ((tok = yylex()) != 0) {
    switch (tok) {
      case NEWLINE: printf("NEWLINE\n"); break;
      case KEY_BEGIN: printf("BEGIN\n"); break;
      case ID: printf("ID[%s]\n", yytext); break;
      default: printf("Unknown[%s]\n", yytext); break;
    } /* switch */
  } /* while */
} /* main */
int yywrap() { return 1; }