flex-2.5.33/examples/manual/cat.lex

   1 /*
   2  * cat.lex: A demonstration of YY_NEW_FILE.
   3  */
   4
   5 %{
   6 #include <stdio.h>
   7
   8 char **names = NULL;
   9 int  current = 1;
  10 %}
  11
  12 %%
  13 <<EOF>> {
  14            current += 1;
  15            if(names[current] != NULL){
  16               yyin = fopen(names[current],"r");
  17               if(yyin == NULL){
  18                 fprintf(stderr,"cat: unable to open %s\n",
  19                         names[current]);
  20                 yyterminate();
  21               }
  22               YY_NEW_FILE;
  23            } else {
  24              yyterminate();
  25            }
  26         }
  27 %%
  28
  29 int main(int argc, char **argv)
  30 {
  31     if(argc < 2){
  32        fprintf(stderr,"Usage: cat files....\n");
  33        exit(1);
  34     }
  35     names = argv;
  36
  37     yyin = fopen(names[current],"r");
  38     if(yyin == NULL){
  39       fprintf(stderr,"cat: unable to open %s\n",
  40               names[current]);
  41       yyterminate();
  42     }
  43
  44     yylex();
  45 }