2.9BSD - /usr/src/cmd/lex/lib/yyless.c

   1: yyless(x)
   2: {
   3: extern char yytext[];
   4: register char *lastch, *ptr;
   5: extern int yyleng;
   6: extern int yyprevious;
   7: lastch = yytext+yyleng;
   8: if (x>=0 && x <= yyleng)
   9:         ptr = x + yytext;
  10: else
  11:         ptr = x;
  12: while (lastch > ptr)
  13:         yyunput(*--lastch);
  14: *lastch = 0;
  15: if (ptr >yytext)
  16:         yyprevious = *--lastch;
  17: yyleng = ptr-yytext;
  18: }

Defined functions